Older Home: Condensation Problem: Walls?

Question

I bought a 100+ year home which has electric baseboard heaters.

Throughout the winter, there was condensation on both the main story and the upstairs -- especially on the walls near the ceilings. In some places it gathered and started running down the wall.

Mold has formed in one wall in the house. (roughly 1 sqft in size) Bleaching it away doesn't help and it comes back frequently. Unfortunately I live in a cold climate, so opening the windows during the winter won't work.

Dehumidifiers do not work, even when constantly on.

It does appear that the house suffers from a lack of insulation in the exterior walls. The windows are vinyl.

How do I stop this excessive condensation? Should I better insulate the walls? The attic? How do I know that this would help?

Answer 1

if your dropping heat to save money this may be problem the warmer the air the more moister it holds  the colder the temp is in the house the moisture will collect on the walls also make sure you have a fan that vents to outside in both the bathroom and kitchen i would make sure the attic is insulated heat rises I would do the walls as a last resort

Answer 2

I would look for a water leak somewhere in the home. Normally, running a heater will dehumidify the home. As the temperature inside rises (in comparison to the outside temperature) the relative humidity in the house falls.

For example, if the temperature outside is 40 degrees and the humidity is 60%, inside a 72 degree house the humidity will be only 19%, which is very dry.

Consider buying a humidistat and monitor the humidity in your home. If it is constantly high (over 40%-50%) regardless of running the heater or A/C there is probably another issue in the house.

Answer 3

When walls are cold they will have water condensing on them. Better insulation will keep the walls from getting colder. However, you said that the walls appear to be adequately insulated. Some simple things that I can think of that would cause as much humidity in your home as you are descirbing would be:

1) Clothes dryer not vented to the outside of the house.

2) No exhaust fans in the bathrooms

3) No exhaust fan in the kitchen

4) No attic venting

5) Leaky roof

I would check those in that order.

I am curios that you mentioned the walls and not the windows because I would think that you would see condensation on the windows first. If you only see it on the walls and not on the windows then I would have an energy audit done and make sure they use an infrared camera while doing it. The infrared camera can detect gaps in the wall insulation which may be causing cold spots.

Answer 4

pickme is on the right track.  Warm air holds more moisture than cold air.  What's happening is a like a glass that has a cold drink in it.  The moisture in the warm interior air is condensing on the cold walls.

Insulating walls & attics would be the first step, and will probably solve the problem (as well as lowering your heating bills).

Answer 5

Your vapor barrier may have large holes or gaps, or may be nonexistent

Answer 6

Come on 100 years old home it's a luxury for the history museum.