Surveyor specification

[FreeD]

Had a specification for internal insulation...fix insulation boards direct to wall with frame fixings to avoid gap where condensation could form...solid wall which has had damp proofing carried out previously...evidence of condensation and possible minor rising damp.

I've always membraned followed by dot and dab insulated plasterboards with integral vapour control

Thoughts pls on surveyors spec

 

[Dansouthcoast84]

isnt integral vapour board the foil back ones? if so wouldnt.dot.dab with them. genuine question.

rising damp maybe backjack 1st half metre up? and if dab insulation board on you shouldnt get condensation on there as your creating a warm wall?

 

[FreeD]

isnt integral vapour board the foil back ones? if so wouldnt.dot.dab with them. genuine question.

rising damp maybe backjack 1st half metre up? and if dab insulation board on you shouldnt get condensation on there as your creating a warm wall?

Celotex insulated plaster board has an integral vapour control layer (not all boards have it) stops moisture laden air on the warm side (in the room) passing through the board and condensing on the cold side (brick work/render) which will be colder once insulated.

 

[Vincey]

Think he’s basically done some reading and maybe got mixed up with his information tbf , wonder if he meant a few nailable plugs to hold them for fire reg
You could phone bg and get exact over phone that’s probably what surveyor did or tried to do

 

[themucky1]

Had a specification for internal insulation...fix insulation boards direct to wall with frame fixings to avoid gap where condensation could form...solid wall which has had damp proofing carried out previously...evidence of condensation and possible minor rising damp.

I've always membraned followed by dot and dab insulated plasterboards with integral vapour control

Thoughts pls on surveyors spec

I don’t agree mate not to be a prick who argues for the sake of it either,
First off I would never insulate internally if there’s a chance of doing it externally, the usual reason/excuse for doing it internally is cost(cheaper).
As for fixing insulation boards directly to the wall I understand that doing this will create a dew point on the internal structure due to the cold air from outside breaching the structure and hitting the warm air inside. To overcome this the wall would have to be battened out and have a vapour barrier installed then insulated then plaster boarded etc etc, now to combat the build up of moisture due to the dew point there would have to be drainage which would then mean removing bricks outside and installing a vent/drainage brick maybe something like a air brick?
Whereas insulating externally the insulation is on the outside therefore slowing down the heat escaping from internally and cold air staying on the outside of the structure and creating a dew point outside the property which would be finished in a silicone render or similar which would then eliminate to need for drainage etc as the moisture would sit on the outside of the system.
I’m pretty sure someone’s gonna come along and tear me a new arsehole now and make me look like a kid lol

 

[FreeD]

Think he’s basically done some reading and maybe got mixed up with his information tbf , wonder if he meant a few nailable plugs to hold them for fire reg
You could phone bg and get exact over phone that’s probably what surveyor did or tried to do

Could use concrete fixings and sticks like on the back but not really happy fixing boards directly to the wall no cavity...first I've heard.

 

[FreeD]

I don’t agree mate not to be a prick who argues for the sake of it either,
First off I would never insulate internally if there’s a chance of doing it externally, the usual reason/excuse for doing it internally is cost(cheaper).
As for fixing insulation boards directly to the wall I understand that doing this will create a dew point on the internal structure due to the cold air from outside breaching the structure and hitting the warm air inside. To overcome this the wall would have to be battened out and have a vapour barrier installed then insulated then plaster boarded etc etc, now to combat the build up of moisture due to the dew point there would have to be drainage which would then mean removing bricks outside and installing a vent/drainage brick maybe something like a air brick?
Whereas insulating externally the insulation is on the outside therefore slowing down the heat escaping from internally and cold air staying on the outside of the structure and creating a dew point outside the property which would be finished in a silicone render or similar which would then eliminate to need for drainage etc as the moisture would sit on the outside of the system.
I’m pretty sure someone’s gonna come along and tear me a new arsehole now and make me look like a kid lol

The dew point will be the solid wall...and condensation will only form if warm air from the warm side passes through the insulated plasterboard. There shouldn't be an issue with air from outside condensing on the back of the insulation as it will be warm?

 

[Dansouthcoast84]

I don’t agree mate not to be a prick who argues for the sake of it either,
First off I would never insulate internally if there’s a chance of doing it externally, the usual reason/excuse for doing it internally is cost(cheaper).
As for fixing insulation boards directly to the wall I understand that doing this will create a dew point on the internal structure due to the cold air from outside breaching the structure and hitting the warm air inside. To overcome this the wall would have to be battened out and have a vapour barrier installed then insulated then plaster boarded etc etc, now to combat the build up of moisture due to the dew point there would have to be drainage which would then mean removing bricks outside and installing a vent/drainage brick maybe something like a air brick?
Whereas insulating externally the insulation is on the outside therefore slowing down the heat escaping from internally and cold air staying on the outside of the structure and creating a dew point outside the property which would be finished in a silicone render or similar which would then eliminate to need for drainage etc as the moisture would sit on the outside of the system.
I’m pretty sure someone’s gonna come along and tear me a new arsehole now and make me look like a kid lol

you been reading the instruction manual? lol

 

[themucky1]

The dew point will be the solid wall...and condensation will only form if warm air from the warm side passes through the insulated plasterboard. There shouldn't be an issue with air from outside condensing on the back of the insulation as it will be warm?

The dew point is where a cold temperature meets a warm temperature and crates moisture, like what happens on some window panes. The warmth will pass through the insulated plasterboard as insulation won't stop heat transference it will only slow it down. The same goes for for the outside it’s not the air from outside it’s the temperature that will pass thorough the brick work as it’s not insulated externally creating a dew point on the inside of the structure. But saying that ewi is a massive grey area anyway lol

 

[themucky1]

you been reading the instruction manual? lol

Yeh Gary Peacy gave it me lol

 

[FreeD]

I do agree better to insulate on outside...but also has its issues, XPS for example traps moisture in the wall and I've har

The dew point is where a cold temperature meets a warm temperature and crates moisture, like what happens on some window panes. The warmth will pass through the insulated plasterboard as insulation won't stop heat transference it will only slow it down. The same goes for for the outside it’s not the air from outside it’s the temperature that will pass thorough the brick work as it’s not insulated externally creating a dew point on the inside of the structure. But saying that ewi is a massive grey area anyway lol

I've heard XPS can cause problems internally on solid walls as it's not breathable so moisture pushes internally. I agree with you though external insulation is better overall, Baumit Opentherrm looks an interesting product.

Yes dew point where temperature meets but the condensation has to happen on a surface and that will be the now colder solid wall. The idea of an integrated vapour control layer in the Celotex boards is to control the level of moisture passed through the boards...these are standard specification for internal insulation, personally I've never had a problem with cavity condensation with these boards but I have heard of people who have had an issue using cheap polystyrene back plasterboards.

 

[Dansouthcoast84]

Yeh Gary Peacy gave it me lol

he only copy and pastes it off google.

 

[Vincey]

Could use concrete fixings and sticks like on the back but not really happy fixing boards directly to the wall no cavity...first I've heard.

Sorry I didn’t read op right , they’d probably advice gypliner system

 

[themucky1]

I do agree better to insulate on outside...but also has its issues, XPS for example traps moisture in the wall and I've har


I've heard XPS can cause problems internally on solid walls as it's not breathable so moisture pushes internally. I agree with you though external insulation is better overall, Baumit Opentherrm looks an interesting product.

Yes dew point where temperature meets but the condensation has to happen on a surface and that will be the now colder solid wall. The idea of an integrated vapour control layer in the Celotex boards is to control the level of moisture passed through the boards...these are standard specification for internal insulation, personally I've never had a problem with cavity condensation with these boards but I have heard of people who have had an issue using cheap polystyrene back plasterboards.

Yeh the place where the dew point would happen on ewi is on the silicone finish as the cold temp wouldn’t penetrate the insulation cus it would be warm from internal room temp. XPs should only be used below dpc for that reason only its denser than eps and stops vapour/water penetration. EPS is breathable but not as much as mineral insulation but to meet the Same u value 130mm mineral ins is needed as opposed to 90mm eps. Fcuk me I need another drink now

 

[tapit]

I do agree better to insulate on outside...but also has its issues, XPS for example traps moisture in the wall and I've har


I've heard XPS can cause problems internally on solid walls as it's not breathable so moisture pushes internally. I agree with you though external insulation is better overall, Baumit Opentherrm looks an interesting product.

Yes dew point where temperature meets but the condensation has to happen on a surface and that will be the now colder solid wall. The idea of an integrated vapour control layer in the Celotex boards is to control the level of moisture passed through the boards...these are standard specification for internal insulation, personally I've never had a problem with cavity condensation with these boards but I have heard of people who have had an issue using cheap polystyrene back plasterboards.

It does not matter where you put the insulation only where you put your vapour barrier.

 

[themucky1]

It does not matter where you put the insulation only where you put your vapour barrier.

So where would you put a vapour barrier on Ewi? And what are your thoughts on drainage if the vapour barrier is on the inside of the solid wall? Where will the moisture wick away and drain to?
Stick to drilling holes in some Gaffa tape son

 

[tapit]

So where would you put a vapour barrier on Ewi? And what are your thoughts on drainage if the vapour barrier is on the inside of the solid wall? Where will the moisture wick away and drain to?
Stick to drilling holes in some Gaffa tape son

ok pop.

 

[Danny]

Proper good thread this

 

[Vincey]

Did the guy get back to you @FreeD about the job

 

[Brimstone]

There is another variable, building occupancy, which affects where you put the insulation and a vapour barrier, if at all. Same as warm roof vs cold roof. If it is unheated and/or used infrequently then a cold wall design with insulation bonded onto the solid wall internally can work.
In this case you may not want a void - Dewpoint can occur inside the solid wall, and dry out externally. Moisture can also form within the solid, and can then destroy the solid materials - which comes back to the point about external insulation and sealing it to prevent it getting in in the first place.

 

[FreeD]

Did the guy get back to you @FreeD about the job

Yes...I suggested to the customer to foam fix the boards...the surveyor was happy with foam fix and that there maybe a small void behind the board...proceeding with this spec.