How much plasterboard adhesive?

[tgstrts]

Hi all,

I'm going to be attaching approx 7 sheets of 1/2 inch, 8x4 plasterboard to masonry walls soon. I want it to stand 1/2 inch proud of the wall (got 25mm back boxes so wanting adhesive plus plasterboard to total 25mm and be flush with the back boxes).

Could anyone advise how many bags of 25kg adhesive would be required to do this? Also, any recommendations on best make of adhesive for the job?

Any help will be much appreciated, thanks

 

[adam1984]

British Gypsum state that 1no 25kg bag gives enough for 2 boards (2400x1200)
Knauf estimate that 1no 25kg bag will do 4.6m2

 

[stevethespreader]

All depends how good you are at putting the dabs on as well I didn't used to do much dabbing but on a site once there was 12 small utility rooms each room had to have 2 walls d & d before the whole room was skimmed "anyhow" one spread used 3 bags in his room and I used 2 when the plastering foreman asked how many bags did you use? How come you used that much? He said ,He does d&d a lot he took us in the next room and he done same walls with one bag

 

[joe-90]

two bags of Wickes stuff should do it. You can use it for taping and filling too.

 

[tgstrts]

Thanks for all the replies.

Adam1984 - I noticed that some of the manufacturers give a coverage guide, but they don't state at what thickness that coverage is, and its unclear to me if they mean 4.6m2 of unbroken adhesive or 4.6m2 of boards done with dot and dab, and if so how many dabs per board - all had me a bit confused...

stevethespreader - I better get more bags then as I haven't done much of this before - I'm bound to have a canny bit wastage as I try to get the knack of it...

joe-90 - thanks, Wickes looks like a decent price as well... So I can use it for the initial bedding of the tape before I finish with jointing compund?

 

[adam1984]

Have a look at this data sheet from BG:

http://www.gyproc.ae/pdf/Gyproc_Plasterboard_Adhesive.pdf

It gives installation details of trowling on the adhesive and also the mixing. Granted it doesn't state what thickness the dabs will be though.

Also google the following and it will bring up the BG site book which give on site installation Guidance:

SITE BOOK - DriLyner - British Gypsum

Remember when you press the boards onto the adhesive the adhesive will spread so you will have to use quite thick dabs to achieve the depth you require. It may be better for you to batten the wall out with 18mm MDF battens and screw the boards to these. This will give you 30mm overall depth for your back boxes. B&Q offer a sheet cutting service for free on their sheet timber so you could get them to rip down or alternatively use timber battens.

 

[stevethespreader]

Thanks for all the replies.

Adam1984 - I noticed that some of the manufacturers give a coverage guide, but they don't state at what thickness that coverage is, and its unclear to me if they mean 4.6m2 of unbroken adhesive or 4.6m2 of boards done with dot and dab, and if so how many dabs per board - all had me a bit confused...

stevethespreader - I better get more bags then as I haven't done much of this before - I'm bound to have a canny bit wastage as I try to get the knack of it...

joe-90 - thanks, Wickes looks like a decent price as well... So I can use it for the initial bedding of the tape before I finish with jointing compund?

Keep the dabs small but deep there no need for great big dollops

 

[tgstrts]

Thanks for all your advice - has definitely helped me make my mind up what to do here... I think I'm going to batten the walls as adam1984 suggests. That'll probably be the best way to get the depth I want for the backboxes. I thought dot and dab would be the best way to do the internal walls but the more I think about it the more I think I'll be better of with timbers. Thanks again