Jim Rooney On The Level

Q. I have a situation that my husband and I cannot for the life of us figure out. We recently noticed a couple of what looks like water stains on our living room ceiling. There are a couple of straight ones, one about one to two feet long and one shorter one. There is also stains around where the ceiling fan is installed to the ceiling. What puzzles us is that there is a bedroom above the living room. It is unoccupied, we just use it for an extra clothes closet. There is nothing on the floor up there such as water spills, or an animal accident. We have an elderly cat and we frequently sit for the neighbors dog. It is carpeted in that room and there is nothing obvious to us like a spill of any kind. Certainly no leakage from the roof. Other facts about the house - it was built in 1984 and there is a dormer in that second floor room along with a small "under the roof" storage area. We do have a fireplace insert on the main floor in the living room that we use all winter long to heat the house. What should we be looking at and how can we figure out what this is and how to repair it?

A. What you are describing is commonly referred to as “ghosting” and is common in older homes or homes that generate slight soot emissions from candles, gas appliances, cooking, tobacco use and I think in your case we can look toward the fireplace insert with which you heat the house in winter. If you were to measure the distance between the stains you’ll discover that they are exactly under a framing member behind the drywall-- probably sixteen inches on center.

Very fine soot and dust particles float around in the household air exhibiting a random distribution and are attracted to the temperature differentials on the face of the drywall over the denser framing members. Sometimes the lines show the house frame in great detail, including wall studs and ceiling joists or the bottom of roof trusses. You can see a real time variation on this theme driving around the neighborhood in the morning after a frost or very light dusting of snow and you’ll see lines on the roofs that reveal the location of the rafters or trusses underneath the roofing.

Now that we think we’ve identified the cause the real challenge is what to do about it. The stains don’t seem to respond to washing, or at least they never have satisfactorily come off through washing for me, especially if they are on flat latex ceiling or wall paint. The only thing that really works is priming over them with a decent primer and repainting. Repainting with a washable latex paint might help with future efforts of stain control.

If you continue to do exactly as you have done in the past the likelihood the stains will reappear after you paint in the same locations is almost guaranteed. Controlling the speed at which they occur might be extended to coincide with your average or normal interior painting cycle of say seven to ten years.

Since your house was built in 1984 it’s safe for me to assume that you have a central air system. If, while you are operating the fireplace insert for heat, you set your heating system’s thermostat fan setting to ON to continue to forcibly mix the household air and run it through the best air filter you can get into the system you may go a long way to control the deposition of these fine particles. Ghosting requires the random floating about of the particles, called Brownian motion. Leaving the fan on will push them around and may disrupt their natural tendencies. You wont be using excessive amounts of electricity just running the fan with the temperature setting set so the heat wont come on unless the fire goes out in the insert.

Ghosting is an annoyance and over a long time can be unpleasant to look at especially if it bothers you but I wouldn’t loose sleep over it. Nothing is rotting or threatening to fall down.

Keep the mail coming. If you've got a question, tip, or comment let me know. Write "On The Level," c/o The Capital, P.O. Box 3407, Annapolis, MD 21403 or e-mail me at jimrooney@jimrooneyonthelevel.com or inspektor@aol.com.