Sadly it isn't unbelievable, but I know what you mean. It is totally wrong. It *might* work (but probably wouldn't) on a parge coat, but we all know that 'volume-builder' 'dry-lining' is not going to be on a parge coat. (and if there was a good parge coat we would probably not be worried about the implied air-leakage anyway!). On very uneven substrates even a full perimeter bead of adhesive is potentially hit-and-miss, but a (5-10mm?) bead of sealant is much more likely to 'miss' than 'hit'.

Oh good, has it been retracted?

@gravelld, in my mind it's mainly to do with typical depth of bead achieved. With dry-lining adhesive that can be 50-75mm, while with sealant it's probably nearer 5-10mm. Coupled with the fact that most of the sealing gets done 'blind' (you can't get a good look at all 4 sides and whether the 'seal' has fully sealed) I think the adhesive would be more likely to hit the spot, literally and metaphorically. You say ''The job of adhesive isn't to form an air seal;'', well no, but that isn't the job of lime plaster or sand/cement, strictly, though both are used very successfully as air-tight parge coats. Although I generally dislike gypsum I expect it should do as good a job as a lime plaster in this circumstance.

Posted By: Nick Parsonsin my mind it's mainly to do with typical depth of bead achieved. With dry-lining adhesive that can be 50-75mm.

Glad Im not paying their adhesive bill! Maybe the plasterers Ive seen are particularly tight, but 15-25mm seems the norm

Posted By: tonyAnd dabs not ribbons

+1
Manufacturers instructions and videos clearly show how to apply dry lining adhesive, anything less is just shoddy workmanship IMO.

I'd go further, that the continuous bead should divide the gap into areas no bigger than about ~1 m2 to stop convection and sideways transfers of heat and vapour.

So three rectangles on each sheet. That means a continuous bead round the edge and then two stripes across the sheet. A total of ~10m of continuous bead on each sheet (yes that's 30 feet without gaps) plus extra for windows corners sockets etcetc.

Putting some bathpanel up recently, I was stuck by how impossible I found this with a gun. The slightest uncontrol of pressure on the trigger, or wobble of the nozzle, and I had a gap or a blob. Going back to fix it, usually made it worse. Nevermind my clumsy hand positioning when I lifted the sheet up.

Granted I don't do this every day and I was gunning the wall not the sheet due to tight floor space. But overall I think the idea is unworkable and the outcome is going to be pretty much the same as if dabs had been used.

I will be going back to glueing and screwing the sheet onto studs as at least there will be tight contact along the line of the timber, and I can foam the insulation to the timber.