Breaking News Bar
posted: 5/28/2017 6:00 AM

Creating a vapor barrier in a basement

hello
Success - Article sent! close
 

Q. My wife and I are in the planning stages of finishing off half of our basement into a couple of bedrooms, and a small living/TV room. I am concerned about water and water vapor creating that mildewy basement smell once all of the construction is complete. To that end, before we start I am addressing any water entry into the basement, to which I believe I have been successful.

So that leaves water vapor. Our foundation is poured concrete with footing drains, and a coating of emulsifier on the outside. I now run a dehumidifier 24/7 in the basement during the summer months to control the humidity. We will be insulating the exterior walls of the basement on the inside. What are our options for doing this (including any necessary wall coatings) that will give us a vapor barrier ranked best to worst in your opinion.

For extra credit, I've seen on HDTV a certain program about siblings remodeling a house, and one of them, let's call him "the builder," insulates interior basement walls with straight unbacked fiberglass insulation. Is this a West Coast thing, and even allowed here in Vermont?

A. I assume you have corrected any grade issues that would encourage basement leakage. Don't count on the emulsifier coating applied on the exterior of the foundation walls to prevent leakage; it's not foolproof and loses any effectiveness over time.

Once you are positive that potential basement leakage has been taken care of after being subjected to several severe rains and one significant snowmelt, the only concern is a high relative humidity (RH) that would cause the mildewy smell of which you are rightfully concerned.

High RH is common in basement rooms. Your running a dehumidifier in the summer is the best strategy, and you might need to continue doing so after the construction is finished.

Be aware that building codes require means of egress from below grade bedrooms. This could be a problem when you sell the house; a qualified inspector would have to flag it.

If you are positive that the footing drains are properly functioning and you know the foundation backfill is made of well-draining, coarse material topped by good soil gently sloping away from the foundation and planted with grass (no shrubs or flower beds within 4 feet), you can safely insulate the foundations walls from top to bottom.

But if you are not sure, only insulate from the top of the basement down to 3 feet below grade in order to let some heat convect into the soil outside to keep frost that could damage the walls from penetrating too deeply.

There is no need to coat the inside of the concrete walls if you have not noticed any dampness on them following persistent or heavy rains and snowmelt.

One good insulation option, if you are planning to do the job yourselves, is to apply 2-inch thick XPS (extruded polystyrene -- Styrofoam and FoamulaR are the two major brands) to clean concrete walls with dabs of Styrobond or polyurethane caulking. Make sure the walls are thoroughly vacuumed to remove any dust, apply the adhesive every 2 feet and firmly press the insulation into the adhesive.

Then build a 2-inch by 4-inch partition, set on a pressure-treated plate, tight to the foam. This will allow running electrical wiring as required by code and any hydronic piping for baseboard heat, if that is your choice. A licensed electrician and a master HVAC contractor are needed for these phases.

Once the wiring and heat piping are in, you can add R-11, R-13 or R-15 fiberglass, stone wool or cotton insulation.

Fiberglass (batts or blanket) is the most common and economical. It comes in several forms: unfaced, foil faced, Kraft paper faced. Choose the type that itches the least. Use gloves, skin and eye protection and an effective mask. Wash your clothing and shower afterward.

Roxul is made from rock and is the best for soundproofing and fire resistance. It is now widely carried in big box stores and some building supply stores.

Cotton insulation is made from recycled jeans and is more expensive, ecologically better, but harder to find.

Be sure you do not compress the insulation behind or in front of pipes and wires. Split the insulation and work half of it behind these pipes and wires and place the other half in front.

Finish with drywall. Even if you have central air-conditioning, you may still need to use your dehumidifier or provide a modicum heat even in the summer.

Q. My wood floors are oiled with liquid wax -- what do you recommend for cleaning?

A. The most important thing to do is to vacuum the floors weekly as a minimum to remove all dust, etc.

A gentle wipe with a clean cloth dampened with clean water is also recommended.

But the best way to maintain your oiled wood floors is to spray them with Bona Cleaner For Oiled Floors. Then, wipe them. Best to do so weekly.

Q. My home is 75 years old, well built and well kept, with hardwood floors covered with carpet. During all these years I have never heard the floor squeak as they are doing now, all over the house. Has my house been too humid or too dry causing this or is it something else beside being old?

A. It is more likely that dryness is causing some shrinkage resulting in squeaking.

Did the squeaking start this year after the heating season started? If so, it may stop once the damp summer air replenishes the floors' lost moisture. If this is what happened, you may need some humidification for next winter.

Q. I need to replace my gutters and the fascia underneath. I read your article about commercial gutters, and that is what I will buy. My question is, what is the best material to use for the fascia?

A. You can either use one of the composite materials for outdoor use or use a wood fascia, pre-paint it and cover it with white aluminum coil-stock.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of "About the House with Henri de Marne" (Upper Access Publishing). He takes questions from readers for this column on his website, www.henridemarne.com, or email questions to aboutthehouse@gmavt.net.

Article Comments ()
Guidelines: Keep it civil and on topic; no profanity, vulgarity, slurs or personal attacks. People who harass others or joke about tragedies will be blocked. If a comment violates these standards or our terms of service, click the X in the upper right corner of the comment box. To find our more, read our FAQ.