Thorfun

true but they're late-ish teenagers so nearly adults! we're not talking little kids. I would happily get the 1300mm x 800mm tray but that would leave only 100mm at the end for a narrow strip of tile and I'm concerned it will look funny. other option is to go for a 1200mm x 750mm tray to give a larger flat area but slightly narrower shower.

afternoon. I've got another question please. our kids shower areas are 1400mm x 800mm. we're going to use an 800mm screen leaving a 600mm entrance. is there any issue with using an 800mm x 800mm tray and then laying tiles flat in the 600mm entrance to the shower area? or should the tray be as close to the size of the shower area as possible? so for the Impey Easy-fit trays that'd be 1300mm x 800mm. I presume that if we run the UFH to the entrance area then any splash/water that sits on it (as it won't 'flow' back to the drain as it's not on the shower tray) will dry pretty quickly so not an issue?

@Gus Potter don't suppose you would have the time to take a quick look at this for me please? I'm trying to work out if I can double board my ceilings if I want to. I 'think' that the dropped MF ceiling has minimal impact on the dead load and it looks like the bottom chord is rated at 200N/m2 which, to my mind, means a load of ~20kg/m2 and so 2 x 12.5mm plasterboard at 8kg/m2 each should be within tolerance. assuming resilient bars and any light fittings are negligible as well.

Look forward to seeing the finished product

Ahh…right. I thought it was some plumbing wizardry that I hadn’t seen before.

what's that pink stuff around the copper pipe? if you don't know I'm sure @Nickfromwales will!

have now read most of the comments and @ETC's first floor layout with no guest room and bigger equal sized kids rooms is much better and very reminiscent of our layout! 🙂 but, like @SteamyTea, I don't normally like to comment on other people's designs as it's very personal and what suits one person may not suit another. so, just go with what you want. 😉

too lazy and didn't read any of the previous comments but had a quick look at your plans and if the above is true then why have you given your children narrow small bedrooms? they don't stay young and small for long and will eventually need desks for school work and having mates round etc. doesn't seem like your architect has given any thought to them growing and expanding. Also, it's very expensive to get on the housing ladder these days so your kids might stay at home well in to adulthood. not sure a 2.5m x 3.9m bedroom would cut it! and, finally, why is the guest room bigger than the kids rooms? for a room that won't get used much it's a real waste of space in our opinion. we didn't build a guest room and only made 3 bedrooms. our kids rooms are 4m x 4m so they can grow in them. if we have guests then we have a room above the garage that can have a sofa bed. or a sofa bed in the TV room. or they can stay at a local Travelodge.

indeed. we specifically found a Cemfloor installer for our screeds as we really didn't want to use an Anhydrite screed due to laitance. just had the ground floor screed done this week, depth varied from 50mm - 75mm (in a few places). installer had no concerns with the depth and we now have a nice level screed to tile on to. interestingly the installer said that if tiling on to it we need to get it sanded to give the adhesive something to stick to. but I did a quick search on here and found a few threads saying that wasn't necessary at all including the very knowledgeable @nod in this thread this was one of the reasons I wanted a cement based liquid screed as I, also, didn't think sanding would be required. so I'm definitely not going to bother sanding!

Even @pocster?

we insulated outside ours

We used TSD for our basement. They’re based in Ireland (we’re not) but that didn’t bother them or us. @Bitpipe used a UK based SE for their basement but I found them a bit pricey. have an extensive read of the basement sub forum as there’s lots of info on there

sadly the house isn't finished yet so we haven't really used the blinds so i can't really comment. but i had to lower a couple yesterday to shade our new screed and they still worked. 😉 when you speak to Tim (Powell) tell him Tom from the golf club sent you his way. i won't get a kick back but he might buy me a drink after golf someday. 🤣

it's in the post

and doing a brilliant job

Thank you. I had a quick read of the link and will look into it in more detail tomorrow.

actually there are a lot more calculations that I posted above. here's a pdf for the joists in question. joist_calcs.pdf it's all Greek to me. I'm hoping someone can tell me what it all means!

and this. anyone able to make heads or tails of it?

this is from the document showing the joist design I managed to find.

The guy from the posi place said that the joist could fail if the load exceeds 200N/m2 . That sounds scary. I might have been able to find the calculations used by the TF company though so will send that off to them and see what they say. it’s a shame Flight Timber went belly up for all those that lost money with them and also as they were always really quick to respond to queries like this. I don’t have that resource anymore and so I’m left to my own devices. im not sure what the beam calculator will show as I don’t believe it’s deflection that’s the issue here as the top chord load is 2060N/m2 and we’re designed for 8mm deflection. But that’s the top chord. The bottom chord is designed for only 200N/m2

does this maths seem correct? 18lm x 0.37kg = 6.66kg / 16.32m2 = 0.41kg/m2 if so, that's nothing! and so with those maths the MF ceiling won't add any extra load i just need to figure out if i can double board with 12.5mm PB and not exceed the 200N/m2 maximum load of the bottom chord. maybe i should post this in boffins corner so all the boffins see it? otherwise it's just me and @pocster bumbling through as usual.

right, more maths required as BG technical support had finished for the day when i tried calling. according to this data sheet the GL1 channels are 0.37kg/lm. i've calculated that i will need 18lm of the stuff. the room is 16.32m2 and the GL1 channels will be spaced at 400mm centres. anyone know how to calculate the downward force imposed on the bottom chord of the posi-joists per meter squared?

SWMBO

this is an issue when the TF company no longer exists. i do have the SE calculations for the frame but would have to engage an SE to double check and that would cost money i don't have. so a decoupled timber ceiling will be my last resort to be honest.

i will try and phone Gyproc and see if they can give loading figures for the GL system.