Flat roofs are increasingly sought-after in both residential and commercial sectors due to their design advantages and versatility. All things said, how much does it cost to build or renovate such a roof? What materials can be used, and how variable are the repair costs? What factors are likely to affect overall roofing project costs? This detailed financial guide is an overview of the options available, price points, and factors to consider to plan a realistic budget and make informed decisions when planning a new roof-building project.
How Much Should You Budget to Repair a Flat Roof?
When it comes to a flat roof renovation or building project, understanding the associated costs is essential to plan a realistic budget. Here’s a cost overview based on different roofing materials used.
Price Per Square Foot for Flat Roof Coatings
Material | Estimated Lifespan | Price Per Square Foot |
TPO membrane | 20–30 years | $9–$12 |
Rubber roofing membrane (EPDM) | 20–35 years | $9–$12 |
Elastomeric membrane | 25–40 years | $16–$19 |
Green roof | 20–30 years | $20,000–$100,000 (overall project) |
Gravel and tar roof | 10–15 years | $7–$12 |
A gravel and tar coating is a cost-effective option for flat roofs. While such roofing requires regular upkeep, initial costs are quite affordable.
TPO and EPDM roof membranes provide a decent price-to-durability ratio. These flat roof coatings are especially sought-after given their weather resistance and ease of installation.
As for elastomeric membranes and green roofs, these are definitely high-end options. Initial costs are rather high, yet may be offset by material durability and green advantages, making for great long-term investments.
What Are the Pros and Cons of Different House Roofing Materials?
TPO Membrane
Advantages
Durability: A TPO membrane has an estimated 30-year lifespan, which makes it a great option for flat roofs.
Low maintenance: Its smooth surface streamlines cleaning and upkeep efforts, limiting maintenance costs in the long run.
Drawbacks
Temperature-sensitive installation: A TPO membrane installation can be compromised by extreme temperatures, jeopardizing the roofing’s weather seal.
Initial cost: While TPO membranes are cost-effective, they’re still priced higher than similar, affordable options, especially for small surfaces.
EPDM Roof Membrane
Advantages
Flexible: EPDM (ethylene propylene diene monomer) membranes are extremely flexible and temperature-, UV ray-, and weather-resistant.
Long-lasting: Given its 50-year service life, it makes for a great long-term investment.
Drawbacks
Aesthetics: EPDM, typically a black, synthetic rubber membrane, doesn’t suit all projects, looks-wise.
Installation: Installing EPDM roofing strips calls for expert-level know-how, and if improperly done, the installation may leak.
Elastomeric Membrane
Advantages
Air-tight: Elastomeric membranes are known for their waterproofing feature, which is ideal for harsh weather conditions, such as those experienced in Canada.
Long-lasting: They have a 25–40-year lifespan and require little maintenance, making for a worthwhile, long-term investment.
Drawbacks
Cost: Elastomeric membranes have rather steep initial costs, which can present as a hurdle for some homeowners.
Complex installation: Installing said roofing material requires specific expertise, which may increase labour costs.
Modified Bitumen and Gravel Roof
Advantages
Low initial cost: Bitumen and gravel roofing are among the most affordable flat roof options, coupled with competitive prices per square foot.
Water resistance: Such roofing can effectively prevent water build-ups, reducing the risk of leaks.
Drawbacks
Maintenance and upkeep: Requires regular upkeep, including additional gravel and waterproofing inspection.
Limited lifespan: Typically, service life falls between 10–15 years; isn’t as durable as that of other materials.
Green Roof Design
Advantages
Ecological benefits: Green roofs regulate building temperature and improve air quality, contributing to a more sustainable environment.
Aesthetic and practical: Green roofing makes for extra square footage to be used as a rooftop garden or patio.
Drawbacks
Expensive: Initial costs for green roofing implementation are rather steep given the structural work and maintenance required.
Complex upkeep: Requires regular, tailored upkeep to maintain plant life and guarantee the roof’s water-tight seal.
Tar and Gravel Roof
Advantages
Low initial cost: Much like gravel and bitumen roofs, this roofing option features among the most affordable.
Repair-friendly: Said roofing can be repaired easily and at a low cost.
Drawbacks
Limited lifespan: This roofing has a more limited service life, typically ranging from 10–15 years and requires frequent renovations.
Environmental impact: Using asphalt isn’t eco-friendly on account of its manufacturing process and non-biodegradable waste.
More information about flat roofing options.
What Factors Affect the Cost of a Flat Roof Construction?
The are several flat roof cost-defining factors. These include, and aren’t limited to, the following:
Roofing type: As mentioned in the chart at the beginning of the article, different materials have different lifespans and price points.
Roof’s square footage: Bigger surfaces inherently cost more to roof, although the per-square-foot cost tends to be lower for substantial surfaces. Bigger roofs benefit from economies of scale, which decreases the cost per square foot.
Structure’s complexity: Roofs with several obstacles (skylight, ventilation system, etc.) or requiring additional structural reinforcements cost more to roof.
Worksite location: Projects set in remote or hard-to-access areas tend to incur extra transportation and logistical costs.
Labour costs: A roofer’s hourly rate will differ significantly based on the region in question. While hiring certified and experienced roofers guarantees high-quality work, it does come at a higher price.
What Other Costs Should Be Considered?
Aside from roofing materials and labour costs, below are other expenses that may be associated with overall project costs:
Regular upkeep: A flat roof must be inspected and maintained regularly to ensure its longevity. This includes duties such as snow removal during wintertime and leak testing.
Insulation and ventilation: To guarantee the occupants’ comfort and prevent moisture-related problems, proper insulation and ventilation are essential. Flat roof systems often require specific ventilation systems to prevent condensation and mould growth.
Permits and regulations: Depending on the region, specific permits may be required for roofing work or application techniques.
Our Advice for Making an Informed Decision
To ensure the successful outcome of your flat roof project, don’t hesitate to contact several contractors and compare quotes to gauge the best possible offer. Careful planning and a thorough understanding of the costs involved and the options available will allow you to make well-informed decisions and guarantee your flat roof’s durability and efficiency.
More information about reroofing costs.
FAQ
What is a flat roof called?
Any low-sloped roof or roof structure with a very slight incline is called just that, a flat roof. However, there are different flat roof types: BUR (built-up roof), Mod-Bit (modified bitumen), concrete, TPO, metal, PVC (polyvinyl chloride), and green.
Is a flat roof a good idea?
Note that there are several upsides to building a flat roof, whether for residential structures or commercial infrastructures. One of the most appealing factors, for both home- and building owners, is that flat roofing construction and repair costs are quite low compared to other roof types, especially since this type of roof doesn't require as much roofing and insulation materials.
Additionally, as mentioned in the article, flat roofs are extremely versatile; they can be transformed into rooftop decks or gardens. Lastly, flat roofs are incredibly energy efficient, keeping utility costs affordable, given that there's no overhead space (attic) to heat or cool.
Can you have a flat roof in Canada?
Yes. In Canada, flat roofs are especially common for commercial buildings or condo towers on account of their cost-effective, durable, and safe design. Also, it streamlines the process of installing rooftop solar panels.
What type of roofing is best for a flat roof?
The best options for flat roofing materials include single-layer membranes and standing seam metal because of the materials' longevity and water-tightness.
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