Home Improvement : Foam Blocks Offer Easy, Insulated Construction

QUESTION: I want to build a super-insulated house with very low utility bills and do much of the work myself to lower the costs. What type of construction can I use that does not require expensive equipment?

ANSWER: One of the most energy-efficient do-it-yourself construction methods utilizes snap-together hollow foam insulation blocks. It is very easy to build yourself and produces a highly insulated and airtight house with low cooling and heating bills. When finished, these houses look conventional.

Once you snap all the foam insulation blocks together to form the foundation and walls, you slip standard steel reinforcing rods in the cavities. Then concrete is poured in the hollow cavities.

The concrete flows throughout all the cavities and forms a solid monolithic insulated concrete wall. The finished wall insulation values range from R-20 to R-30 depending on the specific design of the foam block.

Each foam block (usually made of expanded polystyrene foam) is roughly 10 inches square by 40 inches long and weighs less than four pounds. The blocks for an entire house weigh only several hundred pounds.

In addition to low air-conditioning and heating costs, high strength, and insect resistance, these houses are very quiet. The combination of heavy concrete mass and foam on both sides stops much of the outdoor noise.

Another energy advantage of a concrete/foam block house is the thermal mass of the walls themselves. In the summer, the heavy concrete mass in the block cavities moderates the indoor temperature rise as the outdoor temperature rises during the day.

You can finish the interior by gluing drywall directly to the interior foam insulation surface with a special adhesive. The exterior can be finished with stucco, siding, brick or stone.

For exterior siding, nails are pushed through the foam block from the inside hollow opening before the concrete is poured. For a brick exterior, ties are pushed through the foam insulation as with the siding method.

Another similar type of construction uses larger hollow foam blocks that are made of a mixture of 10% concrete and 90% foam beads. Since the concrete adds strength to the blocks, recycled foam material can be used.

This special concrete/foam mixture is still very lightweight, only about 37 pounds per large wall section. These types of blocks also provide exceptional fire resistance. Once the wall panels are stacked together, concrete is poured into the cavities.

You can write to me at the address below for Utility Bills Update No. 384 showing manufacturers, addresses and telephone numbers for do-it-yourself insulating concrete/foam blocks and for construction details and specifications. Please include $1 and a self-addressed stamped business-size envelope.

Conditioner Can Bring Fresh Air Into House

Q: I would like to get some fresh air into my house. Does it make sense to hook an outdoor inlet duct to the air return system for my central air conditioner and furnace?

A: It does make sense and special duct dampers are available that are made just for that application. Check with your air-conditioning contractor about the proper size for your system. If it is too big, not enough air will be drawn from the room return registers for good circulation.

During the cooling season, only open the outdoor damper in early morning or late evening. Don’t use it at all during very humid weather.

Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.