Please check my tile addy calculations

[trusz]

I've spent many hours reading the forum and gaining a wealth of information for my first DIY tiling job. Many knowledgeable people on here and thanks to you for your help so far!

I'm just putting together a shopping list for my bathroom tiling and I'm trying to work out how much adhesive I will need. Please could someone check my workings below to make sure I'm not way out? :yikes:

On the walls will be 10m^2 300 x 600 x 10mm light grey/off white tiles,
On shower walls 9m^2 300 x 600 x 10mm dark grey
On floor 9m^2 600 x 600 x 10mm dark grey tiles

From what I've read, I will need a 20mm x 10mm round notched trowel giving a solid bed of about 6mm?

I'm looking at buying Mapei Keraflex Maxi Grey for use with the dark tiles and white for the lighter tiles.

On the website they quote 1.5kg per m^2 per mm

So dark grey requires grey addy for 18m^2
6(18 * 1.5) = 162kg so round it up to 9 bags?

Light grey requires addy for 10m^2
6(10 * 1.5) = 90kg so round up to 5 bags?

 

[mz30]

so from what I can gather your going to buy 14 bags of adhesive for 28m2? if that's the case your buying way to many

 

[Sean SML Tiling]

You should be looking around 7 bags any more and id recommend doing a fair bit of prep work before tiling

 

[trusz]

Ok, perhaps I've got it wrong on the thickness/trowel I need. Can you advise? Walls are all dot n dabbed with water resistant PB apart from the wetroom area which has 12.5mm marmox.

Forgot to say the floor is SBR primed 18mm WPB ply screwed on to timber joists with all edges supported with noggins. I also added herringbone struts to make it as solid as possible. The surface is as near to flat/level as I could manage (<5mm dips under a 2m straight edge across any plane). I've stuck 4mm Marmox over the top with keraflex maxi, taped all the joints and put screws + washers every 300mm.

I have UFH to stick down and plan on putting SLC over to cover the cables and tile on top. I'm still not 100% on doing the floor tiling myself at the moment because of the envelope cutting needed over the wetroom tray so I think I might get a couple of quotes for that.

I've spent quite a lot of time, effort and money on the prep work and I think it's a pretty good job but I'm not feeling over confident on the tiling.

 

[Andy Allen]

Should get around 4/5m2 per20kg bag using a 10mm notch trowel

 

[Peter]

No point buying a grey and white of the same adhesive. For 28m, 6-7 bags of white is plenty.

 

[trusz]

Thanks all. Saves me going way over the top there