If you own a commercial building, garage, or ADU with a flat roof in San Diego, TPO roofing deserves your attention. This single-ply membrane has become the go-to choice for flat roof applications across Southern California, and for good reason.
What Makes TPO Work So Well in San Diego
TPO stands for thermoplastic polyolefin. In plain terms, it's a durable white membrane that gets heat-welded at the seams to create a watertight barrier over your flat roof. Unlike the old built-up roofing systems that required layers of hot tar, TPO installation is cleaner, faster, and produces a more reliable seal.
The white surface reflects sunlight instead of absorbing it. In San Diego's sunny climate, this means your building stays cooler and your air conditioning works less. Property owners regularly report lower energy bills after switching to TPO, especially during our warm summers from May through October.
San Diego gets about 10 inches of rain annually, mostly between November and March. TPO handles this well. The heat-welded seams don't separate like glued seams can, and the membrane itself resists ponding water that sometimes accumulates on flat roofs. Quality installation produces reliable results that rarely need leak callbacks.
For ADU projects, TPO makes particular sense. Most ADUs have flat or low-slope roofs where traditional shingles won't work. TPO performs well in these applications, and a properly installed TPO roof lasts 20 to 30 years with basic maintenance.
Commercial property owners appreciate TPO for different reasons. The installation goes quickly, which means less disruption to business operations. The material is puncture-resistant, handling foot traffic from HVAC technicians better than some alternatives. And the reflective surface can help buildings meet California's Title 24 energy requirements.
TPO's heat-welded seams create a continuous waterproof surface. Unlike mechanically fastened or glued systems, there are no adhesive failures or loosened fasteners to worry about.
Thickness options range from 45 mil to 80 mil. Thicker membranes cost more but provide greater puncture resistance and longer service life. For roofs with regular foot traffic from equipment servicing, the heavier material makes sense. For residential garages that see little traffic, standard thickness performs fine.
Installation requires specific expertise. The heat-welding process needs proper temperature control and technique. Seams welded too hot or too cold fail prematurely. Transitions at walls, curbs, and penetrations demand careful detail work. This isn't a DIY project or work for contractors without TPO experience.
Maintenance requirements are minimal but important. Annual inspection catches any seam issues, membrane damage, or drain blockages before they cause problems. Debris removal keeps drains flowing. UV degradation eventually requires attention—typically through coating application after 10 to 15 years.
When comparing TPO to alternatives:
- EPDM (rubber roofing) costs less but doesn't reflect heat
- PVC offers similar performance at higher cost
- Built-up roofing is being phased out in favor of single-ply options
- Modified bitumen works but requires more maintenance
For most flat roof applications in San Diego, TPO provides the best combination of performance, longevity, and value. Get quotes from contractors experienced specifically with TPO installation, ask about their warranty terms, and verify they use manufacturer-approved materials and techniques.
