When old walls are a mess, install new drywall

Q. The ugly walls of a wood frame house built in 1920 have cellulose insulation, lath and plaster covered with old, cracked wallpaper and multiple layers of lead paint. How should they be fixed?

A. The easiest solution would be to cover the walls with three-eighths-inch drywall. That would take care of all the issues.

Q. Could you give me some advice about painting basement walls that are about two-thirds underground? They were badly mildewed, so I washed them with trisodium phosphate and bleach. Then I plugged any holes I saw with Fast Plug. Now I want to paint them. I was looking at Drylok Extreme, but the salespeople keep telling me to use another brand, as the warranty won’t be valid because the walls had already been painted. I don’t care if the warranty isn’t valid, as I just want to do a good job.

Also, water is coming in where the wall meets the floor. I put Fast Plug there, too, and am waiting for some rain to see if that helped. The house has a steep roofline, smallish gutters and two downspouts on the side where the water comes in. The house sits on a slope, also a contributing factor. Would a French drain help? This house is in western Pennsylvania and has a sister house that has no gutters on the problem side.

I’m preparing the house for sale and want to solve some of these problems for the next owner.

A. I assume your basement walls are made of cinder blocks or concrete blocks instead of poured concrete. If that is indeed the case, I would recommend you not apply any waterproofing coating on them.

You mention water comes in at the joint of the walls and the floor and that you put in Fast Plug to seal it. But if water is prevented from leaking in the basement, it will build up in the walls and cause serious problems in the living space as it evaporates. Years ago, I consulted on a small apartment building that had to be vacated and gutted because of that very problem.

You should try to address the leakage issue. If the slope drops toward the house and only surface water from the slope is causing the leakage, a swale can be built a few feet from the foundation to catch the water and lead it around the house. If leakage occurs a day or two after a substantial rain, the water may be following an underground ledge. In that case, a French drain may be needed to capture it and direct it around the house.

In either case, make sure the ground slopes away from the foundation on all sides and that the discharge from the two downspouts is also directed away. Often, water from downspouts swirls around, stays close to the walls and percolates along them, causing problems.

Once you have the leakage under control, if you insist on painting the walls, use a non-waterproofing paint and be prepared for the possibility that it may peel.

Q. My garage is a single-car integral garage, so one of the walls is toward the basement side of the house and the wall is not cold. The wall to the front of the house is 12 feet long and under grade. The side of the house is 25 feet long, and I would say about a foot is under grade. That wall is very cold. The other wall is the garage door, and it is insulated.

My question is: What kind of insulation is best for the ceiling, and which side does the vapor barrier go on if a vapor barrier is needed?

A. Assuming there is conditioned space above the garage, fill the entire depth of the ceiling joists with the appropriate thickness fiberglass with the vapor retarder facing up. Then install fire code gypsum board, taped and painted.

If there is no finished space above the garage, use whatever R-factor you want and staple the insulation by its flanges to the bottom of the ceiling joists — vapor retarder down. Then cover the insulation with fire code gyp board.

Q. My wife and I purchased a townhouse about seven years ago. The house has a cathedral ceiling with about a 2-foot space above the ceiling. During the winter, a moisture line appears in the ceiling along one or more drywall joints.

The homeowners association had a roofer out, and it was first believed that snow and/or rain was blowing in through the ridge vent. The vent was replaced with a newer-style vent when a new roof was installed. (All of the units received new roofs as a result of storm damage.) The ceiling was repaired and painted.

The next winter, the problem returned. The contractor then proposed installing another vent system in the roof, which neither I nor the association believes will solve the problem. It is my opinion that the moisture is from condensation under the insulation. What is your opinion? Should I call a roofer, insulation company or other?

There is another problem in the ceiling. It is a crack that opens and closes with the changes in season. Any advice would be greatly appreciated.

A. Unfortunately, the photos you sent are small and do not show the locations of the problems. It would have been helpful to see where they are in a photo showing the entire ceiling. But I’ll try to help.

One photo shows what looks like a scissors truss roof — steeper chords supporting the roof deck and a shallower set of chords supporting the ceiling finish. If the drywall tape joints have separated, moist, warm air can convect through them and wet the insulation. There may come a point at which the condensation runs and shows up through those joints.

Since you have access to the attic, feel whether the insulation is wet in the areas above the wet joints. Solving this problem will help improve the insulating value of the fiberglass, as wet insulation loses its properties.

Retape the drywall, paint it and see if that resolves the issue. If it does not, you may need to call out a person well-versed in this type of problem — an energy auditor, an experienced home inspector, a general contractor or an engineer.

There may be more avenues of convection of the warm, moist, conditioned air, which may result in condensation on the roof sheathing. Unfortunately, the photo of the attic does not show enough of the sheathing to see if this is a serious problem, but I can see water stains on the sides of one truss chord.

Snow and rain penetration through unbaffled ridge vents is common. Ridge vents should have an external baffle over them to deflect rain and snow and not let either of them penetrate or plug their openings. Unfortunately, few brands offer such a feature. One of the earliest to do so is what is now Shingle Vent II.

The seasonal cracks in the ceiling drywall are caused by what is known as the rising truss syndrome. In the winter, trusses arc up, causing a separation between walls and ceilings. Summer brings the trusses back to normal, and the cracks close up. The solution is to install a molding fastened only to the ceiling so it can move up and down with the seasons. Your photo is not clear enough for me to see for sure if that is your problem, but it’s a reasonable assumption considering that it is a fairly common problem with trusses.

Q. In the winter, we use two ultrasonic humidifiers to keep our house from getting too dry. We started to notice that all glass in the rooms where they operated were forming a film. The windows looked filthy the day after they were cleaned, and eyeglasses left in the rooms also developed this film. Turning off the humidifiers stopped the film from forming, and it does not form in any room that does not have a humidifier. The film wipes off easily, but it is not dirt — it does not show up dark on the rags used to clean the glass. One of the humidifiers is new, so it can’t be filters, and the two are different brands, so it can’t be the brand. We think it’s in the water. Any ideas?

A. You may be the victim of “white dust” — calcium and other minerals in the water that is deposited on any surface as water evaporates.

The solution is to use distilled water or demineralization cartridges, which are available for ultrasonic humidifiers.

Vermont reader’s innovation: “I read in today’s Burlington Free Press about soaking toilet paper with bleach to eliminate mold on bathtub caulk. I’ve done the same thing, but I used cotton balls or pieces of rolled cotton instead of TP. It works great, doesn’t disintegrate and stays in place with no problem. Love your column!”

Thank you for what seems like an improvement over the toilet paper trick. I can always count on one of the readers of this column to teach me a few tricks.

Ÿ Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at henridemarne@gmavt.net.

© 2012, United Feature Syndicate Inc.