A flat roof is an ideal solution for a modern new construction home, a single story ranch or barn-style home, or a home addition to an existing house.
On average, the cost to install a flat roof is $5-10 per square foot, depending on the material you choose and local roofing contractor prices. On a 1,200 sq.ft home homeowners spend $6,000-12,000 including materials and professional labor.
Compared to sloped roofs, such as shingles, tiles or metal panels, flat roofs are easier and faster to install, offer ample room to place HVAC units, solar panels, satellite dishes, etc., and can be easily accessed for repairs and maintenance.
If you are not sure which type of flat roof would be best for your home, you can get 3-4 free estimates from local roofers near you.
What Materials Are Installed On A Flat Roof?
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Flat roofs are available in a range of colors (though white seems to be a go-to choice due to its reflective properties). When it comes to popular flat roof materials, you have a few options you can pick from.
Here, we list 5 popular materials used on a flat roof along with their installation costs, advantages and disadvantages.
The first three materials on this list (EPDM, PVC, TPO) are newer and are single ply membranes which are easier and safer to install. The last two (ModBit and BUR) have been around for decades and are slowly being phased out by the more modern and better roofing options.
EPDM rubber membrane
BUR (built up roofing)
Many homes make use of flat roofs on the garage, sun room, or home addition. Also, flat roofs can be installed as the main roof over the entire house.
EPDM Rubber Roofing
One of the least expensive types of roofing, EPDM is synthetically produced by modifying natural rubber’s properties; as a result, it is more resistant to weather changes.
It goes by a few names: rubber roofing, rolled rubber roofing, and membrane rubber roofing. Because of its durability and low price point, it has become a popular choice for many property owners.
In the early 1960s, EPDM was commonly used in irrigation systems. It was later discovered to be an equally good material for waterproofing flat roofs. The installation is not very difficult. You can easily buy the EPDM which is sold in rolls, along with some strong bonding adhesive and an armed roller for application.
Cost to install an EPDM rubber roof
Like we mentioned earlier, EPDM is very cost-effective; it costs approximately 80 cents per square foot. Besides this, the installation is fairly easy and straightforward, costing you anywhere between $5.50 to $9.50 per square foot (materials + installation).
If you are doing a whole house renovation that includes siding replacement, EPDM rubber roofing is a good budget friendly material to consider.
Pro-tip: If you want a lighter color but don’t want to dent your savings, simply use acrylic paint to coat it with a lighter shade. Several helpful How-To videos are available online to guide you.
– The cost of EPDM is perhaps the biggest advantage it has over the alternatives. Everything, from material to labor charges, costs less.
– The installation of EPDM is also extremely easy. It is lightweight and can be installed fully adhered, mechanically, or ballasted. You can use liquid adhesives or special tape to seal the seams. Easy installation translates to lower labor costs.
– It can withstand cold weather, winds, heavy rains, and hail.
– Aesthetically speaking, EPDM may not be the most attractive material when laid out. Property owners looking for roof options for main areas of the structure may not find EPDM appealing.
– It is available mostly in black, which means it absorbs a lot of heat. This may drive up utility costs. Lighter shades are available, but they usually cost 30% more.
– EPDM can also develop punctures very easily. A fallen branch or a sharp object will easily damage it. While it can be easily repaired, the problems can get worse if water seeps through the punctures.
– It requires ongoing maintenance. Regular roof repairs may be required to extend its longevity.
– It does not handle chemicals, especially citric-based ones, very well.
Generally speaking, EPDM rubber roofs can last up to 10-15 years before they require a resealing; very rarely will you require a replacement in this time frame. Homeowners can consider re-sealing and re-coating the EPDM roof to extend its lifespan.
TPO roofing membrane
Thermoplastic polyolefin or TPO is another flat roofing material gaining popularity in the residential and commercial building space. It is a mix of plastic and rubber, and is available as rolled sheets.
Like EPDM, it is a single-ply application, which means one sheet is enough to do the job. The installation is not too complicated. Sheets are rolled out on the roof, cut to specifications of the roof deck, and then attached.
TPO can be installed mechanically using nails and screws to fix it into the deck, it can be fully adhered using glue, or it can be ballasted or held down using strategically placed rocks or ballasts. The seams of the sheets are welded together using heat to achieve a seamless, monolithic look.
Many modern new construction homes specify a TPO roof, because it offers an attractive combination of price, durability and longevity.
Cost of a TPO roof
Most roofers will be able to install TPO, either mechanically or by gluing the roof. However, heat welding the seams, which is essential for preventing leaks, needs skill and expertise, and it might cost a bit more. The materials and installation prices for TPO can cost $6 to $9.20 per square foot. While it is slightly more expensive than EPDM, it is still a cheaper option.
– TPO is another budget-friendly option. The up-front cost of buying and installing the material is lower compared to other flat roofing materials (except EPDM).
– The material is hardy, and does not crack, puncture, or corrode easily. TPO can withstand chemical damage too.
– It is white on one side, which makes it more reflective. This, in turn, translates to energy savings.
– TPO is also a “greener” option since it can be easily recycled.
– TPO is a relatively new technology, hence getting an accurate review of the material to determine its longevity and durability is currently not possible.
– There is no standard formula to produce TPO. Different manufacturers will have different versions of it, which means some of these variants may be of poor quality.
– You need qualified professionals to install a TPO flat roof properly. If installed incorrectly, you will end up shelling more money in repairs and upkeep.
Again, because TPO is relatively new and undergoing constant changes, there is very little data available on this material to reach an accurate ROI estimate. Most companies offer warranties ranging from 10 to 25 years, which can secure your investment.
Pro-tip: Choose a company that has been working with TPO since 2000, i.e., since the time TPO has been around. This will give you a clear picture of their warranty policy.
PVC roofing membrane
The term PVC usually brings to mind plumbing pipes and not roofing material. Yet PVC or Polyvinyl Chloride is one of the most popular flat roof materials. It is commonly referred to as vinyl roofing. It is the best flat roofing material to use on a high-end home addition.
Being a type of plastic, it is stronger and more durable than the other options available in the market.
PVS comes in two variants; one is used in flat roofs and the other is used in conservatories. It is available as a membrane and is sold in rolls.
The most popular way of installing PVC for flat roofs is by mechanically attaching metal plates between seams and securing them with nails. The seams are welded together to create an even appearance. It can also be installed by using adhesives.
Cost to install PVC roofing
The costs will vary according to the thickness of the PVS membrane and the type of installation. In general, it should cost you anywhere between $6.75 and $10.70 per square foot installed if done by a flat roofing expert.
– PVC has a proven track record when it comes to longevity. It is very sturdy, extremely durable, and tear and puncture-resistant.
– It has fire-retardant properties, which means it can self-extinguish if the roof catches fire.
– Because it is available in lighter shades and has thicker insulation, it is more energy- efficient.
– It is resistant to moisture, fungus, algae, chemicals, and fats from kitchen exhaust vents.
– PVC flat roofs require little to no maintenance, which translates to more savings down the line.
Pro-tip: If you live in an area exposed to hotter temperatures during the year, a white PVC flat roof is an ideal choice as it will reflect more UV rays and control the amount of heat being transferred indoors on hot days.
– One of the biggest drawbacks of PVC roofing material is the cost; it is costlier than EPDM and TFO.
– The installation of PVC can be tricky. If done haphazardly, it can give rise to maintenance issues. It requires professional expertise to install these properly.
– It is not as eco-friendly as EPDM, and can only be recycled with other PVC products.
In terms of ROI, PVC membrane arguably has the best among the available options. An expertly installed PVC flat roof can easily last for 30 years or more. Manufacturers usually offer “lifetime” warranties on PVC flat roofs.
Modified Bitumen Roof
Modified bitumen roofs are a less popular option among all available, but they are still used widely on flat roofs. Modified bitumen is an improved version of the built-up roofing (BUR) system. Made from asphalt bitumen, it has added polymers along with fiberglass and polyester. This combination of materials makes it a very hardy material with an increased lifespan.
The most popular way to install modified bitumen is by rolling out the material on the flat roof that has been heated by a blow torch. Since it is a multi-ply system, a base layer is first attached to the deck mechanically, a ply overlap is adhered to this next, and finally, a granule surface is added that provides energy efficiency and a more appealing look. Modified bitumen is available in self-adhesive and cold-applied adhesive sheets too.
Cost to install a modified bitumen roof
The most effective modified bitumen flat roof system is the multi-ply one, and it can be very labor-intensive since multiple layers have to be applied. Even the newer cold-rolled technologies require a lot of work. You need a professional to handle the installation of
Depending on the type of modified bitumen you pick, the materials plus installation costs will be around $4 to $7 per square foot.
– This is another flat roof system that has a proven track record. Its durability adds to its lifespan making it last longer than several flat roofing systems available today.
– It has high tensile strength, making it less likely to develop cracks.
– The addition of fiberglass and polyester layers makes this roof system very hardy and resistant to damage, even from extreme weather events like storms.
– The seams on modified bitumen flat roofs are heat welded to give the roof a seamless look. This is very important as it helps prevent leaks.
– Again, the top surfacing option can help reduce energy wastage by keeping interiors cooler on hot summer days.
– When it comes to disadvantages, the biggest concern with modified bitumen is the danger it poses during installation. Blow torches on the roof can lead to fires if safety precautions are not strictly adhered too.
– Lack of proper roof insulation or granules can cause overheating of the rooms and damage the roof.
– If you opt for single-ply modified bitumen, there is more risk of wear and tear. This will lead to significant costs in repairs or replacements.
– The multi-ply option is costlier.
– These types of roofs don’t do too well with standing water. If the roof starts collecting water, it will cause early damage to the modified bitumen flat roof.
The right modified bitumen flat roof can easily last for 20 years. Most manufacturers offer long warranties that speak to the roof’s longevity. They are very durable and are mostly rated against wind, fire, and hail.
Pro-tip: Invest in a multi-ply modified bitumen system that includes granules. This will offer UV protection and prevent sun damage to the roof, while also keeping the interiors cool.
Built-up Roof (BUR)
One of the oldest roof types, built-up roofs or BUR, has been around since the 1970s. They are commonly referred to as “tar and gravel” roofs. BUR systems consist of alternating layers of bitumen and other reinforcing materials. With a minimum of 4 layers, this flat roof system is made up of bitumen (asphalt or coal tar), topped with a surfacing.
For installation, heated asphalt or coal tar is spread across the roof using a mop or machine. Solvent-based cold-applied adhesives that do not require additional heating equipment like kettles or tankers are also available. The surfacing used can be an aggregate like gravel, hot asphalt poured over the surface, coatings, or glass fiber. BUR systems today include an insulation layer for energy efficiency.
Cost of a BUR roof
BUR flat roof installation requires expertise and high safety standards. The multiple layer roofing system can be on the costlier side, but then again it has a proven track record. You can expect to pay anywhere between $6 to $10 per square foot installed.
– BUR flat roof systems have a proven track record of longevity. Some of these roofs have been standing for more than 40 years.
– The system also comes with a highly reflecting coating that helps keep the indoors from getting too hot. This can help reduce the energy load on heating and cooling systems, leading to more energy efficiency.
– BUR is extremely durable. It can withstand heavy foot traffic, is resistant to fire, storm, and other extreme weather events.
– It requires very little maintenance, so you can look forward to fewer bucks spent on repairs down the line.
– One of the biggest drawbacks of BUR flat roofs is the installation process. It is slow and can prove to be very hazardous because of the materials involved.
– Because BUR systems require different materials and expertise to install, they are also among the costlier flat roof options.
– BUR is also heavier which means the supporting structure will need to be strong.
– There are a lot fewer expert BUR roof installers compared to other roofing pros.
Pro-tip: Try to secure both types of warranties for BUR systems, manufacturer warranty, and contractor warranty for the workmanship for the installation.
Some BUR roofs built over 40 years ago are still standing today. This is proof of their durability over time. Built-up roofs also require little to no maintenance so you save more over time.
How long does a flat roof last?
In general you can expect a new flat roof to last about 12-20 years. Some materials such as PVC roofing can last a lot longer, such as 30-40 years. On the other hand, EPDM rubber roofs can have a service life as short as 8-10 years.
The difference in the longevity of a flat roof is primarily determined by the climate you live in. Most flat roofing materials do well and have the longest life span when they are installed in a mild climate that does not have a lot of rain, snow, strong winds etc.
Severe weather such as temperature fluctuations, rain and snow storms, hail, wind, very strong sun exposure for many months can shorten the expected life span of a flat roof by as much as 20-30% from what is stated by the manufacturer.
If you live in a harsh climate its best to install durable and reliable single ply roofing membranes such as TPO and PVC. In fact PVC membranes are installed all over New England, which gets snow, hail, rain, for many months out of the year, and they hold up very well in this tough climate.
What is the best flat roofing material?
If you want a flat roof that will last many decades without causing any leaks or other issues, its safest to install PVC roofing. Most seasoned roofers who have been installing flat roofs will tell you that PVC by far outperforms all other flat roofing materials available. The difference in cost is minimal compared to the long term benefits you will have with a PVC roof.
In recent years, TPO roofing has created major competition for PVC roofs. They offer many of the similar benefits and features for about 20% less. If you live in a mild climate and really want to save money, you can install TPO roofing.
However, TPO roofs are not known to perform well in high heat, severe temperature fluctuations, and other types of consistent inclement weather conditions. In this case, PVC roofing is still your best bet.
Tips on hiring a roofing contractor
One of the biggest sources of problems and leaks on a flat roof is faulty installation. Professional labor to install a flat roof is usually 50-60% of the total roof replacement cost. Many homeowners try to save money on a new roof, especially if they have other remodeling projects going on at the same time.
However, its a big mistake to save money on roof installation cost, especially when it comes to flat roofing because this type of roof requires expert knowledge and experience to be done correctly. Roofing pros who install heat welded single membranes, such as TPO and PVC also have thousands of dollars of special equipment.
Because of these reasons, you cannot hire a general roofer who usually puts up asphalt shingles to install your flat roof and save $1,000-2,500 on this. He will not know how to make sure that the roof is watertight and you will see leaks very fast.
Make sure that you only hire a licensed flat roof specialist who has great references from previous jobs.
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