Asked on Nov 11, 2017

How do I avoid deep colored paint from chalking on my interior walls?

Marianne Perry
by Marianne Perry
My home is circa 1790, of timber frame construction. In practical terms, I have uninsulated walls that are 2 3/4" thick. I'm in New England, so when winter weather drops into the teens, heated air hits the cold walls causing condensation. On bad days it looks like it is raining on the walls. I've been advised that the only way to insulate would be to have foam sprayed into the wall cavities and I am afraid this might cause the walls to crack.

I had painted two rooms in deeper shades with a flat finish. The winter condensation seems to cause a highly visible chalking effect that is not easily removed.

My question is what in the paint causes this; would a satin finish seal the paint better, or should I simply resign myself to using light shades where the chalking is less visible? Or, perhaps there is another fix, sealing the walls before or after painting with something?
Several years after painting
One year after painting
  7 answers
  • 2dogal 2dogal on Nov 11, 2017

    The condensation on your walls is caused by too much moisture in the air. Warm air meeting cold does this too. Like condensation on old single pane windows. Your contractor was right, spray foam will work. If a professional does it, it should be warranteed not to crack walls.

    This needs to be fixed, not just repainting to hide the marks. A whole house dehumidifier would be the next best thing to have installed or at least a portable one. If you have a lot of plants, like I do, they will also put moisture in the air. Fish tanks do the same.

  • Candy Walsh Candy Walsh on Nov 11, 2017

    I totally agree with Sal5902, I'd definitely get it taken care of to also keep it from becoming a health issue with mold.

  • Johnavallance82 Johnavallance82 on Nov 11, 2017

    Maybe, Seal the Walls with Sugar Soap, then paint

  • Lynn Lynn on Nov 11, 2017

    You can drill holes in your upper walls in between the studs and blow in insulation. We did it in an older home that had lath and plaster and no insulation. We rented the machine ourselves. No wall cracking. Or maybe seal with a wax sealant that you use after painting with chalk paint

    • See 1 previous
    • Marianne Perry Marianne Perry on Nov 12, 2017

      Hi Lynn,

      Your suggestion to use wax to seal the walls is interesting. The good part is it would be none toxic and fume free. The bad part is waxing all of the walls sounds like a lot of work .

      I would love to insulate, but timber frame is similar to post and beam; the outside sheathing over which the clapboard is laid ( hand sawn rough cut boards in my case) are attached to the posts and almost directly behind that is the lathe and plaster. The posts, although covered by lathe and plaster are clearly visible.

  • Karen V Karen V on Nov 12, 2017

    Unfortunately that is what has happened with me as well when using flat finish paint. I would definitely check with the paint department at a home improvement store, they will probably be able to recommend the best finish to use.

    Good luck with the paint!

    • Marianne Perry Marianne Perry on Nov 12, 2017

      Thank you for your suggestion Karen. I'm curious, did you find a finish that didn't chalk?

  • Susan Bechamp Susan Bechamp on Nov 12, 2017

    Flat paint doesn’t repel water the way a satin, semi gloss or high gloss paint does. When the condensation forms it leaves drip tracks on the walls. When it dries you see the tracks of water as it ran down the wall. This could also cause mold/mildew to form . Since the flat paint is more porous, it allows the moisture to react with the plaster.

    After the walls are insulated, patch any holes and treat the walls to a good quality primer and repaint with a paint finish that repels the moisture better than flat paint. (There are additives you can mix in the paint to fight off mold and mildew).

    Increased air circulation will also help, run a fan if you aren’t getting enough air flow. Don’t forget closet spaces too. Leave the closet door cracked open if you can if it starts getting musty. ( my closet suffered the mustiness until I added ventilation with a door that allowed air flow. I replaced the bottom panel of a six panel door with caning).

    I agree with the advice to use a dehumidifier to reduce the build up of moisture if the condensation continues.

  • Marianne Perry Marianne Perry on Nov 12, 2017

    Hi Susan,

    Thanks for your advise on my paint issue. I think that you are correct, that there may be a chemical reaction between my paint and plaster when the warm air strikes the cold walls. The curious thing is that walls painted a light color do not exhibit any signs of chalking.

    The condensation is not due to a surfeit of moisture as I have never had any sign of mold or mildew, rather, I believe it to be the normal reaction of heated air striking a cold surface. Much like a glass containing cold liquid will develop condensation on its surface, thus the need for coasters or beverage napkins.

    Thanks again,