Drf

Heat loss t'j rr

Rigid insulation t

Slab i

Slab

insulation

Left: Rigid foam insulation on the inside of the footing for a slab foundation doesn't do much to prevent heat loss at the slab perimeter.

Right: Adding 2 inches of closed-cell foam insulation beneath the slab and on the interior of the frost wall is a more effective thermal break and reduces heat loss.

previous slab, but eventually the boards become unusable. By then, they are covered with concrete and permeated with the chemical release agents that keep the concrete from sticking, so they can't be recycled.

Although the initial cost of alternatives such as plywood and metal forms is higher, they save the trouble and expense of replacing forms made from dimensional lumber. They also save good lumber from needless destruction. The release agents themselves are often a petroleum-based product or simply diesel—a waste of oil and a potential environmental hazard. Using a biodegradable vegetable-oil-based formrelease agent is better.

recycled wood for foundation forms

If you don't like the idea of the plastics that go into many types of insulated concrete forms, consider blocks made from cement-bonded recycled wood-chips—Durisol wall forms are one such product. They can be installed above or below grade, come in several widths, and are available with inserts of mineral wool to boost insulating values.

One advantage of the wood-block forms is their ability to absorb and release high levels of moisture in the air without damage and without supporting the growth of mold. Some or all of the wood fiber used to make them comes from postindustrial waste. From an insulating standpoint, they also perform well, ranging from R-8 for an 8-inch block to R-20 for a 12-inch block with a 3-inch mineral wool insulating insert. Blocks are dry-stacked and then filled with concrete.

improving concrete with fly ash

According to Environmental Building News, concrete production produces 8% of global-warming carbon dioxide. One way of reducing this number is to combine concrete with fly ash, a waste product from coal-fired power plants. Using fly ash has a double benefit: It not only provides a way of recycling fly ash but also reduces the amount of portland cement required in the concrete.

Fly ash is a difficult by-product to dispose of. What makes this marriage interesting is that fly ash bonds chemically with

Think Before You pour

In some parts of the country where full basements have come to be expected, foundation walls are typically 8 inches thick and rest on a 12-inch-wide concrete footing. But like oversized headers and unnecessary framing members, these heavy-duty foundations may simply be a waste of money and resources.

Fernando Pages Ruiz is one builder who thinks twice about the real value of building conventions and often finds a less expensive, more efficient way of getting the job done. His book, Building an Affordable House (The Taunton Press, 2005) details a variety of ways to reduce the cost and complexity of construction. By applying value engineering to foundations, he's found a number of options that are worth exploring:

• Reduce the thickness of concrete walls, at least for some parts of the foundation.

• As soil conditions permit, skip the footing altogether.

• Consider foundation alternatives, such as treated-wood foundations and precast foundations.

• Reduce the thickness of slab foundations.

Some of these alternatives may require soil tests or special engineering, and there's no guarantee that local code officials will embrace them. Yet the effort can pay off handsomely in the form of lower costs and a more efficient use of materials.

cement to make the concrete stronger, more water resistant, and more durable than a batch that uses portland cement alone. Typically, 15% fly ash is added to the mix to yield concrete with a compressive strength of 3,500 pounds per square inch—500 psi greater than a conventional concrete mix. In some parts of the country, fly ash is added to concrete at the ready-mix plant—the builder doesn't even have to ask

These insulated concrete forms are made with cement-bonded wood fiber and contain no plastics. With 3-inch-thick insulation inserts in the 12-inch blocks, the R-value of the wall is about R-20.

An insulated foundation becomes part of the house's thermal envelope, contributing to energy conservation and creating a more comfortable indoor environment.

These insulated concrete forms are made with cement-bonded wood fiber and contain no plastics. With 3-inch-thick insulation inserts in the 12-inch blocks, the R-value of the wall is about R-20.

An insulated foundation becomes part of the house's thermal envelope, contributing to energy conservation and creating a more comfortable indoor environment.

Insulated Concrete Forms & Basements

Insulated concrete forms (ICFs) all share a design that combines insulation and concrete to form finished walls. Some types are made with 2 inches of closed-cell extruded polystyrene on both sides of the wall, with spacers in between to hold the form together as the concrete is poured. The spacers do double duty by serving as screw bases for attaching finish wall materials on the inside and outside, to cover the foam. Some ICFs are stacked like blocks, and their internal cavities filled with concrete. In all cases, there is insulation on both sides of the foundation wall that keeps the basement warm and helps make the wall more water-resistant. The exterior surface in contact with the ground should still be coated with a waterproof membrane.

Courtesy Merten Homes

Insulated concrete forms are an easy way to build rigid foam insulation directly into foundation walls, making for much warmer finished spaces inside. Forms are made from foam or recycled wood waste mixed with cement.

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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