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.

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.