Foam Roofing vs Tar and Gravel (BUR) Comparison

If you have a low slope or flat roof the time will come when you need to decide what type of materials will be used for your re-roofing. As mentioned in our Roof Replacement Basics article, re-roofing should always come first on a list of remodeling priorities. The short versions is, you need your roof to protect your investment, which is your home, from the elements. Severe roof problems, created by neglect or lack of maintenance, can allow water damage, or other problems to plague your home when the weather is unkind.

BUR / Mod Bit vs Foam Roofing During Hurricane Hugo

The roof pictured on the right is a modified bitumen, BUR, built up roof. You can see there was severe uplift and that the roof could not withstand the hurricane winds and rain. Now, observe the foam roof on the left, it survived the hurricane! Foam roofs are also very lightweight, strong and have high tensile strength, and they are self-adhering and need no fasteners. Take a look at this article here to see an example of foam roof which withstood gale force winds during hurricane huge!Foam Roof vs Hurricane Hugo

Foam Roof = Long Term, BUR = Short Term

So which type of flat roof, or low slope solution is best for you? The short answer is, foam roofing if you can afford it, but if you must, get a tar & gravel roof built up roof (BUR) (but be sure to maintain it). An EPDM or Mod Bit tar & gravel roof CAN last 20-40 years, but requires maintenance at least every 6 months, and at the 20 year mark, expect to replace the flashing (and if you don't, the whole roof will go). A foam roofing system is well worth the price: it's an excellent insulator, which means reduced energy costs, extremely leak proof, provides a vapor and moisture barrier, and a foam roof last the life of a building. Even with a high quality BUR roof will most likely last twenty years, while a low quality single ply roof will only last 12 years or even less. The foam roof will divert landfill waste, and eventually pay for itself in energy cost savings, while the BUR roof will need to be replaced several times during the life of the building, and will create no cost savings in comparison.

What is Foam?

Foam roofing is a technology innovation, and the polyurethane material which is sprayed onto your roof is the same material used in everyday refrigerators (and even on space shuttle fuel tanks). Foam contains millions of tiny closed cells of trapped air, and although it is very lightweight, it is quite durable, and is walkable about one minute after application. Sprayed foam can provide an R-value of about 6.5 or more per inch, so a 1.5 inch foam roof represents almost an R-Value of 10 (1 inch of wood = about 1 R-value). Sprayed Foam Insulation (the exact same material used on roofs) greatly outperforms other insulators such as blown fiberglass; so adding a foam roof may be all the insulation you need (1.5 inches of foam can be more effective than 6 inches of fiberglass). This has been demonstrated in multiple studies, including one by Oak Ridge National Laboratories.

A Completed Foam Roof:

Cool Roof Coatings Counteract Urban Heat Island Effect

Foam Roofing contractors also (as a rule of thumb) use energy star approved coatings, which are reflective and prevent nasty things such as the urban heat island effect. The urban heat island effect is the net impact of cities full of black asphalt streets and black roofs, which causes increased city temperatures on average of about 10 degrees. This disrupts local weather patterns and increases pollution as well. An asphalt based modified bitumen roof can easily reach 150 degrees Fahrenheit on a 95 degree summer day. Aside from the urban heat island effect, this of course will increase the interior temperature of your home. An importants side note: fiberglass performs very poorly at extreme temperatures (see: fiberglass vs foam insulation). In contrast to black asphalt roofs, Cool roof coatings are applied to foam roofing systems, which reflect the rays of the sun and keep your roof and (even more importantly) your home, cooler.

A Foam Roof Installation In Progress

Here's a foam roof installation in progress. This roof will still need at least an acrylic elastomeric base coat. Most professionals will also install a top coat to ensure the roof needs no maintenance for a very long time. Foam installation requires specialized training & equipment. Be sure your contractor is reputable and well known, or you may be disappointed with the results. For example, the best California Bay Area Foam Roofing Contractor is Dura-Foam. Third party sources like Eichler Network, Diamond Certified, the BBB, and Valuestar confirm this. Foam Roofing is the 'green' (environmentally responsible) choice, because you'll cut energy costs, divert landfill waste, and the cool roof coatings will counteract the urban heat island effect.

A BUR (Built Up Roof, Tar & Gravel) Installation In Progress

If you've ever been around a BUR roof during an installation, you probably still remember the strong sulfuric smell emitted by the vats of tar. To some extent, installing a tar & gravel BUR roof can be dangerous. If the tar spills on a worker, they can suffer 2nd or 3rd degree burns. Bur Roofs can reach upwards of 150 degrees Fahrenheit during a 95 degree day--this means you can expect things to be much hotter inside your building (vs a foam roof), and the extreme levels of heat also shorten the life-span of the roof. If you do choose to install a tar & gravel / BUR roof, be sure to find a reputable contractor on the BBB honor roll, and someone who can be recommended by both old & new customers.

I guess it just boils down to economics... some of us need new roofs and just can't afford a foam roof. Other than the slightly higher price tag, I really don't see why someone would ever choose a BUR roof instead. Foam is clearly the superior flat roof solution. Other than the superior performance, it's also more environmentally friendly. What more would anyone ask...

Find a local Foam Roofing contractor.