Felt or Fiberglass for Flat Roof

[Whoevenknows79]

Looking to replace a flat roof which is leaking. I've had three people out to quote. Two recommend I use felt and one recommends fiberglass. One roofer even went as far as to say he doesn't use fiberglass anymore as it's to problematic. I'm not really sure which way to go. Keen to hear any advice people have. Thanks in advance.

I couldn't find anyone that would even quote to do either when we did our last year.

Everyone is using rubber now, most said their insurance doesn't even allow them to do these older options anymore.

Rubber, it's definitely a lot better and longer lasting than felt ime

Really? Are you based on the UK?

Yep

I had old felt roof replaced and rubber roof fitted with 20year guarantee defo recommend

Ok well this has confused me further!

The roofer that did mine said he won’t fit anything else only rubber now due to their durability and long lasting hence my user name,I feel your pain!

Yep EPDM rubber roof is the way forward. Used for years on modern new builds and extensions - but also now as replacement for old leaky felt roofs.

In Nov 2025, I had my flat garage roof replaced by a local builder, who I had used before for some internal work.

He used fibreglass - overall it looks fine, but I wonder whether I should have gone with a roofer who specialises in such work and could have talked me through the options available.

then you should find another roofer who will quote for rubber

Rubber is generally superior for flexibility, ease of installation, and cost-effectiveness on smaller roofs, while fibreglass is better for durability, structural strength, and complex, aesthetic shapes

No one uses felt these days unless they are unable to afford better (or are DIYing it)

Yep agree with PP

We had a GRP (fibreglass) flat roof done 6/7 years ago. It has now failed and has to be replaced. They will be using EPDM (rubber).

Our flat roof was felted, then coated in bitumen and finally tiled so comfortable to walk on. It replaced a fibreglass roof 27 years ago, and has been problem-free since. The original fibreglass flexed and cracked with big temperature changes, and eventually leaked.