Flat Roofing is Popular in the DC Metro Area
Did you know that nearly all row houses and buildings in DC and Capitol Hill area have flat roofs? And all modern homes with steel frame structures and open floor plans have flat roofs? So if old and new use flat roof construction, it must be the best material for roofing, right? Not Necessarily.
Flat Roofs Hold Water like a Bath Tub
The demands on flat roofs are unique to other materials. Flat roofs are “flat.” At least nearly, but they do slope a tiny tiny bit. And slowly drain into stormwater management systems such as large gutters and downspout drains. Flat roofs need to be water proof because they need to hold standing water and prevent leakage into the underlying wood decking. Contractors who Install flat roofs are very specialized and need to pay careful attention to details.
We Specialize in Flat Roof Systems
Nearly all new flat roofs are made of either TPO or EPDM membranes. So which one is better and what are the pros and cons?
What is the Best Flat Roof Membrane?
60% of all flat roofs installed these days have TPO membranes. But why? What makes TPO singly ply better than EPDM and other low slope systems? Some roofers believe TPO is easier to water proof than EPDM. But there are many differences in the two roofing materials and how they are installed. TPO is more widely used in the Maryland, DC and NOVA areas.
Commercial and Residential Flat Roofing Maintenance and Replacement
Premier Roofing specializes in flat roof replacement and repair for commercial and residential projects. Finding a TPO specialist is important. TPO is technique sensitive compared to asphalt shingle installation. Many of our projects are completed in Washington DC, Silver Spring and Alexandria. We have over 25 years of experience in the roof industry. We are happy to evaluate your project and determine what installation or repair is best for your situation.
Flat Roof Repairs
flat systems typically last 15 – 25 years depending on climate and the quality of the materials. What are the common repairs for flat roofs. Sometimes leaks can be difficult to find in flat roofs. As a roof ages and the membrane begins to fail, it may be better to consider replacement rather than a repair that may not last too long before another needs to be done. How to handle repair vs replacement of a flat roof leak can be complicated. What is the average cost to replace a flat roof?
EPDM Compared to TPO Flat Membranes?
Let’s take a look at the differences in the systems. What are the advantages of TPO and EPDM? What makes one better than the other?
It is really best to ask your Premier flat roofing expert whether TPO or EPDM is best for your project. Usually TPO is a better product in the Washington DC metro area due to the climate. During your project assessment, Premier will make a recommendation. But the basic differences between TPO and EPDM are as follows:
TPO vs EPDM
- EPDM has been used for over 60 years vs 20 years for TPO
- EPDM absorbs heat from sunlight and TPO reflects sunlight
- EPDM is mechanically retained by screws where TPO is glued down
- EPDM seams are taped together whereas TPO seams are melted together with a hot air gun.
- EPDM and TPO are roughly the same cost.
- EPDM on the average lasts 5-10 years longer than TPO.
TPO Flat Roof is Preferred in DC Metro Area?
The above facts about TPO vs EPDM speak for themselves but there are certain situations where one material may work better than another. For example in situations where there may be high winds, TPO may be better because of the higher seam strength. In situations where there is lots of intense sun and long summers, TPO may be better because if reflects radiating heat from the sun where as EPDM absorbs more radiant heat. TPO in this situation will likely prevent less heat from entering the building and reduce cooling bills. In situations where there are longer winters EPDM may be a better product for energy saving reasons as well. EPDM has a longer life on the average, so it will in the long run be the better value when it comes to longevity. EPDM is also easier to install and requires less skill.
Single-Ply Membrane Systems
TPO and EPDM are examples of single-ply membranes. If you see a large commercial roof that looks like a seamless sea of white, you have likely seen a TPO roof. A flat roof is a membrane that attaches mechanically or with an adhesive to the wood decking or to a root-top insulation material. Of course the two most common single ply membranes are:
- Thermoplastic Polyolefin (TPO)
- Ethylene Propylene Diene Terpolymer (EPDM)
Both of these materials differ in their composition, energy efficiency, and installation techniques.
TPO Roofing Systems Installation:
The first step in installing a TPO roof is to remove the old roofing material down to bare wood. Next step in installing insulation. There are a few different kinds of insulation that can be used:
- Polyiso aka Polyisocyanurate – a very popular flat insulation material. It is expensive but has an excellent R-value rating, or insulation value. This will definitely help with the energy bills.
- EPS or Expanded Polystyrene – also has a great insulation value and is very resistant to water,penetration.
- (XPS) Extruded Polystyrene – It’s insulation value and price are between Polyiso and EPS. It is a semipermeable material that has a perm rating of 1. It is not as good of a water and vapor barrier as EPS.
TPO membranes come in sheet widths of 10, 12, and 20 feet. The sheets come in rolls and are un-rolled and cut to size on the job site. Once the membrane has been rolled into place and cut, the seams created are welded together with a hot-air gun.
How Much Does TPO Roofing Cost?
- Existing roof condition
- Roof dimensions
- Roof height and access
- Insulation being used
- Roof penetrations such as vents and air units, skylights, etc
- flexibility in selecting different insulation options. Some products include insulation.
- Installation techniques – There are different ways to install a TPO roof. It can be connected directly to the roof deck or attached with adhesives. It can also be welded through heat in more difficult areas such as protrusions, projections, and chimneys.
- Resists growth of algae and corrosion. Very rarely does TPO need to be power-washed.
- Fire resistant material
- TPO reflects radiant heat. In contrast to EPDM which absorbs heat.
Disadvantages of TPO Membranes
With the popularity of material, there are many different manufactures of the singly ply product. There are many different qualities and you really need to do your research when it comes to the track record and warranties. Long story short, the material will last 10-20 years. The material will eventually fail when is cracks and separates from material breakdown. The roof can also come undone at the seams between where the TPO pieces were welded together. Stress is placed on the seems as the material contracts and expands with changes in temperature and humidity.
Installation Mistakes Lead to Expensive Future Flat Roof Maintenance
Finding a certified TPO specialist is important and will save you money in future maintenance and repairs. For starters, hiring a one-and-done contractor will likely never be found again, because they will have moved on by the time you need service. A true professional will use the best installation methods for your flat roof projects. The biggest mistake in flat roof installation is de-bonding of TPO materials at the seems and separation of TPO from insulation at difficult areas such as chimneys and penetrations.