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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.
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 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.
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.
Click on image to enlarge
Alberta Toll Free 866-994-1950
Darrell cell 403-586-1950
Copyright Qualistat 2009-2011
To determine the moisture content in exterior sheathing, a deep wall probe is placed through the interior drywall and into the exterior sheathing. Here the reading is high but still safe
Deep Wall Probes with Moisture Meter
Checking static pressures on heating equipment to determine efficiency and operations using a micro-manometer and static pressure tip.
Measuring Static Pressure on an AHU
Measuring moisture levels using a non-destructive meter measuring approximately 3/4" depths.
Non-Destructive Moisture Meter
Blower door set up in the front door of this house. The process takes about 15 minutes. If there are high winds we may choose to reschedule the test.
The Blower door test determines air tightness. By depressurizing the house we can calculate the amount of air leakage and the size of all the leakage openings together. Depressurization can also alert you to possible problems when operating mechanical systems
Blower door test
Blower door test
Here are common issues we address regularly

For more detailed explanation click on the following links for more information
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.
Psychrometric Chart
The interior of walls, floors and ceilings dry by vapour diffusion THROUGH materials such as housewraps and papers. Non vapour permeable materials go on the inside to protect the walls from high humidity from the inside of the house.
Vapour Diffusion or permeability
This graph is from a datalogger which records humidity, temperature and dew point. It is useful in determining the reason for high humidity in homes.
Humidity/Temperature Datalogger Graph
No - It's not pigeons. If you have coffee coloured stains on your siding you likely have too much air leakage into the attic, causing condensation and frost - when this melts, it runs back outside leaving these stains
Stains on Siding
Alberta Toll Free  1-866-994-1950
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Since 1986