Help!: First Job

[Hems]

Hi all,
New to the trade and low on confidence so thought i'd run a few things by you, Firstly how important is it to overlay ply onto a small wooden floor (1.78 x 1.52 shower in corner, toilet and sink upstairs modern house) I appriciate that it is good practice however the owner claims there was no backing previously, and the tiler who tiled it since then (awful job hence they want it done again by someone else) also has not applied and ply under his tiles. ? I must be honest the floor does seem very stiff as it is only a small room. I was thinking that maybe i could use say a 7mm ply instead of the recommended 15mm. Also I had thought that I would also tank the floor before tiling, An experianced local tiler whom i drink with has told me that i simply need to prime (using a primer)the laid ply and tile straight over with a flexi adhesive ? .... Can anybody clear this up for me. I also have to remove the mess the last tiler made and fear that the original wooden flooring might get a battering in the process. Bit nervous as very new to the trade any advice most welcome.

[Varley]

Personally I would overlay with 6mm backerboard but if the floor is as stable as you say you could just prime and tile with a 2 part flexible adhesive and grout with a flexible grout (with additive). Wouldn't be my choice though, I always overlay wooden floors just to be on the safe side.

[grumpygrouter]

Got to agree with Marty here. If the floor is solid then the overboarding with ply acheives nothing except extra cost and a step! I presume you are taliking about chipboard on the floor? 6mm hardiebacker laid onto a bed of adhesive and screwed down in accordance with Hardie instructions will give a perfect surface to tile onto. You will get away with Single Part Flexible or Rapid Set flexy.

Alternatively you could go straight onto the boards with either BAL Fastflex or Ardex-flex 7001, and grout with a very flexible grout (in both cases). Both methods approved by the manufacturers of the adhesives.

[Hems]

Many thanks guys, I have not used hardibacker before so i will try and source it (not sure where from) How easy is it to cut around basin pedatsal? One more qustion if i may, i have seen bathroom floors completely sealed around egde's, where tile meets skirting with a silicon sealant, and other that are not ? whats best practice in your opinion. Thanks for advice really appriciate it. Not easy starting out.

[Turkish]

If the skirting board comes down onto the tiles and no water is likely to get under there then i wouldn`t seal but if you`re cutting upto the skirting then you can use the silicone to hide the cuts

Turkish

[Varley]

Many thanks guys, I have not used hardibacker before so i will try and source it (not sure where from) How easy is it to cut around basin pedatsal? One more qustion if i may, i have seen bathroom floors completely sealed around egde's, where tile meets skirting with a silicon sealant, and other that are not ? whats best practice in your opinion. Thanks for advice really appriciate it. Not easy starting out.

We have Hardie reps on here now so i'm sure they will point you to your nearest dealer.

Your right it's not easy starting out but this forums helps a lot, if you are ever unsure of anything just come on here and ask, someone will point you in the right direction.

Keep at it

[Lee1973]

Hi all, there's a lot of info to take in here! I've heard how good Hardibacker and Bal adhesives are, but here comes silly question! isn't the BS 25mm when laying ply? otherwise your works not guaranteed! I thought the miniumum you can go to is 18mm if its srewed down correctly or is this just for large floor areas etc? go easy on me its my first question on here!

[Hems]

Hi lee, im new so dont quote me...but my training notes say bs is 15mm !

[bigneil]

Read the adhesive packing, they will all recomend differently. just make sure you follow the guidlines of the adhesive you intend using.

[bigneil]

PS, if in doubt there is usually a number on the back of the tub/packet for any technical question you may have. i know BAL do that for sure. they will tell you what sort of prep work is needed for your intended adhesive, or if need be, they will recomend a better alternative

[grumpygrouter]

Hi all, there's a lot of info to take in here! I've heard how good Hardibacker and Bal adhesives are, but here comes silly question! isn't the BS 25mm when laying ply? otherwise your works not guaranteed! I thought the miniumum you can go to is 18mm if its srewed down correctly or is this just for large floor areas etc? go easy on me its my first question on here!

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]

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?

[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]

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?

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]

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.

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.