Insulation in garage conversion help

Danny1969

One thing that often lets people down is not the material used but the way it's built. Take a double glazed unit for example. this could be superb at blocking noise and preventing thermal loss but if you let your average window fitted install it then he will undermeasure and shore up the gaps with expanding foam (if you are lucky) and cloaking. Now the noise and heat will just pass through the gaps around the window. This is the same for doors and the joints on the walls. 

When I installed my Window and door in my garage I measured to 6mm as the biggest gap and worked the brickwork out where needed. Then the sills of the window and door threshold were filled with sand (sound and heat goes straight through hollow plastic. All gaps are then filled with acoustic grade fire caulking. 

All sockets should be surface mounted, not cut into the plasterboard. Again heat and sound will go straight through hollow plastic. Ceiling lights the same, don't cut into the plasterboard. 

Plasterboard should be measured to be a good fit within 3mm or so and any gaps filled completely with easy fill .. then lay another layer so the joints stagger and don't land in the same place. Caulk out and tape the joins 

When it's done right it's quite eerie because you enter the room and you can't hear anything going on anymore. Also you don't see any insects because there just isn't any gaps. 

Lestratcaster

Sockets weren't surfaced mounted unfortunately and neither were the LED downlights. They were cut into the plasterboard so if I do it all again I will consider this. The room isn't sound proofed very well.

Just thinking should I do one area at a time (i.e the walls first) it should improve the heat loss at first then move onto the ceiling and lastly the floor or just do it all at once at labour charges are expensive. Probably want to the same people to do it cos of guarantees?

Dominic

Lestratcaster said:

HerbieTheRadDorklift said:

Build a subfloor and insulate that. 

My uncle said its a waste of money to insulate the floor and I think he's right. Most of the loss is coming from the walls and ceilings. 

Got the number of the builder who did some ceiling work for my neighbours bedroom. Will get some options off him and maybe a price on what I'm looking at.

Sorry to shade your uncle but he's wrong
Approx 60% of heat loss is to ground 
Trust me ...I'm a building Surveyor and building technologist

Lestratcaster

Dominic said:

Lestratcaster said:

HerbieTheRadDorklift said:

Build a subfloor and insulate that. 

My uncle said its a waste of money to insulate the floor and I think he's right. Most of the loss is coming from the walls and ceilings. 

Got the number of the builder who did some ceiling work for my neighbours bedroom. Will get some options off him and maybe a price on what I'm looking at.

Sorry to shade your uncle but he's wrong
Approx 60% of heat loss is to ground 
Trust me ...I'm a building Surveyor and building technologist

Well as mentioned above, I could do it in stages, walls/ceiling first then floor.

Lestratcaster

I think the foil thing @Dominic has suggested won't really help. The original insulation system is wrong and I should probably fix this first.

Portioning the room won't necessarily be cheaper either as we will still need to do the stud wall and clad both sides. New door, and probably a second electric ring. So whilst I might have to redo just 2 brick walls I don't think it'll save me any money.

Lestratcaster

I took photos whenever I was at home at the time and this was during the original insulation process. What I noticed now is there's no wooden frame between the boards. Also there's a gap in the bottom corner on the right.

And they simply just screwed the plasterboard straight over, no dot n dab. So the original system is wrong to start with.

Dominic

The gap is shoddy but there doesn't have to be a wooden frame or dot and dab however there should ideally be a 50mm air gap between the brick and insulation that is vented to prevent interstitual condensation ....a few roofing battens used as spacers would do the job

Lestratcaster

Are you referring to using the battens therma foil or with newer insulation boards?

Dominic

They should be behind the board against the brick to provide a ventilated air gap ,then the board (existing can be re-used ) and then plasterboard stuck or screwed straight onto the insulation board

Lestratcaster

They are, they're just too thin. So they kinda did it right just not to the level it needed to be.

Lestratcaster

@Danny1969 is your garage detached from the house or is it part of it? Just looking up u values and the minimum is 0.25 so I think 75mm celotex would be a starting point. 50mm of Rockwool wouldn’t be enough I don’t think. 

Just need the right balance to keep the room warm and not over suffocate it so it can breathe.

I should have a first quote coming through this or next week.

Danny1969

Lestratcaster said:

@Danny1969 is your garage detached from the house or is it part of it? Just looking up u values and the minimum is 0.25 so I think 75mm celotex would be a starting point. 50mm of Rockwool wouldn’t be enough I don’t think. 

Just need the right balance to keep the room warm and not over suffocate it so it can breathe.

I should have a first quote coming through this or next week.

I've done 2 garage studios and a 4200 sqf proffessional recording studio mate  ... Celotex is no good for this purpose, doesn't have the mass. First thing we did when building 2020 studios was gut the unit throw all the Celotex away. 

mrkb

Lestratcaster said:

@Danny1969 is your garage detached from the house or is it part of it? Just looking up u values and the minimum is 0.25 so I think 75mm celotex would be a starting point. 50mm of Rockwool wouldn’t be enough I don’t think. 

Just need the right balance to keep the room warm and not over suffocate it so it can breathe.

I should have a first quote coming through this or next week.

I think you’re mixing thermal and acoustic properties. U values are for heat loss.

 Rockwool has ok thermal but very good noise insulation due to its mass. Cellotex is basically aluminium foil lined foam, so good heat insulation but not much noise absorption capability.

Lestratcaster

Danny1969 said:

Lestratcaster said:

@Danny1969 is your garage detached from the house or is it part of it? Just looking up u values and the minimum is 0.25 so I think 75mm celotex would be a starting point. 50mm of Rockwool wouldn’t be enough I don’t think. 

Just need the right balance to keep the room warm and not over suffocate it so it can breathe.

I should have a first quote coming through this or next week.

I've done 2 garage studios and a 4200 sqf proffessional recording studio mate  ... Celotex is no good for this purpose, doesn't have the mass. First thing we did when building 2020 studios was gut the unit throw all the Celotex away. 

Ok as my garage is at the back of the garden all 4 sides and ceiling are exposed to the cold. My main issue is heat loss. Sound isolation isn’t a problem because I’m 50ft away from anyone. It’s just to keep the room at a stable temperature. Won’t be recording in there. Not through mic’s anyway.

Lestratcaster

mrkb said:

Lestratcaster said:

@Danny1969 is your garage detached from the house or is it part of it? Just looking up u values and the minimum is 0.25 so I think 75mm celotex would be a starting point. 50mm of Rockwool wouldn’t be enough I don’t think. 

Just need the right balance to keep the room warm and not over suffocate it so it can breathe.

I should have a first quote coming through this or next week.

I think you’re mixing thermal and acoustic properties. U values are for heat loss.

 Rockwool has ok thermal but very good noise insulation due to its mass. Cellotex is basically aluminium foil lined foam, so good heat insulation but not much noise absorption capability.

Like I mentioned above more concerned about heat loss. There’s far too much of a temperature drop once the heating has been turned off. 

Danny1969

Lestratcaster said:

Danny1969 said:

Lestratcaster said:

@Danny1969 is your garage detached from the house or is it part of it? Just looking up u values and the minimum is 0.25 so I think 75mm celotex would be a starting point. 50mm of Rockwool wouldn’t be enough I don’t think. 

Just need the right balance to keep the room warm and not over suffocate it so it can breathe.

I should have a first quote coming through this or next week.

I've done 2 garage studios and a 4200 sqf proffessional recording studio mate  ... Celotex is no good for this purpose, doesn't have the mass. First thing we did when building 2020 studios was gut the unit throw all the Celotex away. 

Ok as my garage is at the back of the garden all 4 sides and ceiling are exposed to the cold. My main issue is heat loss. Sound isolation isn’t a problem because I’m 50ft away from anyone. It’s just to keep the room at a stable temperature. Won’t be recording in there. Not through mic’s anyway.

I would still use the tried and tested methods I've mentioned though because I know they work for both heat and acoustics. Do it once and do it right is the best approach. But, pay attention to fitting detail. If there's loads of gaps everywhere and the plasterboard gets cut into then it's a complete waste of time. 

Unfortunately most builders don't consider this and that's why a lot of peoples man caves perform so poorly in these respects. 

Lestratcaster

Yep I get that. That’s why I’m researching carefully and making sure it’s  the right amount. Do you happen to know the u value of 50mm rock wool? It’s more expensive as well. Plus whoever does the reinsulating may reuse some of the existing stuff.

Lestratcaster

Rockwool are saying I need 140mm to meet the 0.025w/m2k u value! Building regs are 0.028 I think. It's not a house though its just a garden studio. 

Lestratcaster

Now they are saying it needs to be 180mm with the flexi to meet 0.25/m2k. 140mm will meet 0.28 which is building regs I think but I think if I put that on both walls and ceiling the room can't breathe and I'll get moisture issues.

I'm also wondering about the air gap, on the ceiling a bloke who came round to measure up and give me a quote said 50mm on ceiling. Didn't say anything walls. 50mm as well?

Lestratcaster

Shit. Just figured out something. If I do the reinsulation again it'll bring the walls and ceiling in a bit more, the door would lose entry width as I can expect a loss of space:



How can I get around this without having to recut the opening for the door entry?