Suggestions for Slate laying problem?

[LotsOfSlate]

Hi
I have 125m2 of welsh slate to lay, I have nearly completed 1 room of 25m2.
I am using instamarc rapid setPB.

I used SLC to prep the floor and tried a few layouts before stating to tile.
the tiles are all calibrated flat backed.

However because they are riven faced they vary somewhat in thickness.
I did sort tiles thick to thin and they vary by upto 8mm thickness.

I have buttered each tile and spread on floor too. Tiles are 600x300mm.

I allowed 8bags at a quoted coverage of approx 5m2, so 3 bags extra.

Well its taken 12 bags!

Now with a further 100m2 to do its will be very expensive to continue at this rate.

So my question is this.
The next floor to do is new cured concrete. dry, clean and flat 35m2.
It has UFH installed.

Could I get away with, not buttering tiles but putting just 5 dollops of adhesive thickset. i.e dot and dab?

I reckon this would save a fortune in adhesive, but how risky is it?
Its my own floor not for a customer.
I do appreciate it could cost alot more if it fails and has to be taken up and relaid.

However, someone may have a solution that I haven't heard of?
Cheers All.

 

[LotsOfSlate]

I should have mentioned the slates are 15-25 thick.
so quite strong.

 

[hillhead]

Dot and dab is out of the question.when you grade them ie sort thickness's you should start with the thickest.use light trowel.ie 6 or 8mm.dont butter back of tile just spread light bit on back like butter on bread.lol.as you progress to lighter ones up your trowel to 10mm etc.by the time you get to lightest you need heavy trowel and possible heavy spread on back too.another solution would be to tile each area with similar thickness? Then maybe split at doors.and bevel to suit! Just ideas.slate has great character so you can do great things with it.

 

[LotsOfSlate]

Hi Joe

Yeh, thats more or less what I have been doing.
Oh, boy its going to be expensive

When you say can do great things with slate, I take it you mean they look good down?

Cheers

 

[hillhead]

Hi Joe
Yeh, thats more or less what I have been doing.
Oh, boy its going to be expensive
When you say can do great things with slate, I take it you mean they look good down?
Cheers

yeah.iv done steps between rooms before.what you say about excessive adhesive it shouldn't be too bad as your using little under the heavy ones .its hard to say though when i cant see your set up.