ruggers

@OwenF Hi, just seen this. I haven't got that far, my project had to be put on hold for the time being. When I completed a full heat loss survey, I was surprised that the addition of internal insulated plasterboard over the whole house made minimal improvement to the total heat loss and it was going to add a lot of money onto the build cost. Every little helps, and I'd have to check again but it was something like 0.4Kw improvement for £2500 extra. I couldn't find anything solid on whether or not a masonry build with cavity insulation was better left without insulated plasterboards for thermal mass reasons, or to add it. In reference to what you've quoted from my older post of adding a vapour barrier behind the battens then adding insulation between them, I'd need to be sure it wasn't going to cause damp from warm and cold surfaces. I think I'd leave the vapour barrier out, apply battens to a parged wall and as long as it was only one room, blower paint could be applied to the sides of each batten if needed.

@jon-lee Once i get them in I'll set the leser up and have a check across the rooms. Spans vary from 3.8, 4.25, 4.9, 2.5m. Thats including the 100mm end bearing. I'll be using dense solid blocks as the lighter more insulating ones don't offer any more to the U-Value. the reason I was going with 50mm liquid screed was initially because of the faster reaction times but thisn't so much of an issue with weather compensation. It's just the extra 25mm of cem floor adds quite a lot onto the price for every 5mm thicker but I do see what you mean if theres a lot of bow in them.

I'm building a 2 storey house with an internal garage thats accessed internally from the utility room. the 2 external walls are 350mm insulated cavity (100/100/50/100), and the 2 internal walls to the house are 300mm full fill PIR (100/100/100) and will only go up to first floor joist level. The 300mm walls separate the garage to utility and the garage to hallway. Theres a room above the garage ceiling, I'm using posi joists on masonry hangers for air tightness, but, the ends of the joists above the garage and hallway/landing are to sit on the 300mm cavity divide wall. I'm now wanting to extend this hallway/landing garage divide wall up to the first floor ceiling level so I have a solid wall up the side of the stairs. I can either do this on the house side single wall only, or continue both sides of the 300mm wall up to the roof truss level, which loses 200mm of space from the room above the garage. If I continue the inner wall right up, but leave the garage side finishing at first floor height with the joists resting on the divide wall, what should I be closing off this cavity with to prevent cavity air working it's way up into my floor void? It will be 100mm PIR so shouldn't be much space for air movement, but unless closed off it's not airtight. It would need to be strong enough to allow the joist ends to sit on it.

This is exactly what i was going to do, i have the stone to the front for vehicles to drive in and park up to be loaded, i just wasnt sure if B.C ask for something under the beam and block, like stone or dry mix. It seems a waste to me if vegetations removed and its away from light, but i was unsure if there was another reason for it. Despite not wanting to due to cost, The only reason i was going to stone the footprint, was with it being a wet site and needing an 8t machine on to dig the mass fill founds, it could all get chewed up if it continues to rain on and off. I need the founds dug in the next few weeks to meet the pre 2022 regs cut off, currently its all graded nice and flat but its wet after just being completed and no land drains in yet.

@nod or anyone, I'm having my site cleared and the foot print of the house plus 360 perimeter path around it down to clay level ready for setting out and founds dug. I haven't spoken to B.C yet but had some saying to stone the whole foot print in 150mm compacted crush stone then set out and dig through, and using the stone removed back on the drive area. Or to leave it as clay, build up to DPC, and dont put anything under the beam and block floor just leaving the air 150mm gap. I think I'd be looking at 80t of stone so £1000.. Whats the drain you refer to underneath?

Thanks Nick, cost of the extra floor pipe was never the issue, I just thought that adding too much pipe might make it too warm. Its one thing I've never installed so I don't know how much adjustment there is on the balancing screws. The whole floor will be open loop so plenty of mass. the 24m2 kitchen will actually be 18 after cupboards. The company mentioned in this post said to run pipes under the cupboards too, to prevent the heated floor transferring to the unheated space. I've never used them JG collet fittings, only the push and twist ones. Tap water wont require oxygen barrier does it

Is it just standard 15 or 22mm Hep2o for potable water or does it have to be barrier pipe to keep oxygen out like the heating pipes? I'd rather keep it simple as you say, It's just the plastic fittings can be bulky, I need to drop some down a block wall to the kitchen. I've used the John Guest lay flat 15mm stuff before but some people said it's crap? The last thing I want is my house being too cold because I got the spacings wrong in the 50mm screed. I'm surprised that a lot of really good heat engineers who know their stuff & do detailed heat loss surveys, just go with 100mm c/c rather than custom to match the rooms loss. I have two 24m2 rooms, ones a living room the others a kitchen. Living room has 1 large window and is 21w/m2, then kitchen has 2 windows and french doors which doubles the heat loss and is 48.4 w/m2. (512w vs 1157w)

I agree with this, but most won't even do 100mm centres when I've asked it's 150mm min for a lot of them, some of them haven't heard of weather comp even in their technical department. None of them ask what floor finish I'd be having & I'm not 100% on floor finishes myself, too early at this stage, It will be a mixture of tiles with either vinyl click or kandean in some rooms. I need to understand how this affects the w/m2 output vs my room heat loss w/m2. I understand DT20 is probably not achievable at under 50°C flow on a gas boiler but at least if I size my radiators for 37.5 MWT, and it ends up a bit higher, I'm heat pump read if need be and at the cost of larger radiators, I'll be running more efficiently. Was this this using 16mm pipe for the radiators and then using the 15mm eurocone to adapt them to 15mm radiator valves?

Hi John, Sorry for the late reply, thanks for the info. I'm aware we're going off the topic from the original post here so I might be better if I start a new topic or drop you a pm if you don't mind. As mentioned my system (pipes & emitters) will be sized for max flow of 47.5C gas or 40C heat pump, both will give a similar MWT of 37.5C. Why is it that most heat engineers advise on going for 100mm centres if your going to run at low temperature, but the chart shows theres no need to? Some suppliers have said only Pex-al-pex is wras approved and pert is best for UFH, pex for radiators and potable water. I'm sure I've seen WRAS per-al-pert. What fittings did you use on the pert pipe, do they need to match the brand of the pipe for the transition to copper? I'm going to have a look at loop CAD, looked on youtube, is it an autodesk product or is there different version? Did you suss it out easy enough?

Thanks John, is loop cad easy to pick up? I can use 2d autocad to an ok level, I've completed a full heat loss survey so have room by room heat loss with w/m2 and know my flow and return temperatures etc for full weather comp. But everyone says to just go for 100mm centres when running a low temperature system. I was considering loop cad and getting bespoke spacing that suit the w/m2 for each room and the floor finishes. The cibse heating design guide covers this. What pipe did you use to your taps? I've also never installed any before and not sure what you can really tell by looking at them, some say a manifold is the same as the next in most situations, others claim some are really poor. Some pipe is wras approved to be used for drinking water. I'm not sure how to tell good pipe from bad or why people prefer top brands like uponor, it's certainly not something I want to skimp on if its going to be buried in screed.

@richo106 or have any other used this company? Seems pretty quiet here but their trust pilot has good reviews. The main things I'd be looking for are, quality of the pipe and manifolds and do their design service recognise low temperature weather compensation.

Are you meaning a timber external door frame? They don't really offer a very good air tight seal, all the ones I've seen with the cill on don't have the jam on the bottom to continue the seal round 360. I'd like to see a correctly fitted seal that works well, where its positioned on the casing, especially the hinge side, and if its routed in just stuck on.

Thats good to know with the small amount required and that it's not enough to affect any colour, I've only ever used cheap everbuild 3 in 1 5L plasticisers for block work in the past. Not buying all the sand at once because I think roughly I'll need 30 bulk bags for 250m2 face brick 245m2 blocks. I need to check that figure is correct. The supplier uses the same sand source from North Yorkshire as some developers who build high spec houses locally need consistency. Just looking at the optimix concentrate, it says 5-10ml per 50kg of cement, so you'd probably only need a few bottles for a full house? I think with Cumbrian wet weather that would go off in no time unless it was kept in a shelter. They do a pre mixed mortar in 0.33m3 tubs but its £40 a tub, lasts 1 day, £70 delivery and £60 deposit per tub.

@Canski Thank you. I'll have a look at the optimix. At least the buckets can be loaded by 1 person. It just needs to be the easiest method for the builder that is fail proof. If counting, everyone forget how many went in at some point or 10.

Hi, I have 240m2 of light grey facing brick to used for my self-build so have been playing around with different sands and ratios to achieve a mortar thats lighter than the brick. This is the shade used on a large development and looks good, so I want to copy it, only they've used a silo. Because it's a grey brick with grey mortar, the colour consistency is key, using other brick colours, you don't seem to need to be as fussy. I think I've got it to where I need to be now with a cheap & simple 5:1 mix of Hanson cement & a buff sand only. I know plasticiser will need added. So, have a few questions if anyone with experience can help? 1. Does adding hydrated lime add any value and does it affect the colour? 2.Does liquid plasticiser affect the colour, if so, in what way, and can you recommend any brands I should aim for or avoid? 3. Whats the simplest way of gauging the ratio without seeming like a pain in the backside for a bricky. Make a wooden gauging box for both the sand & the cement, or use other? 4. Should sand be alternated between bulk bags or is this a bit anal? There's only 2 bricky's and they are willing to work with me, but I want to keep it as easy as possible for them. Gauging boxes all look to be 2 man lift unless this is fine. It's too easy to forget how many buckets of sand have gone in the mixer without one. Any advice appreciated, thanks.

Hi @Johnny Jekyll I'll post my experience so far and see if you can take anything from it. My supply rooms are: 4 x Bedrooms, 1 x living room, 1 x dining room. Extracts are: 2 x bathrooms, 1 x ensuite - Toilet sink no shower, 1 x boiler room which houses the boiler & cylinder & will double up as a drying room with UFH passing through it, 1 x kitchen, 1 x utility room. So for my build I contacted 4 companies, BPC was one of them, the other two i met at the home show and both were very similar in their quotes for spec and price but I found one of them willing to discuss every option in detail much easier. BPC only offered design and supply, not commission being in Ireland. Their prices were good and they also mentioned something up that i need to look into in more detail which was how they recommend sizing the unit for my build. Something i will need to add a post for. The other two companies have told me that a Zehnder 350 is fine and BPC said that I'd need a 450Q or a Vent axia plus B. I need to know if the volume is calculated by ground floor and first floor total volume based on 2.4m ceilings, or by including the 250mm joist void into the calculation like my SAP did saying ground floor was 2.7m (250mm between intermediate floor). My floor space is 200m2. BPC didn't think a 350Q could run under 70% of full power on boost hence the need for a different or larger unit. Taking these comments back to the other designer, they provided an explanation are maintain that the 350Q is fine leaving me slightly confused. When i first made contact, I supplied my preferred locations for MVHR unit, the room plenum locations and my proposed duct runs. the companies seemed to be happy with my design & said it's pretty much where they'd put things too, but I may require an extra vent or two in some of my rooms and this would be calculated in a detailed design. It was due to me having more extracts than supplies. They discussed options of 125 or 160 vents, having 75mm or 90mm pipes. Because i want a very quiet running system I immediately opted for 90mm semi rigid ducting. BPC then said they'd always go with twin 75mm which was different again. A detailed design is going to cost around £700, i had 6 extracts and 5 supplies, I've now been told I will require 7 extracts and 7 supplies, for my large 24m2 living room they will look at the option of either 2 supplies or 2 ducts to one plenum. I'd like to use 90mm ducting. The kitchen diner requires a supply where as I'd only included the extract at the kitchen end, & my larger main bathroom might require further extraction. I think it's possible with good self research to get a 90% efficient design, but as everything's fully enclosed once complete, I only get one chance, So i'm going to pay for the design to ensure everything's been considered by professionals, I'll do the full install to which they've listened to my suggestions and also highlights any bad ideas, then I'll pay for the £450 commissioning service to balance everything & complete the final set up.

I didn't think sips was that low, thought it's just PIR of a certain thickness in structural panels for fire it up quick. I've never looked into it much due it it being fairly expensive but I think it's a great way to build if you can afford it.

Thanks a big difference in U-Value, I wouldn't mind a house built from them if I wasn't paying for it.

@Dave JonesThanks Dave, whats the difference with the marmox blocks and a celcon/aircrete/thermalite block for the first course? I was going to run a course of them round before I build my inner walls with normal block on top. The marmox looks very expensive. I had a look at EPS and I'd need 240mm to equate to 160/165mm PIR. The saving was £700 but by the time I'v bought the extra course of bricks and paid the labour it just works out the same.

@Canski *on quotes just delete the text unwanted and then tap enter twice at the ned of the sentence to split paragraphs* It's always good to hear from experience. It does sound a bit of a pain if the tolerances of the PIR are out. For the price you pay a tenner a sheet and £4500 quid later it should be machines to size. My joists are going on internal masonry hangers. Door and window reveals say they need a wall tie every 225mm so they'll need slit to. I won't be able to use a PC lintel over the external vent because it's all facing bricks otherwise I would.

I was looking at the boards and imagine the tongue at the top and one side adds the small over size but just needs slit into by the wall tie to make the T&G meet tightly together rather than square edge that neatly slips between but then has all the problems of the gaps if incorrectly fitted or a bit of wind gets at them while building. There will be 100 PIR and 50mm cavity spare, 350mm in total so I think 275mm wall ties are the correct ones, need to check the drip loop in the middle is away from the 100mm board. Yes good point, I was thinking of this, I was planning on fitting the vents the same way, it will mean they probably can't be spaced equally from outside, it will just be a case of finding gaps between the beams that align with the brick bond outer wall and within the maximum recommended spacings. I was thinking to build the infill mix up to the top of the first brick on the inner leaf which would be just under the telescopic vent, then we'll have to infill before fitting the vents to the slip coarse. It depends on how high it needs filled to provide support. I'm sure I seen it needs to have a 150mm gap to the underside of the insulation which would work out well. (So lower than my last sketch)

I think if the founds are decent the builders happy to use trench blocks for the first course, I've had a few mistakes with my plans so just trying to get the last part right. I'm not sure how much building control hold you to the plans for below DPC. They've already passed them, we are just changing to suspended beam for heave reasons. If taking the insulation down another block course was beneficial for cold bridging I would but if its so minimal I'd rather spend my time and money in other areas are all to a good standard. Thanks & I will be posting some progress up for others in the near future.

I appreciate what you've said but I've covered this before and I'm due to start in 2 months. Can't use EPS bead we are in exposed weather zone 5 face brick exterior so it's no good. It would be a nightmare to get passed by anyone locally because it's not used, everyones either timber frame or partial fill where we live and behind the times on anything new like weather comp or heat pumps within 70 miles. I agree the blown bead would be a winner and easier. I'm paying extra and using tongue and grooved 100mm PIR to save the hassle of taping the joints and it not sticking in bad weather or people just skipping it. We've had to do a last minute change from slab to beam and block and everyones been very slow compared to other peoples services used so I daren't make a single change bar getting this below DPC agreed. 2 years to get some plans sorted is too long. I just want to get on with it now and be done with changes but I have this last bit to finalise.

Slight edit to the original post sketch. The height of the lean cavity infill can be lowered to suit. Builder doesn't like to run the first course in trench blocks, something to do with them not being as easy to cut and level up if the founds arent level. The first inner leaf block on top of the beam and block floor will be an aircrete type like my last post. My question is, I'd like to know if the cavity wall insulation is fine as it is or has to go down abother 225mm? I cant see any benefit to it being lower down. The screed has insulation under it, the vented void will always be cold air, the inner leaf has the insulated block on it. The way drawn works out well for pallets of xtratherm tongue and groove pallet orders, if i go deeper its into another £1500 pallet so I'd have to do the base coarse in stocked square edge or xps.

Thanks, I'll just stick with the staffs I think, that was my original choice in smooth until offered the ones in the original post. You know they've been tried and tested.