trowel notch size - confused advice

[penguinlicker]

good afternoon,

this website says a 12x12 square notch gives you 6mm deep adhesive. it also says a round trowel leave a 1/3 of its size, so a 10mm round lays 3mm deep.

Trowel: Choose the Right Size For You

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my tiles are 400mm x 150mm, 10mm thick, 1.02kg in weight and going onto plasterboard. should i go for a 10mm square which would give me 5mm thickness or a 10mm round which would give me 3mm?

i'm a bit worried that too thick an adhesive will put the walls overweight. what do you guys use for plasterboard walls?

it's all a bit confusing. thank you for reading any any advice you can give

 

[penguinlicker]

So if the tile is 400x150, and 1kg weight would a 10mm notch trowel be big enough?

 

[Steve6690]

A round notch is generally used for floors, so use a square notch. Has the plasterboard been skimmed or are they bare plasterboard? The tiles would be just under 17kg per m2. a 4mm bed of adhesive would, I think, take you over the weight for skimmed plasterboard but one of the pro's can advise you better.
Skimmed plasterboard can take up to 20kg/m2, bare boards can take 32 kg/m2.
As for the trowel- a 10mm or 8mm is probably ok. Use the smallest one that gives the proper coverage between wall and tile. Too thick a bed will make it harder to keep the job clean and flat.
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View: https://youtu.be/w5RqzOAn_tc

 

[Dave]

8mm trowel will suffice. 👍