# Soundproofing a roof



## Chris Knight (23 Jul 2008)

We have a flat roofed bedroom in our house that has leaked in the past in heavy rain and although now re-felted and waterproof for the last five years carries the sound of the rain all too clearly - enough to wake a light sleeper.

Bearing in mind the likelihood of the possibility of further leaks as the roof ages and also the desirability of reducing the noise level in heavy rain, I am looking for suggestions. At one extreme, assuming planning permission were forthcoming, we could probably have a pitched hip roof constructed, that ties into the main pitched roof but something cheaper/simpler would be good.

Grateful for any ideas!


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## cornucopia (23 Jul 2008)

from what i understand of sound proofing you create a room within a room without any solid fixings from one to the other!!!! a bit hard to do with a ceiling!!
but from what I know you could improve the situation by a couple of methods
1. screw some 1/2" battens up over the existing internal ceiling and board it out with 1/2" plasterboard then either cross line and paper or skim with plaster. If you've got plenty of ceiling height you could increase the size of the batten and fill the void with insulation, the looser the better.

2. glue up/screw up the plaster board with the 1 1/2" polysterne glued to the back of it, then as above dry line or skim.


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## devonwoody (23 Jul 2008)

I would put someone else to sleep in that room and move out myself :x


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## Paul Chapman (23 Jul 2008)

Hi Chris,

This is a suggestion concerning the felt rather than soundproofing. If you decide to keep the flat roof, next time you have the felt replaced, go for the seamless glass fibre stuff (similar to how Waka had his workshop extension roof done). Much, much better than felt. We have several flat roofs where our bungalow has been extended over the years and I had them replaced with the glass fibre stuff a few years ago. Excellent stuff. Although if you can go for a pitched roof, that would be even better.

Cheers :wink: 

Paul


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## wizer (23 Jul 2008)

Our bedroom is the same and I am a very light sleeper. I do dream ('scuse the pun) of putting a sloping roof on.

Cornacopia's idea is the best I can think of, but you can get sound absorbing plasterboard. Called SoundBloc if memory serves.

I also agree with Paul. My kitchen roof was done like that after years of leaks. No problems for the last 3yrs.


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## StevieB (23 Jul 2008)

Do you have gravel or chippings on the felt? I have seen these added with a bitumen layer to act as a barrier for both wind and rain protection, the wind does not lift the felt edges so badly and the gravel gives an irregular surface to stop rain drops 'splatting' onto a flat one. Not sure about level of noise reduction but might be a cheap option to try.

Steve.


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## Paul Chapman (23 Jul 2008)

StevieB":251eb8e5 said:


> Do you have gravel or chippings on the felt?



In my experience, the application of gravel doesn't do much good. In fact it tends to give you another problem, in that you spend hours up a ladder cleaning gravel out of your gutters and drain pipes  

Cheers :wink: 

Paul


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## Shadowfax (23 Jul 2008)

I definitely would not recommend using polystyrene sheet in that situation. Purely from the fire hazard point of view. I am sure it would deaden the sound, though. However, there are better insulation boards than the dreaded expanded polystyrene!

SF


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## big soft moose (23 Jul 2008)

assuming you have the head space , batten round the walls and put a hanging ceiling in support on these with acoustic insulation on the upward side - easy in a small room , next to impossible in a big one


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## Chris Knight (23 Jul 2008)

Thanks for your input guys - seems rather similar to my rough thinking about possibilities. I was interested in your comment on the fibreglass Paul and if we stay with a flat roof, I shall do that. However, on balance I think I will try for a pitched roof. It will probably look better from the outside and won't involve sacrificing headroom inside.


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## Philly (23 Jul 2008)

Chris
I have used Rockwool slabs under a plasterboard skin to soundproof (wrong term really - reduce the transferred sound) walls. Makes a significant difference, especially in the mid to high frequency range.
Pretty cheap, easy to do - you only lose around 75mm from the ceiling.
Hope this helps
Philly


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## OLD (23 Jul 2008)

Just confirming the above my workshop flat roof uses





ply to the top then three layer felt .
you can just hear thunder storm rain but any other is quiet


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## CWatters (23 Jul 2008)

Just for info...the chippings used on flat roofs are to prolong the life of the felt by reflecting UV.


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## markymark12 (23 Jul 2008)

Hi
Something i have installed a fair few times is RB1 resilient bar, sounds fancy but cheap as chips, loss of headroom !.5", screw it up counter to the ceiling joists, and overboard by attaching to the flap of the metal, it makes for a cheap fix which whilst not being perfect will make a worthwhile difference. A screwgun is a must, with a depth setting nose.

Have fun
Mark


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## Chris Knight (24 Jul 2008)

Hmm.. thanks everybody for the further input - I am now planning to get an estimate for a pitched roof with the insulating option as a fall back in case the pitched roof works out too expensive.


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## jasonB (24 Jul 2008)

The alternative to a pitched roof is to just increase the fall on your existing roof, not sure what the span is but just a 50-100mm increase will ensure there is no likelyhood of water pooling on the roof.

This can be done by simply adding extra furrings and while the deck is off add sound insulation batts between the joists. If you don't alter the roof from the outside then its worth ripping the existing ceiling down and adding the insulation from below.

Jason


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