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Hi all,
I'm going to be workshopifying my garage soon, hurrah
From lots of scouring of forums and manufacturer websites, I have a plan of action, but before I jump in I'd really appreciate a sanity check.
The garage is standalone ~5m x ~5m with single thickness brick walls, pillars in the middle of each, pitched roof and uninsulated roller doors. I want to insulate it both *thermally* and *acoustically* (neighbours' houses & gardens are close, and routers, grinders, saws etc. are pretty loud tools). Also, I don't want to seal off the main doors (at least one will be for bicycle, lawnmower, etc). I want to be able to use it in winter without undue amounts of temporary heating or physical exertion!
What I'm thinking is:
ceiling - from the inside out: plasterboard, resilient bars, 100mm high density mineral wool (Rockwool RWA45 or Knauf equivalent), 100mm normal loft insulation.
walls - from the wall inwards: breather membrane, 25mm battens (mini cavity), 50mm cellotex GA4000, VCL, OSB sheet (so I can hang shelves easily). I lose ~90mm of floorspace on each wall.
[Reference: celotex garage conversion "application datasheet" page 8, linked to from https://www.celotex.co.uk/applications/conversions/garage-conversions (it uses PL4000 which has bonded plasterboard and appears to have VCL builtin)].
This Celotex page (http://blog.celotex.co.uk/technical/garage-conversions-part-2/) suggests DPM behind the battens instead of membrane; I suppose it depends on how exposed the walls are?
I know some people advocate tanking but the celotex pages don't show that option.
To avoid sound leaking up the walls straight into the roof space I think I need the tops of the battens/celotex/OSB to snug up to a resilient bar, not direct to the roof trusses.
front doors/walls - the roller doors provide no meaningful insulation; inside that build a ~100mm partition of, from the outside in: plasterboard, 100mm high density mineral wool
(rockwool RWA45 or knauf equivalent), plasterboard. The bottom ~2m of one of these "walls" will be doors hinged outwards through the roller door opening.
I'm considering using metal studs for lightness and possibly less sound transmission than timber.
floor - not sure whether to bother - from the slab upwards: DPM, 20mm cellotex, VCL, 18mm chipboard. Join the dpm & vcl to that in the wall. Except of course at the main doors, where I'll have to edge with timber.
[Reference: celotex garage conversion "application datasheet" page 6 & 7]
I plan to do the walls from slab upwards, and if I decide to insulate the floor then lay this inside the insulated walls.
How thick does the plasic sheet have to be to qualify as DPM?
pedestrian door - meeting U values is straightforward, but acoustic data hard to come by; lots of construction options, with upvc seeming cheapest, perhaps dense (and expensive) composite or steel skin ones better?
window - double glazed unit; again quantified sound insulation data is hard to come by. Any recommendations very welcome!
Is it going to work? My estimated numbers are:
THERMAL
-------
For comparison, U (W/m^2K) for conversion for residiential use (building regs) is:
walls = 0.3
ceiling = 0.16
floor = 0.25
With the materials above I estimate:
walls U = 0.39, (bricks U=3, GA4050 U=0.44)
wall with door + window U = 0.6 (assuming door U=1.6, window U=1.4)
wall/roller doors U = 0.27 (plasterboard U=2.5, 100mm RWA45 U=0.35)
ceiling U = 0.18 (plasterboard U=2.5, 100mm RWA45 U=0.35, 100mm loft insulation U=0.44)
floor U = 0.57 (using calculator below, assuming 20mm celotex)
which is probably sufficient: it should be comfortable and warm up quickly without losing heat too fast; any more insulation is unlikely to cost in.
[References:
slab calculations: http://abuildingsite.com/calcs/Ground Floor Calculator/Ground Floor Calculator.htm
RWA45: http://rwiumbracouklive.inforce.dk/media/395728/rockwool rw slab datasheet.pdf
celotex: http://www.celotex.co.uk/assets/handy-guide-2014.pdf
]
SOUND
-----
Sound seems much harder to control (& estimate). I'm /assuming/ the SRI values are meaningful for the frequencies of powertools.
As a reference I believe the regs for sound reduction are, Rw (SRI):
45dB between rooms
50-55dB for places like (school) music rooms
I assume that 50-55 amounts to barely hearing the music at all, so anywhere in the 45-50 region is probably ok/good for an outside workshop.
Walls: single skin unplastered brickwall, R = 42 dB; the cellotex, OSB etc will increase that a bit but probably not a lot.
I could add a layer of plasterboard on the inside, on the basis that (i) it adds mass; (ii) possibly more absorbant than OSB, though without resilient bars I'm /guessing/ it may not make much dfference and I don't want to sacrifice too much floorspace.
Main doors/partition:
In a Knauf brochure they claim:
metal studs, 12.5mm wallboard each side, 25mm knauf earthwool, 100mm total R = 42 dB
metal studs, 12.5mm knauf silentboard each side, 50mm knauf earthwool, 100mm total R = 59 dB
This is in a brochure for Knauf Silentboard and they're being a bit sneaky in changing both the boards and doubling the amount of insulation. Their graph suggests silentboard is ~10dB better than "standard wallboard", so with standard plasterboard and 70mm dense mineral wool (it's also the thermal insulation) it might be around 50dB.
[Reference http://www.knauf.co.uk/files/download/silentboardbrochure1pdf/808]
Ceiling
The resilient bars should prevent sound travellng along the roof trusses and straight onto the tiles & out the door fascias etc. The 100mm mineral wool should absorb some noise.
But not sure about the single skin of plasterboard - I believe that the sound insulation depends really on two separate-ish heavy layers (plasterboard) separated by a gap, so without one of the layers of plasterboard it might be a bit hopeless. I guess I'll try it & see. I could always add a layer above at a later date if really required, though that would probably require retrofitting a VCL too, which would be a total pain.
So, what do you reckon? Any howlers?
graham.
I'm going to be workshopifying my garage soon, hurrah
From lots of scouring of forums and manufacturer websites, I have a plan of action, but before I jump in I'd really appreciate a sanity check.
The garage is standalone ~5m x ~5m with single thickness brick walls, pillars in the middle of each, pitched roof and uninsulated roller doors. I want to insulate it both *thermally* and *acoustically* (neighbours' houses & gardens are close, and routers, grinders, saws etc. are pretty loud tools). Also, I don't want to seal off the main doors (at least one will be for bicycle, lawnmower, etc). I want to be able to use it in winter without undue amounts of temporary heating or physical exertion!
What I'm thinking is:
ceiling - from the inside out: plasterboard, resilient bars, 100mm high density mineral wool (Rockwool RWA45 or Knauf equivalent), 100mm normal loft insulation.
walls - from the wall inwards: breather membrane, 25mm battens (mini cavity), 50mm cellotex GA4000, VCL, OSB sheet (so I can hang shelves easily). I lose ~90mm of floorspace on each wall.
[Reference: celotex garage conversion "application datasheet" page 8, linked to from https://www.celotex.co.uk/applications/conversions/garage-conversions (it uses PL4000 which has bonded plasterboard and appears to have VCL builtin)].
This Celotex page (http://blog.celotex.co.uk/technical/garage-conversions-part-2/) suggests DPM behind the battens instead of membrane; I suppose it depends on how exposed the walls are?
I know some people advocate tanking but the celotex pages don't show that option.
To avoid sound leaking up the walls straight into the roof space I think I need the tops of the battens/celotex/OSB to snug up to a resilient bar, not direct to the roof trusses.
front doors/walls - the roller doors provide no meaningful insulation; inside that build a ~100mm partition of, from the outside in: plasterboard, 100mm high density mineral wool
(rockwool RWA45 or knauf equivalent), plasterboard. The bottom ~2m of one of these "walls" will be doors hinged outwards through the roller door opening.
I'm considering using metal studs for lightness and possibly less sound transmission than timber.
floor - not sure whether to bother - from the slab upwards: DPM, 20mm cellotex, VCL, 18mm chipboard. Join the dpm & vcl to that in the wall. Except of course at the main doors, where I'll have to edge with timber.
[Reference: celotex garage conversion "application datasheet" page 6 & 7]
I plan to do the walls from slab upwards, and if I decide to insulate the floor then lay this inside the insulated walls.
How thick does the plasic sheet have to be to qualify as DPM?
pedestrian door - meeting U values is straightforward, but acoustic data hard to come by; lots of construction options, with upvc seeming cheapest, perhaps dense (and expensive
) composite or steel skin ones better?window - double glazed unit; again quantified sound insulation data is hard to come by. Any recommendations very welcome!
Is it going to work? My estimated numbers are:
THERMAL
-------
For comparison, U (W/m^2K) for conversion for residiential use (building regs) is:
walls = 0.3
ceiling = 0.16
floor = 0.25
With the materials above I estimate:
walls U = 0.39, (bricks U=3, GA4050 U=0.44)
wall with door + window U = 0.6 (assuming door U=1.6, window U=1.4)
wall/roller doors U = 0.27 (plasterboard U=2.5, 100mm RWA45 U=0.35)
ceiling U = 0.18 (plasterboard U=2.5, 100mm RWA45 U=0.35, 100mm loft insulation U=0.44)
floor U = 0.57 (using calculator below, assuming 20mm celotex)
which is probably sufficient: it should be comfortable and warm up quickly without losing heat too fast; any more insulation is unlikely to cost in.
[References:
slab calculations: http://abuildingsite.com/calcs/Ground Floor Calculator/Ground Floor Calculator.htm
RWA45: http://rwiumbracouklive.inforce.dk/media/395728/rockwool rw slab datasheet.pdf
celotex: http://www.celotex.co.uk/assets/handy-guide-2014.pdf
]
SOUND
-----
Sound seems much harder to control (& estimate). I'm /assuming/ the SRI values are meaningful for the frequencies of powertools.
As a reference I believe the regs for sound reduction are, Rw (SRI):
45dB between rooms
50-55dB for places like (school) music rooms
I assume that 50-55 amounts to barely hearing the music at all, so anywhere in the 45-50 region is probably ok/good for an outside workshop.
Walls: single skin unplastered brickwall, R = 42 dB; the cellotex, OSB etc will increase that a bit but probably not a lot.
I could add a layer of plasterboard on the inside, on the basis that (i) it adds mass; (ii) possibly more absorbant than OSB, though without resilient bars I'm /guessing/ it may not make much dfference and I don't want to sacrifice too much floorspace.
Main doors/partition:
In a Knauf brochure they claim:
metal studs, 12.5mm wallboard each side, 25mm knauf earthwool, 100mm total R = 42 dB
metal studs, 12.5mm knauf silentboard each side, 50mm knauf earthwool, 100mm total R = 59 dB
This is in a brochure for Knauf Silentboard and they're being a bit sneaky in changing both the boards and doubling the amount of insulation. Their graph suggests silentboard is ~10dB better than "standard wallboard", so with standard plasterboard and 70mm dense mineral wool (it's also the thermal insulation) it might be around 50dB.
[Reference http://www.knauf.co.uk/files/download/silentboardbrochure1pdf/808]
Ceiling
The resilient bars should prevent sound travellng along the roof trusses and straight onto the tiles & out the door fascias etc. The 100mm mineral wool should absorb some noise.
But not sure about the single skin of plasterboard - I believe that the sound insulation depends really on two separate-ish heavy layers (plasterboard) separated by a gap, so without one of the layers of plasterboard it might be a bit hopeless. I guess I'll try it & see. I could always add a layer above at a later date if really required, though that would probably require retrofitting a VCL too, which would be a total pain.
So, what do you reckon? Any howlers?
graham.
