Humid summer air could make ceiling repairs unnecessary

Q. I live in a small ranch built in 1989. Recently I've noticed nail pops in most of the rooms in my house. They appear on my ceilings and walls and follow straight lines down the walls spaced about 14 inches apart. Do all these nails need to be removed and replaced with drywall screws? Are the nail pops on my ceiling more serious and will they get worse? I'm not good at spackling so I'll probably need to call in a professional, but not until I receive your response.

A. If the nail pops are only a recent occurrence, they are likely due to a very cold winter and excessive dryness in your house. This has caused the framing to shrink slightly, and it is not unusual.

You may find that the humidity of summer may take care of it. If it does, you should consider increasing the relative humidity (RH) in your house next winter. The ideal is between 35 and 40 percent RH, but that may also result in condensation on your windows if they are not as efficient as they should be, although on a 1989 ranch, your windows should be OK if the builder was conscientious.

If summer does not take care of it, either the nails can be replaced with screws or driven in. In either case, repairs will be needed.

Increasing insulation in the attic may be worth looking at. Depending on where you live, a minimum R-factor of 40 - more in a cold climate - would help keep the ceiling joists warmer.

And if you plan on residing your exterior walls anytime soon, consider having 1-inch thick rigid XPS (blue or pink) insulation carefully applied over the existing siding (if possible) or the sheathing after removal of the old siding.

After the new siding has been applied over the rigid insulation, your exterior walls will be warmer, your comfort increased and your heating (and air-conditioning) bills will be lower, while you also are helping our suffering planet.

Q. I have wooden sliding patio doors. These "French" doors have wooden grilles that are held in place by stainless steel clips, which are set into the surrounding frame and grip the edge of the grilles to hold them in place. I would like to purchase more of these clips, but I can't find out who manufactured the doors. I've sent you a front and back image of the clips. I am hoping you might know where I could secure these clips or what brand of door they may be.

A. Contact Blaine Window Hardware Inc. in Hagerstown, Maryland. The toll-free phone number is (800) 678-1919, and the company's website is at www.blainewindow.com.

If anyone can match what you need, it is Blaine, and the company stocks thousands of parts. You will be asked to send a sample or, perhaps, simply a photo.

Q. About 13 months ago I had my hardwood floors replaced with Brazilian teak cumaru hardwood. While the wood is beautiful, there are numerous spaces between the boards - some very, very noticeable. The installer brought a humidity gauge and some magnets to check where the nails were placed. He said the humidity in the house was too low (16 percent), and that it would affect the boards. Really! The previous maple hardwood floor had no separations. How many people out there have a whole-house humidifier? I do and have since then had it replaced and the humidity in the house is now 30 percent to 35 percent. My question is this: What course of action can I take regarding this problem? The installer will do everything he can to avoid this issue, and I want the floor to look as it should: tight. If I were to try to sell this house in the future, this would be a problem. The floor covers the living room, dining room, kitchen, office, entry, hall and morning room. Please help.

A. When the new floor was installed in February of last year, were the boards tight?

Hardwood comes with a certain moisture content if properly stored by the dealer. It is conceivable that once installed in your house with a very low relative humidity (RH), the boards began to separate if they were not stored properly for several days in the rooms in which they were to be installed to acclimate them to the RH in your house at that time.

What happened last summer? Did the separations close up? Or do you have central air-conditioning that would also keep your home's RH low?

The boards may swell up again with the summer's humidity if you allow them to do so with natural ventilation.

If the boards were originally installed with gaps - hard to believe with experienced installers who would use a pneumatic gun that tightens the boards together - a serious mistake was made.

In that case, if you can prove it, it may have to become a legal matter.

Q. My question today concerns the roof on our summer cottage. The cottage is not insulated and is closed up from October until April with no heat.

In the past 10 years, I have replaced the roof on the back portion of the cottage (which is an addition, also not insulated or heated) three times, and that does not include constant patching. I have done the work myself, following all the guidelines for our area.

As you can see in the pictures enclosed, the roof does not have a steep pitch (only 16 inches over 12 feet) so I have used rolled roofing, which seems to dry up, shrink and begin to crack within a year after it is applied. Within two years of applying it I have leaks, usually where the main roof transitions to the back section. I have had the same problem with the roof on the enclosed porch on the right side of picture No. 2.

I have asked a couple of contractor friends for ideas on a solution, and both recommend rubber membrane under the roofing. One says to put shingles (which, of course, will last longer) over the membrane and the other says to stick with the rolled roofing because of the pitch of the roof.

I would greatly appreciate your thoughts on a solution for this annoying problem.

A. The photos you sent appear to show a greater pitch than you mention. The measurement of the roof should be taken from the connection with the house to the outside wall of the porch and addition; the overhang should not be counted.

I conclude this by counting the number of clapboards where the enclosed porch, which seems to have a sizable overhang, is attached to the main cottage. The roof on the addition does look like it has less of a pitch.

Roll roofing is not a lasting roofing material, but yours has had more problems than it should. And it looks as though you didn't quite get the connection of the main roof and the roofs with roll roofing done right; that is not easy to do, so don't feel bad about it.

Black roll roofing is more subject to the stress of the sun than a lighter color would have been.

The best solution is to have an experienced roofer or general contractor install a synthetic rubber membrane over a soft underlay. It takes experience to tie the membrane under the main cottage's shingles, where you have had the most leakage.

A soft underlay is needed with rubber membranes to prevent them from chafing as they expand and contract under thermal stresses.

If XPS rigid insulation (blue or pink) is chosen as the soft underlay, the rooms below these roofs will be more comfortable on sunny days and as the temperature drops in the fall. It would be a mistake to put more roll roofing or shingles over the membrane; it would punch holes through it.

An alternative is to apply a product like Grace's Ice & Water Shield on clean, bare sheathing. It seals itself around nails and must be covered with shingles.

I would not use roll roofing under any circumstances.

Q. We have a red brick chimney on the side of the house. We bought the house in the fall and there were no white marks on the chimney.

This winter, white marks showed up and look awful. They cover about a third of the chimney. We would like to know how to get rid of them and how to prevent recurrence.

A. These white marks are very likely to be efflorescence. Efflorescence is the dissolved salts in most masonry products left on the surface when the water that brought them to the surface has evaporated.

If they were not visible when you bought the house, I suspect the sellers had the chimney cleaned before putting the house on the market, a pretty normal thing to do when you are selling a house in order to make it look its best. It is not a defect; it is a natural process.

The question is how did the bricks get wet to have the water dissolve the salts? It may be that there was a lot of rain and the bricks are absorbent, or it may be because the chimney is unlined, and is used as the flue for a heating appliance. The combustion gases condensed on the chimney walls and penetrated the bricks, dissolving the salts.

Efflorescence is usually very easy to remove; it can simply be dry-brushed off or, if stubborn, brushed off with some water.

If the problem is external, the bricks can be sealed with a siloxane-based coating, but it is not going to help if the efflorescence is caused by the gases from an unlined chimney. Lining the chimney should take care of it.

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. His book, "About the House," is available at www.upperaccess.com. His website is www.henridemarne.com. Email questions to henridemarne@gmavt.net, or mail First Aid for the Ailing House, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.

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