Insulation 101

I wanted to write this article because my teams frequently find houses with insulation installed incorrectly.  If I can help you, the homeowner, with a few simple tips then you can troubleshoot for yourself, keep your home cooler in the summer and warmer in the winter, and save money!

Attics:

1.      If you are using blown insulation in your attic, do not cover the soffit vents.  You can purchase an inexpensive foam extender in any home improvement store that will keep the airway clear.  The airway allows the attic to draw cooler air from outside and so cools the attic.

2.      Attic vents only work if they have somewhere to draw outside air from. Either a gable or soffit vent will suffice.  It is of no use to install a power exhaust fan without a vent; it will just burn out from continuous use.

3.      Radiant barrier decking only works as per the manufactures specifications if it has a ½ air gap under it.  It will work with a reduced capacity if the air gap is smaller.  Older homes are often close boarded so unless you batten your roof first the reflective value is greatly diminished.

Walls:

1.      Insulation with paper (also known as “Kraft Faced Insulation”) is designed to be installed with the paper on the inside face.  That means the face that is against your sheetrock or interior surface. As your house breathes and the moisture travels through the wall, condensation forms at the junction of warm and cold air.  Paper on the outside face will get damp and grow mold. When insulating an old house from the exterior, care must be taken to follow this procedure correctly.  It is a common mistake to install the insulation in reverse, which leads to mold spores growing on the paper in the wall.

2.      Do not use any paper based loose insulation products in a house without a vapor barrier because it will grow mold.  Choose a cellulose product, preferably with a mold inhibitor.

3.      Spray foam works very well on new applications which have moisture resistant exteriors such as cement siding, brick, stone or composite shingles.  If you have wood siding or wood trim on the exterior of your house it can rot at an accelerated rate, because the moisture has no point of escape.

4.      If you have taken the trouble to open your wall, fill any holes before you insulate. Seal holes around wires, pipes and AC vents with handy foam first.  Those small holes will bleed hot and cold air 365 days of the year.

5.      If you are installing a foam board on the exterior of your new house, make sure it’s the right way around.  Once it’s covered up it’s too late to check.  Sheets from brand name manufacturers have instructions printed on them. Take the time to read them because your superintendent may not.

Floors:

1.      If you are lucky enough to have a pier and beam house, make sure your insulation is installed with the paper up (see “Walls” above, item 1). It grows mold if the paper is facing the exterior. It’s easier to install the other way but that is asking for trouble.

2.      Fill all those holes with handy foam before you insulate.

3.      Caulk around the bottom of your base board, or preferably caulk the bottom plate before base board is installed.

A final note: Exterior Details

There is an entire subdivision in Collin County that has large open joints where the brick meets the fascia and soffit on the attic gables. The gaps were so large on the home I inspected that I could put my hand inside. The location can only be viewed from the roof even though it might be directly over your front door.  Take some time to inspect your roof close up to find out if you may have similar problems.