Make a Rain Proof Portable Generator Housing





Introduction: Make a Rain Proof Portable Generator Housing

About: I am an electrical engineer by education and a software developer by profession. I am like building electro-mechanical models. I also like grilling and barbecuing with passion. To burn my beer cals, I swim...

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.

You can use this link to select and size a generator for your needs.

Step 1: 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

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

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

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

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

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. 

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    34 Discussions

    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. :)

    Looks good, but a couple of questions on the generator:

    1. How many devices are you powering ? 2. Does the gas tank have a drain plug ?


    1 reply


    1. The generator is only 5500 Watts, which is not a lot. I had it to power sump pumps, a fridge, and a few lights, give or take a few; all under 5500 Watts.

    2. The generator does not have a drain plug. There several ways to empty the tank. You can let the unit run until it runs out of gas. You can buy a cheap siphon pump, empty the gas, and then let the unit burn the remaining gas.

    Why not just get a GenTent? a lot of people used them during Sandy and reviews are very positive.

    2 replies

    I would but with your money. I'd rather make something and be proud of my accomplishment.

    Not wanting to be mean but instructables is a web for tutorials on how to do stuff. Not how to buy stuff. That's why.

    Good solution to a very real problem!
    FYI, at many big box home improvement stores, you can now buy 1/4" thickness 4'x8' HDPE plastic sheets; would be more durable and in my locality it's $40-50/sheet. One could also utilize foil-faced fiberglass board insulation for sound-dampening properties on the interior, and compared to other sound-dampening options like foam board insulation, it should withstand heat better. Could also add the sort of vent that is often used on farm buildings, where the tube exits 90* from vertical and swivels away from the wind direction, to allow for good air intake without scooping in rain at the same time. Could do the same for exhaust.

    wood is a bad choice if your trying for quiet it carries sound maybe if you nailed some insulation inside

    1 reply

    Wood will only transmit strong engine noise if the material is in direct contact with the engine. Isolating the box from the frame with rubber will help.


    10 months ago

    What a great idea. I've been looking for a cover for my Yamaha 2600 generator for a while and had settled on using a ice fishing sled attached with bungee cord. I looked at dedicated covers from GenTent ( but the money they wanted was outrageous. There are a few minor tweaks that I'll do when making one of these. Primarily I want to be able to knock it down when not in use but otherwise I like this.

    Thank you I was trying to figure out how to do this when we lose power for days even up to a week with snow, rain and wind. I had the idea but now I have instuctions so I hope to get this built soon. Much needed. Thanks for sharing

    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.

    1 reply

    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.


    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.

    1 reply

    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.

    How did it work out? I know NJ really got hit bad and lots of damage near the water. Hope you got through OK!

    1 reply

    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.