InstaBidsFor homeowners
Types of flat roof: which one fits your roof?
Choose Built-up roof (BUR) for a roof that needs the redundancy of multiple plies, which can be more forgiving of installation errors (HUD Rehab Guide, 1999); Modified bitumen for a roof that must accommodate some roof traffic (HUD Rehab Guide, 1999); Single-ply membrane (EPDM, TPO or PVC) for complex roof profiles, and roofs that must accommodate building movement (HUD Rehab Guide, 1999); Roof coating (over an existing roof) for an existing roof that is still in good condition (DOE, 2010).
The right choice depends on how much roof traffic the roof must take, how complex the roof profile is, and whether the existing roof is still in good condition.
| Type | Best for | Main advantages | Main drawbacks |
|---|---|---|---|
| Built-up roof (BUR) | a roof that needs the redundancy of multiple plies, which can be more forgiving of installation errors (HUD Rehab Guide, 1999) | can be relatively easily maintained and repaired (HUD Rehab Guide, 1999); a gravel-surfaced built-up roof can be made cool with reflective marble chips or gray slag in place of dark gravel (DOE, 2010) | on aggregate (gravel) surfaced coal tar and some asphalt built-up roofs, the source of a leak is difficult to identify (HUD Rehab Guide, 1999); air pockets must be limited, and applying the proper amount of adhesive is critical (HUD Rehab Guide, 1999) |
| Modified bitumen | a roof that must accommodate some roof traffic (HUD Rehab Guide, 1999) | easier to install, and to detect possible roof leaks on, than aggregate-surfaced built-up roofs (HUD Rehab Guide, 1999); the surface can be coated at the factory to make it cool (DOE, 2010) | requires installers familiar with its use, and careful attention to installation details, particularly seaming (HUD Rehab Guide, 1999); products with new polymer types should be carefully researched, because their history of satisfactory use is limited (HUD Rehab Guide, 1999) |
| Single-ply membrane (EPDM, TPO or PVC) | complex roof profiles, and roofs that must accommodate building movement (HUD Rehab Guide, 1999) | lightweight, and can be used over existing roofing (HUD Rehab Guide, 1999) | requires very careful quality control during installation; poor application has led to failures, particularly at seams between rolls (HUD Rehab Guide, 1999); accurate comparative data between single-ply systems is difficult to obtain (HUD Rehab Guide, 1999); EPDM is typically black, and must be formulated differently or coated to make it reflective (DOE, 2010) |
| Roof coating (over an existing roof) | an existing roof that is still in good condition (DOE, 2010) | can protect the roof surface from ultraviolet (UV) light and chemical damage (DOE, 2010) | coatings such as reflective aluminum roof coatings require periodic renewal (HUD Rehab Guide, 1999) |
InstaBids is an AI-run marketplace for homeowners and property managers: describe a home job once, by chat or through your own AI assistant, add photos, and get multiple written quotes on the same scope, compared apples to apples, with no phone calls or home visits before you pick.
Post your job on InstaBids, and contractors can bid in writing on one written scope.
- Describe it onceBy chat, or through your own AI assistant, and add photos.
- Post it and send itContractors bid in writing on that scope.
- Compare line by lineEvery quote is written against the same scope.
- You chooseContact details stay hidden until you pick and they confirm.
For your AI assistant
MCP connector · REST API · plain HTMLHand any of these to your assistant and it can help you write this job's request; you send the request yourself. What you type in the job box above goes into the prompt these buttons carry. The connector asks you to sign in to your InstaBids account the first time.
- MCP connector URL
https://instabids.ai/api/agent/mcp - Agent API (OpenAPI)
https://instabids.ai/openapi.json - Start-request link
https://instabids.ai/intake?from=options-flat-roof&utm_source=us&utm_medium=page&utm_campaign=options&page_type=options#job=flat%20roof%20replacement%20or%20repair - Prompt for any AI, with your job
- ChatGPTOpens with the prompt
- ClaudeOpens with the prompt
- GrokOpens with the prompt
- GeminiCopies the prompt, then opens
Every page is plain HTML. Steps for every assistant: add to your assistant.
| Priority | Choose |
|---|---|
| a roof that must accommodate some roof traffic (HUD Rehab Guide, 1999) | Modified bitumen |
| a complex roof profile, or a building that moves (HUD Rehab Guide, 1999) | Single-ply membrane (EPDM, TPO or PVC) |
| an existing roof that is still in good condition (DOE, 2010) | Roof coating (over an existing roof) |
| the redundancy of multiple plies (HUD Rehab Guide, 1999) | Built-up roof (BUR) |
Get written bids
Contractors who take part bid on one written scope card, so nobody visits before you see any prices.
The contractor you pick may visit once before settling the final price against the percentage the bid stated.
Contractors in your trade see the scope card and your 5-digit ZIP code.
Contact details stay hidden until the homeowner picks a contractor and they confirm the connection.
Homeowners pay InstaBids nothing.
Sources for the facts on this page
- U.S. Department of Housing and Urban Development, The Rehab Guide, Volume 3: Roofs, chapter 9 Low-Slope Roofing (March 1999), government, read 22 October 2026.
- U.S. Department of Energy, Building Technologies Program, Guidelines for Selecting Cool Roofs (July 2010, V. 1.2), government, read 22 October 2026.