LESLIE: Alright. Now we’ve got John in New York who is looking for some help with a condensation issue. Tell us what’s going on.
JOHN: Love your program.
LESLIE: Thank you.
TOM: Thank you, John.
JOHN: I have a stone-type house and it seems like it always seems damp inside.
TOM: OK. Right.
JOHN: I was wondering if that’s a cause of the stone? I’m really not sure of the insulation under it. I was just wondering if I can use a vapor-barrier paint to stop that. And the trim on the inside is at least a ½-inch sticking out – it sticks out about a ½-inch. I was wondering if they have any sort of insulating-type wallpaper or something that I could help insulate the inside without going through the outside. Thank you very much.
TOM: So, the interior-wall finish, is there any frame wall as a part of that or is it plastered right over the stone? I mean what’s your understanding of the wall construction?
JOHN: I think it’s plastered right over the stone.
TOM: Yeah, well, that would make sense.
A couple of things come to mind. First of all, the humidity and the dampness problem, it’s certainly the stones are contributing to that because any type of a masonry product like that is going to be very hydroscopic, so it holds a lot of water and that water can certainly evaporate into the interior space. However, that said, there are a couple of things that you can do to reduce the volume of water that collects on the outside.
The first is start at the roof with the gutter system. Make sure it’s clean, free-flowing and that those downspouts are at least 4 to 6 feet from the house when they discharge. Secondly, look at the grading to make sure that the soil around the immediate foundation perimeter slopes away. You want a drop-off of about 6 inches over 4 feet. Those two things reduce the volume of moisture that sort of hangs at the base of the house and in doing so means there’s a lot less water to be drawn up into the walls, which can therefore evaporate into the house.
The second thing to do is let’s talk about interior ventilation. You want to make sure that you have exhaust fans in the kitchens and the bathrooms that don’t recirculate, that truly take the moisture out of the house.
And thirdly, what kind of heating system do you have in that house, John?
JOHN: It’s oil heat – oil-forced hot air.
TOM: Perfect. With a forced hot-air system, you can install an appliance called a whole-home dehumidifier. There’s a number of manufacturers that make them. They can take out about 90 pints of water a day, so they’re …
LESLIE: From the entire house.
TOM: Right. So it’s not just a one-room dehumidifier or one – like a basement dehumidifier. This works in the HVAC system so it takes – the air that’s coming in the returns runs through the dehumidifier, it pulls out the excess moisture and then it sends that drier air down the line. This’ll be especially valuable to you in the spring and the summer months when there’s a lot of humidity around.
JOHN: OK. Thank you very much.