ruggers

@Canski Thanks for the advice. If the intermediate walls were laser marked like previously described 1m below, it could work out better, but due to the posi joists being 253mm not 225 or 300, I'm thinking it's a bummer for someone to cut 28mm off each block and wouldn't end up very tidy. 2 bricks and a 47mm could make it a lot easier to tie back in with the cavity courses. It's all mathematical and the real world doesn't work this way especially if blocks are cut with bolsters rather than saw cut.

Thanks for the replies. Strange how my plans were passed with no mention of it and very little detail about windows. I will make enquiries. I couldn't find much mentioning if it also covered the glass which seems a big benefit if it does. Uprated locks seem a benefit in a rural area. There seems to be a few types of glass. Standard Toughened Laminated. Other?

I'm looking to build a house next year and have had my plans and building regs accepted pre June 15th. I've been obtaining some quotes for UPVC double glazed windows and came across some questions from the various suppliers. 1. I was asked if I need PAS24/DOC Q specified windows. So one company is quoting without saying they don't make a great deal of difference and if someone wants in they'll get in but it does add a lot onto the price. Another has said it's a new build you will need them and quoted for it. My regs/plans don't specify that it was required and have been passed. Is PAS24 part of DOC Q or are they two separate things? 2. Do these standards just relate to the locks and frames or to the glazing also? Is it worth is or in reality no? I once seena video showing a standard lock being broken into vs an ultion lock. Standard was broke in under 10 seconds.

So i sense a level or sarcasm but are you suggesting posi joist do or don't get blocked up between. Bricking between will help prevent cross travel of sound but services don't just run in one place so there would be a good few missing. I worked out then the 253mm joists if they on hangers would sit well mid span on a 100x47mm timber underneath to tie in with the brick courses but this means you definitely cant brick between.

@TonyTAs in a standard vent slate that just fits into a pitched roof? I've seen the mushroom type on flat roofs but theres others that look much better. It's why I added this post incase others had tried similar things. I could add lots of vents and they don't even work, its a bit of trial and error. I don't mind fitting a vent on each gable or a couple of slate vents up near the ridge on the North side if it helps, I was just unsure if it makes any difference or not with them being so small compared to the size of the roof. A velux is a significant opening size so it will let a lot of heat out compared to a few vents. @TempI think unless I'm going to fully insulate the underside of the roof to keep heat out as per comments above which isn't very cost effective for my use of the room, My best bet will be to add some vents to get the air moving and consider a radiant heat barrier to the underside of the rafters to prevent as much entering and leave a gap at ridge level where the vents are to help steer it in this direction. The rest of the heat reduction will have to rely on the loft insulation on the floor.

Handy little trick. If the joists are blocked up in between them over internal walls, there won't be any space for running the services in the floor void between rooms? Cables, pipes, MVHR ducting.

I agree with you that for ease of installation and air tightness this is the winner, i had a post about these options a few months ago, ledger board vs masonry hangers vs tony tray vs just built in as standard. Because the ledger board sitting tight to the inner face of the wall prevented all of my services reaching the consumer, it meant that the ledger would need packed off the wall by 25mm or so which I don't see as an issue. But I struggled to get certain people to agree because it wasn't something they've experienced before, my plans were 'well' over due completion and I just needed them complete to get on with it. They are passed now but it might be worth me checking with a structural engineer to ask if we can change it. It doesn't affect the plans. Trying to hope the mid span walls tally up in height with the underside of the masonry hangers won't be easy at all. Thanks Canski, I will meet up with the builder and ask what they do and suggest this option. What is classed as a long line, my largest span will be 12m. When posi joists are supported at each end via masonry hangers, any mid span load bearing walls they cross over and rest on, do the joists rest directly onto the block work, or would a timber wall plate be bedded on, the same as you do at the top wall plate for the trusses?

I was meaning the panels sitting over that area of roof slate means that the slate behind doesn't take the full impact of the heat so the radiant heat is reduced within the loft whilst also creating energy via the PV absorbing sunlight. But most panels sit off the roof on rails with an air gap behind them causing a shadow and separation from the slates. An inline PV system fixes direct to the battens via plastic panels so i think the heat stored in the black PV panel will again travel back into the loft space as radiant heat. Thinking about it now, anything fixed to the underside of the rafters to try and divert or radiate the heat back outwards from the loft space probably won't work unless it's sealed from edge to edge like the rest of the thermal envelope being airtight. Using the foil type VCL to the underside of the rafters would have been a nice way to achieve this but unless sealed it would have no where to redirect it too. As it's not a habitable loft with expensive attic trusses, It would cost me probably £5k extra to do it properly. The slates will get very hot on sunny days, we can't stop that, so it's finding the most cost effective solution to diverting that radiant heat back outside.

I wasn't aware of this, so for all upstairs rooms this would be pointless then, except the bathroom if I batten the ceiling to create a gap for down lights into a upvc ceiling to maintain airtightness between loft and bathroom. Are we saying PIR does or doesn't prevent the transfer of heat into a building? If it holds the heat in when it's cold outside, I'd expect it to prevent it from allowing the outside blocks transferring the heat inside on warm days. If I can afford it, I will be adding some solar panels to the South facing front roof, but they will be the inline type so won't have the air gap behind them which shades that part of the roof. The total of panels spread gable to gable will only cover 20% of that half of the roof. I don't feel the need for aircon up North with 2 weeks of heat wave per year but it doesn't take a heat wave to heat the loft space enough to possibly affect my lagged MVHR ducts supplying rooms.

I'm aware of bedding a timber wall plate onto cement at the top of the build to sit the roof trusses onto. But wasn't aware its done at intermediate floor level. So some of my joists ends will be supported by sitting into a masonry joist hanger which will bed down between the courses of the inner block work with the opposite end of the joists resting on on my load bearing internal partition walls also constructed from blocks. I'm not sure if they sit direct onto these inner walls or there also needs to be a 100 x 50mm wall plate too? I wouldn't of thought there would be, and so the internal walls and the cavity wall inner skin wall courses need to match up in courses. I will also have some joists 11.45m long that will span the full house width and each end will be secured into a masonry joist hanger, but mid way along this span will be two internal walls and if the top of these walls were, lets say 10mm higher or lower than the masonry hangers, then the long joists would be bowed.

Do you have an example of the wood fibre or products your referring to that could be used in a loft situation? I always thought that foil backed insulation like PIR was supposed to be as effective at keeping the summer heat out as it is at keeping the heat in when its winter, although my experience has always been as you described, it works in winter but still gets too warm in summer and asking what else can be done to prevent this. Because PIR is basically insulating foam sandwiched between two layers of foil, does that not mean that reflective foil alone on the undersides of the rafters would be a complete waste of time? I was looking at this for example. https://www.toolstation.com/construction-insulation/foil-insulation/c626

So the issue I want to try and control is the over heating of the non-habitable loft space where my MVHR ducts will pass between the unit to the rooms. I can try making a an insulated cabinet around the unit. The radial ducting will be insulated and it will also be under the 400mm of mineral wool. The ceiling between the upstairs bedrooms and the loft I will use PHS Hi-Thermia membrane as a VCL. https://passivehousesystems.co.uk/wp-content/uploads/2020/05/PHS-hi-thermia-membrane-2020.pdf The roof orientation will be North facing rear, South facing front with East West gable ends. It's actually rotated 20 degrees clockwise from North. I wasn't going to continue the PIR insulation up above the first floor but the S.E side brickwork might warm up a lot more than I think. The roof slates are what seem to bring in most of the heat. Looking at your suggestions has made me think that the fans or vents won't be too effective if the thermal mass keeps transferring the heat into the loft again. Standard trusses have braces all over the place making it extremely hard to make a neat job of sealing any foil to the underside of the rafters from eaves to ridge level, but if it doesn't need to be completely sealed and will still be effective, I don't mind adding some to the South Facing side. I don't want it to be like fitting a VCL & then having gaps between all of the joints & it's an expensive waste of time.

I built a dense block outside shed with a slate roof, single skin and had no problems with water ingress for a number of years before I decided to cover it so I think it will be fine over the winter, I'm assuming your PIR full fill will have a small gap to the outer skin (10mm), if correct it's not incontact causing any issues.

Looking to start a self build brick construction. How do I ensure that all of my internal load bearing walls match up in height with my inner leaf cavity walls so that the posi joists are supported correctly without bows/dips. A couple of my Posi joists also span the full width of the build and rest on a couple of internal room dividing walls. Not all builders work to the same standard, some might use lasers for this, what should i be looking for to ensure the best results possible? The ends of the joists will be supported by internal masonry hangers, joist depth is 253mm which isn't ideal to tie in with brick/block course very well.

What are the best options for reducing the summer heat that builds up in a 'cold' loft space on sunny days which comes from radiant heat heating the roof slates? Is air movement the most important, preventing the heat from entering or both? I'm planning to start a self build & will be siting my MVHR unit in the loft on a gable end so I'm looking at ways to reduce the heat up there. There will be 400mm of rockwool but the roof construction will be standard trusses which can make it harder to insulate to the underside of the rafters. I was wondering if adding something like a superfoil roll to the undersides of rafters would help reduce radiant heat, or be a waste of time if it's not a complete taped and sealed envelope. Possibly adding an extract fan controlled off a switch or thermostat.

Can ASHP's modulate down as low as a good condensing boiler or does short cycling affect them more if zones were applied? Does rising electricity prices affect COP?

Have you found your top floor doesn't need it and is too warm due to the heat rising? It's a shame your limited to Tado with them being so expensive. The prices seem to range from £100-160 each. Did you choose RF or wired stats, is the wiring centre tado too and does it control actuators or jus tell the pump & zone valve to kick in?

Chablais, I share your view on the HWRC, if it can be avoided. The 10mm sounds like a good way to avoid this for my furthest outlet. @Adsibob Do you have UFH on both floors, and using the Tado stats, are these still linked to WC or do they replace it? 12 is a lot.

Thanks guys. I'm surprised with the 10mm providing the flow, I didn't think it would be up to the job, it makes life easier dropping smaller pipes down the wall from upstairs & hiding them, then just step it back up before the sink & add a couple of 15mm iso valves. I work it out as being 2/3's of the internal diameter of a 15mm pipe. I don't have very good water pressure in my current property, not sure if this plays a part in delivery time. If i use 10mm, there might not be a need for the HWRC with bronze pump unless theres advantages to one I'm unaware of. @Chablais @dpmiller Do you have secondary hot water circuit or not required? @Beckside Thanks for the detail. The info when searching has been limited and varying on it running 24/7 and some saying it cant be turned off so it's good to hear from someone who has it installed, I know it's been around a long time but it's still quite rare in the UK it seems for the majority. On off features are a definite no, WC vs load comp are my choices. The log burner choice was decided some time ago as we liked the idea of one & we have about 8 years worth of logs, but i know what you mean.

I've just had a thought, so a question for anyone with WC. Which does it work best with, UFH or radiators? WC is proactive & radiators react quickly to changes, but the delays in a screeded UFH system heating an cooling would fall behind what WC was instructing it to do. The mixed rad & UFH system would work completely different. Does anyone know if you can use a Viessmann boiler with load comp instead of weather comp? Strangely their website mentions the addition of an indoor temp thermostat coupled with WC, not sure how that works at all.

@PeterWI think I'll need a HWRC, all outlets would be within 6m of an UVC so fine without one, but the kitchen sink is around 12m away. This will increase if I use a 222-F storage combi due to different location than the tank. If you add a HWRC after the blending valve located at the tank and set it to desired temp 45-47C, would this maintain it's temp enough over a larger HWRC? Are you suggesting to not add all of the outlets to the HWRC? 12-16m in 10mm to the kitchen sink might still take a bit of time, i thought it would give poor flow at that diameter. As an example, I currently have 16m from a combi in 15mm & it take 50 seconds for full temp, it feels like an age. Any reason for the 48c boosted to 65C when using an ASHP but lower if from a gas boiler?

-I didn't think the pump running constantly would be very efficient or allow it to last long, thought there might be an off period in the night like when your set back temp is on or does the heating come on in the night also? Is it best to set up WC room temperature for the room you want warmest & then reduce flow to the rooms you want cooler with UFH & turn down TRV's on radiators? So if you put the wood burner on, the return temps at the boiler will be detected and turn off or reduce the heating to the rest of the house? I think this is where room/load compensation might suit me more than WC. I can understand WC has great comfort levels, but a log burner or hot kitchen can affect the heating to the other rooms. Thats good to know, whats the best temperature to store hot water so people don't scald their hands at the sinks? I keep seeing mixed info on this and it stating commercial & domestic new build from 2010 require TMV's on baths to comply with part G of the regs. I always thought they had to be within a certain distance of the outlet otherwise the tank seems a good place.

Sorry for the delay, I follow topic but not getting notifications without checking. I believe legionella has to be considered with new regs for builds for a number of years now. Either the water needs stored at a higher temp than 62C (ish) or set on some timer program that boosts it every 48 hrs/week/month, unsure of the interval. This is why I wanted to find the easiest solution if i must use an UVC. Having TMV at 5 sinks outlets and 2 baths then trying to hide them but also access them for replacement or servicing seems a right pain, I don't know how long they last. So a couple of WC questions on what you've put. -Does the heating pump run 24/7 in winter, or does it just over run for a period after the burner turns off? -Do you still have a program to turn it off at night or in summer. The house inside is often below 20C in summer but I wouldn't want it calling for heat. -Can you set more than one temperature for the day. Eg: My morning temp is set at a lower temp than at 5pm > in winter, then night is a set back. -This ones confusing me...If you set your WC desired room temp at 20C, does that mean every room has to be 20C? I personally don't need my kitchen as hot as the living room for example. If using radiators, I guess you set the boiler for the warmest room & can then turn down other rooms using TRV's. Not sure how that works for UFH though. -What is if you wood burner fitted, WC won't know whether it's on or off?

I'll look into the cylinders soon, so many types & sizes, solar twins coils, fast recovery ones, Gledhill, megaflo and vitocell, this will determine my boiler size i guess. If designing the flow temps for 50-55C with priority hot water stored lower than 60, how often does the legionella cycle need ran? Are heat loss calcs just each room added up in watts and then totalled together after the relevant conversation factor has been applied based on your DT? I thought my SAP would include the heat losses per room. I was getting my wires crossed with load /room comp & WC. Looking further at WC, you select a flow temp, then a desired room temp, then your coldest day along with a suitable curve & it works with the outdoor sensor to modulate & maintain even temp. But is there an indoor temp sensor, how else can it know what the temp is inside your house and instruct the boiler to turn off once your desired temp has been met if it only has the water flow temp to measure from? Yes most locally don't fit divicons & LLH. Do divicons work with any boiler or viessmann only? I had a look at the mixed ones, do they just fine tune the water temperature as an extra on top of the boiler modulation? I'll size the rads myself but I'll get a company like continel or wunda to do an UFH plan, I was going to go for 150mm centres, someone said I might need 100mm for future proofing for ashp? Out of interest, what size and model tank did you select to go with the W200.

Thanks @Chablais, I also liked the 222-F for the reasons you mention above. Two showers at the same time is the most we will ever need running, or a shower ran after someones ran a bath so quick refill times are required. I hear varying times for this so assuming I need a fast recovery cylinder. It's trying to figure out an option A & B, because heat engineers in business can't be giving away free advice all day, and not a lot of people locally seem to be interested in anything out of the norm, I'm also in Cumbria. I contacted Viessmann regarding their system & storage combi's and they said their warranty is 5 years but can be 10-12 years if fitted by a trained installer, the closest being 50 miles away. I could do with knowing which other boilers have good modulation & reliability to check out. I will be doing a good job of the air tightness but won't be able to achieve the insulation levels some of you have got. What boiler did you end up fitting with the UVC? I suggested a solar twin coil cylinder to a local plumber with both coils connected to the boiler flow for quicker cylinder recovery but they dismissed it as a bad idea saying it wouldn't work.