The paint on our 1794 house with cedar clapboards is blistering on the southern side of the house. Our contractor suggested this is caused because whoever put the siding up neglected to prime the back side of the clapboards, and moisture from the inside is seeping through the cedar. The house is in New England and insulated with blown-in cellulose with no vapor barrier.
Do I need to remove the siding and prime the backs? He says that if I don’t it will just blister again. Would this save me from repainting as often, or is it just something I would do if replacing the siding anyway?
Replies
K:
I can't say that your problem is due to lack of backpriming without knowing more information, but your contractor is certainly correct that it CAN be a problem. I backprime everything, and I prime the cuts too.
Old houses like yours can also be problematic after being insulated, especially with the blown-in cellulose. For a couple of hundred years the relatively open flow of air was able to keep moisture down and to equalize moisture on either side of the clapboards. After insulating, the moisture tends to stay put and cause grief. When there is no sheathing other than the clapboards, the insulation just sits right against the siding, keeping it cool and moist on one side. The other side is hot and dry from the baking sun. Not good for paint.
Other issues causing paint peeling can be related to showers, clothes dryers, or leaks which deposit excess moisture in the wrong areas. Sometimes wood has a waxy surface, bad primer, or burnishing from the planer that causes poor adhesion.
If this is a recurring problem, it might be worth removing the siding and seeing what's what. Sometimes the removal of the blown-in insulation helps, and it is replaced with polyurethane foam insulation, either inside the wall or on the surface. Also, the addition of sheathing and felt paper can help.
If you'd rather avoid that idea, there is one last old-school effort you could try. The old timers would remove the old paint down to the bare wood, treat it with boiled linseed oil and let it dry for several days. Then follow with a coat of oil based primer, and two latex top coats. I wouldn't hold out much hope for this method, though.
John Painter
I've found it's better to just replace the old siding if it's in bad shape with pre-primed cedar siding, and go one step further and back prime the siding with a quality primer like KILZ. I've done several old homes this way, and the paint jobs are still looking fine. One house was done 10 years ago,and the paint job still looks great. It's all about the prep work that makes things work right.
PM/Email me and I'll give you a pointer to my firm's web site, that has an example of a re-siding job on an old house.
Could be a number of things. Backpriming is recommended whether you're using solid color stain, bleaching oil or stain. http://www.wrcla.org/cedarspecs/installing/primebeforeinstalling.asp If the clapboards are original to the house or very old it could a matter of too much paint and time to strip it to bare wood- the final finish is no better than what's underneath it. If the clapboards are fairly new they should have been backprimed. Curious if there's Tyvek behind the clapboards and what type of paints were used for primer and topcoat.
Sir Winston Churchill
A few years ago I remember seeing small thin plastic or aluminum wedges which were designed to slip between the courses of claps. The purpose was to create a small amount of air space between the claps to promote even drying on both sides and thus prevent peeling. Don't know if they work, but it seems logical. Google "siding wedges"
Edited 10/21/2008 10:26 am ET by TommH
Edited 10/21/2008 10:27 am ET by TommH
Another thing to look at, given the age of your home, is whether or not there is excessive moisture entering the walls from the basement. Dirt or brick floor? I know there was a FHB article a feww years ago about paint problems which addressed that issue.
A few years ago I had a paint problem which I ascribed to excess moisture. Some of my experience may be applicable to your situation.
House is an 1840 colonial farmhouse in southern NH with white clapboards ( mostly originals, so no back priming) and plaster on lath on the inside. Heat is with forced hot air with a furnace humidifier. A few years ago when the house was uninsulated, I unwisely adjusted the humidistat so that the furnace humidifier ran most of the time that the furnace was on. I later discovered that there was an air leak in the foundation on the northwest side near a cold air return duct that had partially come loose. This caused the furnace to run more that it otherwise would, which generated high levels of humidity in the house and then into the walls, particularly on the down wind ( southeast) side. I noticed a lot of moisture condensing on both the house windows and the storm windows, particularly in the bedroom on the southeast side. The next spring I noticed some mildew on one of the bedroom baseboards and on a bedroom closet wall, as well as an exterior paint adhesion problem in a fairly recent paint job.
I think that my paint problems would have been worse if the house paint color had not been white. From what I've read, darker paints experience significantly higher solar heat absorption, and thus higher surface temperatures. This leads to higher temperature swings which worsen whatever paint problems are present.
Consider the vapor barrier. My mother's old farm house had the typical bathroom built into was originally a storage area at the back of the kitchen. No, they didn't originally envision a bathroom off the kitchen, who would, but it was the obvious upgrade from the outdoor toilet. Well, with the toilet and bathtub there, the outside paint continued to blister. No vapor barrier was the cause.
I've seen many a house where by looking at the sections of peeling paint on the outside, the location of the bathroom is found. One of my neighbors has this problem and goes the "paint this side of the house every year" scenario. I mentioned the lack of a vapor barrier issue and got the response from his house painter "Painters know paint, carpenters know carpentry period, end discussion..."