What TPO is and why it fits the Central Valley
TPO stands for thermoplastic polyolefin — a single-ply roofing membrane rolled out across a low-slope or flat roof. Its white, reflective surface bounces the valley's intense summer sun, which keeps the building cooler, lowers air-conditioning bills, and meets California Title 24 Part 6 cool-roof requirements for Climate Zone 12.
The membrane's seams are fused with hot air, not glued or taped. That heat-weld turns the whole roof into one continuous, watertight surface and is the single biggest reason a well-installed TPO roof resists leaks for decades.
How DeHart installs TPO
We install TPO in 45, 60, and 80 mil thicknesses, going heavier for high-traffic or hail-exposed roofs. Depending on the building and its wind exposure, the membrane is mechanically fastened or fully adhered.
Every job starts with tear-off and a deck inspection, then new cover board or insulation where it's needed, the membrane, heat-welded seams, and flashed penetrations. You get a flat-rate written bid up front, and we file the CRRC and Title 24 documentation at closeout.
TPO warranty coverage
Manufacturer membrane warranties on TPO typically run 15 to 30 years, depending on thickness and system. DeHart backs the installation itself. A correctly welded, properly flashed TPO roof is a long-term, low-maintenance system — see our roofing warranty page for how manufacturer and workmanship coverage stack.
Buildings we install TPO on
TPO works on almost any low-slope or flat roof: warehouses, retail centers, offices, churches, and agricultural and industrial buildings, plus apartment and multi-family properties. For the full system lineup and pricing, see our commercial roofing page or the Central Valley commercial systems comparison.
Choosing your membrane thickness: 45, 60, or 80 mil
TPO comes in three common thicknesses, measured in mils (thousandths of an inch). Thicker membrane costs more up front but takes more punishment and usually carries a longer manufacturer warranty. The right pick depends on how the roof gets used, not just the budget.
- 45 mil — the entry-level membrane. It works for clean, low-traffic roofs where almost no one walks the surface. We rarely spec it as the only option in the Central Valley, because the valley's heat and UV are hard on thin membrane over time.
- 60 mil — the workhorse for most Stanislaus County commercial and multi-family roofs. It balances cost, puncture resistance, and warranty length, and it stands up to foot traffic from HVAC service techs. This is what we recommend on the majority of jobs.
- 80 mil — the heavy-duty choice. We spec it for roofs with frequent foot traffic, rooftop equipment, or buildings where a leak would be especially costly to deal with. The thicker surface resists punctures and abrasion the longest.
On the written bid we tell you which thickness we are quoting and why, so you can weigh the up-front cost against the warranty term and how the roof will actually be used.
Why heat-welded seams matter
The seam is where flat roofs almost always fail first. With TPO, the seams are not glued or taped — they are fused with a hot-air welder that melts the two membrane sheets together into one continuous surface. Done right, the seam is as strong as the membrane itself.
That is the single biggest reason a well-installed TPO roof keeps water out for decades. Glued and taped seams, by contrast, rely on an adhesive bond that can dry out, lift, and let water track underneath over the years. A heat-weld has no adhesive to fail. Our crews probe-test the welds during the install to confirm every seam is fully fused before the roof is signed off — a bad weld is a future leak, and we would rather catch it on day one than years later.
TPO maintenance and lifespan
A correctly installed TPO roof is one of the lowest-maintenance systems we offer, but “low” is not “none.” A little routine attention is what gets a TPO roof to the long end of its 20-to-30-year range instead of the short end. We suggest:
- Two visual checks a year — ideally spring and fall — plus a look after any major wind or storm event. See our roof inspection service for what a full check covers.
- Keep drains and scuppers clear. Standing water is the enemy of any flat roof. Clearing leaves and debris so the roof drains is the simplest, highest-value thing you can do.
- Address penetrations and flashing early. The membrane field rarely fails first — it is the spots around vents, curbs, and edges. Catching a lifted flashing early keeps a small fix from becoming a tear-off.
- Re-weld, do not patch over. If a seam or puncture does open up, it gets cleaned and heat-welded the same way the original roof was, so the repair is part of the continuous membrane rather than a temporary cap.
When a TPO membrane finally reaches the end of its life, a roof coating can sometimes extend it a few more years rather than replacing the whole system — we will tell you honestly which path makes sense for your building.
"Crew were awesome. Friendly, respectful, efficient. They worked hard, paid attention to detail, and cleaned up everything. Simply the Best."