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Roofing/excessive condensation


We live in Calgary.  The house was spec-built in 1982 (their first house).  We purchased the house 11 years ago, and have been making various renovations, especially for energy efficiency.  Our project last summer was to increase the insulation in the attic.  My brother, who is a certified house inspector in BC, did the work.  While he was up there, he noticed various other issues - there was no venting in the soffits (he fixed this), the skylights needed replacing, and the area around the chimney had some issues.

We had the skylights replaced last fall (a professional skylight company), and I had someone in to fix the chimney problems (a home-handyman company).

Now to the problem:  every window in the house (and sometimes one wall) have very excessive condensation - to the point where it creates puddles on the sills which then start to mould.  We had the chimney guys back to re-do the caulking, which seemed to help for a while, but today the wall (the one with the chimney on it) started dripping again.

We suspect the chimney work (I swear I hear dripping noises).  Who do we talk to?  A roofing company?  A HVAC company?  A chimney specialist?  Any guidance would be very appreciated.

Condensation can be a result of various issues.
If the windows are double single pane, a single window in and out, they will contribute  to condensation as they are inefficient. If they are double-glazed, two pieces of glass separated by a metal spacer bar or tape then the condensation is an internal problem.

The kitchen and the bathroom generate the most moisture in a home and both should be vented to the outside. You mentioned there were no soffit venting before it was corrected but was the venting of the attic adequate to the Alberta Building code?

Are the exterior walls insulated properly and if you have siding that must also be vented to code. I suggest you call in a building science consultant to investigate and find the source of the problem and present a solution.

All the best


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D. John Henderson


My 33 years in the building science business has involved air barriers, waterproofing, and flat & steep slope roofing systems.


My roofing encompasses commercial systems (BUR, mod-bit, single-ply) and residential applications (asphalt shingles, cedar shingles, slate and metal. I am cognizant of code stipulations in regards to FM and UL for commercial roofs.

Attended numerous courses offerd by Roof Consultants Institute, Roofing Industry Educational Institute, Factory Mutual Research Corporation, University of Wisconsin, and BURSI. Lectured for RCI and mentored at a local university for a Building Science Certificate.

Past/Present Clients
Government, commercial businesses such as The GAP, hospitals, school boards as a roof designer.

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