Cavity needed for solid wall insulation?

[spudit2003]

I have a 1890's solid walled (12") house and am intending to install some basic internal insulation across one wall.

Unfortunately i dont have a big budget but am looking at Gyproc Thermaline Plus in either 27mm or 35mm. The wall is currently plastered (and painted) and is in good condition except for behind the radiator where i think moisture has caused it to crumble and a few holes where the dado rail was (which will be put on the new wall).

I understand there can be issues with damp if a wall can't breathe. There are no damp issues elsewhere in the house (except the aforementioned radiator, which i assume is due to hot moist air cooling against the wall).

Do I need a cavity? and if so, how small can i make it? I am very limited with space as the door opens just 2 inches from the wall. Do I need to vent the cavity? if so, where to, and how? (ie. products of a how-to guide). I've read about vapour barriers, and it says that Thermaline plus has some vapour resistance, so what is necessary and where does it go?

Lastly, there is a window, but there isnt room to insulate within the window recess, what is the best way to do the edges?

Thankyou, any help or website links are much appreciated to help me on my first major DIY project.

I know there are better insulating products such a Kingspan and Celotex how ever my budget is limited and the wall area is 40' x 8 1/2', so I unfortunately can't stretch to better products at the moment.

 

[^woody^]

You may be reading too much into things

Just fix the boards with the recommended adhesive and you will be fine. No need to design a cavity and the walls will breathe outwards as normal.

For window reveals, use some thin polystyrene - like wallpaper on rolls and sold as a very basis insulation layer, or the silver foil stuff sold on rolls for putting behind radiators. Then plasterboard

The defective plaster behind the radiator tends to be the heat drying the plaster out and not moisture

 

[spudit2003]

Just fix the boards with the recommended adhesive and you will be fine.

ok, do you mean dot and dab? because i couldnt find any adhesives on their site, but having read about dot and dab that looks doable and a bit cleaner than nails/screws.

Thanks for the quick reply

 

[^woody^]

I've just had a look at the Thermaline data sheets and what a stupid waste of time they are. The one which has the installation and fixing details, does not even tell you how to fix them!

Have a look here instead

www.british-gypsum.com/pdf/SB07_DriLyner_04.pdf

 

[simonjay]

You may be reading too much into things

Just fix the boards with the recommended adhesive and you will be fine. No need to design a cavity and the walls will breathe outwards as normal.

Sometimes it's recommended not to fix directly to the wall for solid walls that are painted or rendered on the outside, since such walls cannot necessarily breathe outwards.
Simon.

 

[^woody^]

Yes, but there will be nothing to breathe with that product and 12" walls