Those Stains on The Basement Walls

Dear NH,
We have a 55 year old house, with a 3/4 in-the-ground basement. I would like to put up finished walls. However, the basement has a moisture problem with efflorescence. I have treated the efflorescence with muriatic acid, with Zypex and with bleach at different times through the last few years but the efflorescence keeps coming back. The basement has good ventilation and we intend on putting radiant heat in the floor. The basement is used year-round and is kept very warm in the winter. If I treat the efflorescence once again and dry out the walls, can I put up the vapor barrier, then 2x4 walls with insulation?

As I know you know now, from experience, efflorescence is a mineral deposit caused by the migration of mineral-rich water through your basement walls. In new concrete work, efflorescence can be a short-term problem that may disappear over time as the new walls dry out. However, if this is a long-term problem there are two possible ways to eliminate it.

Removing all traces of the efflorescence by scrubbing and cleaning with muriatic acid (most dangerous) or phosphoric acid (less dangerous), drying the walls (they do not have to be totally moisture free... just not wet) and applying a quality below-grade cement-based waterproofing paint will definitely diminish and may even eliminate the problem. Be warned... if other sealers or paint products have been applied to the walls, there is the possibility that the waterproofing paint will not adhere and the results may be disappointing.

You need to keep in mind that these waterproofing products are not designed to stop flowing water. Actual leaks must be stopped either by sealing them inside with a concrete patching compound (with a high risk of eventual failure) or doing some more labor-intensive work outside your home. The solution could be as easy as cleaning your gutters. Then again, it could require diverting the water through regrading (if the source is surface water) or even installing a drain system at the base of your foundation. A professional evaluation might be advisable so you can assess all your options. Perhaps the best book on this topic is available in our bookshop. It is The Original Basement Waterproofing Handbook by Jack Masters. You will know as much about your foundation and ground water movement as many of the waterproofing contractors you will speak to!

Once you have eliminated most of the moisture moving through the walls, then and only then can you install your vapor barrier and walls. Yes... even after the waterproofing steps you must still install a vapor barrier because there will still be some low level of moisture movement through the walls. You don't have to worry about mildew... the vapor barrier will form a "stabilizing zone" that will not promote mildew growth... there is nothing for the mildew to feed on!

On the subject of basement walls, there are a few basement wall systems that are both time and labor saving alternatives to standard 2x4 framing. One is offered by Owens Corning and features wall panels with insulation and channels to run electrical, telephone and cable TV wiring. Check it out at Owens Corning .

Dow Chemical offers a somewhat different system, using specially slotted 2'x8' Styrofoam panels that can accommodate a 1"x3" nailer... suitable for the installation of wallboard. Using "green" water-resistant wallboard... at least for the bottom half of the walls... would be advisable. The one drawback to this system is that all your electrical wiring must be on the surface... visit your local home store for the scoop on surface wiring systems. Ain't competition grand!

Don't throw away your dehumidifier. Any below grade area that is anything less than swimming-pool-sealed will have some moisture leaks... especially in the warmer months... and a dehumidifier will keep the air moisture level acceptably low. Again, and I can't reiterate this enough, you are doing this to protect your property and your investment in what will be a wonderful renovation!

If you don't take these extra steps you will regret it. I have seen too many basement renovations that did not take into account the damaging effects of moisture and I have taken roomfuls of once-nice furniture to the dump because of permanent mildew damage. You have to be proactive so that you not only keep the value of your home but increase it through wise use of your hard-earned money!

© 2000 G.G. Alonzy

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