We've upgraded the basic generator soundproofing info from the book: "Quieting: a practical guide to noise control". The new system is shown below. It is based on the fact that air will go around corners well, whereas sound doesn't like to. This baffling method works well for pool pumps and many other kinds of noise sources.
Enclosure is best made of panels of "Soundboard" or "Homasote" (from the hardwood store), with corner support strips of wood (not shown). screwed, (not just nailed) and glued for strength. Plywood is not recommended because wood transmits sound so readily. "MDF" Medium Density Fiberboard is best. A lined, triple wall box as shown is the most effective, but sometimes a double box may work well enough, depending on the level of sound control needed.
For maximum effect, use the 2" thick "Super Soundproofing Mat" for lining your box. Make sure the box is entirely covered: no gaps. Cement edges for a tight fit. If in a damp environment, use our contact cement as it has a mildew resistant retardant in it. See the "Prices" page for ordering and price info. (On the sidebar). Cut strips of mat for the airtight seal for the bottom edge.
Leave about an inch between the inner and outer boxes for air circulation.
Lead or mass loaded vinyl can be attached over the box for even more sound control. Edges must be sealed! Use lead tape and the non-hardening acoustical caulk available on our prices page.