Substrates, areas, and conditions shall be examined with installer present, for compliance with the following requirements and any other conditions affecting performance of roofing system:
a. Verification that roof openings and penetrations are in place and set and braced, and that roof drains are securely clamped in place.
b. Verification that cants, blocking, curbs, and nailers are securely anchored to roof deck at penetrations and terminations, and that nailers match thicknesses of insulation.
c. Verification that surface plane flatness and fastening of steel roof deck comply with project requirement.
d. Verification that concrete curing compounds that will impair adhesion of roofing components to roof deck have been removed.
Protected Membrane Roof Installation Guidelines
Preparation
Substrate shall be cleaned of dust, debris, moisture, and other substances detrimental to roofing installation, according to roofing system manufacturer’s written instructions. Sharp projections shall be removed.
Materials shall be prevented from entering and clogging roof drains and conductors, and from spilling or migrating onto surfaces of other construction. Roof-drain plugs shall be removed when no work is taking place, or when rain is forecast.
At concrete deck, surface of concrete deck shall be primed with asphalt primer at a rate of 0.3 L/m2 and primer allowed to dry.
General Installation Requirements
- Modified bituminous membrane roofing system shall be installed according to roofing system manufacturer’s written instructions and applicable recommendations of NRCA Quality Control Recommendations for Polymer Modified Bitumen Roofing.
- Installation of modified bituminous membrane roofing shall be started in presence of roofing system manufacturer’s technical personnel. Where roof slope exceeds 1:24, sheets of modified bituminous membrane roofing shall be run parallel with slope. Top ends of sheets shall be back nailed to nailer strips.
- Preformed 45° cant strips shall be installed and secured at junctures of modified bituminous membrane roofing system having vertical surfaces or angle changes greater than 45.
- Installations of roofing system components shall be coordinated to ensure that insulation and roofing plies are not exposed to precipitation, or left exposed at the end of the workday, or when rain is forecast. Measures shall include:
a. Providing cutoffs at end of each day’s work, to cover exposed ply sheets and insulation with a course of coated felt, with joints and edges sealed
b. Completion of terminations and base flashing, and provision of temporary seals to prevent water from entering completed sections of roofing system
c. Removal and discard of temporary seals before beginning work on adjoining roofing.
Roof Membrane Installation
- Modified bituminous membrane shall be installed over area to receive roofing, according to manufacturer’s written instructions. Modified bituminous membrane shall be extended over and terminate beyond cants.
- Prior to installing modified roofing membrane, primer conforming to ASTM D 41 shall be applied to the concrete deck, as recommended by manufacturer.
6.4.3 Two plies of modified bituminous membrane, consisting of a base ply and a finish ply, shall be installed, starting at low point of roofing system. Each ply shall be torch-applied to substrate. - Sheets shall be accurately aligned without stretching, and uniform side and end laps shall be maintained. End laps shall be staggered. Side and end laps shall be heat-welded and completely sealed by rolling, leaving no voids. Tears and voids in laps and lapped seams not completely sealed shall be repaired.
Flashing and Stripping Installation
- Modified bituminous membrane base flashing shall be installed over cant strips and other sloping and vertical surfaces, at roof edges, and at penetrations through roof, and shall be secured to substrates according to roofing system manufacturer’s written instructions and as follows:
a. Modified bituminous membrane base flashing shall be torch-applied to substrate
b. Base flashing shall be extended up the wall a minimum of 200 mm above roof membrane and 100 mm onto field of roof membrane. Top termination of base flashing shall be sealed. - For roof drains, 760 x 760 mm metal flashing shall be set in bed of asphalt roofing cement on completed modified bituminous membrane roofing. Metal flashing shall be covered with modified bituminous stripping extending a minimum of 100 mm beyond edge of metal flashing onto field of roof membrane. Roof membrane, metal flashing, and stripping shall be clamped into roof-drain clamping ring.
Protected Membrane Insulation Installation
- Extruded insulation units shall be loosely laid over modified bituminous membrane, with long joints of insulation in continuous straight lines and with end joints taggered between rows, abutting edges and ends between boards. Bottom drain channels shall be installed toward roof drains and scuppers.
- Filter fabric shall be installed over the insulation according to insulation manufacturer’s written instructions. Side and end laps shall be minimum 300 mm.
- Tapered insulation shall be installed to conform to slopes indicated in drawings.
- Concrete-paver shall be installed over ballast, according to manufacturer’s written instructions in locations indicated. Aggregate ballast shall be installed around roof perimeter and equipment edges, if required in the drawings.