Condensation Inside Windows: How to Fix
LESLIE: Kirk in Texas, you’ve got The Money Pit. What can we for you today?
KIRK: Well, I have got a new home – finished in November – that is having some problem with sweating in the windows. Now I’ve got that blow-in, isonene-like insulation all on the exterior walls and everything.
KIRK: Aluminum windows. And I’ve got a heat pump.
KIRK: I told my builder about this a couple of times and I got a hydrometer to check the humidity in the house, that it wasn’t too high, and it looks like it’s about 40 percent.
TOM: And you’re still – so where are you seeing the condensation; on the inside of the windows?
KIRK: Inside of the windows. No, not like in between – not in between the glass or anything.
TOM: Right, on the inside of the window surface. Now are these windows Energy Star-rated windows?
KIRK: You know, they’re aluminum. It’s a new home, a very nice home; they should be nice windows.
TOM: Well, I’ll say this. If the windows are not good windows – if they’re not Energy Star-rated windows; if the glass is not insulated well enough – any warm, moist air in the inside of the house is going to condense on the surface of that glass.
LESLIE: Because of the temperature difference.
TOM: Right. Just the same way that when you go outside on a hot, Texas summer with your iced tea, moisture condenses on the outside of that glass. It’s happening in reverse in the winter because it’s cold outside and it’s warm and moist inside.
Now, you do need to maintain proper humidity levels. If the house is so tight that it needs to have – it may need to have an air-to-air heat exchanger, which will help flush some of that. You may also want to consider something called a whole-home dehumidifier that could be installed into the HVAC system and will actually take out moisture. In fact, these units can take out up to about 90 pints of water a day.
LESLIE: And it takes it directly outside of your house. You don’t have to empty anything. You don’t even have to deal with it.
TOM: Yeah, you can also make sure that you’re covering the basics, in terms of the grading and the drainage outside the house – making sure that the soil is sloped away and the gutters are extending away – because water that collects around the foundation will wick into that foundation and rise up through the house. And finally, you can look at the attic space to make sure you have adequate ventilation up there in terms of ridge and soffit vents. And lastly, I would say look at the ventilation systems in the house; of course the bath ventilation and the kitchen ventilation, make sure they’re working. All of those places are where humidity can form.
I would go back to your builder and put the onus on him to figure this out and remind your builder that if we don’t get this straightened out you may be facing mold problems in the future and you’re going to be back in touch with him and it’s going to get a lot more expensive. I would do it in writing to make sure you’re covered and stay on him to get it fixed.