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Hot air rises. Without air sealing your attic you are allowing warm air to escape from your home carrying with it your hard earned winter heating money. Most people just add insulation to their attic - this will not stop the escaping warm air. The EPA estimates that the typical American home has enough leaks, holes and gaps to be equal to an open window every day of the year. That is significant. We need to seal the air in our conditioned living space from the unconditioned attic space. Every attic needs proper ventilation. We are not stopping the proper air exchange in the attic - we are only stopping the exchange between the house and the attic.

In the past year I’ve been on an energy hog hunt in my house and landed on air sealing my attic before adding blown insulation. I was a bit shocked at the $1,500-$2,500 contractor estimates for attic sealing. I’m all about DIY when it saves me time or money. My cost was under $150 and it took me less than a day. Initially the EPA DIY document seemed overwhelming but once I got started it was straight forward. If you can operate an aerosol can and a utility knife seal your attic. You would not try to carry water in a bucket with a hole in it - so why do we allow our heated air to escape through the many holes in our ceiling. Lets get to work. Save some money, save energy and stay warmer with less effort this winter!

Every attic is different – but I consider mine very average. This is my story and I hope it helps you!

Step 1: Tools and Equipment:

Mask – If you have loose, blown in insulation I highly recommend the 3m changeable filter mask.

Long Pants
Long Shirt
Gloves
Glasses
Spray foam – I used 8 Great Stuff and 1 Daptex because I had it.

Possibly:

Caulk Gun
Fire Caulk
Utility Knife
Scrap metal (flashing, drip edge, recycled scrap)
Foam Insulation Board or Recessed lighting Covers
Self stick weather stripping
2 Draw Hasps (for attic hatch)
A few pieces of scrap wood to sit/lay/stand on.

Step 2: Find the Leaks

I live in a standard brick ranch house that has a gabled roof and about 1,000 square feet of attic floor space. It is big enough to sit, but not tall enough to stand. It has old very low R value blown in fiberglass insulation. (About R-12 according to my measurements). Your house might have a different kind of insulation but that is ok – these theories will work for you too.

Hot air rises and carries with it dust particles that find their way into your attic. Your insulation acts as a filter and traps this dirt. You will be able to spot leaks by finding dirty insulation. This will be on insulation that sits on the attic floor. I was skeptical at first – until I found an unusual amount of dirty insulation all over my attic. Places to look: the tops of walls, drilled electrical wire holes, electrical outlet boxes for lights, pipes, recessed lighting, bathroom vent fan, chimney flashing, dropped soffits over lighting, cabinets, and slanted stairway access.

I removed my attic floor - I suggest you do the same if you think it might be covering leaks or additionally in my case hiding poor insulation coverage.

*Danger – only step on the roof rafters/trusses or sturdy wood placed on
top of the rafters. Otherwise you will put your foot through the drywall ceiling.*

Step 3: Wall Top Plates

Look for the interior wall top plates. Start in one corner and work your way out. Find the dirty insulation and follow it. Push it out of the way. Follow the gaps with a good bead of spray foam.

Step 4: ​ Find Electrical Wires and Boxes

Find the lighting electrical box for each room and cover it with a dose of spray foam. Find Electrical wires that are penetrating the ceiling. Stick the spray foam nozzle in the hole with it and give it a quick squirt. You are not trying to shove foam down the wall – but rather make an air tight cap on top.

Step 5: Recessed Lighting

Recessed lighting can be tricky. They come in two types – IC (insulation contact) and Non-IC (non insulation contact) It is a fire hazard to have insulation on non-IC fixtures. Unfortunately I had halogen non-IC lights. Basically I had 4 large holes in my living room that not only did not have any insulation on them and were not air tight to the ceiling. If you have a situation like me you can build or buy recessed lighting boxes. I built mine out of R-10 foam board. You need to leave at least 3 inches on all sides of the light. So if you have a 4 inch wide by 8 inch tall light you would 10x10x11 box. Notch a hole for your wire and spray foam around the bottom and any gaps in the box.

If you are creative – you can also use spray foam to “glue” your boxes together.

Off the shelf products are available but would have cost me more…however it would have significantly reduced my time in the attic.

This was also a good opportunity to swap my bulbs for dimmable LED’s I picked up off eBay for about $3 each.


Unfortunately mine are currently covered in new insulation. Apparently I neglected to take a photo! Companies like CanCoverIt and Tenmat sell off the shelf boxes.

Step 6: Pipes

I was unable to get a photo of me air sealing around my bathroom vent pipes. It would have looked like a terrible selfie – I had enough space so shimmy over there and hit it with the foam. Pipes will be easy to spot. Be careful some home builders have been known to just shove batted insulation down in the hole around the pipes. If this is your case – grab your utility knife and some foam board or drywall. You will need to fill the hole with something solid and then foam the gaps.

Step 7: Bathroom Vent Fan

The bathroom vent fan is an anomaly. Many people don’t pay much attention to them. Most are installed incorrectly, don’t work properly, leak air and let hot air into your house.

Here are some pointers.

They must be vented to the outside – and not just dump into the attic. This causes moisture issues when they run. It also allows the hot air in the attic to be pushed into the bathroom through the vent tube when not in use. Since my house is brick with no access to the soffits I vented mine to the gable vent. Typically they are vented through the exterior wall or the soffit.

Vent pipes need to be insulated. My bathroom vent fan had a flimsy short plastic dryer like vent hose attached to it. It had no insulating value. So even if it was vented properly (which mine was not) summer heat would penetrate into the bathroom through the vent tube. My suggestion is to buy some insulated duct work from a HVAC supply house. In theory you need as much R value as your attic floor. I picked up some R10 and I plan to wrap it in additional insulation at a later date. This same principal should be applied to your AC duct work if you AC unit Is in your hot attic.

Like recessed lighting bathroom vent fans need a sealed box. Measure and build one out of foam. Leave room to attach your vent. Hit the gaps with the foam.

Step 8: Attic Doors

Access hatches and pull down ladders are notorious for leaks. I have an access hatch. The easiest thing for me to do here is attach weather stripping to where the hatch rests against the casing. This is single sided adhesive - and the sticky side goes down on the casing. Two draw hasps are installed to pull the down down. If you have trouble keeping the hasps down - use a piece of wire, a nail or a screw through the lock hole to keep them shut and tight. Additionally you should have batted or foam insulation on top of your access hatch equivalent or greater than the insulation in your attic.

Step 9: Other Considerations

These things are not in my attic, but they are worth mentioning.

Hot stuff:

Small gaps around hot things like chimneys, chimney flashing, stove/furnace exhaust pipes need fire sealer. This is fancy flame resistant high temp caulk. DO NOT USE SPRAY FOAM! If you find large gaps you will need to fill them with some scrap metal. You can find inexpensive pieces of drip edge in the roofing section of a home store. Some home stores sell smaller sheets in the hardware section as well.

AC Unit and vents:

Any ceiling vents need to be foamed and sealed where they meet the ceiling.

If you have an attic AC unit you should take this opportunity to check the air seals on the duct work. Loose connections should be clamped, taped and caulked. Consider swapping out or upgrading any duct work that is not insulated properly.

Step 10: Rafter Vents

Side note:
Rafter vents should not be completely sealed. Home stores sell rafter vents that can be stapled on to the roof deck. They sit between the roof rafters and extend downward through the insulation and into the soffit. This gives cool fresh air a clear unobstructed path to travel which allows the hot attic air to be vented through the ridge or gable vent via convection. The rising heat will escape and the cool air will be pulled in. If you do not have any installed this would be a good time to put them in.

<p>Very good and thorough information. this from a professional builder. </p>
<p>Awesome! Thanks!</p>
<p>Hi, nice documentation. But you will still have heat bridges on the wooden beams and thus energy losts. You have to put insulation also over the beams otherwise you take risks that your ceiling starts to turn black under the wooden beams. Best regards from blown insulation experts from europe - www.ecofibre.de .</p>
<p>Greetings from the US! After I air sealed the conditioned space from the unconditioned attic I blew in about 35cm of cellulose over the existing fiberglass. </p>
<p>very interesting and useful bar the comments on foaming electrics and ventilation pipes shouldn't run uphill to the outlet in case moisture dose run back</p>
<p>Excellent instructions!!! I have a terrible moisture issue in my attic due to poor ventilation and now I'm realizing because of all the warm air seeping in through the leaks. I've started foaming. I wanted to hire insulation companies, but it seems no one wants to do the hard work of removing the boards and pushing away the insulation; they just want to add vents. Any advice on my chimney, I will get the fire retardant sealer, should I add flashing around the bottom. I am having the chimney re-pointed this week, which is also an issue I didn't realize until recently. I will take any and all advice. I see you covered the bathroom vent with a box, I also have 4 recessed lights that need to be covered; I am assuming this has been the largest issue. Thank you so very much for this, I love the photos. Very informative.</p>
Great walk through. My only question is : If I spray elect. , fans , and the like. What happens if down the road something needs repair or replacement? Will the foam come off easily?
<p>Hello More Cowbell! I commented on your post without reading all of it and seeing rhe photos! I'm nor really good on the computer ot at negotiating sites like this...bit I GET IT...Thankyou for posting such an well explained idea! Apologies that I said it was not clear...its ver clear thanks! Love it! Stebe abx replied to what I wrote and I replied thinking it was you the author of the post...and owner of the attic.</p><p>I discovered this when it was suggested I put doen fibreglass batts...when I'd explainrd, so I thought, that this is not an option.....never mind. I've re-read your post very carefully...ALL of it and several times and thoroughly GET IT! Fortunately I have a very old house (never thought I'd say rhat because of this problem of insulation) but it makes implementing your system even easier since there are no modern things in the attic...just wiring and a lot of dust that falls through thr VJ boards.</p><p>Thanks so much for such a simple solution to my age old problem and again, apologies for not attributing the invention to you!. Now for a hardy fellow who can follow your instructions and foam in and seal all the cracks!</p><p>J</p>
<p>I live in Queensland Australia...the really cold part. It frosts and snows in winter and in summer we drink wine and eat every kind of fruit you can name...at 3000ft above.. Really wish I understood what you are explaining, I would have it done without question. I am a woman of 71. I've lived in a wooden house with VJ board ceilings in every room for 30 years...the dust that comes down is amazing! Cannot put blow in insulation in the attic because...dust!! No other insulation either...dust!!! The electrical wiring is all up there encased in conduit so no foil backed insulation. Two years ago the Government put out a FREE insulation scheme....everyone and their dog was installing...the dogs were not qualified..resulting in many homes burning down and three people getting electrocuted in the attics where the foil touched wiring. I've not been able to decide what to do. So....sad for me, I find your explanation too lacking in detail..not your fault...just.wish I understood. Would be great to halve my fuel bill and have an insulated attic...it looks just like the one in the photo.</p><p>Robin</p>
<p>Hi Jusirela.</p><p>I used to live up there too. Now I live further south in the cold.</p><p>I am happy to advise you if you like.</p>
Thanks Steve-Anx! That's so nice of you!<br>I've had to learn to do a lot of DIY over the years so know what the materials and tools are and have a stanley knfe or two, a caluking gun and goggles and masks...<br>As I mentioned, I've been here for 30 years and am now an old...lady' afflicted with the problems of old age..so won't be me crawling up into the attic...and doubt if the man hole would be wide enough now....So, I think if you would be kind enough to list the materials, tell me what each one is usually used for and where to buy them, then explain what you used them for and how you fitted and fixed them in place...and what your overall brainwave was in.making use of.materials generally used for something else and how and where you used them...that would be help enough. Then, having a good idea of how you effected your attic insulation invention, I could explain it to an able bodied fellow who would be willing to do the job for me.<br>How does that sound, Steve? How are you at doing little sketches to illustrate? I've found that some of my unconventional inventions made better sense when I did sketches for the person doing the job...who had not a clue what I was on about! All they knew was that &quot;Esther&quot; was at it again! (They learnt a few tricks too).<br>I had a closer...( with magnification) look at your photo of the attic.<br>Did you wedge the weather sealer strip into the joins between boards and then..calk/stick/glue it in? What did you de-dust-de-yuk and generally clean the edges of the boards with so the caulk etc...would attach? My attic will need a really good vacuum and clean before anyrhing at all happens. if you did what I just suggested...That makes sense to me...What did you do with the other material you showed in the photo? .Thanks for your offer of assistance. I appreciate it. J
<p>I had a home inspection done several years ago, and the inspector fashioned something out of a large box to trap air from seeping through the door into the attic. He flattened the box and notched it for the stair railing leading up into the attic. When I want to go up there, I just open the door and push the flattened box up into the attic and then pull it back down when I am leaving. Unbelievable the difference a little thing like that made in my heating and air conditioning bills. It sealed it nice and tight, and has probably paid the inspector's fee many times over in savings in energy bills.</p>
<p>I got a fever, and the only prescription is More Cowbell!</p>
<p>Everyone needs more cowbell!</p>
<p>Any concern about the great stuff being in close proximity to electrical connections in a junction box (or similar) as shown in Step 4? Thanks!</p>
As an addendum to my original posting. <br><br>In regards to the net free air exchange rate:<br>Some well meaning home builders, contractors, and home owners will install powered attic exhaust fans to augment the net free air exchange rate. This is a good idea which can quickly backfire if not calculated, and implemented properly. As mentioned previously, there is a specific formula to calculate the appropriate net free air exchange rate for a building, &quot;net free air&quot; meaning the total volume of naturally free flowing air into and out of the attic space. A powered attic exhaust fan will increase the exhaust rate of the air pulled from the attic space. However if the volume of air coming into the attic is less than what is being exhausted, a vacuum condition may develop in the attic space. The volume of air exhausted from the attic space must be equal to or less than the volume of air capable of coming in through other vents. Therefore make sure all soffit vents have unimpeded air flow!<br>So why is this important? A vacuum condition in the attic space can pull air from the living space, thus in part, transfer a portion of that vacuum to the living space. Combustion exhaust gasses can be pulled into the attic from leaky exhaust flues, and/or more importantly, directly from combustion sources into the LIVING SPACE! Combustion exhaust gases can come from various sources, such as, wood or gas fired fireplaces, wood or gas fired stoves, wood or gas fired water heaters, wood or gas fired heaters (space or central), gas fired clothes dryers, or even from an engine running in the garage.<br>From a safety and health perspective, any building with combustion source inside may be well advised to have a free flowing source of fresh air coming into the building from the outside. <br>Breathing combustion gasses is harmful to health, and can cause carbon monoxide poisoning, and even death. <br>To be optimally effective, a powered attic exhaust fan should be installed at the highest level possible (because heat rises), and away from any other naturally free flowing vents. Optimally a powered attic exhaust vent should only pull air into the attic from soffit vents, or any other vent specifically placed to bathe the bottom of the roof deck with its air flow. <br>As a recommendation, only install a powered attic exhaust fan that has a temperature sensor and switch designed to turn the fan on/off at a predetermined attic temperature. Optimally this temperature sensor and switch should be adjustable. Furthermore as a convenience, a switch could also be installed outside and near the attic entry to easily control power to the fan. <br><br>Hope this helps!<br><br>Sent from my iPhone<br><br><br>Sent from my iPhone
<p>actually the minimum air infiltration rate is mainly dependent on the maximum expected number of occupants and type of heating used. gas burners, requires an additional infiltration source.</p><p>and also it is most likely better to have a slight positive pressure from fans pushing air in rather than exhausting with negative pressure. and in the summer, use the fans to push more air through keeping the level below cooler.</p><p>and if you are concerned with maintaining heat, in the winter. you might want to consider, an air exchanger. warmer air in the attic, forms a heat inversion layer in the daytime. but tends to become a heat sink at night with the roof radiating heat to the night sky.</p><p>but the biggest killer for heat loss, is infiltration rate. not the r factor of the walls and celling. heat is vertically polarized, so insulation in the attic should be at least twice as much as in the walls. and having thermo pane windows, are worthless if air is leaking around the sill. so it is important to seal, the window frame to the window with sealer.</p><p>and as i, have stated further down in the replies. it is easy to do a leak test with a window fan sealed good, and using smoke sticks to detect the leaks. </p>
The reason for the adjustable temperature sensor and switch is because there will be a point of diminishing returns. In other words, the cost of running the powered attic vent fan will, at some point, exceed the value of savings. For example if the temperature of the outside air is 95 degrees F, then the best you could hope for is a 95 degree F attic temperature. Realistically, on a sunny day with an outside air temperature of 95 degrees F, an attic will significantly hotter than 95 degrees F, but no less than 95 degrees F. So there is no sense having the fan running trying to get the attic cooler than 95 degrees F. <br>I think a ball park temperature to start with would be the average summer air temperature for the previous year. <br>Hope this makes sense.
<p>I am looking to re-insulate an attic wall (currently insulated, but we can feel the heat coming thru it in the summer in a stairway that adjoins it). I was thinking that along with another layer of kraft-faced insulation, I cover the whole wall with Tyvek (which I &quot;dumpster-dove&quot; to get). What say you (or other commentors)?</p>
<p>Tyvek won't add much in terms of insulation. It will form a water barrier, so be sure that is appropriate for your situation.</p>
<p>Since it will be on the exterior side of an interior wall of the attic (this attic space is the 'empty' area of a little house rook that was added on to years ago, making bedroom spaces on the backside of the peak). The wall was insulated, but not well. We put enough insulation on the rafters or the room beneath to bring it up to an R-50+ value, yet we can still feel heat loss/gain on this wall. I have (more than) enough Tyvek to seal off the wall if it would help. It would not be on the underside of the roof at all, just that one wall. I don't believe moisture would be an issue. Thoughts?</p>
<p>If you are getting air leaks at seams, then tyvek might help to seal off the wall and prevent air from getting in, but if the problem is simply that cold is radiating through the wall due to lack of insulation, tyvek won't help. It has almost no R value itself.</p>
<p>I can feel the cold and heat all over the stairway paneling (the seams are sealed quite well actually). It is insulated with R-15 between the upright joists/studs. What we planned to do was add more R-15 to the spaces and then cover the insulated wall with the Tyvek. If its still a moisture trap that way, then obviously we wouldn't do it. I have an insulated 22 foot by 8 ft wall between my attic and living space which I still believe to be leaking warm air out and surely letting the hot summer attic air in. My thought was that the Tyvek would help prevent the air movement, not act as insulation, except by blocking hot and cold air movement.</p>
<p>first thing you want to do, is confirm where are your air leaks. so you do not waste a lot of time, material and money plugging up the wrong places with no effect.</p><p>this can be accomplished using a window fan, and smoke sticks. make sure you seal the window fan in the window, and the smoke from the smoke sticks, will flow toward the leaks.</p><p>the biggest loss of heat, in most homes is infiltration rates. generally around windows, electrical, shafts, plumbing outlets inlets, sills without sealer. i, have seen air infiltration rates over 30 air changes an hour. but they, should never be less than half or three quarters an hour air change per person.</p><p>if you do not feel comfortable doing this yourself, there are probably companies that can do a more accurate blower door test and leak testing.</p><p>or if you want more information about this, you can write to NREL in Golden Colorado. where i used to work as a scientist, when it was known as SERI. or it's equivalent, in your countries.</p>
<p>You can pull the wall board down, add a second layer of 2x4 studs, offset from the first and spaced out about 1/2 inch with little wood spacers. Then, you can insulate, and cover it back up with sheetrock. The window gets a deeper window sill, which is nice.</p><p>Also, no matter how much insulation you put in, you need to first address the windows. Check them for leakage with a lit punk (incense stick) and then get some insulated drapes with white backings to keep the light out.</p>
<p>Dear Stoobers, I do not have windows in this interior wall between the living space and the attic, which is at R-50. Its the wall that needs more insulation. And its a wall that is a stairwell, so I can't make it even more narrow with more wallstuds and sheetrock.</p><p>Maybe your reply was meant for someone else?</p>
<p>Tyvek is a vapor barrier, and should not be installed OVER existing insulation. It is installed over EXTERIOR walls, between sheathing and siding. Using in your attic would probably be wasted effort and resources. You might be better off removing the existing paper-faced insulation and either installing rigid foam boards cut to fit and wedged between the studs, or applying spray-foam to the wall. (Depending on your budget and skills this is something you can do yourself, as two-part kits and application nozzles are now available, or hire an insulation contractor instead.)</p>
<p>Actually, Tyvek is <em>not</em> a vapor barrier. That's why it is so useful. <em>Liquid</em> water will not pass through Tyvek, but vapor will. That's why you should use it on the exterior side of wall insulation- it will keep any liquid water blown under your siding by windy storms out, but let the insulation &quot;breathe&quot; so it doesn't become damp due to condensation. In general, you want to put a vapor barrier on the interior side of insulation to keep water in vapor form out of your insulation, and tyvek on the outside to let any vapor that snuck past the vapor barrier escape. Of course, in the case of the attic, there's no need for tyvek because your roof (hopefully) doesn't let any liquid in, and it's important to allow lots of free air circulation above the insulation to ensure that you don't get any condensation. (I agree with the overall advice of madamH- just correcting this minor point, because that's what geeks do.)</p>
<p>you want a vapor barrier on the cold side. in a hot humid climate the moist outside air can condense inside your cooler air conditioned walls. in a cold winter climate, it's the warm moist inside air that gets you.</p>
<p>I'm not following you on that... The cold surface is where moisture will condense, so you should use your vapor barrier on the *warm* side, to prevent the warm, humid air from reaching the cold surface on the other side of your insulation, where it will condense. Putting the vapor barrier on the cold side both guarantees that you'll have condensation *and* prevents it from dissipating through evaporation. The result is wet insulation, and eventually mold &amp; rot. That's why Tyvek and the other vapor-permeable house wraps are manufactured for use on exterior walls. You want any moisture that makes in through your interior vapor barrier to evaporate at the interface to the less humid environment outside. I suppose this effect could be reversed in the air conditioning situation, but because heating generally has a much larger temperature gradient involved, vapor barriers are placed with heating in mind for just about any location in North America.</p>
<p>nick: i did get that first sentence backwards. should be barrier on hot side. your reasoning is spot on. </p><p>thanks for reading it. i'll have to see if i can fix it...</p>
The rigid foam was my first thought and the idea was shot down by the SO. He thinks that more kraft-faced would be the better alternative. The fumes from foam would about kill me, so that is out here.<br>Thanks for your comment.
<p>The newest generation of spray-foams don't have much of an odor, at least after drying. This might be a job for a contractor, in your case. I don't know how you'd go about attaching paper-backed insulation to a wall that already has a layer on it... the paper is slightly larger than the wool or fiberglass batt, so the paper can be stapled to the studs. Adding more to an existing wall may require compressing what you already have, which will make the now-existing layer less effective.</p>
Third addendum to my original posting<br><br>In regards to ceiling insulation:<br>Most materials used to insulate do not actually insulate. They actually strive to minimize the movement of air. Air is a poor conductor of heat, as most gasses are. So it is not the insulation material that insulates, it the tiny pockets of air between the insulation material that actually do all the insulating. The less the air moves within the pockets or from pocket to pocket, the better the insulating effect. This explains how cuzzies work, how multi-pane windows work , how styrofoam works, etc.<br>This is why it is critical to have the proper amount of ceiling insulation in the attic. The more insulation there is on top of the ceiling, the more pockets of air there will between the hot zone and cold zone. Thus less heat will be conducted from hot to cold. <br>If you drive around in the winter after a snow, you will most likely see roofs were the snow has completely melted except around the edges. This is because heat is rising from the ceiling, and heating the attic space. The edges still have snow, because they extend past your interior walls, thus there is no heat rising from the ceiling that would otherwise be below. <br>In the north, snow melting from the roof often refreezes as ice once the melt water reaches the edges. After several cycles of this water melting and refreezing, a dam of ice will form at the edge of the roof; causing even more melt water to collect and refreeze. This is called an ice dam. Unfortunately ice will then begin to slowly lift the shingles, and damage the roof itself. <br>One strategy to prevent ice dams, is to keep the attic air as close to the outside air as possible. This helps to prevent the snow from melting before the outside air temperature is above freezing, thus allowing all the snow to melt simultaneously. No more ice dams!<br><br>SO with that being said, in the north, any water pipes that run through the attic must have adequate pipe insulation directly around the pipe, and also be well below the top of the ceiling insulation. <br><br>Sent from my iPhone
As a second addendum to my original posting<br><br>In regards to the net free air exchange rate:<br>In order to calculate the air flow for a soffit vent it is necessary to determine the size of the opening of the vent. Obviously this would be easy if the vent didn't have any type of screening mechanism. For example a 12&quot;x12&quot; inch vent opening would yield a 144&quot; square inch opening. So how to calculate a screened vent opening? Unfortunately it is necessary to refer to the manufacturer's specifications to determine the screened vent opening. I cannot understate the necessity of this step!!<br>For a certain manufacturer, who manufacturers screened aluminum soffit vent material in huge rolls for soffit installers, a 12&quot;x12 inch piece of this screened aluminum soffit vent material might only provide 8 to 9 square inches of vent opening. This is a HUGE reduction of space! If a soffit installer did not know the manufacturer's specification, and assumed a 12&quot;X12&quot; inch vent opening would provide 144&quot; square inches of open space, then the installer would have underestimated by 95&quot; square inches!<br>Now imagine if the installer made this same mistake for every 12&quot;x12&quot; inch vent installed in the entire soffit. That would be en extreme error in calculating the soffit venting needed to provide the proper net free air exchange rate. <br>No air coming into the attic means no air going out of the attic! <br>This problem is even further compounded if the insulation installer, blows particulate insulation into the vented soffit cavity. No Bueno!<br>This same level of diligence must also be applied to determining the size of the opening for exhaust vents in order to calculate the proper net free air exchange rate. <br><br>Unfortunately this scenario is far to common. I actually addressed a building code inspector about this exact problem. The answer I received was unbelievable! I was told that building code inspectors cannot be expected to know the manufacturer's specification of any specific building material. WOW! <br><br>In regards to sealing the air gap between the chimney flue:<br>Nothing should be touching the chimney flue unless specifically designed to do so. This even includes fire resistant insulation. Fire resistant does NOT mean heat resistant. Fire resistant material can still conduct a high degree of heat without igniting. <br>If anyone tells you different, ask that person to hold something fire resistant while you apply a torch to it. Well that may not be the best example, but you get the idea. <br><br>Hope this helps!<br><br>Sent from my iPhone
Oops! 144 - 8 is 136, not 95. Don't know how that typo occurred. Sorry! So the installer would have underestimated by 135&quot; inches.
<p>Great information $$$$$$ saver.</p>
<p>I have a question, being &quot;older&quot; and female, I don't know a lot about this: 1988 an addition was added to my home with 3 recessed spotlights in kitchen and a combo bathroom vent fan/heater/light, all of which is (was) accessible from attic. I was losing a lot from my bare attic, so my brother blew in what appears to be a type of &quot;paper&quot; (?) insulation all over the attic floor to a depth of 2 feet (I didn't use this attic). Now I am wondering about the bath fan/heater being buried in this insulation. It IS vented to the outside, but is it a fire risk??? I loved the heater portion but am now afraid to use it....The recessed lights so far have not showed any signs of trouble....Please advise and thanks in advance</p>
Sherri,<br>As a rule of thumb, nothing electrical should be covered with insulation without specifically being designed by the manufacturer to be covered with insulation, especially cellulose (paper) based insulation.<br>I think you have good intuition to suspect a possibly hazardous situation. <br>IMHO, giving the type of advice you are asking for would be foolhardy without actually being there. <br>So I HIGHLY recommend asking one of your city's building inspectors to go out to your home and have a HANDS ON look at your specific situation.<br>Furthermore, I do not recommend asking local builders, contractors, or property appraisers, etc, because the likelyhood you may not be taken seriously since you are female. Much like a female trying to discuss engine problems with an auto mechanic, unfortunately she probably wouldnt be taken seriously. <br>Sad but true. <br><br>Hope this helps, and good luck. <br>
<p>I highly question covering those electrical boxes with foam. More than once I have had to go up in the attic and access a box from up there. Had it been covered with foam it would have been a nightmare. </p>
As an addendum to my original posting. <br><br>In regards to the net free air exchange rate:<br>Some well meaning home builders, contractors, and home owners will install powered attic exhaust fans to augment the net free air exchange rate. This is a good idea which can quickly backfire if not calculated, and implemented properly. As mentioned previously, there is a specific formula to calculate the appropriate net free air exchange rate for a building, &quot;net free air&quot; meaning the total volume of naturally free flowing air into and out of the attic space. A powered attic exhaust fan will increase the exhaust rate of the air pulled from the attic space. However if the volume of air coming into the attic is less than what is being exhausted, a vacuum condition may develop in the attic space. The volume of air exhausted from the attic space must be equal to or less than the volume of air capable of coming in through other vents. Therefore make sure all soffit vents have unimpeded air flow!<br>So why is this important? A vacuum condition in the attic space can pull air from the living space, thus in part, transfer a portion of that vacuum to the living space. Combustion exhaust gasses can be pulled into the attic from leaky exhaust flues, and/or more importantly, directly from combustion sources into the LIVING SPACE! Combustion exhaust gases can come from various sources, such as, wood or gas fired fireplaces, wood or gas fired stoves, wood or gas fired water heaters, wood or gas fired heaters (space or central), gas fired clothes dryers, or even from an engine running in the garage.<br>From a safety and health perspective, any building with combustion source inside may be well advised to have a free flowing source of fresh air coming into the building from the outside. <br>Breathing combustion gasses is harmful to health, and can cause carbon monoxide poisoning, and even death. <br>To be optimally effective, a powered attic exhaust fan should be installed at the highest level possible (because heat rises), and away from any other naturally free flowing vents. Optimally a powered attic exhaust vent should only pull air into the attic from soffit vents, or any other vent specifically placed to bathe the bottom of the roof deck with its air flow. <br>As a recommendation, only install a powered attic exhaust fan that has a temperature sensor and switch designed to turn the fan on/off at a predetermined attic temperature. Optimally this temperature sensor and switch should be adjustable. Furthermore as a convenience, a switch could also be installed outside and near the attic entry to easily control power to the fan. <br><br>Hope this helps!<br><br>Sent from my iPhone<br><br><br>Sent from my iPhone
There are several problems with the original posting as well as some of the comments. So in no specific order:<br>1) Do not use METAL or anything else to seal the air gap around the chimney flue, unless the seal is specifically designed for that purpose. That air gap is there to prevent heat transfer from the flue to the surrounding materials, and thus reduce the likely hood of spontaneous ignition. Metal, more so than other building materials will readily conduct the heat from the chimney flue to any material it touches. <br>2) Do not vent any exhaust fan to the soffit vent. Soffit vents are for air intake into the attic ONLY. All exhaust fans should be vented out to the exterior, otherwise anything in the exhaust can, and most likely will buildup on attic surfaces. This includes not only bathroom vent fans (fart fans), but more importantly kitchen vents due to the grease content of the exhaust. <br>3) There is an exact calculation to determine the ratio of soffit (intake) venting to roof (exhaust) venting. The calculation takes into consideration the &quot;footprint&quot; of the attic and the pitch of the roof to determine the &quot;net free air&quot; exchange rate. The air in any attic space should be dynamic, and freely exchange with the outside air. Counterintuitively, the attic air should be as close to the outside air as possible, otherwise moisture and mold can become a problem, and ice dams can form above the soffits in the winter. Furthermore if the exchange rate is low during the summer allowing the attic air temperature to rise, any insulation on top of the ceiling will act as a heating blanket at night. The take-away here is to ensure the air exchange rate for your attic has been specifically calculated and implemented for YOUR specific house. <br>4) Radiant heat barriers installed under the roof decking and joists can, and most likely will cause premature failure of roofing shingles. This happens because the heat that is normally radiated into the attic space is reflected back at the underside of the roof decking. This increases the temperature of the roof decking, which will in turn will radiate the heat back to the bottom of the roof shingles. If roof shingles become too hot, the manufacturer installed adhesive on the backs of the shingles will prematurely fail, the color texturing will begin to come off, and finally the edges of the shingles will curl. This failure can be exacerbated in areas with high winds, because the shingles will begin to blow off due to the failure of the adhesive. If you read the manufacturers warranty for roof shingles, the are specifics to the limitations of the shingles, and the liabilities of the manufacturer. <br>5) Install attic insulation according to EPA and DOE recommendations for your geographic location. By U.S. regulation, every new home must have a series of insulation depth markers installed in the attic to indicate to potential home buyers the depth of the insulation. <br>Unfortunately building inspectors and code officials rarely enforce this. <br><br>As a matter of my personal experience; unfortunately much of the information I have provided here is completely or in part unknown to builders and contractors, or is simply dismissed due to financial incentives. If you have any doubts, please do the research on your own. Also have a look at the building codes for your area. <br><br>Good luck!<br><br>
<p>If I install open cell SPF insulation under my roof (new construction) and seal the attic, where does the gas go if there's a leak in a gas line that runs through the attic? Even a tiny leak would cause a build-up over time. Is there a way to mitigate this potential problem? I would install gas leak detectors, of course, but don't want to rely on them.</p>
<p>The goal is to seal the connection of the attic to the ceiling, not the entire attic. See the very last paragraph &quot;Side Note&quot;.</p>
<p>Hello</p><p>Gas pipes are routinely run through floating floors with EPS floor insulation.</p><p>Firstly, of course, there shouldn't be gas leaks. Get a pressure leak test done to reassure yourself. Another possiblity is to slip a duct over the gas pipe and ventilate the duct somewhere. No gas transport system is entirely leak-free. I worked with hydrogen gas at 300-bar - hydrogen molecules will get through the pores in solid looking fittings and tubing. Domestic gas is a mixture of larger gas molecules (methane, butane, propane etc.), but the big difference is that the pressure (UK) on the user side of the company meter is 20-millibars - that's a 50th of atmospheric pressure and a real disincentive to leaking. Barring damage, the only place you get leaks in gas systems are joints, soldered and compression. Sniff those with a flammable gas detector, or use a spray (foam) detector</p>
<p>great write up, but in your section </p><p>&quot;Hot stuff:</p><p>Small gaps around hot things like chimneys, chimney flashing, stove/furnace exhaust pipes need fire sealer. This is fancy flame resistant high temp caulk. DO NOT USE SPRAY FOAM! If you find large gaps you will need to fill them with some scrap metal. You can find inexpensive pieces of drip edge in the roofing section of a home store. Some home stores sell smaller sheets in the hardware section as well.&quot;</p><p>You should actually use fire block pillows to fill in large gaps! Then once filled you then use the fire caulking all around the pillows, NOT SCRAP METAL!</p>
<p>Hi It is a balmy -30 today and my attic is completely uninsolated. Found out when it was too cold for the expanding foam, caulk and adhesives to work. I'll get at it this spring. Your covering of electrical boxes is against code but the rest is what I am hoping to do. My problem is the slope on the roof makes it that you can not reach the edges of the roof even with an extender on my foam gun. Anyone have any ideas how to deal with this. I have thought of pouring some loose material and using a long extension on a broom and shoving it in that way but a two part closed cell foam would do a much better job.</p>
<p>This is great idea, but fraught with potential problems.<br><br>1) electrics - cables, junction boxes should'nt be covered, it would be in breach of UK regs, unless you derate the power-handling. Even running cables in ducts and trunking should be calculated for loss of free air cooling, plus junction boxes need to be accessible for inspection.<br><br>2) planning ventilation is crucial - I've seen attic spaces wet through with condensation dripping from the tile underfelt, especially the old bitumen/sand/hessian stuff. People wonder where it comes from - people breathe moisture out, bowls of water, plants, cooking, washing etc. - propane heaters are the real wet-makers. Increasing insulation in the wrong place makes the attic colder, and vents with fly meshes soon choke up with dust.<br><br>3) cold air draughts - if you have any form of studwork construction, you will be amazed at how much cold air gets around - ceiling voids, wall voids are the highways, even electrical sockets and switches. I now routinely tape all chipboard flooring joints and seal between skirting boards<br><br>In the UK, there are two roofing practices - warm roof and cold roof - there are more warm roofs in Scotland - in my opinion, warm roofs should be standard practice. A warm roof is insulated under or between the rafters, a cold roof is the traditional tile and felt construction and relies almost entirely on air leaks and draughts to prevent condensation.<br><br>I converted mine from a cold roof to a warm roof by adding 40-mm of foil covered PUR rigid insulation to the entire roof, under the rafters, air-sealed throughout - made the world of difference, a bit like a roofspace conversion. However, I upped the ventilation between old felt and the new PUR surface by adding vents at the facia. To be doubly sure, I put in temperature and humidity monitoring, and added internal vents and ducts to pull air through the ventilation gap if the humidity got anywhere close to dew point.<br><br>There has been an unexpected bonus. Temperatures in the air gap can get to 20-C on a winters day with sunshine, and 50 to 60-C in summer. With the fans in place, and some control gear, this warm air can be redirected back into the roofspace, adding a warm air pillow above the ceilings. A possible next step might be to install water circulation pipes in the air gap to havest the warm water potential. A lot easier to install than panels on the roof with all that entails.<br><br>UK regs now call for all new builds to be essentially airtight with controlled ventilation. If houses were built to the same airtightness as cars and as well insulated as a freezer, we would be quids in - traditional building practice is the stumbling block.<br><br>All said, you are on the right tracks and a job well done.</p>
<p>Excellent information. Though I probably won't do 90% of what you wrote by myself, I will seal the door in my attic. That is easy to get to and my closet is always cold in the winter. I may try to find a handyman to do the rest for me. I would say $500 is all I would pay for a day's work, though I never earned that much. My back just could not take the bending. Thank you.</p>
<p>Excellent energy-saving tips!</p>

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