Theory question for a plaster expert, please!

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PotatoSoup

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I understand that it is now good practice to dot and dab drywall adhesive in ribbons with a continuous line around the perimeter- but how come it's not commonplace to just stick the whole board on using a full bed of drywall adhesive? It's quicker to throw on and smooth out the adhesive rather than do the ribbons, isn't it? What am missing, please?
 
PotatoSoup said:
I understand that it is now good practice to dot and dab drywall adhesive in ribbons with a continuous line around the perimeter- but how come it's not commonplace to just stick the whole board on using a full bed of drywall adhesive? It's quicker to throw on and smooth out the adhesive rather than do the ribbons, isn't it? What am missing, please?
Click to expand...
Expense and no give to flat board all over!
Edit: I'm DIY, have put boards on and know how expensive the adhesive is
 
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Thank you, lost in the light :-) No give is good when it comes to plasterboard, isn't it? Won't crack the plaster skim?
 
You can't push it in with a full bed, there's nowhere for the adhesive to go. The dabs will "squish" when you press against them so you can get the boards plumb - depending how plumb the wall is anything from a few mm to an inch or more. Also the air gaps contribute to the thermal efficiency of the wall. In terms of give, the "fixings" will be at least as closely spaced as a stud wall.
 
So it's significantly more expensive to do a full bed of drywall adhesive, you can get the plasterboard more level with dabs and it will adhere better and the air behind helps with thermal efficiency.... So definitely a better method then!!! Thank you so much for explaining - I appreciate it!!!! :-)
 
I always put adhesive around edge so it's air tight.
Stops cold air blowing behind boards.
Also stops the flex on edge causing cracks.
 
OP,
To answer your original question: the field of the board is pressed into dabs as others have explained above.
The ribbons of adhesive that you refer to are a continuous line at the base of the wall and the same at the top - the purpose is as a fire precaution against smoke funnelling and drafts.
It used to be in British Gypsums guidance notes (& the Regs ?) but few plasterers seem to bother.
 
Thank you :-) Yeah, I knew the reason for ensuring the plasterboard is fully sealed but I just didn't understand why the suggestion was never made that people could fully coat the back of the board or wall in adhesive as it would have also acted as a parge coat, wouldn't it? So a two for one benefit. But the explanations given make sense.
 
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