CT1 and/or Sikaflex for a shower tray installation?

[Nickfromwales]

Biggest gotcha is cross-threading the waste when you turn it in to tighten it. Makes you think it's tightened up snug underneath but it hasn't. Set it up dry and count the number of turns it takes to get it snug, then count them again when you seal and give the final tighten up. 

[Onoff]

7 hours ago, Nickfromwales said:

Biggest gotcha is cross-threading the waste when you turn it in to tighten it. Makes you think it's tightened up snug underneath but it hasn't. Set it up dry and count the number of turns it takes to get it snug, then count them again when you seal and give the final tighten up. 

 

Don't you also advocate not allowing the wastes to spin as you do them up so you compress rather than "smear" the sealant?

[Nickfromwales]

1 minute ago, Onoff said:

 

Don't you also advocate not allowing the wastes to spin as you do them up so you compress rather than "smear" the sealant?

Yes. The part that goes underneath shouldn't be spun, only the top part. That way you don't get the rubber washer displacing and the trap going off centre.   

[CC45]

I guess its @Nickfromwales query but happy to receive any advice from numerous experts on here...

 

So its time to buy the necessary bits (skimmer is calling around tomorrow - I'm hoping he will be able to do the bathrooms / unsuits fairly soon - its then time for the trays to go down) ready for the shower trays

 

Sikaflex - is THIS the one to seal between the stray and the cement boards? https://www.screwfix.com/p/sika-sikaflex-ebt-all-weather-sealant-clear-300ml/7286d

 

Primer - https://www.toppstiles.co.uk/tprod3071/bal-primer-1ltr.html?utm_source=google-shopping&gclid=EAIaIQobChMItIy35YOk2gIVRrvtCh2MsAowEAQYAiABEgIQjPD_BwE&gclsrc=aw.ds#fo_c=2258&fo_k=80de937287d34cdea089275da61fe442&fo_s=gplauk  acceptable to use on the timber floor prior to the flexible tile adhesive?

 

And finally - the adhesive...  https://www.toppstiles.co.uk/tprod44754/bal-max-flex-5kg-white.html

 

Don't want to skimp on quality items - I don't want to have to redo this job!

[Nickfromwales]

Bal is too expensive.

[Nickfromwales]

27 minutes ago, CC45 said:

I guess its @Nickfromwales query but happy to receive any advice from numerous experts on here...

 

So its time to buy the necessary bits (skimmer is calling around tomorrow - I'm hoping he will be able to do the bathrooms / unsuits fairly soon - its then time for the trays to go down) ready for the shower trays

 

Sikaflex - is THIS the one to seal between the stray and the cement boards? https://www.screwfix.com/p/sika-sikaflex-ebt-all-weather-sealant-clear-300ml/7286d

 

Primer - https://www.toppstiles.co.uk/tprod3071/bal-primer-1ltr.html?utm_source=google-shopping&gclid=EAIaIQobChMItIy35YOk2gIVRrvtCh2MsAowEAQYAiABEgIQjPD_BwE&gclsrc=aw.ds#fo_c=2258&fo_k=80de937287d34cdea089275da61fe442&fo_s=gplauk  acceptable to use on the timber floor prior to the flexible tile adhesive?

 

Don't want to skimp on quality items - I don't want to have to redo this job!

All the above are spot on. 

[CC45]

I didnt think the prices were ott!  Not keen on toppstiles as an outlet but they are convenient tbh.

 

Cheers @Nickfromwales

[Nickfromwales]

8 hours ago, CC45 said:

I didnt think the prices were ott!

At £20 for 5 kilos that bal works out £80 a bag . Way OT ( F ) T. 

[CC45]

So where should I be looking then Nick?  What would a reasonable price be?  I will need a lot when the serious tiling begins....

[CC45]

Bought some Bal from Topps Tiles for £20 (20kg bag) in the end - needs must.  Before the floor tiles go down I will find a cheaper supplier.

 

If I butter the underside of the tray - I assume I need to fill the whole tray - even the 'trough' near the edge?  That's going to be a heavy lift!

 

 

 

[Nickfromwales]

10 hours ago, CC45 said:

Bought some Bal from Topps Tiles for £20 (20kg bag) in the end - needs must.  Before the floor tiles go down I will find a cheaper supplier.

 

If I butter the underside of the tray - I assume I need to fill the whole tray - even the 'trough' near the edge?  That's going to be a heavy lift!

 

 

 

The area that's been ground flat is where you need to apply the adhesive. Don't fill the rest of the area, and don't put any where the trap will sit.

In the dip either side of where the trap goes put a generous blob and let it squeeze out as you push the tray into place. 

[CC45]

and none around the edges?  Surprised you've got time to reply @Nickfromwales!  It must be beer O'clock on Buildhub SOS now?

[Nickfromwales]

37 minutes ago, CC45 said:

and none around the edges?  Surprised you've got time to reply @Nickfromwales!  It must be beer O'clock on Buildhub SOS now?

None on the edges, the stone resin is tougher than you are heavy . Back filling the gap along the front leading edge with tile adhesive is what I do, but I doubt I'd it makes a blind bit of difference TBH 

[CC45]

Tray went in yesterday - feels very solid.  Thanks to @Nickfromwales for advice.

[TheMitchells]

We got our tray in too yesterday following the advice here.  although we didnt use the primer.... Cringe....?  seems completely set and no movement.  Now just have to decided on which tiles to use - there is too much choice!  Picture to follow.....

[TheMitchells]

@Nickfromwales you recommend on this post, Ultra tilefix Pro primer. https://www.pureadhesion.co.uk/ultra-tile-proprime-it-enhanced-water-based-acrylic-primer-1-litre.html

 

Can you tell me if you always use this and is it just to make sure the tiles dont fall off?  we used Aquapanels on the walls and the Knauf website doesnt say anything about using a primer.  is it 'belts and braces' or is it needed? 

thanks.

[markharro]

HI hoping to bring this thread back to life and seek the input of the shower tray maestro @Nickfromwales !

 

I have attached some photos of the current state of my own instal. I have a very heavy duty steel Bette tray that I am planning to instal in a recess in our concrete slab. First thing to say is that the concrete is the final floor finish and I know this makes it hard for ourselves. The recess is deep enough now to accommodate the tray and its lies flat although just a few mms below the surface of the concrete when dry fitted. 

 

My main question is how to bed it down? It is very rigid and it seems to me that it will be fine just supported on its 4 perimeters? So what to use under these? The plan is to use Sikaflex on the tray perimeter upstands to seal between these and the Hardie backer boards. Can I also use if between the bottom of the tray perimeter and the concrete or would it be better to use tile adhesive? thanks.

[markharro]

Any takers on the above post? I was thinking I should maybe call Sikaflex tech support?

[Onoff]

23 hours ago, markharro said:

Any takers on the above post? I was thinking I should maybe call Sikaflex tech support?

 

I'd use flexible tile adhesive and a full bed at that under the tray. As I'm slow I wouldn't use rapid set, just leave it for a couple of days. Not sure on the depth of the "recess" under the tray. If "deep" you can save on adhesive by bonding a cement board down first to take up some of the gap. You can get Aqua Panel for instance in 6mm. You'd have to cut it to go around the trap of course. Stick that down then more on top followed by the tray.

 

Only what I've learnt on here. Standing on the shoulders of giants etc. 

[Pocster]

1 hour ago, Onoff said:

 

I'd use flexible tile adhesive and a full bed at that under the tray. As I'm slow I wouldn't use rapid set, just leave it for a couple of days. Not sure on the depth of the "recess" under the tray. If "deep" you can save on adhesive by bonding a cement board down first to take up some of the gap. You can get Aqua Panel for instance in 6mm. You'd have to cut it to go around the trap of course. Stick that down then more on top followed by the tray.

 

Only what I've learnt on here. Standing on the shoulders of giants etc. 

I also used flexible adhesive to bed my stone shower tray ( weight around 100kg ) . Not going anywhere .

[markharro]

Thanks guys. From the Bette website I see this - https://www.my-bette.com/en/product/features-and-installation/bettelevel

 

So I think thats confirmed that the tray is fine without any full bed support. I am going to go with my plan - Sikaflex under the rim bottoms!

[Nickfromwales]

Hi. Busy times sorry! 

Interesting mix with the steel tray, but they’re pretty robust tbf.

 

Firstly pack a couple of handfuls of dry tile adhesive where the waste elbow joins the underground pipe. 
 

Then bench 270° around, sides and rear, and also set 4 pads of tile adhesive about 8” away from the trap, then lower the tray onto that wet bed, level, run a fair bit of water into the tray to test the waste and trap for leaks, and then leave for 24hrs to cure.

At the front you’ll need a ‘mouth’ cut into the concrete floor so you can see under the front edge of the tray, firstly to allow you to look under when wet testing, and secondly to back fill.

Once the above is done you’ll be set in 2 sides and rear and dry, plus around the trap, but the trap won’t be supported. Mix up some Mapei builders screed (flexible screed with fibres, Screwfix or tile merchants usually carry it) and pour it into the mouth you’ve left using cardboard as a funnel.
 

Fill it until there’s a good amount under, possibly less than 2 bags by your pics, and then the trough you’ve chased out for the trap and pipe work will all flood with the leveller. This will support the bottom of the trap so when you stand on it accidentally, particularly with your heel, you won’t have any movement.
 

The dry adhesive will stop any leveller going where it’s not wanted/prevent its loss at that junction.

 

Clean and seal around the tray with CT1, open a beer, and call the tiler. 👌👍🫡

[markharro]

@Nickfromwales Ok this is food for thought thanks. A couple of questions from this. I think I get most of your steps but I don't think I will be able to do it this way. The main issue is the mouth - the powerfloated concrete slab is our final floor finish so we want to avoid cutting in to it in such a visible way. So basically the tray needs to go in once and for all. I appreciate that this does not make it any easier. You will see from my last post that this tray can also work with feet supporting the corners. It seems to me that if it is robust enough to work that way why do I need an tile adhesive under the main body of the tray?

 

Can I ask why the trap might need support? Again from the Bette example if you were installing it with the type of height these legs would give would you need to support the trap? The problem I see with supporting the trap is that we need to get it positioned dead centre so when the tray goes down it mates up exactly. When I tried a dry fit it was out a bit but had enough wiggle to pull central. If I bed it down in advance some way (my plumber had suggested using sand) I think I will lose that fine adjustment!?

[Nickfromwales]

5 hours ago, markharro said:

@Nickfromwales Ok this is food for thought thanks. A couple of questions from this. I think I get most of your steps but I don't think I will be able to do it this way. The main issue is the mouth - the powerfloated concrete slab is our final floor finish so we want to avoid cutting in to it in such a visible way. So basically the tray needs to go in once and for all. I appreciate that this does not make it any easier. You will see from my last post that this tray can also work with feet supporting the corners. It seems to me that if it is robust enough to work that way why do I need an tile adhesive under the main body of the tray?

 

Can I ask why the trap might need support? Again from the Bette example if you were installing it with the type of height these legs would give would you need to support the trap? The problem I see with supporting the trap is that we need to get it positioned dead centre so when the tray goes down it mates up exactly. When I tried a dry fit it was out a bit but had enough wiggle to pull central. If I bed it down in advance some way (my plumber had suggested using sand) I think I will lose that fine adjustment!?

These things are easier to do than explain lol

You can set the tray in 3 sides around with the mouth being on the sacrificial sides, eg left/right/rear, but the issue of wet testing/proving the waste and pipework isn’t leaking remains, I guess?

 

It’s common practice, for me anyways, to have the sump of the trap set into adhesive or captured by the leveller/backfill medium, just given me seeing these crack and fail over time when unsupported. If the manufacturer doesn’t specifically state in the MI’s that the waste atop (what you’d step on when showering) can take your weight then reverting to my methodology would be ‘wise’, but if it says you can throw some shapes in there and it’s bombproof, then take with a pinch.