Flat Roof Replacement Cost: Materials, Installation, Pros & Cons

Choosing the ideal roofing material for a flat roof can be challenging due to limited yet extensive choices. Unlike traditional roofing materials such as asphalt shingles, tiles, and metal, the options for flat roofs include PVC, TPO, EPDM rubber, BUR, and more, each presenting unique advantages and disadvantages.

EPDM rubber membrane on residential flat roof credits: GenTile

Roof Slope Dictates What Materials are Suitable

Why don’t traditional roofing materials work on flat roofs? Although theoretically you could try using shingles or tiles on a flat roof, that would almost certainly result in an immediate roof failure with numerous leaks!

Sloped roofing systems like shingles and concrete or clay tiles are designed to shed away rainwater, relying on overlapping layers that work alongside the roof’s slope to shed rainwater and snow.

Flat roofs, on the other hand, have minimal to zero pitch. If you were to try using traditional water-shedding materials like shingles, the lack of roof slope would allow rainwater to seep beneath the shingles or tiles, rotting the substrate and causing interior leaks.

Asphalt Shingles

$8,500
Average Cost
Metal Roof

$15,500
Average Cost
Flat Roof Membrane

$11,500
Average Cost

See what local pros charge Enter your zip code

Interestingly, most flat roofs aren’t completely flat but have a low slope to divert rainwater away from the roof, ensuring good water drainage and preventing any unwanted water accumulation, which could lead to premature leaks.

Covering a flat roof requires a different set of skills compared to pitched roofs, especially when it comes to ensuring the integrity and longevity of the flat roof membrane seams.

Water, especially standing or pooling water, is the most significant threat to any poorly sealed seams in a roofing membrane. In fact, most flat roof leaks are caused by either poorly sealed membrane seams (on newer roofs) or the old membrane seams coming apart (often due to freeze-and-thaw cycles), allowing water to infiltrate the roof.

The takeaway here is that flat roofs must either be impenetrable to standing water or have a well-functioning drainage system to prevent the accumulation of water (pooling). One can either physically cover an object to make it water-resistant (like a tarp) or apply a barrier coating (like deck stain or lacquer). Similarly, flat roofs can be covered physically with materials like PVC or EPDM rubber membrane or coated with tar or spray-on silicone.

Flat Roof Installation Cost:

Flat roof replacement costs usually range from $7.50 to $14.50 per square foot with one of these systems: EPDM, TPO, or PVC membrane. The cost fluctuates based on the type of roofing material, removal and disposal of the old roof, number of layers, roof deck condition, additional required repairs, desired insulation level, presence of parapet walls and skylights, roof accessibility, and home location.

A typical residential flat roof measures between 1,000 and 1,500 square feet, giving you a total replacement cost range of $7,500 to $21,750.

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PVC Roof Options and Costs 2023: PVC vs. TPO Membrane

PVC membrane installed on a flat roof

PVC, technically known as Polyvinyl Chloride is really vinyl roofing, though is routinely referenced as PVC roof.

PVC competes with TPO and EPDM in the synthetic roof membrane arena, and indirectly with all other roofing materials including BUR, modified bitumen, and structural standing seam roofs designed for lower sloped roofs.

Membrane roofs are usually applied to flat or low-slope roofs but using a single-ply membrane on a sloped roof is also possible and common on roofs with slopes between 1:12 and 3:12.

Why not just use traditional roofing materials (asphalt shingles or other tiles) on a low sloped roof? Because they are very likely to leak unless a minimum specified slope for shingles or tiles has been met.

When used with a slope, the overlap of those materials is designed to shed water away from the roof deck. Whereas flat roofs have only a slight pitch, and any standing, or pooling water, could lead to immediate leaks and rotting soon thereafter.

PVC membrane is a kind of roofing material that can withstand pooling or standing water — puddles of water that accumulate on roofs with low slopes.

Cost

Of the three primary membrane roof types, PVC is the most expensive. EPDM is the least costly option, and TPO is somewhere in the middle.

TPO allegedly offers the benefits of both the other types, yet that material keeps undergoing formula changes, and so compared to PVC and EPDM is considered less reliable, particularly when it comes to warranties.

Prices for residential installs can vary greatly. A roofer is likely to quote differently than a professional PVC installer, probably less, but also likely to not have the proper tools. A fair range is between $8.50 and $14.50 per square foot or $850 to $1,450 per square, depending on the project complexity and location, when installed by a PVC expert.

For a typical 1,200 square foot flat roof, you can expect a total average cost range between $10,200 and $17,400 for a new PVC roof mechanically attached to a roof deck. The cost includes all the necessary materials and supplies, professional installation, building permits, and installation warranty.

Asphalt Shingles

$8,500
Average Cost
Metal Roof

$15,500
Average Cost
Flat Roof Membrane

$11,500
Average Cost

See what local pros charge Enter your zip code

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EPDM Rubber Roof Cost, Plus Pros & Cons in 2023

Welcome to the default, or old school, material for flat roof installations. It’s technical name: Ethylene Propylene Diene Monomer is a mouthful. While it is simply a rubber material, we’ll go with EPDM since everyone else does.

EPDM rubber roofs compete directly with TPO and PVC single-ply membranes as a low-slope roofing material. EPDM, though, tends to only be used on flat roofs while PVC and TPO are sometimes used on sloped roofs.

Average Cost To Install a Flat Roof Typical Range: $8,675 - $12,340
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