Flat Roof Costs for 2017

Modern Home with a Flat Roof Are you looking to replace an old flat roof over your house or porch?

The most popular flat and low slope roofing materials installed on many homes across the US are single ply membranes: EPDM Rubber, PVC and TPO.

To help you budget, We have compiled up to date pricing data on the material and installation costs of these membranes.

We will also discuss features and top manufacturers, so you can select the best flat roofing product for your needs.

How Much Does a New Flat Roof Cost?

Depending on the size and complexity of your flat roof, you can expect to spend anywhere from $5.50-7.50+/sq.ft installed on a new single ply membrane (excluding insulation). So if you have a simple 1,500 sq.ft. ranch style home, you will pay $8,250 – 11,250 on your flat roof. If your roof is over 3,000 sq.ft., most contractors will give you a 3-7% discount for large volume.

You can also use our Roof Replacement Cost calculator, to get a more accurate estimate for your particular project.

Keep in mind that you should only install a single ply membrane on a roof slope of . If you exceed these requirements and put a flat roof membrane on a higher slope, you will face a lot of

Not all flat roofs are simple, and there are a number factors that will drive up the total price tag. Essentially, the more penetrations (chimney, skylight, roof hatch) and curbs your roof has, the more material and flashing will be required to complete the job, which will increase the total material cost. On a more complex roof, the installation is also more difficult and time consuming, which will increase the cost of labor.

Cost of Different Single Ply Roofing Membranes

Cape Style Home with a Flat Roof

Here is what you can expect to pay for each of the three single ply membranes. Note, that the estimates include materials and installation. It does not include insulation, tear-off or other additional items discussed below.

Note, that singly ply membranes come in different thickness, typically ranging from 45 to 90 mil. A thicker membrane improves the roof’s longevity and durability.

EPDM Rubber

Cost: expect to spend $5.50 – 6.50 / sq.ft. installed, or $8,000 – 9,750 for a 1,500 sq.ft. roof.

EPDM Rubber is the oldest and most frequently installed of the three single ply membranes. Its popularity is primarily due to low cost (its the cheapest of the three), ease of availability and DIY installation and repair options. It offers good weather resistance, withstands thermal shock and hail damage, and remains flexible in frigid temperatures.

EPDM does not require any special tools and materials for installation (everything can be purchased in Home Depot), which makes it popular among inexperienced roofers and DIY savvy homeowners.

On the down side, a rubber membrane only lasts 10-15 years (issues can start to occur as early as after 5-7 years of service life), is prone to leaks, ponding water, seam failures and other issues that result from the membrane’s design.

Top manufacturers include: Carlisle, Johns Manville (JM)

TPO Membrane

Cost: expect to spend $6.00 – 7.00 / sq.ft installed, or $9,000 – 10,500 for a 1,500 sq.ft. roof.

TPO (thermoplastic polyolefin) is the newest of the three single ply membranes. Because of its unique features and cost-effective pricing, it is currently the second most popular flat roofing material in the residential market and is steadily growing. While technically a rubber membrane, TPO’s unique formulation and seamless design avoids many of the problems that plague EPDM. It offers many features similar to its direct competitor, PVC membrane, such as superior leak protection due to seamless design, high puncture resistance, high solar reflectivity, which translates into energy efficiency, durability and low maintenance.

On the down side, TPO roofs have had a history of documented problems of membrane failures, particularly when exposed to prolonged periods of heat and UV rays. These have been primarily attributed to poor membrane formulations during the time when many manufacturers where experimenting and looking for ways to cut costs. However, in recent years many of these issues have been taken care of. Still, its recommended to get a TPO membrane from a reputable company who has been producing this product for at least 15 years, and has a strong track record of success.

Top manufacturers include: GAF, Flex, and Carlisle.

PVC Membrane

Cost: expect to spend 6.50 – 7.50 / sq.ft. installed, or $9,500 – 11,250 for a 1,500 sq.ft. roof.

Originally developed in Europe, PVC (Poly Vinyl Chloride) membrane is a premium quality flat roofing material. Unique heat – welded seam technology offers unparalleled protection against leaks, membrane break down and deterioration. It also reflects up to 95% of harmful UV rays, offering energy efficiency and savings. In fact, PVC is considered to be the most durable and long lasting flat roofing material, with a service life of 30+ years.

The biggest drawback for many homeowners is the high cost. Another rare, but serious issue is membrane failure due to unprofessional, poor installation. PVC is a specialty material that requires training, knowledge and expensive installation equipment. Consequently, its essential to only hire a contractor who has a proven track record and references of installing PVC roofs.

Top manufacturers include: IB, Flex, and Carlisle.

Cost of Flat Roof Insulation

White TPO Roofing Membrane on a Modern Ranch Style Home

In addition to the membrane itself, you need to budget for the cost of roof insulation. The default insulation that contractors install is fiber board. However, keep in mind that it actually does not provide any insulating properties and simple serves as a base for installing the roofing membrane. a 4×8 board costs $9.94.

If you are looking to have real insulation on your roof (which we highly recommend), you will need to install PolyISO Rigid Foam insulation. Because there are no other insulation material options for flat roofs, you will need to pay for ISO board.

ISO insulation comes in a range of thicknesses, which impact the R-value.

The thinnest size is 1 inch and has a 6 R value: $45-50/100 sq.ft. So if you are looking for 18 R value, you will need a thickness of 3 inches, which will cost you $135-150/100 sq.ft.

Additional Flat Roofing Costs

Modern House with a Flat Roof
There are a number of additional costs that you may run into when installing a flat roof. Here is what to budget for:

Tear-off and removal of old roofing $0.75 – 3.00 /sq.ft depending on the type of material and number of layers
Penetration Flashing (chimney, skylight) or curb $250 – 500 each, depending on complexity
Small Pipe Flashing $50 each
Large Pipe Flashing $75 – 100 each
Roof Drain $180- 250 each
Replace Damaged Plywood $75 – 90 for each 4×8 sheet
Install Stainless Steel PVC Clad Edge Metal $7 – 8 / ln.ft. Recommended on roofs of homes located within 1 mile from the ocean.

Cost of Built-Up Flat Roofing Materials

Flat Roof Design on a Modern House

In addition to single-ply roofing membranes, you have the option of built-up roofing. This was the default flat roof material, before the invention of single-ply membranes about 40 years ago. However, built-up roofs are still installed today on residential homes due their relatively low cost.

The two most popular materials are Modified Bitumen and Rolled Asphalt. You can expect to pay $5 – 6.5/sq.ft. installed depending on the number of layers you need. This does not include the cost of insulation or tear-off. Thus, you will pay around $7,500 – 9,750 for a simple 1,500 sq.ft. roof.

Keep in mind that to properly install any built-up roofing material, your roof slope needs to be at least 1/12 inches.

Why We Don’t Recommend A Built-up Flat Roof

Compared to single-ply membranes, built-up roofing materials are outdated by all modern construction standards. While being initially inexpensive to install, both modified bitumen and rolled asphalt flat roofs pose a lot of problems, such as:

1. potential fire hazard during installation
2. too many seams create the potential for more leaks
3. very difficult to trace and repair leaks
4. difficult to flash any type of roof penetration
5. flashings don’t last more than 5 years without repairs.
6. very expensive to remove and dispose of
7. much more prone to leaks than single ply membranes.

Published/updated on: March 24, 2016

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