To enclose portable generators, build an insulated enclosure using cement blocks, fiber board, foam, rubber mulch bags and construction plastic. Cover the cement blocks with plywood, and attach foam to the plywood to create an additional layer of insulation.
Begin enclosing portable generators by digging a hole around 1 foot in depth and about 1/2 feet larger than the shelter using a shovel. Place construction plastic at the bottom of the hole and place approximately 10 to 11 rubber mulch bags over the plastic to fill the hole. Alternatively, use cut tires for this purpose.
Position cement blocks on the mulch bags so that the sides of the blocks are touching. Use blocks that measure 15 inches in length, 7 1/2 inches in width and 3 to 4 inches in thickness. When correctly placed, the cement blocks should look like a floating deck.
Rest a fiber board over the blocks. Ensure that the board is stable. Position the generator over the board. Place 10 cement blocks each, five per row, on the sides and rear side of the generator. Insert foam in the cracks of the blocks.
Cut plywood into strips of suitable size, and nail them to the cement blocks. Cover all the blocks in this manner. If desired, attach foam to the plywood strips using glue before nailing them to the blocks.