10 Flat Roofing Terms You Need to Know

If you own a house it’s fairly likely that you also have a flat roof. This might be on top of a garage, porch, shed or extension.

If you’re thinking of reroofing or installing a new flat roof, it’s important that you get the right roofing material for you. Things to consider include how long they last, how easy they are to repair and how much they cost.

But when researching roofing materials, you may come across words and phrases you don’t know or understand. To help you in your search for the right flat roofing material, we’ve come up with 10 flat roofing terms and definitions you need to know.

1. Single ply membrane

Single ply membranes are roofing materials that come in one single layer. They are waterproof, and include EMPD rubber, PVC, TPO and TPE. Single ply membranes are often more expensive than other flat roofing materials. But they tend to need less maintenance and last longer.

2. UV light damage

The sun gives out UV (ultraviolet) light. This can cause radiation damage to flat roofs. Over time it will break down chemical bonds in the roofing material, which can lead to weakening, warping and leaking. To protect your roof from UV damage, you can apply solar reflective paint or chippings.

3. Substrate

The substrate is the part of a flat roof that the surfacing material attaches to. It’s usually made up of gypsum or plywood boards.

4. Alligatoring

Alligatoring refers to cracks in asphalt. It’s so called because the cracking can resemble scales, as it doesn’t go all the way down to the roof base. Alligatoring needs rectifying before the damage gets worse and leads to leaks in your roof.

EPDM roofing
Image via Pinterest
5. Blistering

Blistering is when bubbles appear in roofing materials. This is usually due to air or moisture trapped under the surface.

6. Canopy

A canopy is where a roof structure projects or overhangs off a building. Canopies are usually over entrances and unsupported at the far end.

7. Joist

A joist is a beam that supports a floor, ceiling or roof. It’s usually made out of wood or metal.

8. Lap seam

A lap seam is where overlapping pieces of roofing material join together.

9. Mansard Roof

A Mansard Roof is a sloped roof that turns into a flat roof at its highest point.

10. Ponding

Ponding is when rain water collects on your flat roof and hasn’t drained off after 48 hours. Ponding can weaken your roof, especially in freezing conditions. You don’t have to act immediately if you notice ponding on your roof, but you should keep an eye out for damage. If you’re having the roof replaced you should make the roofer aware of the problem so they can rectify it.

Knowing these terms and what they mean should help you find the right flat roofing material for you. To find a roofer to install your new flat roof, fill in our online form. We’ll connect you with up to 4 local contractors, who’ll give you a quote.

Evy Coe

Evy works for Quotatis as a Content Marketing Executive. She loves to write about interior design and help homeowners with their DIY projects.