TRULY insulate your loft (or attic!) - and save the planet

Being time rich and money poor, I wanted to cut my outgoings, and be a bit greener.

So I fixed SF40 SuperFOIL to the underside of my rafters to keep warm, cut bills and save the planet: www.superfoil.co.uk/SF40-titlepage.html

I chose SF40 because:

a) It nails to the roof, so you can still use the loft for storage
b) It has a radiant heat barrier
c) It is the equivalent of fitting 450mm (18 inches) depth of fibreglass*
d) It should keep us cool in summer too

I expect there are other products you could use, but this one seemed right for us.

There are a lot of steps to this instructable, but it's not as complex as all that. I waste a lot of time talking about nailguns and such. You can skip to step 16 if you want.

NB: Apparently what we Brits call a loft is what our Yankee cousins call an attic. For them this 'ible is about attics.

* Clarification: fibreglass does not block radiant heat; the quilt does. In order to get the same savings, you would have to install 18" of fibreglass. But this does NOT mean that the R values are the same. See the manufacturer's brochure illustrated in the second pic of step 3.

Step 1: And here it is

I need the floor space because I keep a load of old tut in my loft. If you don't store things in your loft, you could just lay loads of layers of fibreglass - but you still wouldn't have the radiant heat barrier the quilt gives you and the fibreglass will still have gaps.

You can use insulating boards; but they don't give the same insulation value, and you can't cut them with a pair of scissors.

Comments

[casperboost]

This is a great idea, especially with our energy conscious society now. Just to clarify though, this shouldn't be done on the roof of ATTIC though with the blown (or bat) insulation on the floor, right? Only for a LOFT? I am a air conditioning repair man, and doing this in an attic seems like a super bad idea.

[LDW]

Attic = loft = attic. Same thing.

> doing this in an attic seems like a super bad idea

Presumably because you're locked into the COLD ATTIC principle. Like so many repair men. And you've probably got some cockeyed ideas about condensation.

Go back to square one. The idea is to stop heat going out of the roof, da? So nothing that does that is bad, nyet?

Read up on the WARM ATTIC alternative. Keep the heat in the house. Yes, insulate the floor of the loft/attic. But also stop the heat leaving the attic for the sky by insulating the roof - especially, as in my case, where the loft/attic is used for storage. Plus conventional insulation does nothing whatever about radiant heat, so you're saving there too.

Also benefit from cooler summers. Actually, it's all here if you read it.

[kwazai]

you could add a perferoated pipe at the ridge to collect solar heat in the winter- I've seen pool heaters use this. One of the sites even had the calcs to determine if it was adequate to heat the swimming pool. The offgassing of the underside of the roof probably would not be good to breathe so a water based heat transfer would be needed to keep it breathable hot air if wanted.

[No_Where_Fast]

No heat escape from your roof up here in northern Canada can be an extremely bad thing... I have an extremely well insulated roof that requires shoveling every winter - to explain: My house was an old, log, summer cabin that was winterized and now has another insulated, tin roof over top of the original. You would think that a tin roof would be throwing the snow off on it's own, but no such luck. There is absolutely no heat escape so the snow just piles up. Come mid winter my doors start closing a little less square and things start to creak a lot more than usual. Not to be a pessimist though. Still a great instructable :)

[michaelcozens]

Ever consider using some of that "anti-ice-dam" wire, possibly across the whole of your roof? Tin should be especially good at picking up the heat from the wires and warming enough under the snow to cause a liquid layer to form immediately above the roof, facilitating an avalanche.

[LDW]

That's good - the snow acts as another insulating layer... :-)

[_soapy_]

If the weight of the snow didn't crush the house, then yes, it would be great! As it is, I'm sure he doesn't want a warm coffin.

[LDW]

:-)

[rattle09]

I do not recommend anyone do this to a roof covered with asphalt shingles. There must be an airspace between the underside of the roof sheathing that is clear to the ridge of the roof. At which, there must be some type of ridge vent. Without these the summer sun and heat will literally bake your roof and with in a short couple years the shingles will curl up and be ruined. Your shingle warranty will also be void.

[tcup]

Ah, good tip. How then, does one safely insulate their roof? I have a ridge vent at the peak of my roof. My roof developes huge icecicles during the winter.

[Mike44]

Yeah, as rattle09 said, you probably don't have continuous airflow from your soffit up to your ridge vent. Look up pictures for attic venting - there's some on the Pink Panther insulation site: http://insulation.owenscorning.com/homeowners/

You may have a situation something like this with no air flow: http://www.nylumber.com/images/ice2.JPG

What you want to do is add those styrofoam spacers (raft-r-mate polystyrene attic rafter vents): http://roofing.owenscorning.com/homeowner/accessories/ventilation/raftrmate.aspx

[tcup]

Thanks guys for your advice. The only insulation in my attic is on the floor. I never heard of rafter vents. I'll have to look into them. I'll be doing that job myself so I will have to buy everything peacemeal as I can afford it. Meanwhile I'll be adding calcium chloride to the areas of my roof, that I can reach. I saw something that says to fill knee high panty hose with calcium chloride then lay them on the edge of your roof, that will prevent ice from forming. This will be interesting, I hate hights.

[michaelcozens]

You can also get wiring kits that have you tack a warming wire in an up-and-down curving pattern on the overhanging portion of your roof. You can then plug this wire when you notice ice starting to form, and melt tracks through the ice dam to allow the accumulating water that can back-up under your shingles and into your attic to flow off the roof. It's a longer-term fix, because you can just leave it up year-round and use it as necessary.

[michaelcozens]

One thing you can do with the panty-hose is to tie a long rope to one end, and just throw them up onto your roof while letting the rope dangle to the ground. This way, you can retrieve and re-throw the package until you get the position right, and also pull it down to refill it or put away in spring. Voila! No roof-climbing required.

[tcup]

Last winter, I tried the calcium chloride in the knee high panty hose thing. It worked. Unfortunately, my house had the look of a bordello with all those panty hose all along the roof edge.lol. Then after winter was over, there were black stockings all over the yard, somewhat embarrassing. But the main thing is that the method worked, I had some icicles but not as much as previous.

[rattle09]

There is a styrofoam product made that is designed to fit between the rafters. Its concave shape allows an area of ventilation from the lower roof edge to the ridge vent. You would install these prior to the process that is described here in this instructable. This will allow the heat to escape from below the roofing therefore helping keep it cooler.

[LDW]

Well I don't have rattle09's knowledge of asphalt shingles, but AFAIK you should be safe if you fix the quilt to the underside of the rafters - in which case there will be a gap the same depth as the rafters between the roofing material and the quilt.

Best check with the manufacturers. Someone here has recommended:

www.eshield.net

and they look OK to me.

[LDW]

There must ALWAYS be an airspace between the quilt and the roofing material. That's why it's fixed to the underside of the rafters - although it can be used in certain new builds immediately below the roofing material - see www.ecofoil.com/Applications/Roof-Insulation.

[h3idi]

I love that they warn you of the glare if using outside. Safety first! ;)

[Mike44]

This is a great idea, especially with our energy conscious society now. Just to clarify though, this shouldn't be done on the roof of ATTIC though with the blown (or bat) insulation on the floor, right? Only for a LOFT?

[LDW]

Erm... sorry Mike444 - I don't think I know the difference between an attic and a loft. AFAIK they're the same thing. What did you mean?

[mephit]

I think we've run into a bit of a language issue. I'm guessing that Mike44 is a fellow American and therefore confused by your use of the word loft. In the US, loft can often mean just the upper habitable storey of a building or even just large, open living spaces usually converted from commercial property and often having very high ceilings (i.e., they're "lofty"), whereas the attic is the area just under the roof often used for storage. This means you can actually have an attic over a loft. Confusing, I know. In answer to Mike44's question, though, this is being done to what we here in the States would call an attic. In this case, a floor has been planked in on top of the insulation covering the joists of the attic making it appear to be a more finished space than many Americans are used to seeing in their attics.

[LDW]

Ah - thank you, mephit. Tricky animal that English language...

You are in the right of it: my attic (we use that word interchangeably) has floorboards in it - as explained in step 5.

The title of my 'ible has been amended accordingly.

[mephit]

As that wit Shaw said, we are "two people separated by a common language." I have found it handy on more than one occasion to be an American with a large number of UK relatives.

[Mike44]

Ha true true, well, not quite American....I'm Canadian, but us North American's probably use a little bit different lingo than what you use 'across the pond' :)

Attic: mainly an UNLIVABLE space at the top of your house; has roof trusses throughout the support the roof, so you can't really put a 'livable' space up there; insulation along FLOOR of attic keeps building heat inside (http://www.arrow-insulation.com/img/photos/beforeandafter/large/attic_insulation_after_3.jpg)

Loft: a LIVABLE space where the roof trusses are placed more off to the side in such a way to provide a livable space in between; the insulation is placed along the ROOF/WALLS of the loft; thus there may be no true 'attic' space above (http://i37.tinypic.com/ax1da1.jpg)

I guess my question was just getting to the idea that by installing this on the roof of an ATTIC which already has insulation on the floor would kind of be defeating the blown in floor insulation. Then the heat would be trapped within the metal blanket and blown in insulation, leading to problems.

Also, yes, it's absolutely critical to maintain an airspace between the roof proper (like the plywood) and insulation from the soffit at the bottom of the roof up to the space where the ridge vent is:

http://www.inspectapedia.com/BestPractices/Figure2-57s.jpg
http://www.nachi.org/images10/ridge-vent-baffles.jpg
http://education.nachi.org/images/upload/soffit-ridge_vent.jpg

[mephit]

Ah! excuse me for the incorrect assumption, then. I imagine ya'll get tired of being mistaken for us. :D

I'm not a contractor or roofer or insulation specialist or anything, so please excuse me if I say something stupid, but aren't you assuming there's a ridge and soffit vent system? Not every building has them. I know my house doesn't have either. It's got an old-style rotary attic vent, but no soffit vents. My house was built between 1946 and 1949. There are plenty of other buildings around of a similar age that might not have a modern vent setup. Would they still need the airgap between the roof decking and the insulation?

[Mike44]

Oops, yes, sorry, I should have clarified! :) I'm assuming a more 'recent' house. With an older house like yours though, you probably don't have to be as concerned to get this airflow going because they were built "less airtight" back then when compared to today's houses (vapour barrior, polyseal, acoutiseal, etc. the works nowadays!). There will probably be some natural airflow somewhere there! Oh, and I do believe that those revolving roof vents are (*I think*) about equivalent to the ridge vent. At least that's what I've been told!! Don't quote me though :) Seems logical though. With that being said though, they are much less airtight, so you may experience heat loss through the attic. Do you get any icicles forming on your roof at all?

[mephit]

Don't know yet. I only bought the house in May of this year and I live in the Southeastern US. We're currently having a cold-snap, so I'll keep an eye on it, but I seriously doubt they'll form. My house has nothing but the original inch or so of insulation in the attic floor and no roof insulation of any kind. The heating system seems to mostly be heating the attic and not much the rest of the house. The roommate currently living in the attic room says it gets surprisingly hot up there while our downstairs area is still pretty chilly. I'm wasting dollars and energy I'd rather not waste, so that's one of the reasons I'm interested in this 'ible. Unfortunately, the entire attic space has been thoroughly and very cleanly floored with the inadequate insulation between the ceiling below and the floor above. Factor in the additional fact that more than half of the attic space has been converted into a room (just under the ridgeline, of course!) and it basically means I'd have to gut my attic to re-insulate it. Whee......

[thecheese429]

Instead of relocating your antenna outside, you might try just using the foil itself as one. Attach a wire to it and make sure it contacts the metal component, then run that to your TV.

[mattadamsnet]

Good luck with that, an antenna is a tuned instrument, if it works it would only be by luck.

[LDW]

Oooooh! Happy thought! Wish I'd thought of that!

[wolfsmane]

Have you tried doing this yet, LDW? Let us know what kind of signal strength you get please.

[mbainrot]

Becareful working with foil insulation, allot of people die when they drive a staple through a power cable and create a massive electrofyed surface

[LDW]

Power cable? Why would you have power cables on the underside of the roof?

[chapa-de-frente]

i like how your thinking, hilarious, but for your attic lights and anything else you may have, like a powered attic exhaust system (but many houses now have passive systems, using simple physics to ventilate your attic). people like to run some of these wires along the ridge line.

[LDW]

OK, I get it.

It is ALWAYS a bad idea to punch staples through power cables. Caveat emptor.

[mbainrot]

What happened with the insulation scandal here in the land of aus, was the foil insulation was being stapled onto the rafters in the roof that support the ceiling.

Also you may have an evaporative cooler, they require power.

Houses also have power in strange places, thankfully with our house it was back in the age when people didn't really trust the wire that was carrying their juice, so said wire was encased in steel tubing which was properly grounded. Incase of a fault, it would short to the metal pipe and trip the breaker (failing that, the fuse on the power line)

[LDW]

I'm only repeating here what it says on the user instructions: carbon monoxide.

Of course, they may have made a mistake!

[NoseyNick]

You serious? Not Carbon *DI*oxide? A very very different beast.

[antcity]

Here is a link to some info about the dangers of installing foil insulation as widely publicised in Australia following the death of 4 workers who were electrocuted while installing foil insulation as part of the Australian governments subsidised insulation scheme which as subsequently been cancelled. Millions of dollars has been spent rechecking all the homes where this type of insulation was installed by dodgy contractors as there were ongoing fire safety concerns. The article does stress that the issue mainly lies with installing it in older houses that frequently have wiring problems within the roof.

http://www.renovateaustralia.com/2010/02/11/how-safe-is-the-foil-insulation-in-your-roof/