Vapour control barrier in drylined walls?

[WWilts]

Cannot see how a VCL can work with drylining (plasterboard on adhesive frame). Where would it go? Intention is to boost airtightness a bit. Else it will be taped plasterboard.

[tonyshouse]

No need to worry as all the draughts will ventilate vapours away as they diffuse or get drawn in ?

[TonyT]

Adhesive frame- do you mean dot and dab?

[WWilts]

10 minutes ago, TonyT said:

Adhesive frame- do you mean dot and dab?

Yes, but frame and dab. So in addition to dots there will be a continuous frame of adhesive all around the perimeter of the plasterboard lining. Intended to reduce the amount of cold air that drops down into the room.
Does drylining allow any kind of membrane to be used as a continuous air barrier?

Edited October 16, 2021 by WWilts

[TonyT]

You aren’t dry lining, best to change terminology 

 

you are dot and dabbing and it’s common to use a complete line of adhesive.

 

Use vapour check plasterboard 

 

[WWilts]

Can an airtight membrane be included? Easy to visualise an airtight membrane lining the internal face of a cavity wall inner leaf. But would that allow the attachment of plasterboard?

[tonyshouse]

Continuous ribbon of adhesive is supposed to happen but rarely does 

[Dudda]

Is it a new build? You can add a parge coat to the walls first. This is a very wet layer of plaster. So wet you can put it on yourself like a thick layer or slurry paint. A lot of members here have done that, myself included. The quality of the plasterboard doesn't matter as much then

[TonyT]

https://www.soudal.co.uk/pro/products/coatings?f[0]=categorie%3A1062
 

can also be used

[MJNewton]

18 hours ago, TonyT said:

you are dot and dabbing and it’s common to use a complete line of adhesive.

 

Use vapour check plasterboard 

 

 

Will the adhesive stick to the foil lining? 

[James94]

Read somewhere your supposed to prime the back of foil plasterboard prior to adhering to wall.

Regards. James

[SteamyTea]

20 hours ago, WWilts said:

Intended to reduce the amount of cold air that drops down into the room.

Where is this air coming from, and is it bypassing any insulation?

[WWilts]

1 minute ago, SteamyTea said:

Where is this air coming from, and is it bypassing any insulation?

Presumed leaky walls (outer brick, inner aircrete block, 10mm mortar 1:5). Despite concave tooled joints that are reasonably well filled. Cavity to have bonded EPS beads blown in.
 

[SteamyTea]

4 minutes ago, WWilts said:

Presumed leaky walls (outer brick, inner aircrete block, 10mm mortar 1:5). Despite concave tooled joints that are reasonably well filled. Cavity to have bonded EPS beads blown in.
 

If the cold, outside air, is getting past the beads in the cavity, this negates the point of insulation to a certain extent.

Are you going to render on the outside to improve this?

[WWilts]

32 minutes ago, SteamyTea said:

If the cold, outside air, is getting past the beads in the cavity, this negates the point of insulation to a certain extent.

Are you going to render on the outside to improve this?

Some outside air might get in, or inside air might get out, if the wind gets very high outside. Presumably through minute gaps in the mortar and any air channels remaining in the bonded beads.

 

No render, facing brick outer leaf.

Parge coat will help. Could an airtight membrane be attached to the inner leaf internal surface, and then the parge coat placed on the airtight membrane? Suspect there will not be sufficient key to hold the parge coat to the membrane.

Edited October 17, 2021 by WWilts

[WWilts]

pics of joints (external face of brickwork, internal face of blockwork).
Look ok to me, although an aluminium post is fixed to brick mortar each day for a line, and it leaves a small hole. Will ask for those holes to be sealed with mortar.

Trying to understand it all so that the generally co-operative and trustworthy builder can be pushed only where it is necessary.

 

Edited October 17, 2021 by WWilts

[SteamyTea]

1 hour ago, WWilts said:

beads blown in

Sorry, thought you had already had the beads in.

 

[Dudda]

Forgot the membrane. It's not needed and you'll need to introduce battens if you want to use it on the walls. You have blockwork internally which is perfect for the parge coat I mentioned earlier. Go around with airtight tape and tape everything; around doors, windows, floor to wall, walls to airtight membrane in the ceiling, around all pipes and cables going from inside to outside. Then add the parge coat. This will give you a brilliant airtight home to Passive House standard and is something you can do yourself to save money if needed.

 

You do not need an airtight membrane to the walls but do for the ceiling.

[WWilts]

On 17/10/2021 at 19:39, Dudda said:

Go around with airtight tape and tape everything; around doors, windows, floor to wall, walls to airtight membrane in the ceiling, around all pipes and cables going from inside to outside. Then add the parge coat

3:1 sand:cement? Lime required? Any need for any other ingredients?

[Dudda]

Ya 3:1 sand cement is perfect. No lime needed but lots of water. You want it like a wet paste. I used a large sweeping brush to apply it. It's very easy but very messy. It splashes everywhere. 

[WWilts]

On 17/10/2021 at 19:39, Dudda said:

Go around with airtight tape and tape everything; around doors, windows, floor to wall, walls to airtight membrane in the ceiling, around all pipes and cables going from inside to outside. Then add the parge coat

Given how messy it is, would it be ok to put the parge coat on before the penetrations by cables etc? And then rely on airtight tape to seal around the penetrations? Else the screed might have patches of slurry making the surface uneven.

[James94]

Is it worth adding any polymer/latex additives to the parge  mixture, would they make a difference to the finish or just extra costs?

Regards. James

[WWilts]

Thinking of VCL on inner face of inner leaf blocks, held to wall by battens. Then plasterboard fixed to battens, skim.

 

Would 500 gauge VCL suffice? And are there serious disadvantages to this approach?