What trowel notch size/shape?

Hiya

Seeking help. I've searched the forums, but can't find the specific information that I desperately need!

Okay. [b]I'm trying to find out what trowel notch size/shape I need to lay my tiles.[/b] Here are the details of the installation:

- porcelain wall/floor tiles
- size: 450x450mm (approx 18"x18")
- wall application from floor to just shy of ceiling
- in bathroom around bath and shower
- substrate: gypsum plaster (over 8 weeks old)

I am confident that I have suitable adhesive and grout, but I really need to get the trowel notch size right -- I had trouble properly bedding the tiles when I used them on the floor with a 3mm V-notched trowel (I bet that's so wrong!).

Another thing: [b]Should I use the same notch size/shape for installation on horizontal surfaces (floor/worktop) as on vertical ones?[/b]



Many Thanks for your replies

SOS

[NETT Darren]

You should be using a 10mm floor trowel for both wall and floor applications in this case and be using a flexi adhesive cement or a porcel fix cement adhesive, you will have to be really carefull that you use an acrylic primer (bal apd) on the plastered wall as the cement adhesive can react with the plaster causing crystals to form between the two resulting in tile failure

Thanks for the reply darren. I received the same advice a few days ago after phoning up the chappie at the tile shop where I bought my adhesive. So, I bought a 10mm round-notch trowel and have been practicing my technique on small shelf areas before I tackle the large wall.

Since I bought Ardex X 7 G Plus (polymer-modified cement-based) adhesive, I thought it was best to stay with the one manufaturer and went for Ardex P51 primer instead of the BAL alternative. It is designed for the same purpose.

I must say: I'm quite surprised that materials technology is so advanced and ultra specific. Once you make the fateful decision to try and use the most suitable materials for the job, rather than the cheapest or the easiest to obtain/apply, specification becomes the lion's share of renovation!

I would use a 20mm round notch Thick bed solid bed on this size of tile to get 100% coverage because its a shower area, you may also consider tanking the shower area.

Oh! Traxman, I think I am confusing my terminology -- the trowel is actually a 20mm round-notch (thick bed, solid bed) trowel. The depth of the notches is 10mm, and I thought up until right now that it was the depth of the notches that determined the name of the trowel! So to clarify, the notches are round, 20mm wide, and 10mm deep.

And, yes, I am tanking the shower area (Ardex WPC). One question: Does it reduce the effectiveness of the tanking process if I tank only the areas of the wall near the shower, leaving bare other areas of the same flat wall that are further away from the shower?

Many Thanks for your replies.

Its only necessary to tank the area that the pressured water will hit. Be generous with your calculation though.

Thanks Concept. No worries with the tanking though. After the first coat (of two) It appears that I have enough to cover the entire bath/shower alcove.

Thanks for everyone's help

[jaytiler]

10mm would be fine

[Leatherface]

Why not try the special trowel from Karl Dahm - comes in 2 sizes - wall & floor - gives a really good solid bed. You can order online from Karl Dahms website.

Thanks jaytiler and STELLA. That Karl Dahms trowel looks a bit gimmicky, no? What is the practical purpose of those little in-between notches? (I can't find the Karl Dahms website -- does anyone have an address?)

FYI, I'm kind of screwed anyway with my floor tiles. I laid them quite a while ago with the wrong kind of trowel -- the bedding is far too thin and there is incrediblly poor coverage. And on plywood no less! I'll have problems with them throughout the life of the bathroom. Its almost hilariously funny. Almost. Ah well... you live, you learn.

[Leatherface]

All i can sat is give it a whirl

[Dan]

The Karl Dahm trowel is based on a thick-bed solid-bed trowel. So before they had the notches in they were just a half round notch. But after studying how the adhesive is pressed around as you apply preasure and do the wrist twist action thing, a few manufacturers found that sometimes the half round alone didn't actually give 100% coverage 100% of the time. So a few manufactuers have now started to make thick-bed solid-bed trowels with the notches in them which helps you lay the tiles quick as you can assure yourself that they have 100% coverage pretty much 100% of the time.

Very very good trowel design.