Currently, the average cost of replacing a flat roof is $7,500-11,000 for a 1,600 sq.ft. ranch style home.
The most popular flat roofing membranes installed on homes across US are: EPDM Rubber, PVC and TPO.
We will review the material and installation costs for the most popular flat roof materials. We will also discuss pros and cons of each roof as well as top manufacturers, so you can select the best option for your home.
If you are ready to install a new flat roof, get free estimates from local roofing pros.
How Much Does A Flat Roof Cost?
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Depending on the size and complexity, you can expect to spend anywhere from $5.50-7.50 per sq.ft. to install a new flat roof, (excluding insulation).
So if you have a simple 1,500 sq.ft. ranch style home, you will pay $8,250 – 11,250. If your roof is over 3,000 sq.ft., most contractors will give you a 3-7% discount for large volume.
Keep in mind that you should only install a single ply membrane on a roof slope of up to 3:12. If you exceed these requirements and put a roof membrane on a higher slope, you will face a lot of problems down the line.
Not all flat roofs are simple, and there are a number factors that will drive up the total price. 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. This will inevitable drive up the total material cost. On a complex roof, installation is also more difficult and time consuming, which will increase the cost of labor.
You can use our Roof cost estimator to get an accurate price quote from a local roofing pro.
Flat Roof Materials Prices
Here is what you can expect to pay for each flat roof membrane. Note, that the estimate includes materials and installation. It does not include insulation, tear-off or other additional items discussed below.
It’s important to realize that singly ply materials come in different thickness, typically ranging from 45 to 90 mil. Thicker products are more expensive, but they greatly improve the roof’s longevity and durability.
An EPDM roof costs $5.50 – 6.50 per sq.ft. installed. This is equivalent to $8,000 – 9,750 for 1,500 sq.ft. of rubber roofing.
EPDM is the oldest and most frequently installed single ply material. Its so popular mainly because of the following advantages:
– low cost (its the cheapest of the three)
– ease of availability
– DIY installation options
– DIY repair options.
It offers good weather resistance, withstands thermal shock and hail damage, and remains flexible in frigid temperatures.
EPDM roofing 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, rubber only lasts 10-15 years (issues can start as early as after 5-7 years of service life). Moreover, it is prone to leaks, ponding water, seam failures and other issues that result from the membrane’s design.
Top EPDM manufacturers include: Carlisle and Johns Manville (JM).
On average, TPO costs $6.00 – 7.00 per sq.ft installed. This amounts to $9,000 – 10,500 for a 1,500 sq.ft. roof.
TPO (thermoplastic polyolefin) is the newest of the three membranes. Because of its unique features and cost-effective pricing, it is currently the second most popular residential flat roof and is steadily growing.
While technically a rubber material, TPO’s unique formulation and seamless design avoids many of the problems that plague EPDM membranes. It offers many features similar to its direct competitor, PVC, such as:
– superior leak protection due to seamless design
– high puncture resistance
– high solar reflectivity
– energy efficiency
– low maintenance
On the down side, TPO roofs have had a history of documented 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 TPO materials 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.
The total cost to install PVC roofing is $6.50 – 7.50 per sq.ft. This is equal to $9,500 – 11,250 for a 1,500 sq.ft. roof.
Originally developed in Europe, PVC (Poly Vinyl Chloride) is a premium quality roofing material. In fact, PVC is considered to be the most durable and long lasting membrane, with a service life of 30+ years. The main advantages include:
– heat – welded seam technology, which offers unparalleled protection against leaks
– resistant to membrane break down and deterioration
– reflects up to 95% of harmful UV rays
– superior energy efficiency
– savings on heating and cooling
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.
Flat Roof Insulation Prices
In addition to the membrane itself, you need to budget for the cost of insulation. The default insulation that contractors install is fiber board.
However, keep in mind that it actually does not provide any insulating properties and simply serves as a base for installing the roofing membrane. A 4×8 board costs $9.94.
If you want to have real insulation on your roof (which we highly recommend), you need to install PolyISO Rigid Foam. Because there are no other insulation options for flat roofs, you will need to pay for ISO board.
Polyiso 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 per 100 sq.ft.
Additional Flat Roofing Costs
There are a number of additional roof installation costs that you may run into.
|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.|
In addition to single-ply membranes, you have the option of installing a built-up roof. In fact, this was the default choice before the invention of EPDM and PVC about 40 years ago. However, built-up roofs are still installed today on residential homes due to their relatively low cost.
The two most popular materials are Modified Bitumen and Rolled Asphalt.
You can expect to pay $5 – 6.5 per 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 spend $7,500 – 9,750 for a simple 1,500 sq.ft. roof.
Keep in mind that to properly install any built-up roofing, your slope needs to be at least 1/12 inches.
Why We Don’t Recommend A Built-up Roof
Compared to roof membranes, built-up roofs are outdated by all modern construction standards. While being initially inexpensive to install, both modified bitumen and rolled asphalt 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.
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