Exterior Doors
This section discusses factors
to consider when selecting exterior doors
Conduction
through the door and frame
The majority of heat loss
through doors is by conduction through the door itself. Most entry doors in new
Manitoban homes use steel insulated doors. Steel doors are typically made with
either expanded polystyrene insulation glued between two sheets of metal with
a wood perimeter frame or polyurethane insulation foamed in place between the
two sheets of metal. Of the two, the polyurethane core has a higher R-value and
is better at reducing heat loss.
Air
flow between the door and frame
Possibly more important
than conduction of heat energy through the door is airflow between the door and
frame. A good quality nylon jacketed compression foam weather-stripping, provided
as standard equipment with most pre-hung doors sold in Manitoba, does a good job
at sealing off air leaks.
Conduction
through glazing lites in the door or sidelights
Heat can be lost through
any window glazing in the door just as it can through windows. It is important
to insure that the glazing in your door be of the same quality as the windows
in the remainder of your home.
It is not uncommon for doors to be supplied with double glazed windows or if triple
glazed, the air spaces may be reduced to ¼" in width. If the remainder
of the windows in your R-2000 home are high performance glazing and the door glazing
is lower performance glass, condensation on the door glazing will be a constant
concern throughout the winter months when other windows in your home are free
of condensation.
Airflow
between the doorframe and rough wall opening
You can purchase the most
energy efficient door on the market but install it poorly and you'll still experience
drafts and energy loss. An airtight connection must be made between the doorframe
and the rough opening in the wall. Once the door is installed structurally to
the wall framing, the space between the door frame and wall should be partly filled
with batt insulation and air sealed with either low expansion spray in place foam,
ethafoam rod and caulking, or contractors tape, similar to that used to tape exterior
air barrier materials.
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