Urgent Flat warm roof design advice needed
Posted: Tue Jul 14, 2020 6:02 am
Hi, my first post after having tried to get logged on, but here now.
I am in the UK and started a garden music arts room project at the beginning of march 10n concrete cavity walls on block and beam floor.
The building is under permitted development and near boundary so max 2.5m height restriction.
my original design was for a warm roof rubber, 18mm OSB , 100mm cellotex , waterproof membrane, 18mm osb which projected over the outside wall , which has been built up to 10mm below the OSB, sealed with acoustic foam , then a layer of green glue bonding to another sheet of 18mm OSB which is sat on 175 x 50 joists , sat on the wall plate which is bedded on neoprene rubber strip , I was planning to concrete block in the gaps between the joists which are cut back to the edge of the plate and seal with acoustic foam and add 50mm rw5 between the joists , isolation clips then 1 layer of 15mm knauf sound board , MLV and 12.5mm knauf sound board.
Since pressing go and starting covid hit and my career as a function performer has ceased to be viable in the medium term so I have refocused on using the building for recording vocal against track, band rehearsal/ recording and use of the control room for video conference and voice over work, so the importance for the building to be sound proofed from passing jets from the airport, police helicopters and barking dogs is even more important , also the building needs to be capable of live band sessions with minimal sound spill rather than just the voice over track and mixing.
I want to add 50mm of Rw5 or rw3 or ideally 100mm between the joists , and with a view to adding an intensive 50mm green roof on top at a later stage should I need it/ can afford it.
But then CONDENSATION! I was aware that there is generally accepted balance of 2/3rds of the u value above and 1/3rd below, which although none of the manufactures seem to want to recommend a Hybrid roof anyway but adding extra U below the makes the risk of condensation very high apparently.#
I was sure I saw a roof either on here or in rods book about a vented flat roof made to meet code but can't seem to find it.
If it was vented , due to my almost parapet outer walls I was thinking of venting with mushrooms
So everything has ground to a halt due to the roof , with what to do , so
Does anyone have any reliably condensation safe warm roof advise designs or formula that can get me going again ?
If anyone could help I would really appreciate it
Thanks Paul
I am in the UK and started a garden music arts room project at the beginning of march 10n concrete cavity walls on block and beam floor.
The building is under permitted development and near boundary so max 2.5m height restriction.
my original design was for a warm roof rubber, 18mm OSB , 100mm cellotex , waterproof membrane, 18mm osb which projected over the outside wall , which has been built up to 10mm below the OSB, sealed with acoustic foam , then a layer of green glue bonding to another sheet of 18mm OSB which is sat on 175 x 50 joists , sat on the wall plate which is bedded on neoprene rubber strip , I was planning to concrete block in the gaps between the joists which are cut back to the edge of the plate and seal with acoustic foam and add 50mm rw5 between the joists , isolation clips then 1 layer of 15mm knauf sound board , MLV and 12.5mm knauf sound board.
Since pressing go and starting covid hit and my career as a function performer has ceased to be viable in the medium term so I have refocused on using the building for recording vocal against track, band rehearsal/ recording and use of the control room for video conference and voice over work, so the importance for the building to be sound proofed from passing jets from the airport, police helicopters and barking dogs is even more important , also the building needs to be capable of live band sessions with minimal sound spill rather than just the voice over track and mixing.
I want to add 50mm of Rw5 or rw3 or ideally 100mm between the joists , and with a view to adding an intensive 50mm green roof on top at a later stage should I need it/ can afford it.
But then CONDENSATION! I was aware that there is generally accepted balance of 2/3rds of the u value above and 1/3rd below, which although none of the manufactures seem to want to recommend a Hybrid roof anyway but adding extra U below the makes the risk of condensation very high apparently.#
I was sure I saw a roof either on here or in rods book about a vented flat roof made to meet code but can't seem to find it.
If it was vented , due to my almost parapet outer walls I was thinking of venting with mushrooms
So everything has ground to a halt due to the roof , with what to do , so
Does anyone have any reliably condensation safe warm roof advise designs or formula that can get me going again ?
If anyone could help I would really appreciate it
Thanks Paul