Three systems cover most flat and low-slope roofs on Spokane homes: TPO, EPDM, and torch-down modified bitumen. All three keep water out. They differ in how they are installed, how they age, and what they cost.
TPO
A white thermoplastic membrane with heat-welded seams. The reflective surface keeps the roof and the rooms below cooler in summer. Typically 20 to 30 years, and generally in the middle of the three on cost. The welded seam is its strongest feature and the reason installer skill matters so much. More detail in our guide to TPO for homes.
EPDM
A synthetic rubber membrane, usually black, with seams joined by adhesive or seam tape rather than heat. Very flexible and handles cold and freeze-thaw movement well, which is a genuine advantage through a Spokane winter. Also 20 to 30 years typically. The black surface absorbs heat rather than reflecting it, which is a plus in January and a minus in July.
Torch-down (modified bitumen)
Asphalt-based sheets applied with an open-flame torch, usually in two layers. It is a proven, tough system that stands up well to foot traffic, which is why it turns up on roofs people actually walk on. Commonly 15 to 20 years, the shortest of the three. Because it involves an open flame on your roof, it is not the right choice on every house.
How to actually choose
For most homeowners replacing a residential flat roof, the decision comes down to a few questions:
Do the rooms under this roof cook in summer? Lean TPO, for the reflective surface.
Is it a small, awkward section, or does the structure move a lot? EPDM is flexible and forgiving.
Will people walk on it regularly? Torch-down takes traffic well.
Is the existing roof still structurally sound? Then a coating may beat all three on price and disruption. Worth pricing before you commit to a tear-off.
What matters more than the material: all three of these fail at the seams and flashings long before they fail in the middle of the roof. A well-installed torch-down roof will outlast a badly installed TPO roof every time. Ask whoever quotes you how they handle the transitions and the penetrations. Our flat roof team works across Spokane and Airway Heights.
Not sure which system your roof needs?
We will look at what you have now and tell you honestly whether it needs replacing at all - a coating is sometimes the better buy.
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