Installation Guide

Rigid Insulation
Numerous types of rigid insulation are now in
use, and may be made from expanded
polystyrene beads, rigid urethane laminate, low
density fiberboard, or from fast-setting liquids
poured on-site. They vary in thickness up to
more than 50mm and in length and width
depending upon the manufacturer. All these
types are efficient insulators and are usually of
sufficient density to hold the weight of a
normal roof covering without the need for
lumber bridging.
Metal Deck
The covering of metal decks with shingles or
shakes presents a rather unique problem. These
decks are often used for economic reasons, but
they generally require a finish roofing capable
of shedding the weather. In addition, aesthetic
considerations often require that the deck itself
be covered with a material such as Western
Red Cedar shingles or shakes to provide a
pleasing finish. When a metal deck is to be
covered, consideration should be given to the
use and placing of vapour barriers. If
insulation is placed on top of a metal deck, the
entire roofing system must be taken into
account. For example, wood members must
not be sandwiched between two vapour
barriers. If this is unavoidable, the wood
member should be preservative treated before
installation. In some cases, the seams in a
metal deck can be sealed to create an effective
vapour barrier. Boards or a panel deck must be
used as a nailing base for the shingles or
shakes, supported by vertical lumber members
fixed to the deck. This can be achieved in a
number of ways:
1. On a corrugated deck, vertical lengths of
lumber are fastened to the deck and
horizontal boards or panels are applied
across the vertical pieces. If insulation is
required, it is best placed on top of the
vertical members, held in place by the nails
fastening the boards or panels to the
members (Figure 18).
2. On a sheet deck, or where the corrugations
are very shallow, it may be necessary to use
angle clips to attach the vertical members to
the deck. The clips should be nailed to the
lumber and bolted or screwed to the deck.
Boards or panels are then applied as before.
If there is a likelihood of excessive moisture
buildup, as may be encountered in ice arenas,
the cold weather roof principle can be
employed, supplemented by mechanically
produced air flow if necessary.
Cedar shingles or shakes
(applied as per specification)
Exterior panels
Rigid insulation
Vapor barrier (if required)
Wooden deck
Joist
Cedar shingles or shakes
(applied as per specification)
Boards
Rigid insulation
Vapor barrier (if required)
Steel deck
Purlin
Cedar shingles or shakes
(applied as per specification)
Boards
Rigid insulation
Vapor barrier
Steel deck
Vertical lumber member
(preservative treated–
do not sandwich wood
member between two
vapor barriers)
Vertical lumber
member
Purlin
Fig. 17: Specialty Roof Deck – Panels over Insulation
Fig. 18: Specialty Roof Deck – Steel Roof
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