TL;DR
Get backup power and energy gear delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
A homeowner in Westchester County, New York, is seeking advice on a proposed over-roof for a poorly drained, uninsulated flat roof on a 1970s post-and-beam house. The plan would add slope and insulation while preserving the home’s appearance, but the source material describes a proposal and questions—not a completed project or a verified design.
A homeowner in Westchester County, New York, is considering an insulated over-roof to replace the failing membrane on a 1970s flat-roof house, aiming to correct ponding and improve energy performance without changing its defining low-profile appearance. The plan is a proposal presented in a question to GreenBuildingAdvisor; the available source does not establish that construction has begun or that the assembly has been approved.
The house is a contemporary post-and-beam design in Climate Zone 4A. Its existing EPDM roof is described by the homeowner as poorly installed, patched and at the end of its service life. The roof has little slope, and water ponds in places; the homeowner says a raised section of drip edge along the back further impedes drainage toward the gutters. The original roof layers are not confirmed: the owner believes there may be an older torch-down roof and fiberboard beneath the EPDM.
The proposed work would strip the existing roofing and install taped 7/16-inch ZIP sheathing over the tongue-and-groove roof deck as an air barrier, a topic also discussed in insulating a roof from the inside. Above it, the owner proposes 1½ inches of mineral-wool board, a raised sloping frame of 2-by-8s at 24-inch spacing, and a second sheathed deck. The assembly would then receive four inches of polyisocyanurate insulation and a new EPDM membrane. The stated target is a roof slope of 0.5 in 12 toward the rear and an overall insulation value near R-60.
The raised roof would cover the living space, with short parapets on three sides intended to conceal the slope. Existing overhangs would remain at roughly their current thickness, and the homeowner says skylights would be removed and covered. The owner also describes a tapered cavity beneath the new framing and questions whether it needs to be filled, similar to considerations raised in this discussion of insulation on a roof deck. These are design intentions and assumptions in the original question, not independently verified construction details.
Balancing Roof Drainage and Design
The proposal addresses two linked problems: water management and heat loss. A new membrane alone would not, by itself, correct the reported low spots or the high rear edge; the proposed slope is meant to direct water toward the back of the property. Improving insulation and air sealing could also make a difference in a house the owner describes as having little roof insulation and very leaky original sliding doors.
For readers facing a similar renovation, the case illustrates why a roof assembly must be evaluated as a system rather than as a list of insulation products. The planned roof adds weight and height, changes drainage, and places materials in layers with different temperatures and moisture behavior. The homeowner’s R-60 target and proposed foam thickness are goals, not proof that the finished roof will perform as intended. Structural capacity, flashing, parapet details, membrane compatibility and local requirements can all affect the result.
The design also involves a trade-off between energy work and architectural character. Keeping the overhangs and hiding the new slope could preserve the home’s horizontal profile, but the raised roof and parapets still require careful detailing where they meet walls, gutters and existing structure.
Products Worth Considering
Amazon Kindle Paperwhite (2024, 16 GB) – 7-inch Glare-Free Display, Black
Bose Smart Soundbar 700 with Alexa, Black
DJI Osmo Mobile 7P Gimbal Stabilizer with Mic Mini Transmitter, Infinity Black
As an affiliate, we earn on qualifying purchases.
A 1970s Roof With Limited Insulation
The home’s roof is supported by large glue-laminated beams spaced about 6½ feet apart, according to the homeowner. Tongue-and-groove 2-by-6 boards span between those beams. The underside remains exposed in some rooms, an interior feature the owner wants to retain. The beams cantilever about four feet beyond the front and rear walls, while posts carry them at the exterior and near midspan.
The house also has extensive original sliding glass doors. The owner says the glazing creates a greenhouse effect during late-afternoon cooling periods but provides little insulation, and describes the doors as leaky. The roof is the owner’s stated first priority; broader plans include reducing the amount of glass and improving air sealing and insulation while retaining as much of the original design as possible.
The source is a homeowner’s question published by GreenBuildingAdvisor, not a project report. It gives the owner’s observations and proposed layers, but does not provide a completed building assessment, construction drawings or a response confirming that the proposed assembly is suitable.
“I would like to do an “over-roof” that would (i) fix the drainage and ponding issues with a 0.5/12″ slope to the back of the house and (ii) create space for significant insulation with the goal of getting to the R-60 range.”
— The homeowner, in a question published by GreenBuildingAdvisor
Key Design Details Still Unverified
The source does not establish whether the existing roof layers have been opened up or inspected, so the actual condition and composition of the roof deck remain uncertain. Nor does it confirm whether the beams, posts, foundations and proposed new framing can support the added materials and loads. A structural review would be needed before treating the proposed framing as buildable.
Moisture behavior is another unresolved issue. The homeowner believes the proposed insulation above the sheathing is sufficient for the climate, but the source does not include a project-specific analysis of condensation risk, air leakage or drying potential. The question also leaves open how the tapered cavity would be handled and how parapets, edges, gutters, skylight closures and membrane transitions would be detailed.
No contractor estimate, permit decision, code review, final assembly specification or construction schedule appears in the source. The stated R-value is an estimate based on proposed materials, not a measured result. The actual outcome would depend on product specifications, installation and continuity of the air and water-control layers.
Professional Review Before Construction
The next step is not specified in the source. Before work proceeds, the homeowner would need a site-specific review of the roof structure, drainage plan and full assembly, including connections at the parapets and roof edges. A qualified roofing professional and structural engineer can assess the existing conditions and proposed loads; an energy or building-science professional can evaluate moisture control and insulation placement. The project should also be checked against local building and permit requirements.
Once those details are resolved, the owner can compare the proposed raised framing with other ways of creating slope and insulation, then confirm the membrane and flashing specifications with the installer. Until a final design or construction update is reported, the over-roof remains a homeowner’s plan rather than a completed renovation.
Key Questions
What is an over-roof in this proposal?
Here, it means a new raised roof assembly built above the existing roof deck. The proposed layers would add slope, insulation and a new membrane, though the source does not confirm the final design.
Why does the homeowner want to add slope?
The owner reports that the current roof has ponding water and little slope, with a high rear drip edge that may obstruct drainage. The proposed pitch would direct water toward the back of the house.
Is the roof expected to reach R-60?
R-60 is the homeowner’s target, based on estimated contributions from the proposed insulation layers. The source does not verify the calculation or report a completed roof’s performance.
Has construction started or been approved?
The source provides a homeowner question and proposed assembly. It does not say that construction has started, that a professional has approved the design, or that permits have been issued.
Source: greenbuildingadvisor.com
