Concrete Slab Insulation: Under Slab vs Over Slab

Installing concrete slab insulation is a great way to save on energy usage, adds extra comfort and warmth, and increases the value of your home so that you have a higher resale value, or a higher value when refinancing or getting a loan. Installing insulation after the house is already built is an easy process, and when laying the foundation a solid layer of insulating sheets can be installed with the concrete slab, which is the most efficient route to go.

Under Concrete Slab

If the concrete slab has not been installed yet, it is an easy process to insulate as you build. Before pouring the concrete slab, add a layer of polyethylene sheets on top of the rock layer to form a moisture and water barrier, and then include a foam board layer, usually made from polystyrene, before the concrete is poured and allowed to harden. This gives an insulating barrier between the soil or rock and the foundation, which aids in interior climate control.

Over Concrete Slab

If the concrete foundation has already been poured and has cured, which is usually the circumstance, then several steps can be taken to insulate the slabs. First of all, on the outside of the walls, an insulating plaster can be spread on. After this plaster dries, a weatherproofing layer is then added over it.

Materials Used as Insulations

For insulating the inside of concrete slabs, foam board insulation is used. A weatherproofing layer of plastic is first installed next to the concrete, and then the framing is installed with a concrete gun, if you are finishing the walls, then the foam boards are cut and installed with the silver backing facing towards the slab. Secure the boards to the wall with glue to hold them into place. If you are hanging sheetrock, or other wall material, then you can go ahead and do so now. If you are only insulating the walls and not planning on finishing the walls, then you need to secure the foam insulating boards to the concrete slabs with the concrete nail gun. If you have any gaps, such as around electrical outlets or windows, be sure to use a spray foam insulator to completely weatherproof the slab.

Using Both Methods

If you want the maximum amount of insulation possible, it is best to follow the directions above and insulate the interior and exterior, which will ensure that energy is saved by allowing you to control the climate inside your home effectively. If you have not laid the concrete yet, then utilize all three forms of insulating that are available.

Applying these simple steps will not only increase the value of your home, but will raise the comfort level and lower your energy costs. Most homes built today are not insulated as well as they should be because it saves up front time and money, but if you have control over the construction stages of your house, or are remodeling on your own, then add insulation to all of the concrete slabs because it will improve many aspects of your home, as well as raise the quality of living.