Many of the building codes these days require that basements be insulated to just below ground level. In this way the bare cement on the walls is covered to below the earth and therefore the heat will not go out into the air. This is sound thinking to a point. The part that isn't brought up is that, regardless of where the cement is facing it will always take heat from the home.

This includes the cement floor. In a recent government study it was concluded that basements are responsible for between 20% and 35% of a homes total heat losses. In addition to the fact that earth has a poor insulation factor the shrinkage of a home's wood structure after time will produce minute cracks which will let cold drafts into the home through the top of the foundation wall and through window sills.

Basement Design

Old Basements: Since they were first introduced as part of the home's foundation basements were usually made from rock, either dry-stacked or mortared. Brick was also a prime choice. Many of these stone basements are still in existence although, unless parged, will allow water to get into freely

Concrete Basements: Poured cement basements have been around since the 1920's. They are made with forms placed on a concrete footing and the concrete is poured to produce walls reinforced with steel rebar. Many homes do not have basements, but are built on a pad (slab on grade), and still others have a partial basement or crawl space.

Wood: Newer basements in the dry areas of the country are being built out of preserved lumber. Although a strange concept they work very well. They are warmer and and do not have the condensation problem of concrete.

Before Insulating a Basement

Check Water Flow: The origin of many basement problems is ground water. If the walls get damp and water seeps in through the seams in the foundation it would be a good idea to first check the gutter system and make sure that the troughs and downspouts are operating correctly. In addition check the water flow around the home after a rain and make sure that it is draining off the property and not pooling in hollows. Correcting this problem may be as simple as digging a trench and putting in 4" perforated pipe to collect the water and steer it away fro the home. If it is really bad you will have to digg around the foundation and put in drain pipes.

Consistent Dampness: Besides the mold and mildew smell you can identify dampness by white mineral deposits. This could be corrected by steering the ground water away from the home. It may also mean that there is not enough air flow getting into the basement and this can be corrected with a ventilation system.

Cracks: Both concrete walls and floors can crack. This was due to the shrinkage of drying cement when the home was built or the movement of the home when settling. These should be addressed by a professional crack sealing company before any insulating.

Insulating the Outside Walls

If you are going to excavate to put in drain tile this would be a great opportunity to insulate from the outside. In this way you can seal the home and prevent the cold of touching the foundation. A waterproofing membrane can be put over the walls and down over the foundation. Then rigid foam insulation can be attached over this and, finally, a protective covering. Then the area can be backfilled. What this does is to seal off the whole foundation from the outside and turns the concrete walls into a thermal mass. This means that the walls absorb heat from the basement and, instead of it going outside, the insulation stops this and the heat is transferred back into the home. This is a very efficient system.

Insulating the Inside Walls

There are several ways you can insulate inside depending on how you want the inside finished.

1. Stud Frame and Fiberglass: This is the standard way of insulating. The wall is framed with 2' X 4' studs and the spaces are stuffed with fiberglass batts. Then vapor seal is stapled over this and the wall is sealed with caulking. Finally the drywall is installed. This will provide up an R-value of up to 14.

2. Stud Frame and Rigid Foam: The wall is framed and rigid foam sheets fill the voids. The R-value is similar but there is a lot of cutting required. As well the foam is more expensive but it will not get soggy if there is condensation.

3. Stud Frame and Closed Cell Foam Spray: Foam is great because it gets into every crack and seals the wall entirely. A 2" foam covering is equal to R-15 or what fiberglass can give. There is no need for vapor seal or caulking as there will be no cold drafts coming in after it is sealed.

4. Rigid Foam and Strapping: Rigid foam is attached to the concrete wall with cement bolts and then 3" strapping is put in the grooves for the attachment of drywall.

5. Soft Foam: This product is malleable with a smooth surface and usually used for walls that will not be finished with drywall. It is expensive but can be attached to the concrete and then the cracks filled with caulking. It can be as high as R-12.

6. Close Cell Foam Spray: For non-finished basements this can be applied to the cement walls and then spray painted. It will seal off the wall and provide up to R-15. Whatever type you choose you will get noticeable savings in energy.

Sealing Windows and Doors

Check the window jambs in the basement and use a can of expanding foam to seal any holes. If there is an outside door in the basement check the weatherstripping to see if there are any leaks. If the wind comes from that direction you might want to look at putting an on a storm door as a wind break.

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