Insulation For Your Home - Moisture Control

Part 3 of 3 - Vapor Barriers and Installation Tips

Vapor barriers... to use or not to use? THAT is the question!

Moisture within the walls of your home can cause serious problems.  In the colder months, moisture tends to move from the inside to the outside of your home.  As it passes through the walls, it may condense within them, causing the potential for rot and mildew.  In walls with insulation, the water may condense within the insulation decreasing its R-value.  In the worst case, moisture can actually freeze within the walls, accumulating until a thaw melts it and causes visible damage to your home such as wall or ceiling staining!

A vapor barrier is designed to keep moisture in your home from getting inside your walls.  As mentioned earlier, batt and roll insulation come with a vapor barrier attached.  However, leakage can occur where the facings meet.  This is especially true if you do not staple the facings to the front of the studs, but instead either just press the insulation into place or staple it on the inside of the stud... a common practice with foil faced insulation.  For the best possible vapor barrier, supplement the facing by installing a 4mil or thicker plastic tarp over the entire framed wall before tacking up the wallboard.

Attics present a special problems for vapor barriers!

Consider this... in the winter, there is a constant rising of heated air in the home.   This warm air carries large amounts of moisture which attempt to pass through the ceilings and walls.  To completely stop this movement of moisture is ludicrous... it will find a way out!  So it is thought that it is better to allow some of the moisture to escape into the attic area.  If your attic is properly ventilated, the moisture will quickly be removed by the circulating fresh air with no harm to anyone... you, your home... or your pocketbook!  Using a kraft paper faced insulation laid between the ceiling joists... paper facing down, of course... will provide a slowing of the vapor movement without completely stopping it.

Vapor barriers are generally not needed in climates where the temperature is normally above freezing. Having a vapor barrier is not a negative... it is just unnecessary.   Consult with your local building supply store or building inspector if you are unsure whether you need one!

Installing insulation... wisely!

Installing insulation is easy and quick... probably the easiest part of any renovation except for laying on the chaise lounge after the job is done.  OK... installing the switch plates may be a LITTLE easier.  Anyway, as a do-it-yourselfer, you know (from reading the brilliantly written sections above) that your product choices are limited... either loose fill or batt, blanket and roll insulation.

In a brief format, I am going to tell you what you should know to install insulation wisely.  I say "wisely" because the mechanics of insulation installation are simple.  Unroll the batt or blanket.  Press it into place.  Unfold the edges of the facing and staple it in place, if necessary.  Done.

But it is the little things... the finesse if you will...  that makes a simple job a great job.  If you follow these guidelines, you will get the best insulation bang for your buck and minimize the chances of insulation related problems.

Special insulation considerations for attics...

Problems insulation and vapor barriers can cause...

As many benefits are there are to insulation, there are also skeletons in the closet.   I have been asked many times over the years about unusual mildew growth on walls and ceilings or wet areas on walls where there is no apparent roof or plumbing leak.   Since these events occur only in the winter months, the obvious culprit is a poorly planned or poorly installed insulation/vapor barrier system.  Unfortunately, this can be a problem without an easy fix; cutting open the walls may be required to find out just what inside the wall is causing the problem.

To complicate the situation further, there may be culprits on the outside of your home, too.  Oil paints are natural vapor barriers and they can cause moisture that would normally pass through the wood siding to linger and condense.   Blistering exterior paint is a sure sign of moisture within the walls... yearning to be free!

Oh, your house has artificial siding?  Well, aluminum or vinyl siding installed over a non-breathing insulation board can also be a suspect here, decreasing your home's natural ability to breathe.

Before you get the wrecking ball, here are a few less expensive things you can try.

Visit these websites for more information...

Owens Corning, at, has a wealth of information on installation of their fiberglass and plastic foam insulation products.  Love that Pink Panther... even if he has become crassly commercial!

GreenFiber, one of the leading producers of cellulose insulation, makes their case for cellulose's superiority.  One interesting twist is that they use some recycled paper and wood products in their manufacturing process, making their "fiber" even more green.  You be the judge, at

If you are interested in insulating foam... polyurethane to be precise... visit North Carolina Foam Industries website at   They not only product foams for insulation, but also for mattresses, roofing and marine floatation.  Amazingly enough, their foams are used to insulate the fuel tanks of the Space Shuttle!

To read Part 1, click HERE!           To read Part 2 click HERE!