Putting celotex onto a large wall

[davemars11]

PLEASE HELP!!!!
The wife and I are renovating an old chapel and need to insulate the internal walls.
I have a 215mm brick wall and have to use 60mm celotex + 12.5 duplex board. The problem is the front wall is 6.5m wide and 5.4m high, I have run a plumb bob down and the wall is out by approx 40mm top to bottom.
Not sure where to start and how to fix celotex.
Any ideas appreciated as we are doing the work ourselves and we did not have a clue about building until we started this project.

 

[Deluks]

PLEASE HELP!!!!
The wife and I are renovating an old chapel and need to insulate the internal walls.
I have a 215mm brick wall and have to use 60mm celotex + 12.5 duplex board.

Celotex and foil backed plasterboard isn't necessary. The celotex is already covered in foil which provides an inner vapour barrier, you simply tape up the joins with silver alu foil tape for a good seal. Then use normal (cheaper) plasterboard.

Who recommended using duplex? Architect or BCO (my fiver says the architect)

The problem is the front wall is 6.5m wide and 5.4m high, I have run a plumb bob down and the wall is out by approx 40mm top to bottom.
Not sure where to start and how to fix celotex.

Nothing to get in a tizz about, 40mm is nothing over such a huge wall. Pack out the wall
with timber battens until it's flattish.

*note: you can get plasterboard with the insulation and vapour barrier already attached. Far quicker/easier/cheaper for this type of job.

Any ideas appreciated as we are doing the work ourselves and we did not have a clue about building until we started this project.

Good luck, may god be with you (...and see you here again real soon!)

 

[davemars11]

[Celotex and foil backed plasterboard isn't necessary. The celotex is already covered in foil which provides an inner vapour barrier, you simply tape up the joins with silver alu foil tape for a good seal. Then use normal (cheaper) plasterboard.

Who recommended using duplex? Architect or BCO (my fiver says the architect)

The architect told us to use duplex to stop any damp as the building is 100 years old


Nothing to get in a tizz about, 40mm is nothing over such a huge wall. Pack out the wall
with timber battens until it's flattish.
Thanks, is this the best way;
1. I put a 40mm batten horizontal along the bottom of the wall.
2. I put a 20mm batten horizontal along the middle of the wall.
3. I fix 60 mm vertical battens to wall and to horizontal battens at 600mm centres.
4. I put celotex between battens and then fix plasterboard over the top.


*note: you can get plasterboard with the insulation and vapour barrier already attached. Far quicker/easier/cheaper for this type of job.

Thermaline super 60mm £35 a board
Celotex and duplex £21

Thanks for the help...Dave

 

[Deluks]

Whilst I appreciate that the material costs are cheaper, the extra work involved makes it more expensive from a time=money perspective. Obviously if you are doing all the work yourself, and there are no deadlines to meet then this is a moot point.

Duplex plasterboard is no answer to damp. Damp is a seperate issue and should be treated at source before any other work is carried out.
The foil backing is to ensure that moisture in the air does not pass through the walls and condense on the other side which causes, erm, damp!

As the celotex is foil backed already, no other vapour barrier is necessary. If worried, for peace of mind just stick up a large sheet of polythene over all the insulation before plasterboarding.

You've probably bought all the stuff now anyway so again, a moot point.


Regards to packing out, no hard fast rules as such. Simply measure, cut, measure, cut, plane, cut, measure etc etc until it's all flush.
You don't want all the insulation between the battens as that will create a cold bridge to the outside. When all the battens are installed and level, fix all the insulation over that, or a combi of between/over using different thicknesses of board until you get your min. 60mm all over the wall. Don't go less than 25mm over where the battens are.

 

[davemars11]

Thanks Deluks, I have already got celotex and boards so will have to use these.
The way I understand it is that I fix a 50 x 25 batten at top and 50 x 65 batten at bottom of wall and then cut and plane the rest to fit.
I then fix 60mm celotex onto the battens.
Do I then fix plasterboard with 100mm screws through celotex onto battens ? or do I batten again with 50 x 25 then fix plasterboard