Retrotec Residential Pressure & Air Leakage - Manual (Page 16)

Page 16 of 75
©Retrotec Inc. 2014
Doors leading from upstairs into most basements (in northern climates) should be open during the test, as
basements are normally conditioned by supply registers, un-insulated ducts, pipes and the un-insulated floor
above.
If the basement has no usable living space, supply registers, or has insulated supply ducts or an insulated ceiling,
it could be considered unconditioned, in which case the door from upstairs should be shut during the test and a
basement window should be open so that the basement is at outdoor pressure.
2.3.2.5. Attic Hatches and Pull-Down Stairs
Attic hatches:

If in the conditioned space, must be closed for the test.

If outside the conditioned space, should be open for the test.
If the attic access is in the ceiling of an unconditioned garage, or outside of the thermal envelope, the access and
the main garage overhead door should be open (even though this may not be the normal position). This is
especially true if ducts or the air handler are located in the attic above, or in the garage itself. The objective is to
ensure that during the test, the same pressure difference is created across all the surfaces of the pressure
envelope. This requires that the attic be well ventilated.
2.3.2.6. Garage Door
Large garage doors are usually left closed. However, they must be open if the Blower Door is installed in the
main door between the house and the garage. It should also be open if the air handler/furnace is located in the
garage, or if there is an attic access in the garage ceiling which is being left open during the test.
2.3.2.7. Unconditioned Crawlspace Vents and Hatches
Unconditioned crawlspace vents and hatches should be open during the test.
2.3.2.8. Skylights
If the skylight has a moveable opening in it, such as a ventilation slot, it should be shut. Some skylights have lay-
in translucent plastic panels at ceiling level to diffuse direct sunlight. They are sometimes quite flimsy and brittle
and can get pulled down (and broken) during a test. Remove or secure them if required.
2.3.3. Exhausts and Intakes
2.3.3.1. Enclosed Furnace Rooms or Closets
Furnace rooms with separate combustion air intakes from outside (or an attic or crawlspace) are to be
considered outside the thermal envelope. Ensure that gas or fuel oil appliances won't fire (for safety), but do
not seal the air intakes or flues. The door to the house should be closed.
2.3.3.2. Fireplaces
Glass doors should be closed. If a damper is in place, it should be shut before conducting a test. Even when
shut, many dampers will leak a considerable amount of air, often enough to blow ashes out onto the living room
floor during depressurization. Clear out the fireplace or lay newspaper sections over the ashes to deflect the air
stream.
The fireplace must be cold and completely out. If a house has hot, smouldering coals or ashes, but no fire, the
fire will still need to be put out. The best solution is to use a metal ash bucket and take everything outdoors
before quenching the coals with water.