I have noticed stains on the drywall sloped ceilings in the upper floor of my home.  What are the causes? Can I do anything to eliminate the causes of this staining?

Unlike flat ceilings, vaulted or cathedral ceilings do not have an attic space so inspection of the interior cavity is not possible without removing your drywall. However, the usual cause of moisture stains on vaulted ceilings, apart from roof leaks, is a lack of adequate ventilation above the insulation. Walk on the roof if it is not too steep. Is the roof deck soft and spongy in some areas? Does your roof “make ice” along the eaves in the winter? Are the shingles curled even though they are less than 12 years old?

These are signs that your vaulted ceiling is not properly ventilated. There should be at least two and a half inches (65mm) of air space between the insulation and the underside of the roof sheathing or strapping. Your soffits should allow air into that cavity. At the ridge your roof should have vents to allow the soffit air to escape. This flow of outside air will ensure condensation cannot build up on the ceiling surfaces in your home. You may have to cut out a small area of drywall to confirm a lack of venting. If there is little or no air flowing above the insulation, the only long-term solution is to expose the insulation, install continuos venting and re-install your interior drywall.  

Back to Questions



This article was written by Steven Cannon, a Registered Building Official and partner in Lynch Building Inspection Services Ltd. of Nelson, British Columbia. It originally appeared in The Nelson Express.

Key words: building, home inspection, house, British Columbia, BC, Castlegar, Creston, Cristina Lake, Edgewood, Grand Forks, Kaslo, Kootenay, Kootenays, Midway, Nakusp, Nelson, Salmo, Slocan, Trail, Yak, Ymir