ruggers

Thanks Temp, I've just used one of them traps for a mates bathroom, I installed a 40mm tray onto 6mm ply which was on top of 22 Weyrock. I cut out a circle into the weyrock to fit the trap but the only problem I found was the top of the nut securing the waste pipe to the trap was fouling the underside of the weyrock leaving a gap between the trap and the underside of the tray, so i needed to cut more out of the floor. It would be nice to find trap where the outlet sits lower down the trap body. So with the method you describe above, you mention installing the pipe then the insulation, membranes and screed. Do you split the insulation either side of the pipe, lay some under and over or cut a channel out of the PIR that sits above the waste pipe? I suppose I'll need to purchase the tray early on if installing pre screed, i was hoping to install stud walls after the screed for this room but might have to revise this.

Valliant got some of the best system boiler reviews in my research. Combi's I've found baxi platinums to be excellent, now with 10 year warranty. Insulation in the liquid screed will work the best and 50mm will give a good reaction time. You won't get better than the porcelain tiles for heat conductivity, nice and cool in summer too, LVT will still be great though due to it being so thin. I've just been told to also use 400mm loft insulation, is this the new standard, it was 270-300mm? @JohnMo What's the reason for this, in an unvented cylinder would doing this not mean that the CH is constantly drawing temperature away from the stored DHW, using gas only, how do you heat the DHW tank if the CH is lower?

Not sure if this one is for the plumbing, bathrooms or the design section. For my self build, I was planning on having a beam & block ground floor construction and having a small bathroom or shower room with toilet and sink. The architect has changed the bath to a shower and also now using a concrete slab floor. The make up from top down will now be. 50mm screed with wet UFH inside, membrane, 150mm insulation, 100mm concrete slab, membrane, sand blinding, stone. With a P shaped bath I was planning to keep the waste pipe above the finished screed tight against the wall with some boxing in as it leaves through the wall to an outside drain. How if possible can I fit a shower trap into a screed floor along with the 40mm waste pipe and not clash with the UFH pipe which was planned to cross its path? Normally you'd bed the stone resin tray down onto a finished surface and ensure the trap fits correctly but the pipe would already be encased at this point with no play in it. I could possibly replan the ufh pipe route so it wasn't in the way but I'm not sure how to install a shower waste pipe and trap so that it's in a finished position before the floor screed. Once set if wrong it's a disaster. Any advice from plumbers or designers would be appreciated.

Interesting to read the pro's and cons of fitting insulation before or after MVHR, plumbing and electrics. I've been thinking about the same. I see nods point of people having to or not wanting to work around pre installed rockwool but also the pro's of pre fitting it so that full slabs can be installed and not having to later cut around plenums and down lights etc. I will be the one installing 85% of the plumbing and MVHR but not the wiring. If I'm passing semi rigid ducting down from upstairs to the ground floor plenums, the ducting will have a nice sweeping bend on it into the 253mm posi joist void, so I'm thinking the ducting will naturally sit better in the lower half of the joist with insulation above? For maximum acoustic performance, is there any best position for the rockwool to be placed. Eg does having is hard up against the underside of the 22mm flooring work differently with no air gap either side?

All of them are good examples but I'd expect the genie clip with tech sound 50 to work very well as theres less contact patches. Sound struggles to travel through different layered materials with varying thicknesses. So on double glazed windows, if you can have the inner and outer panes of glass at different thicknesses it stops the frequency travelling through so easy. The same applies to the walls when your decoupling the plasterboard with the rubber sheet or using two different types of plasterboard. You might want to also decouple the stud work from the floor walls and ceiling but it depends how far you want to go. Staggered twin stud walls work best with rockwool in both.

I'll make enquiries about top hun joists. Would the TT still be used for this? My thoughts with both chords sat on the wall using the TT method and 253mm joists, with the wall ties being every 2 courses of block at 450mm, the spacing won't work out. The membrane would have to go up an extra course higher to avoid feeding it back in through & around notched blocks. It is possible as per a previous diagram someone posted on here which you replied to, but it would mean having the wall ties on the same course as the joists are sat on as well as the membrane under them, there would be no mortar to secure the wall ties down if they're slipped under the membrane. Having them a course above or below would pierce the membrane. Unless I misunderstanding it, I can't see how to work it around wall ties.

I didn't think top hung was possible, I suppose with a bearer under the bottom chord as well, then it has good support, but top hung with bearer over the bottom chord, what benefit would that have? Are you still suggesting to use the membrane wrapped around the joists?

Are you meaning that using a grey concrete common brick for a course or two combined with solid dense blocks it will form cracks?

Thanks for the photo, appreciated. It certainly helps with that gap behind to run services as that was the only draw back I could think of. I need to discuss the 3 options with my architect, I've been back & forth between wall bearing using tony tray, masonry hangers or ledger board. The joiner I'll be working with & the Architect are most familiar with wall bearing joists but not so familiar with airtightness to a high level. The three options seem to be similar in cost. TT requires the membrane which I need to check which type is used & further info on installing end & corner detail. Ledger board requires cheaper hangers and resin fixings and masonry hangers are a little bit more expensive but probably the easiest install method. There doesn't seem to be a lot

Didn't realise you can add spacers behind a ledger board because it would affect the structural dynamics and add more stress to the wall anchor bolts. the most I'd need to add behind would be 15mm water pipes and cable access between floors and where the returns drop back down to the fuse board located in the attached garage. A wall chase would be too deep and wide and not help air tightness really.

Some good info. there Rishard. I've used a ledger board on one side before and the other end build into the inner leaf but it was over a decade ago using solid joists and I'd never heard of airtightness back then. What are the restraint straps you refer to, are they part of the hanger or an additional brace? How have you seen services like cables and pipes pass the ledger board between ground floor and first floor? I've noticed they do a green glue 3mm joist tape now that you can apply to each joist top and screw down through the 22mm board into the joist. It's supposed to offer some acoustic seal and prevent squeaks the same as glue. Looks good but not seen any reviews yet.

Thanks Joe, The only way I can think that masonry hangers could let in in would be at a later date after the floors been walked on jumped on etc and over time little cracks appear. Adding some soundproof paint around each hanger might help with this if it has some flexibility in it.

At this stage I'm able to discuss these options and they can take it to the SE if required. Somethings require one others don't. I think the ledger plate would require some SE input. Adding the membrane around the outers of the joists Tony tray method seems a good way to it when using 253mm joists. Pending how the block work is fitted around that size of joist ends it could end up with notched blocks and more potential for air leakage. Using hangers hung from 2.7m down would leave 2447mm ceiling height, then ceiling board and wall board would leave around 30mm between bottom of plasterboard and ground floor. Slight extra cost for the masonry hangers. The joist company said 253 is standard, they'd have to look to see if 225 or 300mm can work for my spans and the cost. The two things I keep reading but getting no solid answer on are: 1.Masonry hangers can cause a lot of potential air leakage issues in future with partial fill cavity. I thought they'd be a great seal? 2.Masonry hangers can induce a lot more floor spring than wall bedded method.

Were you on standard joists to match your brick work. No issues with springing or squeeks? The 253mm high makes a lot of labour for a brickie, notching around 50 joist ends sounds messy and costly. Manthorpe do a nice joist seal but it's wasted if the notched blocks around it aren't airtight. I liked the idea of no.3 for air tightness & being able to level the floors easily for any block work irregularities, but it requires all of the ledger plates to be nice & straight and it makes it hard to pass services/cables between floors close to the outside walls having to work around the ledger board.

I was unsure if this post should fall under airtightness or build construction. Looking for advice from anyone who's used this depth of joist and considered good airtightness. The joist companies have recommended 253mm deep posi joists for my masonry self build with cavity wall which is an odd size for block work courses being 225mm. How do builders get around this? After speaking to people on here regarding air tightness around joists for a build that will have MVHR, I'm looking for advice on the best way to fix the first floor joists to the inner leaf so I can discuss this with the person doing my building regs plans. There seems to be 3 different methods but I'm not sure which is the best and the pro's and cons. Cost vs labour and airtightness. 1.Joists supported sat on the inner leaf. (Optional Tony tray method) 2.Joists hung off masonry hangers that fit over the wall. 3. A timber ledger board fixed to the face of the inner leaf and secured to the wall by mechanical fixings, then the joists attached via timber joist hangers. Would this method be best for airtightness and make levelling floors easier between inner leaf and inner supporting walls?

As per previous two comments the staggered stud wall thats decoupled from each other offers the best gains from my research but unless your washer shakes around a lot on the floor or pressed back against the wall, most of it will be airbourne sound so the doors a weakness. Look at adding something like rockwool rw45 between studs and then soundblock board. You could decouple the board to stud using green glue tape or adhesive sealant. Drop seal on the door if you dont have mvhr. Sound cant travel through a vacuum but we cant live that way so its minimising impact and airbourne

I don't think a vapour barrier will be required on masonry walls by regs when i receive my completed plans, I'm just considering anything that may help pending the cost of it vs how much it involves. I know the architects plans will mainly just be software pulling over standard data and it will take suggestions to add anything extra to it. I'll be adding a parge coat now, but as others mentioned, these may crack over time especially while bedding in, and once covered with board, it wont be visible. The D&D walls will be getting full perimeter seal, ceilings vapour barrier and I presume internal stud walls too? I thought it might have been a good belt and braces idea to also fix a vapour barrier behind any walls I'm using battens on as I wouldn't have the D&D seal if the parge cracks. The posi joists are an awkward size 253mm high & don't match the block courses, so if allowed, i think a bolted on wall plate attached to the face of the inner leaf would be best to hang joists off then rest on internal walls. If they have to go on the inner leaf, Tony tray or something like the rubber joist seals. What are ceiling vapour barriers adhered to block work with, butyl tape or tube sealant? Apart from the brick work and slating the roof I'll be involved with most parts either on my own or assisting trades I know or who've been recommended so hopefully can keep it right if I get enough info. Once I start I'll post up any work for others to learn from the good and bad points.

I agree the wet plaster is a great option for masonry inner leaf, but with 100mm PIR partial fill cavity wall construction I'm looking to add further insulation to the inside of inner leaf whether that be D&D insulated board, or insulated boards on top of wall battens providing space to run some services, or some form of insulation between battens & standard board on top. The latter would have a lot of cold bridging though. A couple of ground floor walls will require water supply pipes dropped down but thats about it. Some rooms I can afford to lose a little off the inside, others not so much but would like to keep insulation thickness consistent. Looked at blown bead & I don't feel comfortable with certain things I've read plus, I'm in a severe wet/wind driven area with partial face bricks so not recommended after consulting one company. Great points there Nick, I never considered parging before the joists go in via hangers or wall plate method same for the trusses and leaving a big enough gap between last truss & gables to be able to parge & add insulation. How are vapour barriers adhered to concrete block walls to prevent an airtight seal with battens over? Does this mean neat or a lightly diluted SBR painted onto the perimeter of the slab and lapping up onto the walls or in addition to using Purple paint you mentioned. I can't see how SBR alone would form any find of seal?

Nod that sounds really fast for what I'd expect. I understand you don't have to polish it up or get it tidy but it just seems a lot of area to cover in a few hours floating on. Do you prefer sand and cement or the sound coat or other? I imagine it plastered on being a better job than brushing it on thinner it's just getting the labour in Cumbria.

Does this apply easier or require much less work than the likes of bonding and multi finish? I can't even image one house being completed in 2 days with a float. Very hard to get plasterers where we are.

I'd be more concerned about it being the other way affecting the cable, it was in the small print when i looked on the kore website. Sleeving would get around this anyway as you say.

What was your choice or mixture for parge coat, Yes MVHR was planned from the start, Spoken to a few companies and favoured two over the others but would like to do more research on this and not cut corners.

@SBMS I'll be similar wall area as yourself, actually around 40m2 less. I've been reading some of the posts on here, had a look over the Kore system website but it says that for the West coast area its severe wind driven rain zone and a render finish is required instead of brick finish. The cavity is already 150 for the partial fill. It's hard around here to get any labour to do anything different to traditional. Most people won't entertain wet plaster only board skim, PIR all the time if not timber frame which I looked and it was at least 20k more for the build. Reading some older posts I seen two comments I didnt understand one mentioning to sleeve all pvc cabling coming into contact with the beads and another saying any opening DPC to be laid flat. I will have to check that again.

I'm looking to start a 100mm pir partial fill this year. How does EPS beads compare in price compared to PIR sheet, do the plan needs changed much? Can you also use this with facing brick exterior as theres a lot of mortar with potential to let in more water than a rendered finish.

@ProDave @Russell griffiths @Nickfromwales I thought it's much better to jump onto this relatively new post rather than start a new one repeating what many have before. i'm in the final stages of submitting B regs to building control for a masonry build 100mm partial fill cavity house, so if there's any small changes I can make, now is the time. So i have further stupid questions to ask ? I've read a lot of air tightness posts yesterday and theres for and against to all. Theres wet plaster, or parging the inner leaf, then adding a membrane then battens and boards followed by skim finish, or dot & dab with sealed perimeter boards dab with or without parging. Before I heard of sealing the inner wall,I was just going to dnd board to the block having a complete perimeter of dab on each board. Q1. Over 2 floors I have roughly 140m2 of exterior walls that would require parging, how long would this take a professional? Can i brush it on like tanking instead of floating? Q2. What kind of membrane are we using for walls under battens, theres so many? is it duct taped to the ceilign vapour barrier and butyl taped at the bottom to the masonry? Q3. Metal back boxes, i can seal around these with a seal and or board dab, but how do you seal the cables coming into the box? Q4. Do battens/boards/voids not make it even worse for fixing anything to the boards over dnd? Q5. Does a wet plaster finish not make a house lose heat quicker than a plain or insulated board finish when a PIR partial fill cavity is used? I see it too ways, the inner leaf retains the thermal mass via cavity insulation, but boards inside or even better, insulated boards would prevent your heat getting to the inner leaf as quick.