Flat and low slope roofs come in a few main types, and two of the most common are TPO and built up roofing. Both can protect a building well for many years. The better choice depends on your building, your budget and how the roof is used. Here is a plain comparison to help you decide. If you want a second opinion on your own roof, local roofing professionals can inspect it and explain what suits your building.
What Is TPO?
TPO stands for thermoplastic polyolefin. It is a single sheet membrane, usually white or a light color, that is laid over insulation. The seams are welded with hot air, so the sheets fuse into one continuous surface.
Because the surface is light, it reflects sunlight and helps keep the building cooler. TPO is also lighter than layered systems, which matters on older buildings.
What Is Built Up Roofing?
Built up roofing, often called BUR, has been used on flat roofs for many decades. It is made of several layers of asphalt and reinforcing fabric that are built up on the roof, then topped with a protective surface such as gravel or a coating.
The result is a thick, tough roof that handles foot traffic well, which is useful when technicians often walk the roof to service equipment.
Side by Side
| TPO | Built Up | |
|---|---|---|
| Layers | One sheet over insulation | Several layers of asphalt and fabric |
| Seams | Welded with hot air | Layered, with few exposed seams |
| Heat | Reflects sunlight | Darker unless coated |
| Weight | Lighter | Heavier |
| Foot traffic | Fair, walk pads help | Very good |
| Repairs | Patches weld in place | Patches are built up in layers |
Coastal and Inland Buildings
Near the coast
Salt air and fog put extra stress on any roof. Ask about materials and fasteners that handle moisture well.
Inland Vista
Strong sun and heat make a reflective surface attractive, because it can ease the load on air conditioning.
Costs to Think About
Compare the cost over the life of the roof, not only the first price. These items all add up:
- Materials and insulation
- Labor and the time needed for installation
- Drainage work, such as tapered insulation
- Yearly inspections and small repairs
A cheaper system that needs frequent repairs can cost more in the end, while a well chosen system with regular care can serve your building for many years.
Upkeep for Either System
- Clear drainsRemove leaves and trash.
- Inspect twice a yearSpring and fall.
- Limit trafficMark safe walk paths.
- Fix small damageDo not let it grow.
- Keep recordsPhotos and notes.
How to Choose
Start with the building itself. Check the roof frame, the amount of foot traffic, the budget and the climate around your property. A roofer who inspects the roof in person can tell you which system fits and why.
Ask each roofer to explain why they recommend one system over the other. A good answer talks about your building, not a sales pitch. Ask for a written estimate that lists the insulation, the membrane or layers, the flashing at edges and walls, and the drainage plan.
If TPO looks like a good fit, ask about TPO roofing services and what the process includes, from the first roof check to the final test of the seams.
Quick Answers
Is TPO good for hot weather?
Its light surface reflects sunlight, which helps keep the roof and the building cooler.
Can a new roof go over the old one?
Sometimes, but it depends on the condition of the old roof and on local rules. A roofer should inspect it first.
How often should a flat roof be checked?
Twice a year and after any major storm is a good routine.