InstaBidsHow much for flat roof?
This survey has no flat or low-slope roofing-specific figure. The figure below covers all "Added or replaced roofing" jobs, so read it as context, not as the price of flat or low-slope roofing alone.
Context: all "Added or replaced roofing" jobs
$10,000 was the median homeowner survey figure for data years 2021-2023 in the United States. For all jobs in the AHS category “Added or replaced roofing”, households reported a typical range (middle half of 1,820 American Housing Survey data points, the United States, 2021-2023) of $5,800 to $16,000.
Updated 2026-11-03
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.
For homeowners, property managers, landlords and HOA boards.
| What was measured | Median | Typical range (middle half) |
|---|---|---|
| For all jobs in the AHS category “Added or replaced roofing”, households reported | a median of $10,000 | the typical range (middle half of 1,820 American Housing Survey data points, the United States, 2021-2023) was $5,800 to $16,000 |
How measured: hired-out finished jobs, survey-weighted, not adjusted for inflation. Source: U.S. Census Bureau, American Housing Survey 2023, data read 16 October 2026.
These figures are estimates from U.S. Census Bureau, American Housing Survey 2023, data years 2021-2023, read 16 October 2026, for the United States. They are not a quote, and they are not a promise of what any contractor on InstaBids will charge. Your price depends on your home, the materials and the contractor. Get written bids before you decide.
- 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?trade=roofing&from=cost-flat-low-slope-roof&utm_source=us&utm_medium=page&utm_campaign=cost&page_type=cost&job=flat+low+slope+roof - 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.
Cost of replacing a flat roof: what work does the survey cover?
These figures cover all jobs in the AHS category “Added or replaced roofing”, rather than flat roofs alone.
Source: U.S. Census Bureau, AHS 2023 Value Labels Package, read 16 October 2026.
DOE Building America Solution Center: “In high-wind zones, low-slope ("flat") roof assemblies (slope less than 2:12) with a waterproofing roof membrane cladding need to be able to resist the wind pressures that can act on them during high-wind events such as hurricanes.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
The flat roof and its exposure are details you can describe once in an InstaBids roofing scope.
How much is a flat roof with a single-ply membrane?
DOE Building America Solution Center: “Low-slope roof coverings include built-up bitumen roof systems, modified bitumen roof systems, and single-ply roofing membranes, including thermoplastic membranes such as TPO (thermoplastic olefin), PVC (polyvinyl chloride), and KEE (ketone ethylene ester), and thermoset membranes such as EPDM (ethylene propylene diene monomer).”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
Name the single-ply material in your InstaBids description so contractors write bids on that covering.
Cost for flat roof: which insulation layers are included?
DOE Building America Solution Center: “Low-slope roof assemblies that are insulated above the roof deck are typically constructed from multiple layers (Figure 1), including plywood or OSB deck sheathing, one or more layers of rigid isocyanurate or extruded polystyrene (XPS), and an upper covering board of plywood or OSB.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
List the deck, insulation and cover board in your InstaBids roofing description.
Cost of flat roof: how is the membrane attached?
DOE Building America Solution Center: “Single-ply roof membranes can be either mechanically attached or fully adhered to the low-slope roof's rigid insulation or cover board.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
The membrane attachment method belongs in your InstaBids job description for contractors to bid on in writing.
How much does a flat roof cost when retrofitting an existing roof?
DOE Building America Solution Center: “An existing low-slope roof can be retrofitted to improve the water-resistance and wind resistance of the roof as described in the Description tab of this guide.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
Describe the existing flat roof and the proposed retrofit once on InstaBids so contractors see the same work.
What flat or low-slope roofing includes
Where a quote below names a city or county, it is that office's own rule, shown as one example; the permit office for your home may set different rules.
| What the source says | Where it comes from |
|---|---|
| High-wind membrane: “In high-wind zones, fully adhered membranes are recommended.” | U.S. Department of Energy, Building America Solution Center, read 2 November 2026. |
| Air control layer: “Additionally, a fully adhered air control layer (“air barrier”) should be installed at the lower deck sheathing, and joints in the rigid insulation should be sealed or taped (Figure 6).” | U.S. Department of Energy, Building America Solution Center, read 2 November 2026. |
Include the air barrier and high-wind membrane details in the roofing scope you describe on InstaBids.
Line items a written bid should list
- Rigid foam layers: “Install one or more layers of rigid foam insulation with seams staggered and taped.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
- Roof deck seams: “Seal the roof deck sheathing by covering the entire plywood or OSB sheathing with a self-adhering “peel and stick” membrane or by sealing the sheathing seams with compatible tape.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
- Tape application: “Tape should be applied with a roller to ensure consistent pressure.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
Your InstaBids scope can name foam layers, deck seams and tape application for contractors to address in writing.
How to compare written bids like for like
Ask every contractor to bid in writing on the same line items listed above, then compare the written bids line by line.
Lower-deck alternative: “The fully adhered air control layer (“air barrier”) at the lower deck sheathing can be omitted if the lower roof deck sheathing joints are sealed with tape or membrane strips that are compatible with the plywood or OSB sheathing.”
Source: U.S. Department of Energy, Building America Solution Center, read 2 November 2026.
With the lower-deck sealing approach described once on InstaBids, you can compare written bids on the same roof assembly.
Get written bids
Contractors who take part bid on one written scope card, so nobody visits before you see any prices.
Sources for the figures on this page
- U.S. Census Bureau, American Housing Survey 2023, https://www.census.gov/programs-surveys/ahs/data/2023/ahs-2023-public-use-file--puf-.html, read 16 October 2026. U.S. government work; no endorsement implied.
- U.S. Census Bureau, AHS 2023 Value Labels Package, www2.census.gov/programs-surveys/ahs/2023/AHS 2023 Value Labels Package.zip, read 16 October 2026.
- U.S. Department of Energy, Building America Solution Center, basc.pnnl.gov/resource-guides/low-slope-flat-roofs, read 2 November 2026.