What is the best material for a flat roof? and What are flat roofs called?
With the weather in the Hill Country area of Texas, a flat roof takes a beating. Days of hot sun then days of hard rain and hailstones followed by days of ice and snow. Over a year, a roof can experience every type of weather a person an image. So, as the owner of a commercial structure with a flat roof, you need to know what to look for in the way of roof repairs and roof replacement.
Let’s start with the most basic question, “Are flat roofs really flat?”, and the answer to that is no, they are not. For engineering purpose, a structure has to have some slant or slope for drainage, or a flat roof would simply cave in at some point.
Typically flat roofs are made of large, single sheets of BUR, EPDM, Modified BUR, PVC, or TPO in large sheets the installed in various ways and fastened to the roof substrate by different methods. While you can’t keep a flat roof from aging or developing leaks simply because you know what type of material the roof is, being educated and informed of different types of a flat roof material will help you make the best decision when it comes to repairs and replacing your current roof.
Here, we offer a brief summary of these flat roof materials:
- Bur or Build Up Flat Roof: Installed on commercial structures for over 100 years and still used with confidence today. Made with layers or stacks of roofing felt and melted hot tar then after 2 to 4 layers/stacks, topped with loose crushed stone or gravel.
- Modified Bitumen Flat Roof: Similar to the BUR described above, using 3’ wide rolls of asphalt, but only 2 layers/stacks on top of the base sheet then a cap sheet to top it off. This is installed with either hot tar or an adhesive of cold applied solvent. It may be installed with an open flame that torches it to the substrate and newer versions of this flat roof material is a peel and stick product.
- EPDM Rubber Flat Roof: This flat roof material is installed by weighing it down with large river stone or by gluing it down. Typically installed as a black roofing over a flat roofing boards made of fibers or insulation board or fiber board.
- Spray Polyurethane Foam Flat Roof: A layer of high density polyurethane foam is sprayed on then a waterproof coating that is an elastomeric material in either a gray or white color. .
- Thermoplastic membranes PVC or TPO Flat Roof: Single layers of gray or white material is adhered in a method similar to how the EPDM rubber is installed. Sometimes, it is mechanically attached using plates and screws.
Do flat roofs always leak?
The most common reason that a flat roof leaks is because you hired an inexperienced roofing contractor. The next reason is budget. When you combine those 2 things together, you’re going to have a leaking roof.
Another cause of a leaking flat roof is having the wrong type of material on the roof. A flat roof with EPDM material cannot be repaired using roofing tar. An inexperienced roofing contractor will likely try this because they don’t know how to work with EPDM roofing.
A third reason a flat roof is likely to leak, again, relate this to an inexperienced roofing contractor and a tight budget: Lack of roof flashing. Flashing is a must around roof protrusions and roof transitions on commercial and residential roofing. Without flashing, a flat roof is prone to leak. The roof protrusions we’re talking about are:
- HVAC system
- Vent pipes
Perhaps the biggest leak cause for a flat roof is poor drainage. A flat roof has some slant or slope, it is engineeringly required. It also needs drainage and if that drainage isn’t sufficient or becomes clogged, then the water will pond and seep into the membrane. From there, a leaking flat roof is just a matter of time.
This also relates to a flat roof with overhang, because without that overhang, while a professionally installed flat roof material will encourage water to flow toward the drain, the overhang assist and assures this happens.
How long do flat roofs last?
Flat roofing experts tell us that A professionally installed and maintained flat roof can have a life expectancy up to 40 years. The different materials and what type of climate can affect this time frame, and most important is the maintenance and upkeep of the flat roof. The more regiment the maintenance and upkeep, the longer a flat roof will last. Call (512) 677-6817 today for your flat roofing needs in Georgetown, TX.