Seam separation
What causes it
Welds that were made too hot, too cold or over a dirty surface can open over time.
How we repair it
Clean and probe the seam, then re-weld it or heat-weld a cover strip over it.
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TPO at a glance
What Is TPO Roofing?
TPO is a white, single-ply thermoplastic membrane. Sheets are rolled out over insulation, fastened or adhered to the roof, and joined with hot air so the seams fuse into one watertight surface.
Inside a TPO roof
A typical TPO roof assembly, top to bottom
TPO membrane
Heat-welded seams, white reflective surface
Cover board
Protects insulation, adds puncture resistance
Insulation
Polyiso boards, often tapered for drainage
Vapor retarder
Where the building calls for one
Structural deck
Steel, concrete or wood
Comparing TPO with other systems?
Download the full Roof Systems Comparison Guide for lifespan, cost, and maintenance details on TPO and every other major system.
Pros and cons
TPO Roofing Pros and Cons
TPO's strengths are installed cost, welded seams and reflectivity. Its limits are grease and chemical resistance and a dependence on careful seam welding.
Installation
How Is TPO Roofing Installed?
A TPO roof goes on in seven steps, from a moisture survey of the existing roof to probe-testing every welded seam. Most of the roof's long-term performance is decided at the seams and details.
- 1
Inspect and core-cut the existing roof
A moisture survey and core cuts show what is under the surface and whether the roof can be recovered or needs a full tear-off.
- 2
Prepare the deck
Remove failed roofing where needed, repair damaged decking and replace any wet insulation.
- 3
Install insulation and cover board
Boards are fastened or adhered to the deck. Tapered insulation is added where water needs help reaching the drains.
- 4
Lay out and attach the membrane
Sheets are rolled out and secured by fasteners along the seams, full adhesive or induction-welded plates, depending on the wind design.
- 5
Heat-weld the seams
Robotic and hand welders use hot air to fuse each overlap into a single, continuous sheet.
- 6
Flash edges, curbs and penetrations
Pre-formed corners, pipe boots and edge metal seal every place the roof meets a wall, unit or pipe.
- 7
Probe-test and final inspection
Every seam is probed for gaps. Warranted roofs get a manufacturer inspection before the warranty is issued.
Warranty starts with the install
Manufacturer warranties require a certified installer and documented details. Nations Roof installs TPO as a certified installer for the manufacturers listed on our Qualifications page.
Lifespan
How Long Does a TPO Roof Last?
15 to 30years
A commercial TPO roof typically lasts 15 to 30 years. Where a roof lands in that range depends less on the membrane itself and more on how it was installed and how it is maintained.
Membrane thickness
Thicker sheets resist punctures and weathering longer.
Seam and detail quality
Most TPO leaks start at a seam, flashing or penetration.
Drainage
Water that ponds for days ages the membrane faster.
Inspections and maintenance
Small repairs caught early keep the roof in service longer.
Climate and exposure
Sun, heat, hail and rooftop exhaust all shorten service life.
Typical service life by system
With proper installation and regular maintenance
TPO15 to 30 yrs
EPDM20 to 30 yrs
PVC20 to 30 yrs
Mod Bit15 to 25 yrs
Built-Up20 to 30 yrs
Metal30 to 50+ yrs
01020304050+
Years
Cost
What Drives TPO Roof Cost?
TPO sits in the $$ tier, among the most cost-effective commercial membranes. The final price for a specific roof comes down to six factors, so a written estimate follows an inspection.
Relative installed cost by system$ lowest to $$$$ highest
$ to $$
Coatings
$$
TPOEPDMMod Bit
$$$
PVCBuilt-Up
$$$$
Metal
Tear-off or recover
Removing the old roof adds labor and disposal. A recover over a dry, sound roof costs less.
Insulation
Required R-value, tapered insulation for drainage and cover board all add material.
Attachment method
Mechanically attached systems usually cost less than fully adhered ones.
Membrane thickness
60 and 80 mil sheets cost more than 45 mil, and support longer warranties.
Access and complexity
Building height, staging, rooftop units and the number of penetrations.
Warranty level
Longer, more comprehensive manufacturer warranties require more of the system.
Get a written number for your roof
A free inspection confirms the existing roof's condition and whether a recover is possible, then becomes a written TPO estimate.
Problems and repairs
Common TPO Roof Problems and How We Repair Them
Most TPO problems start at seams, flashings and drains, not in the open field of the membrane. Caught early, nearly all of them are repairable with heat-welded patches and new flashing.
Seeing one of these on your TPO roof?
Our crews repair TPO roofs from 40+ branch locations. See how commercial roof repair works, or start with an inspection.
Best fit
Best Buildings and Climates for TPO
TPO is the system most often specified for warehouses, offices, retail and data centers: large, flat roofs where installed cost and reflectivity matter most.
Most often specified
Also common
Climate fit
Hot and sunnyStrong fit
A white, reflective surface helps lower cooling loads.
Mixed climatesGood fit
Performs well across most of the country with proper insulation.
Cold with freeze and thawWorks, with care
TPO performs in the cold, though EPDM stays more flexible in extreme cold.
See every system side by side in the best roof by facility type matrix.
Next steps for an existing roof
Maintain, Restore or Replace a TPO Roof
An aging TPO roof has three paths. An inspection with a moisture survey shows which one fits, based on the condition of the membrane, the insulation and the deck.
Not sure which path fits? Read repair, restore or replace.
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Alternatives
TPO vs. Other Commercial Roof Systems
Choose TPO for cost and reflectivity on large, flat roofs. Choose PVC for grease and chemical exposure, EPDM for extreme cold, and modified bitumen for heavy foot traffic.
Still deciding between TPO and another system?
Answer 6 quick questions about your building, roof, climate and budget, and get a matched roof system.
TPO Roofing FAQs
What is TPO roofing?
TPO (thermoplastic polyolefin) is a single-ply membrane used on flat and low-slope commercial roofs. Sheets are fastened or adhered over insulation and heat-welded at the seams into one continuous, watertight surface. White TPO is highly reflective.
How long does a TPO roof last?
A commercial TPO roof typically lasts 15 to 30 years. Membrane thickness, seam quality, drainage and regular maintenance decide where a roof falls in that range.
Is TPO better than EPDM?
Neither is better for every roof. TPO has heat-welded seams and a reflective white surface that suits warm climates. EPDM is a rubber membrane that stays flexible in extreme cold and has a longer typical service life at the low end of the range.
Is TPO a good choice for a restaurant or food processing roof?
Usually not. Grease, oils and some chemicals from kitchen and process exhaust degrade TPO faster. PVC is the more common choice for those roofs.
Can TPO be installed over an existing roof?
Often, yes. A recover installs a cover board and new TPO over the existing roof when it is structurally sound, the insulation is dry and local code allows another layer. Core cuts and a moisture survey confirm it.
Can a TPO roof be repaired?
Yes. Damaged areas are cleaned and covered with heat-welded TPO patches, and failed seams are re-welded. Older, weathered TPO needs extra surface preparation before new material will weld to it.
How do I keep a TPO roof warranty valid?
Schedule regular inspections, keep records of all roof work and use a certified contractor for every repair. Unauthorized repairs and missed maintenance are the most common reasons a manufacturer warranty is voided.
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