Make a rain proof portable generator housing

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Picture of Make a rain proof portable generator housing
I live in New Jersey and as I write this instructable on October 28, 2012, we are about to be pounded by hurricane Sandy,  To keep my sump pumps going, I decided to buy a portable generator in case the power goes out.  The only generator I could get my hands on is this behemoth 225 lbs Generac 5500 watts generator.  Keep in mind that I cannot run this generator in a covered open area.  First on all, other than my small covered porch I do not have any other covered open area, secondly with 100 miles an hour wind, there is no such thing as covered and open.  I had to make a cover which will protect the generator from rain and I will need to provide ample opening for it to breathe and dump its exhaust.
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Step 1: The design

Picture of The design
As I mentioned before, the generator needs to be protected from the rain.  It should be able to breathe.  The cover should be beefy enough to stay on the generator.  If I was a sheet metal guy like the Tuttles from The American Chopper, I would have done every thing in sheet metal with a cool paint job.  Unfortunately my skills are limited to some crude carpentry, so I decided to make a plywood housing with louvered vents for air circulation.  I did think of generator getting hot and found the hottest part to be the exhaust muffler.  I decide to put a aluminum sheet as a shield against the heat.

Step 2: Start with the top

Picture of Start with the top
I used a 24" X 32" X 0.5" plywood as the top.  Rest of the structure of the housing would be attached to the top.  I still had some nice hardwood railing bars left from the deck I built.  I attached those bars to the plywood using 1" long deck screws.  In the picture below you see two sides already attached.

Step 3: Make the side and front panels

Picture of Make the side and front panels
I cut pieces of plywood as per the design.  I used three pre-fabricated louvered vents (sold in Lowes and Home Depot for $1.50 a piece.)  I cut the slots in the plywood equal to the open area of the vents.  To cut the slots, I marked the rectangular area to be cut first.  I made four holes using a dremel inside the boundary of each line of the rectangle.  I used the jig saw to cut straight on the pre-marked lines to get a decent rectangle.  I fastened the vent on to the plywood using 1/2" machine screws.

Step 4: Make the rear panel

Picture of Make the rear panel
The rear panel is smaller than rest of the panels because it used on the exhaust side and I wanted the exhaust fumes to go out with very little obstruction.  However, the rain was still a concern and as I mentioned before the exhaust muffler gets really hot, I needed to protect the plywood from burning from the heat.  I had some flashing sheet laying around.  I cut a piece of sheet slightly bigger than the rear panel and attached it from inside on to the plywood using 1/4" machine screws.  Note that flexible aluminum flashing can be bent as a canopy to stop the rain and let the exhaust out.

Step 5: Attach all the panels to the top panel

Picture of Attach all the panels to the top panel
In this step I attached all four panels to the top panel using 1" deck screws.  I ran out of plywood so you will see that I used a smaller piece of plywood to cover the entire area.  To secure the panels from moving I used some L brackets to fasten two panels together.  The part where one panel was made of two pieces of plywood, I fastened them together as well using a flat bracket. I used some outdoor sealant caulk in between the joints to keep the water out.  The reason why I did not use a carpenter's glue for the joints is because I do not know yet whether my contraption will work or not.  If it does not work because the generator is not getting enough air, I may need to remove a panel or two.  A carpenter's glue due to its bonding strength will make this task extremely tedious.  I filled all the cracks with caulk.  After the caulk dried I sealed the plywood with the deck sealer.

Step 6: Conclusion

Picture of Conclusion
I will secure the housing on the generator by wrapping it with a bungee chord to stop it from being blown away by strong winds. 
What happens next, only time will tell.  My design seems to be sound. I will keep you posted. 
triumphman2 years ago
Are you Irish?
kabira (author)  triumphman2 years ago
I could very well be! I like beer, I like whiskey, and I love (I mean love love) corned beef! I do attend St. Patrick's Day in New York off and on. I am sure there is more to being Irish, but I hope, what I mentioned above suffice. :)
My portable generator has always been stored in my garage where there is a designated storage area for it to be especially guarded from harsh weather conditions like rainstorms or winter. However, to be able to build this rain proof casing for the generator would be beneficial especially if we were to be caught in an unexpected shower while using it outdoors.
kabira (author)  ChristopherJames3 months ago
Hello Christopher,

Yes, that was the idea behind the whole project. The project was done four days before the hurricane Sandy, which did a major damage in New York and New Jersey. Luckily for me the the power was gone for only twelve hours. We had some lights in the house, thanks to the generator, running on my driveway with rain and 70-80 MPH wind.

Generator was a sought out commodity at that time. If you are interested, here is the store of how I acquired it.


tbird4812 years ago
Why not just get a GenTent? www.gentent.com a lot of people used them during Sandy and reviews are very positive.
Tom 72 years ago
it would be better to cut a larger top that covers and over hangs the side walls. that would help the structure last longer in the rain.
some padding inside to soften contact points with help sound vibration.
kabira (author)  Tom 72 years ago
I do have clearance of about 2 " on each side. However, it was my intent to keep it a tight fit because I did not want winds to turn the cover into a parachute. Sound insulation was not into consideration at all because the unit was outside, and I was constantly worried about the fire hazard due to excessive heat. However, I am sure there is soundproof insulation available which could be more temperature tolerant.
burntbob2 years ago
How did it work out? I know NJ really got hit bad and lots of damage near the water. Hope you got through OK!
kabira (author)  burntbob2 years ago
Considering that I live quite inland, there was no water damage. There was just damage to the roof due to winds. And, of course, we lost electricity, and that is where the generator came in handy.
poofrabbit2 years ago
Congratulations on being a finalist in the be prepare contest!
reddog923962 years ago
Step one should be "don't buy a generac". Just some advice for the future, they tend to crap out much more often than some other brands, although the other brands are more expensive. This is cool though! Thanks!
kabira (author)  reddog923962 years ago
Thanks Reddog! Beggars could not be choosers! There were only eight generators left in the entire New Jersey before the hurricane Sandy! If I had time, I would have purchased a generator which runs both on gas and propane.
swindmiller2 years ago
Hello from a fellow Sandy victim in Maryland...hope every one is ok and safe. I bought my first generator although I have been pondering the idea for months after our last 7 day outage.
This is exactly what I was looking for and was wondering how it was holding up. We are getting pounded as I type this so I know you are getting it worse :)

I have a gazebo that I had the generator under but as you said with the winds it got soaked anyway. I read mixed comments about people saying they leave their generator out in the rain and others saying to never use it in the rain. I had it out there for hours not running and just decided to bring it in the house (not running) until I need it, it was wet so I am drying it off now I will store it in the shed after the storm when not using it but think I need something like this for the rain and snow.

I was under the assumption that the whole thing got hot but you say just the exhaust gets hot? That's why you used the sheet metal, right?

kabira (author)  swindmiller2 years ago
Hello Scott,

I hope you are safe and dry now. As expected we lost power right when we needed it the most. The winds were very strong. I not only tied the housing to the generator and then tied the generator to my truck from flying away. Luckily nothing like that happened. The pumps worked constantly. We just got our electricity back. Damage wise, there nothing major except for a few missing roof shingles.

I hope we don't have to deal anything like that for a year or more.

Good Luck!
Great to hear!! How did the cover hold up? Did the generator get wet?
kabira (author)  swindmiller2 years ago
Thank God! It worked out very well. I tied the cover and tied the generator with my truck, just in case. However, I did not see any lift inside the cover because the louvered vents helped released all the air pressure.

How did you make out with the storm?
No issues, we got lucky.
Schmidty162 years ago
did u stain it
kabira (author)  Schmidty162 years ago
No, just sealed it using deck sealer.
Tupulov2 years ago
Quick and easy project. I was thinking about doing something like this for my generator and this was the idea I needed. I like the way it allows complete mobility of the generator. As for heavy winds, I'd sink a ground anchor on either side and use a tie-down strap to prevent the wind from causing problems. Well done.
pratchered2 years ago
Is there enough room for the power outlets? It looks like a tight fit. I might try to do something similar for mine. Nice job.
kabira (author)  pratchered2 years ago
Hello and thanks for the comment. Actually my picture shows wrong measurement for the width. The genset is only 21 inches wide, which gives me almost 3" for the power chord plug and the bend of the chord.
MrOddjob2 years ago
Hi Kabira. A very nice neat job on the generator. I wouldn't worry too much about engine aspiration problems, with 100 mph winds blowing at it, it'll likely be turbocharged! However I do have concerns about it's ability to stay on the ground. I may be wrong but if winds of that speed get underneath that box, it's a good bet that it's going to turn into a flying machine.

I hope it doesn't happen and that you and your family come through unscathed.
Good instructibles though, I may use this in the near future. Stay safe.