Help!: First Job

[grumpygrouter]

Don't have BS in fornt of me but I think it states 15mm minimum. As 15mm doesn't appear to be available in Britain you need to go up a size which is 18mm. BAL will not guarantee a floor if boarded with less than 15mm ply if it is used to stiffen the floor unless you use a 2 part bal product like Fastflex.

[Turkish]

Are you refering to Ditra Lee? If so it doesn`t negate the need for ply, it`s an uncoupling membrame to use where lateral movement is suspected. Every situation should be taken on it`s own merits IMO so in some cases you can get away with no ply or reduced thickness.

Turkish

[grumpygrouter]

Originally Posted by Lee1973

hi Hems, I'm skiving at work so haven't got my notes with me! i'm also new and not tiling yet as I'm still in the Army, did my course back in April and I'm doing some more training next week 15mm probabley is the miniumum I said 18mm off the top of my head better dig my notes out for next week!!! it just goes to show how good this place is for learning usefull trade knowledge, Schluter systems do a special matting that replaces the need for any ply its on U tube looks mint has anybody tried it? is it any good?

Schluter Ditra IS NOT a substitute for ply if the floor needs strengthening, Ditra provides isolation against LATERAL movement of the substrate NOT deflection. Your tiles will still crack if the floor has bounce!

[Hems]

Hi mate, good luck with your training, I left forces this year, done a great tiling course, but its amazing how much there is to learn. Just checked again and bs does say on timber floors minimum overlay should be 15mm. The point we were discussing early however is that on a very small room with a very stiff floor there may be a better alternative as 15mm plus adhesive plus tile would mean granny might need a ramp to get up it ! as well as creating other problems around the pedastals of sink and toilet, and door height etc. The guys on here know there onions, i have looked at backer board and its perfect for the job. As for gaurentees etc if it comes up i will take that on the chin and put it right i guess......oh mate what a bloody steep learning curve.

[Lee1973]

Hi Grumpy, sorry didn't spot your reply there! I thought we had to lay ply on floors to stop them failing?

Originally Posted by grumpygrouter

In what situation are you looking to lay ply? Are you talking about strengthening the floor or have you just picked up somewhere that you MUST lay ply first before tiling?

[Lee1973]

cheers to everyone answering my questions its good to have access to experts so easily!
Hems fair one it makes sense the smaller the room the less flex its going to have, I've got the learning curve to come mate!! still at least I get loads of daft questions out of the way here first!! good luck mate.

[Turkish]

Just keep asking away Lee cos there`s no daft questions

Turkish

[grumpygrouter]

Originally Posted by Lee1973

Hi Grumpy, sorry didn't spot your reply there! I thought we had to lay ply on floors to stop them failing?

Chipboard isn't the best substrate to tile onto because if it gets wet it can "blow" or worse collapse altogether. However, it can be tiled straight onto if appropriate adhesives are used. BAL Fastflex and Ardex-flex 7001 are just two that give instructions for doing so, there are others too from the likes of Mapei and others.

Ply-ing out a floor is done to add strengtth to the floor to reduce deflection, i.e. bounce when it is walked on. It is the bounce that causes tiles and grout to crack and fail.

There are many tilers on here who will not tile a chipboard floor without overboarding as they feel more comfortable with the end result and they feel it is more secure. I personally do not follow that idea, as sometimes the customer will not accept the extra cost or they do not want to have what effectively can be a 30mm + step up to the tiled surface.

When faced with timber floors, you must make a judgement as to what is the best way to proceed. if the floor requires boarding then tell the customer so and give them the final say. if they don't not want the extra cost and you feel the floor would fail without it, don't take the job.

if on the other hand the floor is solid but you feel that the floor may get wet, waterproof it! You don't always need to board it out.

Ask back here on the forums if you are ever not sure. Someone will have the correct answer.

[Hems]

Thanks grumpy its great advice and great to know there is help at hand, In this case as I said at the start I do feel that the floor is stiff enough, the tiles that are down at mo have been down since before xmas with no sign of tile or grout cracks the only reason they want it pulled up and re tiled is the fact that the last tiler sent out by the insurance company done such a bad job (it really is awful) so I may use backer board as you suggested or may just water proof unsure yet, How easy is the backerboard to cut around toilets and pedestals ? and if i did decide to just waterproof, do you mean tanking (paint on weber or ardex type) ? Its hard to quote for the job until I decide which path to take, considering I have to rip out all the old as well. Feel like im in at the deep end There was me hoping for a nice straight forward splash back as a first job !!

[Lee1973]

Thanks Turkish its good to have all the advice on here

Lee.

Originally Posted by Turkish

Just keep asking away Lee cos there`s no daft questions

Turkish

[Lee1973]

Ok where was I!! thanks Grumpy what you and everybody else on here has said makes a lot of sense. I got a bit mixed up at work earlier what I ment was on tongue and groove Chipboard etc you should overlay with 18mm exterior ply then screw down. To be honest like you said Grumpy its down to judgement on the ground but as a newbie I would be enclined to advise the client on that being the best policy,
Thanks to you all again

Lee.