Loose grit on flat roof

[Lad]

Hi,

I've just had a new flat roof fitted and noticed that quite a lot of the grit on the felt (I'm not sure the technical term for them but it's the stuff that gives the roof that rough texture) have come off and into the gutter and onto ground. Is this normal or have I been given sub standard felt? If I rub my hand on the roof, they seem to come off easier than I would expect. I imagine that over time, more will come off. Is there anything that can be done to seal them in place? What happens when too much have come off - will the roof be prone to leaking?

Thanks.

 

[Burnerman]

The grit gives a protective layer to the bitumen, by reflecting the suns rays and the like.....in time the loose stuff will reduce.
Its always an issue with the grit coming down drain pipes and blocking gullies etc, so its best to keep them baled out.
With felted roofs, leave them be unless you have to walk across them, and refrain from brushing!
John

 

[Lad]

Thanks for your reply, John. Over time, I assume that there would be patches where the bitumen would start to show when the grit gets weathered away. Will these be weak spots for leaks and should anything be done to them at that stage to beef up that protective layer? I was concerned that quite a lot has been lost (well to me it seems a lot) so soon after installation but are you saying this is perfectly normal?

 

[Burnerman]

A good quality mineralised felt should retain most of its grit for years, but you can expect it to be a bit on the thin side on corners etc where the felt has stretched a little. If splits are noticed, thats when replacement is due.
If its left alone, all should be well, but I'm certain that felts, like everything else, must vary in quality to some degree.
John

 

[Lad]

Thanks, John. I hope that I've been given a good quality felt and that it will retain most of the grit in the years to come despite a lot of loose grit is being blown/washed off at the moment!