external wall insulation

[hertspaul]

Hi... im renovating 1930's house at mo and pretty much a novice. The kitchen has been stripped back to bare brick walls. Im currently batoning and plasterboarding internal walls but was after advice for thermal insulating the external wall which is double bricked- no cavity. I was gonna baton with 22mm strips of wood and screw on 9.5mm foiled back plasterboard ( mainly to save space really ). Just wondered if this was sufficient ?

 

[noseall]

Hi... im renovating 1930's house at mo and pretty much a novice. The kitchen has been stripped back to bare brick walls. Im currently batoning and plasterboarding internal walls but was after advice for thermal insulating the external wall which is double bricked- no cavity. I was gonna baton with 22mm strips of wood and screw on 9.5mm foiled back plasterboard ( mainly to save space really ). Just wondered if this was sufficient ?

You havent mentioned any insulation whatsoever.

You would normally expect to fix 40mm celotex or similar to a 215mm solid wall. This insulation can be bought bonded to a plasterboard sheet so the two can be fixed in one hit.

 

[hertspaul]

Cheers mate. Take it its best to fix both onto the wooden batons to keep an air cavity to stop any moisture build up- is that right?

 

[noseall]

Cheers mate. Take it its best to fix both onto the wooden batons to keep an air cavity to stop any moisture build up- is that right?

Sounds like a plan.

 

[wwwebber]

Cheers mate. Take it its best to fix both onto the wooden batons to keep an air cavity to stop any moisture build up- is that right?

Sounds like a plan.

I'm in similar position. I'll be soon renovating an entire house with solid walls and no cavities. My plan is to leave current interior plaster on external facing walls and then dot and dab 30mm thermaline plus ontop and then skim.

Any good ?.

 

[boulderman]

Hi Noseall,

How do you know what thickness to use?

(Soz for the questions all in one hit) The walls that need insulating have tiling and I wish (at the surveyors suggestion) to line with PIR boards underneath them. Should they go flat against the wall? I would have thought that would keep moisture from getting in. The warmth retained will prevent condensation I´d have thought.

Is 40mm sufficient? I was wondering about using a thicker layer on the North facing wall (no cavity, only brick and block). I was going to use a thinner layer on the South facing wall.

Do you prefer Celotex over Xtratherm and Kingspan, I heard Kingspan is easier to cut (circular saw is best).

Cheers,

 

[noseall]

How do you know what thickness to use?

40mm pur foam board has been recommended (by architects) and accepted by b.c on a recent job. Heat loss calc's also are a great help.

(Soz for the questions all in one hit) The walls that need insulating have tiling and I wish (at the surveyors suggestion) to line with PIR boards underneath them. Should they go flat against the wall? I would have thought that would keep moisture from getting in. The warmth retained will prevent condensation I´d have thought.

Creating any air gap will only seek to aide the insulative properties of the wall, provided the air is stagnant, i.e. not moving. If the wall is solid 9" then moisture is unlikely to "get in". You are more likely to have trouble with damp air within a room than out.

Is 40mm sufficient? I was wondering about using a thicker layer on the North facing wall (no cavity, only brick and block). I was going to use a thinner layer on the South facing wall.

Do you prefer Celotex over Xtratherm and Kingspan, I heard Kingspan is easier to cut (circular saw is best).

Celotex and kingspan are the recognised generic proprietary brands, but all perform well. The u value or heat loss figures are more relevant than brand names.