MortarThePoint

Interesting as I gravitate towards mortar because it's a material I'm much more familiar with. Would adding SBR give you more confidence, or you'd still air towards the flexible tile adhesive. I know some tray manufacturer's suggest a very weak sand:cement mix at perhaps 8:1 which I can appreciate would be pretty weak. I'd be more inclined towards 6:1.

Binder is correct, thanks. This link says "Products using ECOSE Technology are formaldehyde-free."

Some will already know, but a quirk of my build is I am trying to avoid introducing anything that will off gas lots of formaldehyde (or other things too). I'm less concerned about off gassing paint which lots of people worry about. The reason for that is that the layer is very thin and we aren't living in the house yet, so it should hopefully have finished by time we are in. That's not to say that it's not a point of discussion with 'the client' on occasion though. I have spent a lot of time looking at Plywood and thought I would dump some of my learnings here for anyone who may be interested. There may be inaccuracies, so feel free to correct. Glue: Remember that the wood itself contains formaldehyde, so the main variable is the glue. The two most commonly used glues are Urea Formaldehyde (UF) and Phenol Formaldehyde (PF). PF is stronger and emits less, but is more expensive. Europe (& UK): This is according to the standard EN 13986, the lower class of which is E1 (0.124mg/m3) which has higher emissions than many other standards. There is an informal E0 classification (?? mg/m3) and Germany have adopted an E0.5 or E05 limit (0.08mg/m3). Ikea have apparently used an E0.5 type standard for a while. It's all about to change with the adoption of a new standard, EU 2023/1464 which introduces a tighter limit (0.062mg/m3 for "furniture and wood-based articles"). That new standard will be effective from Aug 2026, but some companies are already stating compliance. It's worth noting that Finland also have their own standard, M1, with a limit of 0.010mg/m3, so 12.4 times tighter than E1. USA: California has the CARB Phase 2 (CARB P2 or CARB2) limit of 0.05ppm for hardwood plywood. I'm not sure how they work it out, but I've seen articles that say Europe's E1 is equivalent to 0.10ppm so is twice CARB2. CARB2 is adopted nationwide, but the office standard is EPA TSCA Title VI limit which is the same 0.05ppm limit. Japan: They have a 4-star scale, the strictest of which is F**** (or F4) with a limit of 0.005mg/m2h. Despite using a different measure from the rest, I believe this to be the strictest standard. China: As per Europe's EN 13986, but adding E0 (limit 0.050mg/m3) and ENF (limit 0.025mg/m3). Effectively being in Europe means we are currently only governed by EN 13986 and so most products only state that they are E1 and, quite reasonably, that's all most suppliers understand. There is a chance of finding M1 compliance stated which is one of the tightest limits globally. Some manufacturer's (e.g. Riga) clearly set out the various standards that they meet in a more global context. For example here is an extract from Riga birch ply: Some example products I have found: Birch: Riga Ply (meets F4), Wisa may be good but documentation not so clear Radiata Pine: AraucoPly (meets F4) Poplar: Panguaneta (meets F4) Marine: I have yet to find a marine ply (i.e. meeting BS 1088) which meets any formaldehyde class other than EN 13986 E1. I would like to though so if anyone has found one please add it here Other notes: NAF - no added formaldehyde which means only that which comes from the wood. OSB3 easily available as NAF (e.g. SterlingOSB Zero OSB3 widely carried by merchants) Glass wool insulation - Knauf' standard "Ecose Technology" uses a formaldehyde free blowing agent MDF - Medite Clear is an NAF MDF, but no moisture resistant version as far as I know The other chemical often considered is pentachlorophenol (PCP)

So you'd go cement board, but of the options given it would be Option (2) Mortar down 35mm thick paving slabs. Cement board would be better as it allows a hole to be cut for the waste pass through rather and then still providing support to the corner of the tray past the waste. I'm guessing in reality there isn't any load applied to a tray in that location anyway. I'm a wuss about Cement Board so I think I'll go with the concrete slabs & mortar and for the corner I will screw some timber to the wall and have mortar between that and the tray. I've had a wasted day trying to source plywood, but that's a whole other story.

The McAlpine ST90CP10-NRV is just (53mm + seal) deep from the underside of the tray to the trap's bottom (image below). There wouldn't be enough space between the pipe and tray to fit 18mm ply though, so I would have to cut a channel in the ply all the way to the edge of the tray which could weaken it. Conversely, the trap that came with the tray (Crosswater STHFW6190, second image below) has about 33mm between underside of tray and top of pipe and is overall about 73mm deep. The screed is 65mm deep over HCF and the waste pipe is already raised up 40mm above HCF by other factors. That connection point is 1.5m from the shower waste position, so these two options work out as a rise above unfinished floor of: McAlpine ST90CP10-NRV : 40mm + (18mm/m * 1.5m) + 73mm - 65mm = 75mm, so about 60mm above top of tile (i.e. FFL) Crosswater STHFW6190 : 40mm + (18mm/m * 1.5m) + 53mm - 65mm = 55mm, so about 40mm above top of tile (i.e. FFL) Another thing to like about the NRV valved one is that it can act like an air admittance valve (AAV) so I wouldn't have to worry about the shower trap drying out. It's in the kids' bathroom, so they may not be showering for a few years as they are young enough to prefer a bath.

I have to raise it to get the required waste fall unfortunately

Not sure why I didn't spot this at the time, but you can use two 45 degree conversion bends to make a 42mm offset. You'd then need to use a straight coupler to connect to the pipe, but that's easy and doesn't affect the offset. You could use a 45 degree conversion coupler and a standard 45 bend to get an intermediate offset as well.

@Nickfromwales I'm gearing up to do this now. What approach would you take?

Some people just CT-1 staddle stones down and CT-1 does have good strength (CT1: Tensile: 2.9N/mm2=29kg/cm2, PGB: Tensile: 22kg/cm2, Shear: 11kg/cm2). 150mm x 150mm should have at least 24kN strength which is plenty, though that would assume perfect conditions. 10% of that figure would still be plenty. I think I will still use a threaded anchor though as that allows accurate alignment. https://www.ct1.com/wp-content/uploads/bsk-pdf-manager/2020/09/CT1_Product_Info_sheet_TRIBRID_10_09_2020.pdf https://www.ct1.com/wp-content/uploads/bsk-pdf-manager/2020/06/Power-GnB-Product-Info-sheet-12-05-2020.pdf As far as I can tell PGB is a gloopier CT1 with better initial stick (i.e. grab).

I've found some staddle stones without pins in, just pre-drilled 16mm (50mm deep) holes. That allows the use of stainless pins. Their straight sided not tapered. There's a product called a Dowel Screw or Hanger Bolt that has a wood thread on one end and a machine thread on the other end. That should work well to screw into the end of the post and then resin anchor into the staddle stone hole. Some dowel screws have flats and some have a hex socket at the end of the machine thread. I think I'd want about 40mm sticking out of the timber unless I deepened the hole in the staddle stone. That's less anchorage depth than in the Fischer table, but should still be good. Also the dowel screws seem to top out at M12, so the 16mm hole is a little large, but hopefully OK. Another option is to drill a deeper 14mm hole on the other end of the staddle stone and use it the other way up. An advantage of an oversize hole is it allows a bit of centring tolerance. https://www.westfieldfasteners.co.uk/Bolts-Screws-Metric/Dowel-Screw-Hanger-Bolt-Centre-Hex-Drive-M12x120-A2-Stainless.html

Thanks for taking the time to photograph. It does look the same. Do you think under firing it would allow the plastic to be picked off and then tighten it the last bit as a screw? So much for their claim "Six times faster to install than standard wood screw". The head looks quite a lot larger than the (unavailable) Clad-Tite head which is also a shame. Are you aware of any other nail gin screws?

Interesting, thank you for the heads up. Do you know how long ago that was as they appear to have made changes to the strip, but that may have made tings worse. When they actually fired OK, were they good otherwise?

Definitely planning on stainless. The Paslode Stainless aren't much more expensive either. I prefer using screws as it is much easier t remove and sort things out if there is a mistake. For cladding, I also like the idea of under driving it using the nail gun and then tightening it as a screw to get the depth spot on.

I wanted to use the Clad-Tite screw from Tite-Fix for my feather edge cladding, but they don't currently stock it so I can't get any. What is really nice about it is that it is collated and can be fired by a nail gun. It then behaves like a small headed screw and can be taken in and out using a TX10 bit. It should also allow firing the 'nail' not quite all the way and then fine tuning with the screw feature. "Fits most gas powered guns" I see Paslode do a similar product, Nailscrew. It has a narrower shank (2.8mm vs 3.1mm) and uses a TX15 bit instead of TX10 so looks to have a larger head. Being a Paslode product, I guess it will only work with Paslode nail guns but I would have to hire a nail gun anyway so that's not really an issue. Has anyone used these or a similar product or got some other suggestions?

We're going with feather edge cladding (not the T&G shown below) above a brickwork plinth. The construction drawing detail calls for Code 4 lead, but the separate written specification document doesn't mention it. Is it needed? The Plinth stretcher bricks are actually headers but are Class A Engineering brick. The lead is a cost but also not a nice material if growing things near the garage. --------------------------------------------------------

I've heard some people say it's better to tile without the bath in place. What's the best approach here? The bath will sit in a timber frame so I could build that to provide an accurate reference for the tiler to hold the tiles back from.

The usual risks of Amazon apply, but here are some promising looking tapered options: 110/50 PP pushfit https://www.amazon.co.uk/Water-Reducer-Reducing-Sleeve-Übergangsrohr/dp/B01JH34JHA 110/50 PP pushfit https://www.amazon.co.uk/Ostendorf-175720-HTsafe-Reducer-Piece/dp/B075HXH9S5?th=1 also smaller pushfit 110/50 PVC solvent https://www.amazon.co.uk/sourcing-map-Reducing-Coupling-Connector/dp/B07KZDWMBQ For those wanting to adapt from 40 to 50 without losing too much height: Aquaflow offset https://www.toolstation.com/solvent-weld-reducer/p27594 (Polypipe make an equivalent too) Polypipe WS59 (best option) https://www.polypipe.com/housing/above-ground-drainage/waste/solvent-weld-waste-system-abs/reducer-40mm-50mm-ws59w Unknown ?double socket? https://www.victorianplumbing.co.uk/2-x-1-5-waste-pipe-reducer

I need to fit a shower tray with its underside about 50mm above the screed for most of its area. There is a hold back in the screed in the area of the waste so deeper in that area, but I can happily mortar in bits of paving slab onto the hollowcore concrete floor there. Most legs have a minimum height greater than this and require a sheet of plywood too. What would you recommend? Options that I am considering already: Mortar down 35mm thick paving slabs. With a 7.5mm bed of mortar below the slab and 7.5mm bed of mortar between the slab and the tray I'll hit the 50mm required. Will have to cut some curved slabs which could be tricky. Make a timber frame out our 50mmx25mm battens and put 18mm plywood over the top of that. Then a 7mm bed of mortar will hit the 50mm required. Not too keen on adding a load of wood underneath in an otherwise all concrete setup Find a 1100mm x 800mm left offset quadrant shower tray that has space underneath and can have a hole cut in its skirt. Not sure such a thing exists Any suggestions for what I should dress the raised edge with? i.e. between the tray and the floor tiles

Assuming there is no wall or unusual load above, a 6x2 would likely be sufficient for a 3m span anyway https://nhbc-standards.co.uk/6-superstructure-excluding-roofs/6-4-timber-and-concrete-upper-floors/6-4-8-timber-joist-spans/ It's all looking promising. Also, this joist is carrying (34cm/2)+2.5cm+6cm = 26cm of floor where all the others are carrying 40cm.

How deep would you notch be at its deepest? Your image suggests about 25mm

https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists Lots of US guidance has notches in bottom as well and there the rule is maximum depth D/6 and maximum width D/3 and avoid square edges (where D is the depth of the joist). On that basis a 1" deep notch wouldn't be a problem. Not in the middle third of the joist span though. I know US code is irrelevant to the UK, but it sometime provides me with some comfort. Your image makes it look like you'd only be shaving a small amount off. Perhaps a triangle that is 1" x 1". That means that you are leaving 75% of the material that would be cut out by a full width 1" deep notch. Should be fine, especially given it is so close to the wall and therefore not supporting as much floor above as an ordinary joist.

What is the distance between the joists?

Do you think it would be an issue if the 50mm pipe entered the 110mm pipe at the bottom rather than at the top as you have it?

It looks like this joints at the top of the 110mm pipe rather than middle or bottom. Do you happen to remember who makes that adaptor?

@Nickfromwales Jethro may have made a whoopsie on this one. I'm worrried that the 40mm pipe entering the stack circled in red is a problem for two reasons: It's 180mm rather than min. 200mm offset from the 110mm branch entry from the WCs. Does the Floplast SP190 Branch count as swept and mean I'm OK? It is directly opposite another 40mm pipe. I think I've seen a fair few other setups like this though or am I imagining it? Am I right to worry, or do you think it's all within the slack of interpretation?