Home
Projects About Contact Request a Project Estimate
Flat and low-slope membrane roof on a residential or commercial Ontario building

Flat & Low-Slope Roofing

Flat Roofing Systems for Residential and Commercial Buildings

ARKSTRUX coordinates complete flat and low-slope roofing systems for residential, commercial, multi-residential and architectural projects across Toronto, the GTA and selected Ontario locations. From roof replacement and new construction to insulation, drainage, custom flashings and membrane installation, each project is reviewed as a complete roofing assembly.

Request a Project Assessment View Flat Roofing Projects

Liability insured · WSIB coverage · Serving Toronto, the GTA and selected Ontario locations

Complete Roofing Assemblies

More Than a Waterproof Membrane

Flat and low-slope roofing requires a complete water-management system — not just a waterproof surface. Proper drainage, compatible insulation, vapour control, secure perimeter details and correctly integrated penetrations all contribute to the long-term performance of the roof.

ARKSTRUX reviews the building type, existing roof conditions, drainage, roof use and project specifications before recommending an appropriate system and installation approach.

Where project conditions allow, the roof assembly should be designed to promote positive drainage toward roof drains, scuppers or other approved drainage points.

Key project types

  • Residential flat and low-slope roofs
  • Commercial and industrial buildings
  • Multi-residential properties
  • Additions, garages and extensions
  • New construction
  • Roof replacement and recovery projects
  • Roof repairs and maintenance
Close-up of a flat roof membrane with drainage and perimeter details

Systems & Options

Roofing Systems Selected for the Project

ARKSTRUX coordinates multi-ply and single-ply roofing systems based on the building type, roof configuration, existing substrate, drainage requirements, expected use, project specifications and budget.

2-Ply SBS Modified Bitumen

A reinforced multi-layer roofing system commonly used for commercial, multi-residential and custom low-slope applications. Its base and cap membranes provide multiple layers of waterproofing and allow detailed integration around drains, walls, curbs and penetrations.

Typical applications

Commercial and multi-residential buildings, residential flat and low-slope roofs, additions and extensions, parapets and complex roof geometry, and replacement and recovery projects.

Typical Scope of Work

  • Remove or prepare the existing roof
  • Inspect and prepare the roof deck
  • Install vapour-control components where required
  • Install insulation and cover board
  • Install base and cap membranes
  • Detail drains, scuppers, curbs and penetrations
  • Complete perimeter and wall flashings
  • Complete final inspection and cleanup

EPDM Roofing

A flexible single-ply rubber membrane used for residential and commercial low-slope roofing. Depending on the specified assembly, EPDM may be fully adhered, mechanically attached or installed using another manufacturer-approved method.

Typical applications

Residential flat roofs, commercial buildings, additions and garages, large relatively open roof areas, and new construction and roof replacement.

Typical Scope of Work

  • Prepare or remove the existing roofing
  • Inspect the roof deck
  • Install insulation and cover board where specified
  • Place and attach the EPDM membrane
  • Complete seams, corners and terminations
  • Integrate drains, scuppers and penetrations
  • Complete perimeter flashings and edge details
  • Complete final inspection and cleanup

TPO Roofing

A heat-welded thermoplastic single-ply membrane designed for commercial and low-slope roofing applications. TPO systems commonly use light-coloured reflective membranes and welded seams to create a continuous waterproofing surface.

Typical applications

Commercial and industrial buildings, retail and multi-unit properties, large open roof areas, projects requiring a reflective membrane, and new construction and roof replacement.

Typical Scope of Work

  • Prepare or remove the existing roof
  • Review the deck and substrate
  • Install vapour control and insulation where required
  • Install an approved cover board
  • Place and attach the membrane
  • Heat-weld membrane seams
  • Detail corners, curbs and penetrations
  • Integrate perimeter flashing and drainage
  • Inspect completed seams and details

PVC Roofing

A heat-welded thermoplastic roofing membrane used where durable seams and resistance to certain chemicals, grease or oils may be important. The selected membrane and complete roof assembly must correspond to the building's use and project requirements.

Typical applications

Restaurants and food-service buildings, commercial and institutional properties, roofs exposed to grease or certain chemicals, mechanically attached or fully adhered assemblies, and specialized low-slope applications.

Typical Scope of Work

  • Evaluate and prepare the existing roof
  • Remove incompatible materials where required
  • Install insulation and cover board
  • Place and attach the PVC membrane
  • Heat-weld seams and membrane details
  • Integrate drains, curbs and penetrations
  • Complete perimeter and wall flashings
  • Inspect the completed assembly

Built-Up Roofing — BUR

A traditional multi-ply roofing system constructed from alternating layers of bitumen and reinforcing felts, typically finished with gravel, a mineral surface or another protective layer. Its layered construction provides redundancy and is commonly associated with larger commercial roof assemblies.

Typical applications

Commercial and industrial buildings, existing BUR roof replacement or restoration, large low-slope roof areas, projects requiring a robust multi-layer assembly, and protected or gravel-surfaced roofs.

Typical Scope of Work

  • Remove or prepare the existing assembly
  • Inspect and prepare the deck
  • Complete vapour-control and insulation work where specified
  • Install multiple roofing layers
  • Install the specified surface protection
  • Detail drains and penetrations
  • Complete parapet, perimeter and wall flashings
  • Complete final inspection and cleanup

System selection note: Not every roofing system is suitable for every building. Final system availability, installation method, membrane specification, insulation package, fastening requirements and warranty eligibility are confirmed after the project conditions and applicable manufacturer requirements have been reviewed.

Components & Construction

Every Layer Has a Specific Function

The final roof assembly is developed according to the building, existing conditions and selected membrane system. Depending on the project, it may include the following components.

Structural Roof Deck

The supporting surface for the complete roof assembly. Existing decking must be reviewed for damage, deterioration and suitability.

Vapour-Control Layer

Used where required to help control indoor moisture movement into the insulated assembly.

Roof Insulation

Contributes to thermal performance and may improve drainage through a tapered insulation system.

Cover Board

Provides a stable membrane surface and may improve impact resistance and dimensional stability.

Waterproofing Membrane

The primary waterproofing layer, selected with its attachment method for the project.

Drains and Scuppers

Direct water away from the roof; position, condition and capacity form part of the system review.

Curbs and Penetrations

Skylights, HVAC equipment, plumbing vents and other penetrations require integrated membrane and flashing details.

Perimeter and Wall Flashings

Protect roof edges, parapets, adjoining walls and transition points.

Vented roof cavities and compact insulated roof assemblies require different approaches. Component order, compatibility and specification must be determined for the individual project rather than treated as one universal configuration.

Project Options

A Scope Based on Existing Conditions

Flat and low-slope roofing projects range from new installation to complete replacement, roof recovery or targeted repairs and maintenance. Each option includes a different scope of work.

New Roof Installation

For new buildings, additions and major structural renovations where the complete roof assembly is installed over a new or prepared structural deck.

Scope of Work

  • Review drawings and specifications
  • Prepare the deck
  • Install required vapour control
  • Install insulation and tapered drainage components
  • Install cover board and membrane
  • Integrate drains, scuppers and penetrations
  • Complete custom perimeter and wall flashings

Complete Roof Replacement

The existing roofing system is removed to expose the underlying assembly, allowing damaged components to be identified and replaced before the new system is installed.

Scope of Work

  • Remove and dispose of existing roofing
  • Assess the roof deck
  • Replace approved damaged materials
  • Install insulation and drainage improvements
  • Install the complete membrane
  • Complete new flashings and roof details
  • Clean and review the work area

Roof Recovery

Where the existing roof and structure are suitable, an approved roofing assembly may be installed over the existing roof without complete removal.

Scope of Work

  • Review the existing roof
  • Perform moisture investigation where required
  • Prepare the existing surface
  • Install the specified separation layer, insulation or cover board
  • Install the membrane
  • Modify drains and penetrations
  • Complete new perimeter and transition details

Repairs and Maintenance

Targeted work may be completed where the existing roof remains serviceable and full replacement is not yet required.

Scope of Work

  • Leak investigation
  • Localized membrane repairs
  • Seam and flashing repairs
  • Drain and scupper maintenance
  • Penetration and curb detailing
  • Debris removal
  • Maintenance recommendations

A recovery system is not suitable for every roof. Existing conditions must be reviewed before this approach is confirmed.

1

Project Information

Collect building, roof, leak, drainage, access and project-scope information.

2

Roof Assessment

Review visible membrane, flashings, drainage, penetrations and substrate conditions.

3

Additional Investigation, When Required

Assess unclear membrane, moisture, insulation, drainage or deck conditions.

4

System and Scope Selection

Define the roofing system, installation approach, insulation, drainage and details.

5

Written Proposal

Identify the selected system, included work, assumptions, exclusions and pricing.

6

Installation Coordination

Coordinate materials, access, schedule, safety requirements and installation team.

7

Installation and Detailing

Install the assembly, membrane, drainage, penetrations and flashings.

8

Final Review and Cleanup

Review completed work, clean the site and provide available documentation.

Why ARKSTRUX

One Contractor for the Complete Flat Roofing Scope

Multiple Roofing Systems

ARKSTRUX coordinates the major elements of a flat or low-slope roofing project through one point of contact — from system selection and project planning to membrane installation, drainage details and custom metalwork.

Complete Project Scope

Roofing materials, accessories, custom flashings and installation are coordinated within one project scope, giving the client one point of contact from planning to on-site execution.

Custom Flashings and Metal Details

Roof edges, parapets, curbs, penetrations and other project-specific conditions are coordinated with custom metal details.

Residential and Commercial Applications

We work with homeowners, property managers, contractors and design professionals across residential, commercial and multi-residential flat roofing projects.

Project-Specific Installation Team

Installation is coordinated by a project-specific team matched to the selected system, roof configuration and building requirements.

Repair and Maintenance Options

Where the existing roof remains serviceable, targeted repairs and maintenance may be considered instead of full replacement.

Project Pricing

Pricing Based on the Complete Roof Scope

Flat and low-slope roofing is priced individually because each project requires a different combination of preparation, demolition, insulation, drainage work, membrane installation, flashings, access and safety measures.

ARKSTRUX reviews the roof conditions, defines the required scope and coordinates the appropriate installation team before providing a written proposal.

Final pricing depends on:

  • Roof size and configuration
  • Selected system
  • Existing assembly and substrate
  • Removal and disposal
  • Number of roof layers
  • Insulation and vapour control
  • Tapered drainage
  • Drains and scuppers
  • Curbs and penetrations
  • Parapets and flashings
  • Building height
  • Access and logistics
  • Project approach
  • Specifications and warranty requirements

Final pricing is provided after the project scope and site conditions have been reviewed. HST is additional unless otherwise stated.

Request a Project Assessment

Flat Roofing FAQ

Common Questions About Flat & Low-Slope Roofing

Find answers to common questions about flat and low-slope roofing systems, drainage, maintenance and pricing.

A flat roof is not necessarily perfectly level. It is a roof area with limited slope that requires a continuous membrane or another system designed for low-slope conditions rather than a conventional water-shedding shingle application. The acceptable slope and assembly depend on the selected roofing system, drainage design, building conditions and applicable requirements.

There is no single system that is best for every building. Selection depends on the roof deck, existing assembly, drainage, roof use, penetrations, exposure, attachment method, project specifications, budget and available manufacturer-approved assemblies. ARKSTRUX reviews these factors before confirming an option.

Sometimes. A recovery assembly may be possible when the existing roof, deck, structure, drainage and moisture conditions are suitable. Additional investigation may be required, and damaged or moisture-affected materials can make full removal the more appropriate approach. Recovery is confirmed only after project review.

Small residual areas may remain after rainfall on some roofs, but persistent or extensive standing water should be reviewed. Drain position, roof slope, deck movement, blocked drainage and insulation layout can all contribute. Acceptable conditions also depend on the selected membrane and manufacturer requirements.

Yes, a designed tapered-insulation layout can help create or improve slope toward drains or scuppers where the roof configuration allows it. The layout must be coordinated with drain elevations, curbs, perimeter heights, insulation requirements and the complete roofing assembly.

Some work may be possible in cold weather, but snow, ice, surface moisture and temperature can limit deck preparation, adhesives, primers, sealants and membrane application. The substrate must be properly prepared, and the selected system must be installed within its manufacturer requirements. Weather may require rescheduling or a different approved method.

Equipment is typically supported on suitable curbs or other approved details, and the membrane is integrated with compatible curb, corner, termination and flashing components. Penetration work should be coordinated before or during the main roofing installation so that drainage paths and membrane details are not compromised.

Yes. Periodic professional review can identify blocked drains, debris, membrane damage, open seams, deteriorated sealants or flashing concerns. The appropriate inspection frequency depends on the system, roof access, building use, surrounding conditions and significant weather events.

Permit requirements depend on the municipality and the actual scope, including structural changes, insulation, drainage, rooftop equipment and other building work. The applicable authority or project professional should be consulted before construction when the requirement is unclear. This page does not replace a permit review.

Available material, workmanship or system warranty terms depend on the selected product, assembly, installer requirements, project conditions and written proposal. No universal warranty applies to every flat roof. Any included warranty must be confirmed in the project documents before work begins.

Flat and low-slope projects are priced individually. Cost depends on roof area, existing layers, removal, deck condition, insulation, drainage, membrane system, penetrations, flashings, access and project specifications. ARKSTRUX provides final pricing after the scope has been reviewed. HST is additional unless otherwise stated.

Start Your Project

Planning a Flat or Low-Slope Roofing Project?

Tell us about the building, existing roof conditions and the work you are considering. Upload available roof photos, drawings or specifications, and ARKSTRUX will review the information to determine the next step.

Request a Project Assessment Upload Roof Photos or Drawings

Residential · Commercial · Multi-Residential · Architectural