and another thing

[sarahbowen82]

Does anyone know what type of gravel / stone you pput on top of a felted flat roof to improve drainage - i asked at my local DIY shop and the bloke looked at me like I had 2 heads!! help please...

[jake-the-peg]

That's probably because gravel on felted roofs cannot improve dainage.

Rain falls on the roof runs to the gutter and goes down the down pipe.

Gravel is added normally to protect the surface from degradation due to sunlight

http://www.diynot.com/pages/rg/rg016.php

normally light coloured limestone chips or pea shingle something like that.

Your local DIY probably thought there was some new product he hadn't heard about - he's probably leafing through catalogs as we speak

[sarahbowen82]

thankyou for your advice x

[sarahbowen82]

after another inspection on the flat roof last night i have decided that the felt is ok, but the gravel is very dirty, covered in moss and gunk etc. In light of the comments you have made, does the gravel need replacing or i am making more work for myself than necessary?

[jake-the-peg]

It's probably not the end of the world. I guess moss has a habit of retaining water You could give it a good treatment with round-up or a similar weed killer if it offends although I'm not sure about whether you're allowed to let that stuff go down the drain.