Help! My Flat Tar and Shingle Roof is Leaking

Pictured: A recently installed Built Up Roof (BUR) also known as Tar and Gravel:

Question: (Frank)

I own a few large flat roof industrial buildings, some have tar and gravel and some have rolled roofing. Some areas of my roofs have asphalt shingles and flashing. The time is approaching when I'll need to replace this roof (I think it's about 15 years old) and I've been trying to research my options and make an informed decision. I heard about some 'expanding' foam that is supposed to get hard enough to walk on and is good for insulating and protecting roofs from leaks. I'm really running out of patience with my current type of roofing and contractor. They keep coming out here and 'fixing' my leaks, but new leaks keep springing up. My total square footage is about 16,500 feet between three buildings.

Below: Aspahlt shingles are made of bitumen covered fiberglass or organic material, surfaced with chipped bits of man-made ceramic:

Answer: (Expert) Yes, a Sprayed Foam Roof is A Good Choice

Clearly, you'll need to replace your existing roofs because they are leaking, old, and worn out. As you mentioned your buildings have flat roofs. Although there are other "good" options, a foam roof system (also referred to as SPUF, SPF, PUF) is probably by far the best choice for any flat roof. Foam Roof systems are insulating, water proofing, monlothic barriers, and they require less upkeep than most other roof types. If you've got a lot of obstructions such as pipes, vents, ac units, solar units, or ductwork on your roofs, foam is also superior in those cases, since it can be sprayed to mold and fit any shape. Be sure the final topcoat used by whatever contractor you select is a 'cool roof', energy star approved elastomeric coating. Hot Tar roofs, depending on how dirty or dark they are can read over one hundred fifty degrees farenheight on a 95 degree day. This can make things quite hot inside your building unless you have extensive insulation. A foam roof with a cool roof coating will stay cooler and prevent that type of heat transfer from going on. The reflective coating also helps the roof last longer, since it stays cooler and absorbs less sunlight.

Below: foam roofs insulate, correct ponding, and provide a leak proof monolithic barrier, while cool roof coatings also provide a reflective surface. Foam roof systems, properly installed also last the life of the building, which means, eventually a foam roof will pay for itself in energy cost savings.


Assuming you've only got a single layer of roofing substrate, your roofs can just be cleaned, and foam roof systems can be installed right over the existing roofs. However, if you've got multiple layers of roofing, you'll need a contractor to come out and take a look, to decide whether one or more layers should be removed.

Select a Qualified, Well Trained Foam Roof Contractor

Foam does require a skilled contractor, so you'll want to talk to old customers & new ones to be sure everyone still recommends them. You may also want to check their licence with the state contractors board (this can be done online) to make sure they are in good standing. You can also see if they are rated by agencies such as diamond certified or value star. And of course, you may want to check your local BBB to see if the company has any outstanding complaints.

High Visibility Requires a Very Skilled Applicator

If your roof is highly visible from ground level, you'll want to be very sure that the applicator is experienced. Spraying a smooth foam roof depends on several factors, including the heat of the hoses (A&B components are combined as the material is sprayed on to the roof, and how much it rises or does not depends on the heat of the liquid). This becomes tricky when outside temperatures are too hot or too cold, or too damp (humid). Foam can only be applied on a dry surface (or it will not properly 'stick' or seal. Excessive wind during the application can also cause problems (this happens more if your roof is higher than two stories). Contractors have measures for dealing with this, but if winds are too extreme some of these measures can become impractical.

Foam vs Built up Membrane (Hurricane Hugo, Puerto Rico)

The roof on the left is an SPF foam roof, and the roof on the right is a built up membrane (bur) roof. Both of these buildings were hit equally hard by hurricane hugo, so why did the spf foam roof remain intact while the other roof was severely damaged? Foam roofs are sprayed on and have no joints, they seal to whatever surface they are sprayed on to, and need no fasteners. Foam roofs are also very lightweight, strong and form a single monolithic barrier. When properly installed, the foam forms a smooth, continuous surface, which as displayed, can even withstand gale force hurricane winds. And, as displayed, most other roof systems are not anywhere near durable as a foam roof. Something else to keep in mind, a professionally installed spray foam roof lasts the lifetime of a building.

SPF Foam Installation Conditions

You must be sure the existing roof substrate is completely dry when installed a foam roof over it. Once a foam roof is installed, any trapped moisture could cause the old roof materials to rot. Be extra cautious if you have a wood deck on your roof. As far as weather goes, an ideal day for spraying SPF foam is a warm and sunny day with low humidity.

Flat Roofing Materials Ranked in Order of Quality

For best results, your old underlying roofs should be torn off. Should you decide against foam roofing, then you'll need to choose a single ply material to cover the roof (from cheapest to most expensive, and lowest to highest quality): 1-Modified Bitumen (cheapest & lowest quality), 2-EPDM, 3-TPO, 4-PVC, 5-Foam Roofing (most expensive & highest quality).

1-Modified Bitumen (torch down) - pictured: a modified bitumen roof install in progress:

Modified Bitumen which can be done as 2ply or single ply (2ply is of course more expensive than single ply--and higher quality). Modified bitumen roofing is made of a reinforced polymer sheets surfaced with mats, films, foils, and mineral granules.

2-EPDM (Ethylene Propylene Diene Terpolymer) - Below: an EPDM installation in progress.


EPDM (Ethylene Propylene Diene Terpolymer) is a rubberized roofing material, used for its versatility in varying weather conditions.

3-TPO (constructed from ethylene propylene rubber) - Pictured Below: a TPO roof install in progress.


TPO (Thermoplastic Polyolefin Membrane) is a plastic, fabric enforced membrane, used due to its reflective nature, normally attached with an adhesive, or fasteners.

4-PVC (a highly-engineered, flexible, thermoplastic membrane ) - Pictured: a PVC roof installation.



PVC (Polyvinyl Chloride) this is another membrane type roof, generally installed in a reflective color and sealed with hot air (no torch required). All membrane plastic or rubber type roofs (EPDM, TPO, PVC) tend to get brittle with age, pulling away from edges, and cracking. As they age they also become more difficult to repair.

5-SPF Foam Roofing (mentioned above already; this is the highest quality flat-roof material) - Pictured: a base coat is applied to a foam roof.


Foam roofing stands alone as a superior flat roof solution, due to it's capacity to last the life of the building, correct ponding, and endure all weather conditions including heavy rain and snow. Normally reflective coatings are used, and foam is a phenomenal insulator as well. However, foam requires experienced technicians, and you'll only experience great results with a properly trained installation crew using the right methods. Foam is also limited to warmer geographic areas, and can be difficult to install in places such as Alaska where most days of the year would be too cold or humid for installation.

If you're in a place with extreme winds, such as Florida, you may want to take a look at the hurricane hugo picture above (up a few paragraphs). Just keep in mind a foam roof can withstand a hurricane, and most other roofs cannot. If you still decide you don't like foam, then make sure whatever system is installed is a 'fully adhered' system (not just nails, or staples, etc).

Replacing Your Shingles

Below: a shingle roof replacement in progress:

For the shingle section of your roofs, if possible, I would just have the foam roof system applied on the entire building, especially considering that this is an industrial building. However, if you decide to re-roof with shingles, keep in mind that asphalt shingles are the cheapest and lowest in quality, while shale is the highest quality, but very expensive. Also, be sure to install plastic membrane ice dam protection if you're in a colder climate area (this must be before the new shingles or tiles are laid).

If you're in the California Bay Area, the leading foam roofing contractor is Dura-Foam: Bay Area Foam Roofing (in business nearly 30 years, over 10,000 installations, BBB Honor Roll)

Flat or Low Slope Roof Replacment

I think this article provides sound advice for anyone that needs to replace flat or low slope roof. On a sidenote, I've heard of a special type of shingle called Sea Green Shale which is supposed to last 100-200 years! I think it's more for really nice buildings (it's probably expensive). Perhaps that's not a good option for something like a warehouse which is more function than form.

I have heard a lot of good things about foam roof systems. I especially like that picture you've posted about the hurricane with the foam roof vs that bur roof. Wow, look at that damage! Pretty wild stuff. If I can afford a foam roof, that's what I'll be putting on my home for sure!

Learn more about Foam Roofing.