By the time a leak is located, the building’s structural frame is complete, but the exterior cladding and drywall are not yet in place. The floor has been poured. The openings for plumbing and electrical lines in the attic floor have been cut and sealed. The best time to locate a leak is usually after the structural contractor has completed their work.
By the time the leak is located, all penetrations must have been installed and sealed (ventilation ducts, range hood, flue ducts for fireplaces and sauna stoves, water and sewer lines, central vacuum system exhaust pipes, pipe penetrations in the subfloor, e.g., conduit for electrical wiring or geothermal heating).
The following installations must be completed before locating the leak:Exterior doors and windows
- The exterior doors and windows are installed (the front door does not need to be installed).
- Around windows and doors, the joint between the frame and the exterior wall has been sealed with urethane, tape, a wood strip, or a suitable sealant.
- The door thresholds have been sealed.
Floor joists
- The pipe penetrations have been sealed with urethane or a suitable sealant against the floor.
- The joint between the subfloor and the wall has been sealed. (A tried-and-true, though not mandatory, method is to cut the underlayment on top of the concrete and then apply a suitable sealant to the joint between the wall and the subfloor.)
Attic floor
- The joints in the attic floor’s vapor barrier (vapor barrier board, vapor barrier film, or urethane panels) have been sealed throughout and connected airtight to the exterior wall’s vapor barrier.
- The joists for the attic floor have been installed. The measurement is performed under negative pressure, which can damage the attic floor’s air barrier if the joists are missing.
- The pipe penetrations have been sealed with collars and vapor barrier tape against the attic floor’s air barrier. The fireplace flue has been sealed against the attic floor’s air barrier.
Walls
- The air barriers on the walls have been sealed throughout.
- The openings in the exterior wall (the fresh air duct of the ventilation unit, the exhaust pipe of the central vacuum cleaner, cable conduits, etc.) have been sealed with urethane or a suitable sealant.
- The airtightness test should be performed before painting and plastering work, or a few days after such work has been completed.
You give
- The building has electricity.
- In a duplex, the openings between the units must be sealed.
- In buildings with two or more floors: There must be a staircase between the floors, as the person conducting the measurement must be able to move between the floors inside the building.
- If there is a garage attached to the house that is connected to the same ventilation system as the house, the garage’s exterior door must be installed. If the garage has its own ventilation system, the door between the apartment and the garage must be installed.
Before the measurement:
- Close the windows and doors securely.
- Do not light a fire in the fireplace for about 24 hours before taking the measurement.
- If the house is unheated, turn on the heater about 24 hours before the measurement. The goal is to create a temperature difference between the outside and inside of the house so that leaks can be located using a thermal camera.
- To locate a leak, building materials, furniture, and other movable objects that can be moved without undue difficulty should be moved so that they are no closer than approximately one meter from the exterior walls of the house.
- Make sure there is sufficient general lighting in the building so that the measurement can be taken without any problems.
During the measurement:
- Set aside 3–4 hours for the measurement. For most of that time, you can work on other tasks at the same time.
- It’s good to have a carpenter on site who can make the necessary repairs.