Creating a soundproof enclosure around a portable power generator will considerably reduce the noise it makes. You can buy such a box from a few in-store and online retailers for any size and model of generator have. Or, you can save yourself a little money and take up an interesting project by doing it yourself! Follow the steps below to build a soundproof cover for your generator before the next time you have to use it.
Step 1 - Take Measurements
Obviously, the size of your insulated enclosure will depend on the size of your generator. Take accurate measurements of the generator with a measuring tape and write them down. Then, make sure to add several inches on every side to take the soundboard thickness, insulation thickness, and ventilation provisions into account. Write down a final measurement for each side and the top in a clear space when you're finished. This way, you minimize the risk of cutting your board to the wrong specifications.
Step 2 - Cut out the Box
Cut out the box as per your measurements using a circular or table saw. If you can’t find MDF or a soundboard, you can use regular plywood; it just may be a little less effective. Label your four wall pieces and your single top piece with a pencil so there's no confusion later.
Step 3 - Make Holes for Ventilation
Measure the diameter of your ventilation ducts, and mark two circles to cut. The first needs to be on the top piece, at one end rather than centered, and the other should be cut from a wall piece that will sit on the opposite end of the box from the top one. Then, lay your box pieces out on your flat workspace with the four walls surrounding the top.
Step 4 - Add the Vinyl MLV Insulation
The key to good insulation is adding layers of free space that allows the sound to dissipate. The best materials for this are those that minimize sound by the same principal and are layered for added effect. The first layer you want to add should be made of vinyl MLV (mass loaded vinyl). Cut it to size and glue it directly to your soundboard.
Step 5 - Caulk the First Layer
Use special acoustical caulking mix to seal the edges of the vinyl. Regular caulk will do the job, but will not be as effective when it comes to soundproofing.
Step 6 - Glue on Foam Mat
Foam matting made of closed cell vinyl nitrile will be ideal for the job; you can find it at your nearest home improvement store. Again, cut it to size and glue it directly to the vinyl layer, caulking the edges once more to complete your insulation.
Step 7 - Put the Box Together
It's time to finally assemble your enclosure! One by one, attach all four walls together using nails or screws. Then, you can permanently secure the top in place with nails as well.
Tip: Some made opt for a design with a hinged top for easier removal of a smaller generator. However, your vents will have to be done differently, as the hoses will present an obstacle.
Step 8 - Install Venting Ducts
It is very important to supply air and proper ventilation to the generator for it to properly function. Combustion is impossible without air, and a lack of it will cause the generator to heat up to potentially dangerous levels. When venting exhaust from a soundproof box, use venting ducts with lots of bends in them; since sound waves travel in a linear path, bending and curving will cause sound to lessen.
Thread the hoses into the holes you cut earlier and then secure them in place. A small vent should be placed over these openings as well.
If you like, there specialist soundproofing materials that you can use. These might be costly, but they are extremely effective, used in marine equipment to totally deaden sound. Rock wool and plaster boards are common examples. Another option is to go for two insulated boxes with a few inches of space between.