Soundproofing a warm flat roof

[geraldthehamster]

Does anyone have any thoughts on soundproofing a yet-to-be-built warm flat roof against traffic noise? The ceiling would have exposed timber joists, so resilient bars and a suspended ceiling are not an option.

Proposed design (from the top) is EPDM, ply, insulation (at the moment planned as foiled Celotex), VB (if this is needed as well as the foil on the Celotex), deck, joists. Below the deck, possibly a couple of inches of extra insulation and PB between the joists for half their depth.

We also thought of incorporating Rockwool acoustic batts in the design but I’m by no means sure if this is appropriate, or where you'd put it. I did come across Rockwool Hardrock Multi-fix (DD) boards whilst Googling, but I haven’t used them and couldn’t find any online prices for them.

Any suggestions for products or techniques welcome.

Cheers
Richard

 

[Mw Roofline]

I don't know, but I'd go with a three layer built up felt system instead of EPDM and whatever insulation you need, say 125mm do it in different sizes like 2 lots of 50 and 1x25mm but I'm really no expert. All i know is differing sizes of insulation is better than one think single size.

What about the noise getting in from the eaves, fascias? Also if there is a window, you'll probably have more outside noise coming in through that that your roof