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Unlike solid wood shiplap and plywood sheathings, OSB is a great source of food for mould
massive air leakage under exterior wall. Many houses are built without caulking or sill gasket used under wall to floor connections. That is why floors are cold
Air leakage produced when house is depressurized and infrared inmaging used to visibly determine air leakage (dark wispy areas around light)
Air leakage into the wall cavity.
Depressurizing the home and then using a thermal imaging camera to "see" the air leakage. (dark lines on right side of jamb extention show where this window failed)
Infloor heating tubes can be checked using infrared thermogrpahy
Water testing to determine the EXACT leakage location.
Evidence of water penetration at some point
Reverse paper laps under windows accounts for the majority of leaks in stucco homes
Stucco thickness is insufficient - Should be at least 3/4". This sample was 3/8"
Hairline cracks result when stucco thickness inadequate
Improper flashing & lap over the stucco portion of the intersect between claddings
Stains on the stucco as a result of improper flashings. - This will also damage the sheathing below from long term wetting
More moisture trapped inside the walls
6 year old house - vapour barrier installation was incorrect. Air leaked from the house into the wall cavity causing sweating. Limited drying allowed rotting
Paper was improperly lapped under this window and caused major water damage
Mould from moisture build-up in this wall. The exterior has EFIS acrylic stucco which significantly reduces drying
Mould inside this wall from unsealed door bell wire
Bearing wall rotted from moisture being trapped in the wall. OSB is actually a type II vapour barrier and limits drying
Major air leakage in the ceiling of this home lead to heavy condensation build up and leaking from pot lights.
Condensation during winter. Warmer days produce melting and water trying to exit from the interior to the exterior
Poor paper lap applications causes the majority of stucco leaks.
Order of installation was backwards on this project. Inexperienced or no supervision
Extremely poor instalation - Peel & Stick membrane MUST be installed with primer and must be protected from UV and other damaging effects during the construction process
Inability of the stucco to drain, casuing staining. bottom edge of stucco MUST have a flashing that has building paper lapped over, followed by the weep screed or stucco stop over the paper.
Common damage - mostly caused by lack of knowledge
Absolute humidity is the actual amount of water vapour in the air and does not change with temperature. This chart shows what the relative humidity will become as the temperature is raised or lowered.
Humidity Explained
Phychrometric Chart
Location of various barrier systems. Poly is often used for both air and vapour protection- notice the challenge at joist headers and cantilevers when this is done.
Barrier System Locations
Potlights - huge air leakage points. This potlight during a 15km/hr wind shows 4.5 km/hr wind blowing into the house. Suction on the leward side during winter can produce a significant amount of condensation build up in the attic.
The interior of walls, floors and ceilings dry by vapour diffusion THROUGH materials such as housewraps and papers. Non vapour permeable materiasl go on the inside to protect the walls from high humidity from the inside of the house.
Vapour Diffusion or permeability
Click on image to enlarge
Alberta Toll Free 866-994-1950
Darrell cell 403-586-1950
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