Expert: James Ball - 12/31/2009

Question
QUESTION: I have a 2 story home in illinois with a vinyl sided chimney chase. When the weather turns cold, condensation forms on the under side of the chase cap and on the walls of the chimney chase above the roof line. The chase is insulated on the house side for both stories, and is only insulated up to the floor joists for the second story. Also I have my bath vents vented outside. The water drips and "pings " on the top of the firebox of my prefab fireplace. The fireplace is right above a closet in the basement which has my sump pump in it. The space with the sump pump is not sealed from the chimney chase other than the floor joists and the OSB floor material. As soon as the sun comes out and heats up a little it starts to drip. Where do I start? I may have a leak at the chase and storm coller, but I don't think thats all of it. I don't think I can get into the chase to insulate the rest of it. Any help would be great.

ANSWER: Hello Jason, wow, I would say to start by trying to re create or during this "drip" get in to the chase and see where it is coming from and going, can it be the flashing/storm collar? maybe.
If this was a wall leaking I would say open the wall and see where it is coming from.
Also keep i mind water is a funny thing it will always find its way "down hill" and can follow a floor joist and leak in a different area, but start with the chase and see what you find.
keep me posted
Happy New Year
James

---------- FOLLOW-UP ----------

QUESTION: James

Thanks for your response. I have been in the chase and it is condensation dripping from the chase cover. Can I put a vent at the top of the chase similiar to a roof or gable vent to let the condensation out? Also is it a problem to leave the chase open to the attic? Could the moisture come up through the first floor, floor boards from a sump pump pit. Or could it be coming from the attic if moist air blows in and I don't have it sealed from the attic? If the attic should be sealed from the chase, should I just use OSB or similiar or plastic or both? Thanks again and Happy New Year to you.

Answer
Welcome back ?Jason, it sounds like the water it dripping from the underside of the top/chase cover? are you sure it is not getting in from the top? did you try covering the top of the chimney with a tarp (DO NOT COVER ANY HEATING FLUES AND DO NOT USE FIREPLACE'S) this will eliminate the flashing, storm collar and cap.
does the attic have any condensation?, you might have to put some vents in the attic and chase
at this point you might want to get a good contractor in to go over what you have.
Happy New Year
James