Deck & substrate
Plywood, concrete, metal, wood framing and open-beam conditions affect fastening and adhesion.
Commercial single-ply roofing
A TPO roof selected for the building beneath it.
We evaluate the deck, attachment conditions, insulation, drainage and rooftop equipment before recommending a mechanically attached or fully adhered TPO system.
Deck firstAttachment starts with the substrate
Two primary methodsMechanical or fully adhered
Heat-welded seamsCalibrated field and detail work
Commercial & residentialAssembly chosen for the property
Start with the existing roof
The membrane is only one part of the system.
Before choosing plates, screws or adhesive, we need to know what the new roof will attach to—and what the existing assembly is hiding.
Zenith evaluates the roof deck, existing layers, moisture concerns, open-beam conditions, parapets, edges, curbs, penetrations and drainage. That information determines whether the project calls for tear-off, an approved recover assembly, mechanical attachment or a fully adhered installation.
No one attachment method is automatically “best.” The right answer must fit the building and the selected manufacturer-approved assembly.
Existing assembly
Layers, trapped moisture and current membrane condition determine whether tear-off or recover is appropriate.
Insulation & drainage
Polyiso, cover boards, slopes, drains and crickets are coordinated as one roof assembly.
Roof details
Curbs, pipes, walls, edges, conduit and equipment are planned before the field membrane goes down.
Attachment options
Two common ways to build a TPO roof.
Both approaches can perform well when the deck, fastener pattern, adhesive, insulation and membrane are part of a compatible system.
01
Mechanically attached
Approved insulation and membrane components are secured to a suitable deck with plates and fasteners. The fastening pattern is selected for the assembly and roof zones.
- Useful where the deck can accept the specified fasteners
- Can use polyiso, cover board or an approved recover board
- Requires deliberate perimeter, corner and penetration detailing
02
Fully adhered
Compatible insulation and membrane layers are bonded with an approved adhesive system. This can be appropriate where visible fasteners below or substrate conditions make mechanical attachment undesirable.
- Creates a smooth, continuously bonded membrane field
- Adhesive selection follows substrate and manufacturer requirements
- Walls and vertical surfaces are commonly fully adhered
Other engineered attachment methods exist. Zenith scopes the project around tested components and the requirements of the selected manufacturer—not a one-size-fits-all detail.
Zenith commercial TPO process
A complete assembly built around the deck and rooftop details.
This project shows one mechanically attached installation—from deck and curb preparation through insulation securement, membrane welding and finished details.
Roof preparationDeck, walls and curbs prepared for the selected assembly
AttachmentPlates and fasteners into the approved substrate
Vertical detailsAdhered walls, curbs and compatible terminations
ProtectionWalk pads located around serviced rooftop equipment
Recover and overlay options
An overlay is an engineered decision—not a shortcut.
Some existing roofs may qualify for an approved recover assembly using fan-fold, insulation or a cover board. Others need removal so wet materials, damaged decking or incompatible layers can be corrected.
- Confirm the existing assembly and deck can accept the new system
- Check for moisture and damaged substrate before covering it
- Confirm recover eligibility with the selected manufacturer
- Coordinate edge heights, drains, curbs and transitions after added thickness
The details decide performance
Every interruption in the membrane needs a plan.
A clean white field does not make a complete roof. Long-term performance depends on how water is managed at the edges, walls, pipes, curbs and service paths.
Curbs & walls
Compatible membrane, corners, termination bars and water block are selected for each vertical condition.
Pipes & penetrations
Pipe boots, clamps and welded details are coordinated with the penetration and membrane system.
Edges & parapets
Clad metal, perimeter securement and transitions are detailed wherever the roof meets an open edge or wall.
Walk pads
Designated service paths help protect the membrane around equipment that requires routine access.
Heat-welded seam control
The sheets become a roof at the welds.
Field seams are welded with calibrated hot-air equipment. Corners, curbs, pipes and transitions receive compatible hand-welded detail work.
Membrane surfaces are prepared as required, automatic welding equipment is adjusted for site conditions, and the crew hand-rolls and checks details. This is where clean preparation and consistent workmanship matter most.
01Clean and prepare the lap
02Set the welder for membrane and conditions
03Heat-weld field seams consistently
04Hand-detail and probe completed welds
Low-slope residential TPO
The same system thinking applies to homes and manufactured housing.
Residential low-slope roofs can have different deck, access and permit conditions than commercial buildings.
On one manufactured-home project, the existing metal roof remained in place and a fully adhered assembly was selected. Zenith used compatible adhesive, perimeter termination and water block details based on the conditions of that roof.
We confirm the applicable permit authority, substrate and manufacturer requirements before recommending the assembly.
Zenith TPO process
From field conditions to documented closeout.
The final scope is project-specific, but every good installation follows a disciplined sequence.
- 01
Inspect & verify
Document the deck, existing layers, moisture concerns, drainage and roof details.
- 02
Select the assembly
Choose tear-off or approved recover, insulation, cover board and attachment method.
- 03
Prepare the roof
Correct damaged substrate and coordinate curbs, penetrations, edges and transitions.
- 04
Install & weld
Place the approved components, weld seams and complete compatible detail work.
- 05
Quality control
Check seams, terminations, drainage paths, protection pads and the completed roof.
- 06
Close out
Clean the site, provide project documentation and complete applicable warranty paperwork.
TPO roofing questions
What property owners ask before choosing a system.
The answers depend on the roof in front of us. A site evaluation turns these general options into a buildable scope.
What is the difference between mechanically attached and fully adhered TPO?
Mechanically attached systems use approved plates and fasteners into a suitable deck. Fully adhered systems bond compatible assembly components with approved adhesive. Deck, wind design, building use and manufacturer requirements guide the choice.
Can TPO be installed over an existing roof?
Sometimes. The current roof must qualify for an approved recover assembly. Existing moisture, deck damage, incompatible materials, edge heights or drainage conditions may require removal instead.
Can TPO be used on a residential low-slope roof?
Yes, when the substrate, slope, details, permit requirements and selected manufacturer assembly support TPO. Residential and manufactured-home roofs are evaluated individually.
How are TPO seams sealed?
TPO seams are joined with calibrated hot-air welding equipment. Field seams can be completed with an automatic welder, while corners and roof details are hand-welded and checked.
Does Zenith use one standard membrane thickness or manufacturer?
No. We select the membrane specification, insulation and attachment method around the roof, building requirements and an approved compatible system. The process is designed for the property rather than limited to one manufacturer or one membrane thickness.
Commercial TPO estimate
Let’s identify the assembly that fits your roof.
Tell us about the building, leaks, current roof, rooftop equipment and any access or scheduling constraints. We’ll use the site conditions to scope the next step.
- Commercial buildings, HOAs and facilities
- Low-slope residential and manufactured housing
- Tear-off, approved recover and insulation options
- Mechanically attached and fully adhered systems
Secure estimate request
Request a TPO roof estimate
Use the existing Zenith estimate form. Required fields and submission behavior remain unchanged.
Property owners & real-estate professionals: Transaction inspections, certifications and written reports are paid professional services. View the real-estate price list.
Build the right assembly