Insulation suggestions for timber frame

[trimattrdg]

Could anyone suggest a simple way I can insulate this single skin bay window? I was originally going to wood fibre and lime this wall but after issues with installation I ended ripping out and having frame built. Plan now is 15mm wood wool on top of frame with lime on top. The rest of wall being 3 coat lime with some form of insulation in the frame (the bay wall has a lime scratch coat on) - the frame gap is around 100mm deep. I do have a load off wood fibre offcuts left which is a mix of 40mm and 60mm - was thinking maybe I could sit it tight in frame or considering just putting mineral wool in frame but not sure if I need VCL etc , just want to keep it simple as looking to get the wool wool board put on and plastered later in the week.

 

[Zebra]

Sheepswool would be good.....then OSB for strength internally and as a vapour control layer, then finish with thin woodwool board and lime plaster.
But if you've got lots of wood fibre you could use that, to save time. You'd have to pack it tight though because air gaps are the enemy.
Mineral wool would also be fine and probably a better insulator than wood fibre.
A VCL is advisable to prevent condensation inside the frame. As I said, OSB is cheap and readily available and lends strength too, and you can cut socket backboxes into it.

 

[Toby Newell]

I would leave out the OSB, WWCB should be enough, OSB is weetabix in waiting.

 

[Toby Newell]

In the US of A, where coincidentally they have the most destructive tornadoes on earth and make most of their residential buildings out of wood... they use quite a lot of OSB. There have been three large class action lawsuits that I am aware of, amounting to several $hundred million, one for sidings that rotted, one for roofing board that rotted and one for price fixing.

OSB is a hideously and pointlessly useless material and waste of energy, I never use it and would never fit a floor to it.

It's actually fairly moisture resistant on it's uncut face, at the cut edges it's basically weetabix and does the weetabix thing.

I have zero idea why people use it, nothing that rubbish is good VFM. I've seen multi £10k's floors in £MM houses ruined by OSB and chipboard subfloors.

At least MDF looks kind of solid, OSB actually looks like weetabix! So no excuses.

 

[trimattrdg]

Interesting I was thinking OSB was plywood but actually see what it is now, think I’m going to take the WW only approach in this case

 

[trimattrdg]

Found min wool awful to work with (apart from the fact it cut nicely) but fairly happy with the result. WW going on today

 

[mh12]

View attachment 13094
Found min wool awful to work with (apart from the fact it cut nicely) but fairly happy with the result. WW going on today

Excellent job. Couple of questions if I may (will help me and others in similar situations I'm sure)
1) What size of studs have been mechanically fixed to the wall?
2) Did you conside wood fibre batts instead of mineral batts and what depth of mineral wool batts did you opt for?
3) Did you end up covering the insulation with wood wool board and finsihed with lime skim coat?
Thank you

 

[trimattrdg]

Excellent job. Couple of questions if I may (will help me and others in similar situations I'm sure)
1) What size of studs have been mechanically fixed to the wall?
2) Did you conside wood fibre batts instead of mineral batts and what depth of mineral wool batts did you opt for?
3) Did you end up covering the insulation with wood wool board and finsihed with lime skim coat?
Thank you

Thanks, in this case the joiner used 3x2 timber (untreated) although may want to use treated. The insulation is 100mm mineral wool (rockwool) bats (think they are called the acoustic version and in the same as we used under floor. We fixed 25mm wood wool on top and them line plaster directly onto this (preferred 25mm to 15 as less brittle) . We have recently done hallway also with similar approach but using sheepswool (would recommend as much nicer to work with) but in this case only 50mm insulation due to orienting the studs to give more space in room.

 

[mh12]

Thanks, in this case the joiner used 3x2 timber (untreated) although may want to use treated. The insulation is 100mm mineral wool (rockwool) bats (think they are called the acoustic version and in the same as we used under floor. We fixed 25mm wood wool on top and them line plaster directly onto this (preferred 25mm to 15 as less brittle) . We have recently done hallway also with similar approach but using sheepswool (would recommend as much nicer to work with) but in this case only 50mm insulation due to orienting the studs to give more space in room.

Many thanks for the clarification. Very helpful.
Just wondered whether you contemplated the wood fibre route instead of mineral wool and finally what centres between the studs were chosen 400 or 600?
Sorry , no more questions

 

[trimattrdg]

Many thanks for the clarification. Very helpful.
Just wondered whether you contemplated the wood fibre route instead of mineral wool and finally what centres between the studs were chosen 400 or 600?
Sorry , no more questions

We did originally use this wood fibre , but just don’t get in with it and found studs better for attaching window board to etc , I know many others recommend wood fibre but I struggled to find someone willing to take the time to work with it and install correctly and it ended up a mess (I’m sure technically it’s better insulation if installed correctly). Where we used wood wool in hall was 600mm centres and 1200x600 boards . In bay it was only small area so distance between studs not really as critical.

 

[trimattrdg]

We did originally use this wood fibre , but just don’t get in with it and found studs better for attaching window board to etc , I know many others recommend wood fibre but I struggled to find someone willing to take the time to work with it and install correctly and it ended up a mess (I’m sure technically it’s better insulation if installed correctly). Where we used wood wool in hall was 600mm centres and 1200x600 boards . In bay it was only small area so distance between studs not really as critical.

We did originally use this wood fibre , but just don’t get in with it and found studs better for attaching window board to etc , I know many others recommend wood fibre but I struggled to find someone willing to take the time to work with it and install correctly and it ended up a mess (I’m sure technically it’s better insulation if installed correctly). Where we used wood wool in hall was 600mm centres and 1200x600 boards . In bay it was only small area so distance between studs not really as critical.

Excellent job. Couple of questions if I may (will help me and others in similar situations I'm sure)
1) What size of studs have been mechanically fixed to the wall?
2) Did you conside wood fibre batts instead of mineral batts and what depth of mineral wool batts did you opt for?
3) Did you end up covering the insulation with wood wool board and finsihed with lime skim coat?
Thank you

Also to add in the bay i don’t think it was 3x2 timber as the 100mm insulation wouldn’t have fit , can’t remember what was used (in our hall it was 3x2)