Re-roofing encompasses both primary membrane
replacement and replacement of the entire roofing assembly above
the structural deck.
Due to the unique nature of re-roofing, relief
from the Warranty Certificate standards may be requested. When
relief is requested, applications shall be made in a written
submission to the ARCA Warranty Ltd. Technical Committee. This
request for relief is termed a “Variance Request” and
must contain all pertinent information explaining why relief is
The Warranty Certificate standards, as itemized
in this manual, are applicable to re-roofing as well as new
construction, with the exception that the existing drainage slope
may be retained in a conventional membrane design if less than
The maximum roof slope permitted for re-roofing
is 1:6 (2"/ft.).
Sheet metal flashings, including lead flashings,
adhered to the primary membrane shall be replaced with new
materials. Base and cap flashings may be reused provided they are
in good condition, fabricated to the Warranty Certificate standard
and fit properly.
The Warranty Certificate can only be issued on
self-contained roof areas. Control joints may be required to create
a self-contained area when partial roofing system replacement is
carried out. Special attention to drainage provisions may be
Roof mounted equipment may need to be removed
and reinstalled to facilitate replacement of the roofing system
beneath them. Equipment mounted on properly constructed curbs of
sufficient height may not require removal.
A minimum clearance of 100mm (4”) shall be
maintained between the underside of service lines and the surface
of the completed roofing system.
When the existing BUR systems is of a different
bitumen type than the new system to be applied (e.g. Coal tar pitch
to asphalt), care must be taken to ensure that the two dissimilar
bitumens do not come into contact with each other.
In some instances there may be two (2) roof
systems one above of the other, over an existing roof area. Where
two (2) primary membranes are present and both primary membranes
shall be removed.
Prior to reroofing, all damaged or deteriorated
decks and substrates shall be replaced or repaired with similar
BUR-10.2 Primary Membrance
When considering an existing conventional
insulated roofing system for primary membrane replacement the
following factors require evaluation:
The effect that the lack of a vapour retarder may have had on
the failure of the existing membrane,
The type, condition and thickness of the existing insulation
and the amount of moisture that may have infiltrated the insulation
The existing roof deck type and its structural integrity if
moisture reached the deck, and
The attachment of roofing system components to their existing
When membrane replacement is undertaken,
uncorrected defects hidden from view, such as wet insulation or a
deteriorated deck, could jeopardize roofing system
Wet and damaged insulation shall be removed and
replaced with new insulation, to match the existing
When an existing vapour retarder membrane is
present, or when the existing insulation is fully adhered to a
concrete deck, care must be taken to ensure all wet insulation is
located and replaced.
Under no circumstance shall a phenolic resin
insulation product be left in place or reused.
Existing wood fiberboard, mineral fiber/perlite,
glass fiber or Stramit primary insulation may be left in place
whether or not they are covered by a secondary insulation/cover
Existing polyisocyanurate, urethane, foam glass,
cork, expanded polystyrene, glass fiber less than 38 mm
(1.5”) thick and extruded polystyrene primary insulation less
than 38mm (1.5”) thick must be removed and replaced, except
when covered by a secondary insulation/cover board consisting of
wood fiberboard or perlite insulation. Exercise extra caution to
ensure that all wet primary insulation is located and replaced when
there is a secondary insulation/cover board in place.
When the primary membrane is being
removed from stramit or glass fiber insulation that have a facer,
the condition of the insulation facer after the tear off determines
the surface preparation method for the application of the new roof
membrane. When re-roofing over stramit the first layer of approved
coverboard must be mechanically fastened to the structural joist or
deck. If the first layer is fiberboard, then the second layer of
approved 12.7mm (1/2") coverboard may be adhered or mechanically
fastened with screws and plates. When thermal upgrading is
required, the first layer of the secondary insulation/coverboard
may be substituted for/by the upgraded insulation material.
Attachment requirements remain the same.
Regardless of the primary insulation type or the
presence of an existing secondary insulation/cover board, in all
cases a new secondary insulation/cover board layer meeting ARCA
Warranty Certificate application standards is required to provide a
consistent substrate for the application of the new roof
Polyurethane Foam Adhesive may NOT be used
to adhere insulation or cover board to existing fiberglass
insulation, perlite insulation or stramit.
BUR-10.3 Roofing System
After tear-off the exposed substrate shall be
inspected for deterioration or damage and repairs undertaken prior
to the application of the replacement roofing system.
Control joints, parapets, curbs and roof/wall
junctions shall be adjusted to comply with the minimum height
requirements for new construction.
For conventional and combination designs, the
application of a vapour retarder is a requirement whether or not
the original roofing system contained a vapour retarder
An existing vapour retarder may be left in place
if well adhered. Any wet or damaged membrane shall be removed and
an additional one (1) ply of felt adhered with hot bitumen shall
cover the entire membrane surface.
When primary membrane replacement occurs over
existing insulating stramit, or over rigid glass fiber insulation,
inspection of the exposed insulation by an ARCA Accepted Inspector
is required at the time of tear off, for both rural and urban
projects. Additionally, if there is a history of leaking, the
inspector shall perform moisture meter or cut tests, one (1) for
each 1000 ft² of insulation area. These inspections are in
addition to the normal inspections for warranty issuance.
ARCA administration shall be notified of the
condition of structural stramit decks prior to reroofing.