Planning an EPDM roof is much easier when the measurements, edge details and accessories are considered together. RoofBuildr from Stonegate Supplies guides you through that process visually, then converts your answers into a project-specific bill of materials.
This guide explains each stage, what to measure before you begin and how to check the result before adding anything to your basket. RoofBuildr makes ordering more straightforward, but its recommendation depends on the information you enter.
What is RoofBuildr?
RoofBuildr is Stonegate Supplies' online EPDM roof planning tool. Instead of calculating membrane allowances, adhesive coverage and perimeter trims separately, it builds a material specification from the roof you describe.
The live tool has seven core stages: Roof, Measurements, Details, Voids, System, Extras and Materials. When the chosen edge details include coloured trims, a Trim colours stage is inserted before Extras, making eight stages. It currently supports a simple rectangular roof, an L-shaped roof and an apex roof. The on-screen roof plan highlights each dimension and edge as you work.
At the end, RoofBuildr shows the measured area and perimeter, selected membrane size, required products, supplied quantities, individual prices and project total. You can name and save the project or add the calculated materials to your basket.
Before you start: what information do you need?
Measure the roof itself rather than relying only on drawings, especially on refurbishment work. Have the following ready:
- The roof shape: rectangular, L-shaped or apex.
- Every requested dimension, in metres.
- How each edge finishes: gutter edge, kerb or upstand, meets a wall, or no trim/customer supplied.
- The roof-deck surface: OSB/timber, existing GRP, metal deck, or felt/asphalt.
- The number of outlets and pipe penetrations.
- The size, material, quantity and position of any rooflight voids.
- Whether you already own the installation tools or want to add them.
Take dimensions from the points shown by RoofBuildr and record them consistently. Do not deduct rooflights from the overall dimensions: the tool states that rooflight voids add flashing materials but do not reduce the membrane.
Step 1: choose the roof shape
Open RoofBuildr and select the shape closest to the roof you are covering.
Simple rectangular roof
Choose this for a roof with four straight perimeter edges. RoofBuildr asks for the length and width, highlighting the relevant edge on a top-down diagram.
L-shaped roof
Use this for a roof with one rectangular cut-out. Follow the labelled diagram carefully and make sure the smaller return measurements describe the actual geometry.
Apex roof
Select this for two sloping planes meeting at a ridge. Measure the sloping roof surfaces as prompted, not merely the horizontal building footprint.
If the roof is more complex than these options, ask Stonegate Supplies for project-specific advice rather than forcing it into an unsuitable shape.
Step 2: enter the measurements
RoofBuildr presents one measurement at a time. Enter the dimension in metres and use the highlighted line to confirm which part of the roof it represents. On a rectangular roof, the first prompt is the longest edge and the second is the width measured at 90 degrees.
Check decimal points and units before continuing. Entering 450 instead of 4.50 will create a radically different specification. For more measuring guidance, read How Much EPDM Membrane Do I Need?.
Step 3: describe the roof details
Set every edge finish
Choose a treatment, then tap each matching edge on the roof plan. The available treatments are:
- Gutter edge for an edge discharging into a gutter.
- Kerb / upstand where the membrane turns up at a raised perimeter.
- Meets a wall where the roof abuts masonry or another vertical surface.
- No trim / customer supplied where a RoofBuildr-supplied trim is not required.
Every edge must be assigned. This matters because perimeter lengths drive products such as Sure Edge Gutter Drip Trim and Sure Edge Kerb Trim. Select “no trim” only where a supplied trim genuinely is not required.
Choose the roof-deck surface
Select OSB/timber, existing GRP, metal deck, or felt/asphalt. RoofBuildr uses this choice to determine the configured preparation and adhesive products. The surface must still be sound, compatible, clean and suitable for the system. For timber deck guidance, see EPDM Roof Deck: OSB3 vs Plywood.
Step 4: record penetrations and rooflight voids
Outlets and pipes
Record every roof outlet and pipe penetration. You can position penetrations on the plan or enter the total quantities. RoofBuildr now also presents matching live catalogue fittings in the same section. Outlet choices can include an EPDM Horizontal Drain Kit, Horizontal Outlet 100mm and Internal Drain 68mm Kit; pipe choices include EPDM Pipe Boot size options. The penetration quantity feeds the detailing calculation, while the selected fitting quantity determines what is added to the basket. Check that both figures accurately describe the job.
Rooflight voids
RoofBuildr asks separately whether the roof has skylights or rooflight voids. If it does, add each void with its reference, length, width, upstand height, material, quantity and position. Voids add the required flashing materials but do not reduce the membrane size.
For practical detailing advice, read How to Install EPDM Around a Rooflight and How to Seal EPDM Around Pipes and Roof Penetrations.
Step 5: choose the EPDM system
Select the roofing system offered for the project. RoofBuildr reads available membrane widths from the live catalogue and uses them when specifying the sheet. The current workflow offers ClassicBond 1.2mm EPDM Rubber Roof Membrane, a cold-applied, one-piece system suited to garages, extensions, dormers and garden rooms.
The aim is to supply a practical single-sheet size with an installation allowance, not simply the bare roof area. The final screen separates measured dimensions from supplied membrane width, cut length and supplied area.
Step 6: choose trim colours when prompted
If the roof build includes a coloured perimeter trim, RoofBuildr adds a Trim colours stage. Choose a finish for every applicable trim before continuing. The current Sure Edge gutter drip trim choices are Black, White and Anthracite Grey. Check the selection against the fascia, windows and other visible finishes on the project.
Step 7: choose optional extras
RoofBuildr displays tools relevant to the system and project. Options can include a DIY Installation Kit, Professional Installation Kit, membrane scissors, mini roller, penny roller and professional seam roller.
This stage is optional. Choose only what the job needs; if your team already carries the correct tools, continue without adding duplicates.
Step 8: review the material specification
The Materials screen is the most important checking point. It shows:
- The roof shape, calculated area and perimeter.
- The measured roof size and supplied membrane size.
- The required bill of materials, including variants and quantities.
- The reason each product has been included.
- Unit prices, line totals, VAT and the total including VAT.
- Optional recommendations, which do not change the total until selected.
For a timber-deck project, the result may include the membrane, EPDM Water Based Deck Adhesive, Rubber Roofing Contact Adhesive, trims and matching corner pieces. The exact list depends on the details entered.
Review every line against the roof. Confirm that the membrane orientation works on site, access is sufficient for handling the sheet, edge types are correct, penetrations have not been missed and the delivery quantity matches the displayed supplied quantity.
Saving the project or adding it to your basket
Give the calculation a recognisable project name, such as the customer surname and roof location. Use Save Project to retain the specification or Add Roof to Basket to transfer the calculated materials into your Stonegate Supplies basket.
Before checkout, check delivery access, lead times and any additional items not governed by the calculation. Saved projects are useful when preparing several estimates or returning after confirming a site detail.
Common RoofBuildr questions
Does RoofBuildr replace a site survey?
No. It converts your information into a product specification. It cannot verify structure, falls, drainage capacity, substrate condition, site access or measurement accuracy.
Does it deduct rooflights from the membrane area?
No. RoofBuildr keeps the rooflight void within the membrane calculation while adding the flashing materials required for the upstand detail.
Can I use it for an irregular roof?
The live tool supports rectangular, L-shaped and apex roofs. Seek project-specific advice for more complex geometry.
Why is the supplied membrane larger than the measured roof?
The membrane needs an installation allowance at the edges. RoofBuildr shows both the measured roof and supplied sheet size before ordering.
Are tools automatically added?
No. The Extras stage is optional, and recommended products do not affect the total until selected.
Can I change an answer?
Yes. Use Back or the completed stage buttons to revisit earlier information, then review the recalculated materials before saving or adding them to your basket.
Final checks before you order
- Recheck every roof dimension in metres.
- Confirm the shape matches the actual geometry.
- Verify all edge finishes, outlets, pipes and rooflights.
- Check the substrate choice and condition.
- Review supplied membrane dimensions and the handling route.
- Read every bill-of-materials line and its inclusion reason.
- Confirm quantities, VAT, delivery requirements and site-specific extras.
When those checks are complete, start your RoofBuildr project and build a clear EPDM materials order from the roof in front of you.
