SimonD

It does seem to be the goto. That's an amazing price you got there for the slabs, I can't get anywhere close to that locally. Can you add me to your account??? - about 175m2 of 100mil slabs would do me fine for the rest of the house ??

Always difficult to know exactly what product they might have used. Both the Lynvale and Xpanda tapes have BBA certs with expected lifespan equal to that of Compriband. They're also not exactly cheap alternatives.

Thanks, yes, I totally agree that the complete construction plays the major role, but in terms of the mineral wool, I do need to understand its response across frequencies. Some of Rockwool's commercial range shows a remarkable performance at fairly thin thickness at only 50mm, but it's a resin bound mineral wool board, whereas the domestic product looks to be inferior. It's also interesting to note that the practical absorption coefficient for some mineral wool reduces at some frequencies even with greater thickness, so the rule about thickness doesn't always hold. But all of the mineral wool products do tend to perform best at 1k hertz upwards. The sheeps wool product does have the certificated test data for building regs part E compliance. For this particular instance in the wall I'm starting by looking at using a staggered timber stud wall with resilient bar, extent of plasterboard to be determined once I know the most troublesome frequencies for the room in question. I may go double stud if necessary. Intermediate floor wise I'll have a resilient layer on top of subfloor, acoustic insulation between joists, a timber resilient layer of 50mm, which can be filled with insulation and I also have the floor height to add an additional resilient bar prior to plasterboard - not quite enough for a suspended ceiling. Inside, the room will have acoustic absorption measures. I have some very specific requirements to adhere to with this one ? One word..headache..for me that is..

I've been scrabbling around to find sound reduction index charts for both Rockwool acoustic insulation slabs and Knauf acoustic roll. The only manufacture I've so far found that makes easy access of this info is Thermafleece although I've found some for Rockwool commercial products. I've emailed tech support for both companies but wondered if anyone here might have the data to hand as I need to make some initial calcs for a wall and ceiling buildup. Ta

Yes, I have used loads of the 15mm wide 5-12 from this company. I've also used other thicknesses up to 25mm. It all works fine. I've more recently used Xpanda tapes as this was slightly better financially and still bba. Can't really tell the difference other than slight variation in colour - one darker grey than the other.

Those pin holes are a very strange thing indeed. Re the distributor and RK39, I'd have one question to ask and that is how much experience the distributor has specifically working with wood fibre. RK39 is designed for thicker application on masonry substrates and wood fibre behaves very differently, so it's not just about the waterproofing aspect. Is it designed to bond with the wood and does it have modifiers to make it lighter, for example (RK39 at recommended thickness is nearly double the weight of thin coat)? Baumit StarContact is the adhesive/basecoat used in Baumit's ewi systems. If the distributor the plasterer has spoken to can reference lots of work with wood fibre, I mean years of experience and can show this render works over the long term, then fine. Otherwise treat the opinion with great care. The reason I'm saying this is that I've spent over 3 years talking to people and researching woodfibre ewi and found out that there are a lot of people (including reputable suppliers) in the UK that pretend to know what they're talking about regarding suitable render on wood fibre - there's also a hell of a lot of random detailing approaches which are insufficient. In this time I've been recommended everything from lime putty to hydraulic lime to other weird and wonderful solutions, even using hemp fibre in the basecoat instead of mesh. There is, unfortunately, a lot of bs out there that stems from a lack of experience and knowledge about the product. It even goes down to the basics that suppliers and installers often don't even know they've got to measure the moisture content of the wood prior to render application. In the end, thanks to a Baumit distributor putting me in touch with them, I ended up speaking to someone who has years of experience working with the material on the European continent and they understood the product much better. Lime Green is one company who also have a good understanding and their hydraulic lime render for wood fibre has been modified to work with wood fibre. Sorry to bang on in what might seem a negative way, but I remain dubious about the opinion RK39 should be fine. As a side note, the guy I spoke to with loads of experience in the field suggested I add a cavity and install render board outside the wood fibre explaining that this is a safer approach in this country. If I'd known that when I was building my structure, I would have modified my designs accordingly. Unfortunately, like you I seem to be stuck with the direct render and will have to see if it lasts.

RK39 is a cement free render - lime only.It also doesn't have fibre reinforcement. Be careful here as lime only render may not be suitable for application onto wood fibre even if it has added modifiers (I've discussed this very topic with lime render manufacturers technical departments and there are multiple reasons why - thermal shock, moisture management etc.). The required thickness is also different as the base coat and topcoat on RK39 for external use is minimum 13mm, probably 15mm. The thin coat is only 9mm. Big difference in weight. Why has your plasteres decided on this change of product? Has he actually gained technical advice directly from Baumit? If you're dubious about MC55W, I'd question whether RK39 is a suitable alternative. You might be better off looking at the European technical assessment documents for Pavatex and see which alternative thin coat renders are available. For mine I also had a choice of using certain Weber products. Edit: If you're after a lime only render from a different manufacture, then Lime Green sell one suitable for woodfibre (although primarily developed for their woodfibre ewi system) - it's quite expensive, mind you.

I've done the same, works really well mix and match. I use it a lot for diagonally bracing the transom sides of the scaffold, especially when building higher towers or when using the narrower 3 board transoms. Also handy to create a lifting point for winches.

Kwikstage. Price will ultimately depend on the configuration.

Great clarification by @Gus Potter. I had similar trouble with my architect & structural engineer, even though the architect introduced us to the SE. I thought things were strange when my architect phoned me up to ask if I could ask the SE some questions re the design. SE was terrible at responding to anything or communicating so sacked him (so was the architect and I dropped him later on). I brought in another SE who relied on architect's slightly more detailed planning drawings for the structural scheme. Neither communicated with each other so I picked up the phone and told them in no uncertain terms that we needed a pow wow. Banging some heads together softly over coffee and a spread of drawings on the dining table worked wonders and we were able to proceed, all in good terms. I'd pick up the phone, explaining to the professionals something along the lines that as their client it would be really helpful to have a structural design and drawings that fit together to enable you to build the house and if they could facilitate this you'd be forever grateful. It may help to remind them what needs to be done ? Just saying professionals in this field rather often seem to need reminding that client service is integral to their role ?

To follow on from what's already been said, what are the sizes of your windows? You can definitely do them yourself but to risk repeating what's already been said, there are two mains questions to consider: Do you have the machinery/equipment/manpower to take delivery, unload and lift the windows into place or are you willing to get it in and use it? Do you know how to detail the window installation and are you willing to spend the time to learn? I've done it twice. The first time they were standard sized windows in a renovation. The delivery driver kindly helped me unload, sharing the carrying to the back of the house. The carpenter I used and I could easily lift the windows into place. Easy. The second time I had to hire in a telehandler for offloading nearly 2t of windows and doors, and lift 3g windows up to 200kg and 2.5 x 2.6m using hired in specialist glass lifting equipment. Luckily on the 2nd the manufacturer provided me with all the detailing information necessary for self install. Machinery and equipment hire/purchase cost me about £1k and I've definintely spent a few hundred on the airtightness/sealing/fitting tapes, sealants, foams, spacers and flashings needed. It also took me a long time to finish it! As for warranty risk, it really depends on whether I've followed the detailing instructions correctly or not. If you're lifting any especially heavy or large pieces, you'll need to think hard about your lifting plan - this was the most challenging aspect of my 2nd fitting. 2nd time was a right headache and fraught with high stakes risk! It scared the hell out of me, but got done in the end without any mishap.

Hmmm, GBS wanted about £8k to install mine! I know this company has a great reputation but I went elsewhere as my experience of finalising an order was very underwhelming and they seemed disinterested in my custom.

If you can, wait until autumn to install those board on boards. You'll get less problems with the heat and sun and give the timber time to aclimatise over the winter and spring. In terms of the cracks, you're better off looking at an exterior wood filler, like Liberon Wood Filler HTH

Yes you can. The detailing obviously needs to change somewhat as you need to fix the battens through the wood fibre into the timber frame/masonry wall. Having a rainscreen outside the wood fibre insulation is recommended now in several parts of Europe to protect against wind-driven rain. I have to say, next time I use wood fibre I would swap out the direct thin coat render for a rain screen. Much better insurance long term, I believe. HTH.

I've got a few glulam lintels but my construction is hybrid masonry and timber so not entirely encased in masonry, just sitting on it. I designed the lintels to be visible. There are a few places that will sell you beams cut to length. With the company I used I just sent them details of the openings together with drawings and asked them for equivalent glulam, it was no problem design wise. However, they were more expensive that steel lintels and a lot more expensive than concrete ones. Span wise mine are about 2.5m.

Do you know the size of the hob and oven? A high output induction hob can get you up to nearly 12kWand a double oven over 4kW. More usually it's around 7kW for the hob on a 32amp spur, but some even come with a 13amp plug. Do you have a friendly sparky to get a second opinion?

I simply do not know where to begin commenting on that white paper. Just looking at the number of caveats and get out clauses, not to mention the rowing back on certain proposals, GHG which died as a farse, then the promise of banning gas boilers in new houses has been rewritten to a promise to 'consult' on the idea. Almost every substantive proposal has something like, if cost effective and practical, or if parliament has the time. Oh and then there's a very comprehensive promise to maintain expenditure, maintenance and development of the gas network to transport gas. The investment cited is a piffle compared to what is really going to be required, but the excuse in the white paper is that the cost will essentially be pushed to the private sector and public, all smoothed over with a platitude that their role in promoting competition will reduce cost. There is no significant investment here by the government. There are some glimmers of sense mixed in the waffle, like they recognise the power distribution networks will need to be significantly modified in light of renewables, but only a minor note that policy and network costs form a significant proportion of cost to customers and that this cost is going to rise. Not much mention of changing network policy to actually further promote transition of energy, something that is holding things back right now and which favours the old boys of fossil fuels. And when it comes to housing, we're still years behind where we perhaps could have been if the government hadn't decided to scrap the zero carbon homes policy that was due to come into force in 2016. At least they're honest in saying they have no idea where things will be and that they are relying heavily on technology that doesn't exist yet, or that has yet to be developed at sufficient scale, which means massive risk. All I can find myself able to give them dues for is publishing a white paper that does seem to acknowledge they're aware they might actually need to do something.? Okay, taking a deep breath, rant over ?

Just make sure that these larger rads get sized to the correct Delta T for your future heating system. It's now quite common for manufacturers to provide output data for low temp systems, at 40 & 30 Delta T. If you are planning ASHP at some time in the future, then for efficiency you could need radiators up to double the size and you need to design the heating system according to different flow rates more suitable for the heat pump. There's lots to do to make it work that mostly isn't communicated by installers looking to sell a unit with water tank. Even if you insulate, make sure you take all the necessary airtightness steps - a leaky well insulated house just isn't worth the effort or cost. One thing you can do is design your heating system for a heat pump but buy a low temperatue boiler to use until heat pump prices come down. Predicting how things are going to go in the near term re net-zero heating is nigh on impossible as the government seem to have no proper plan in place to make it happen, nor have they even begun to cost it all out and budget for it. The most important thing I'd like to suggest is that you live in the house for a year before settling on your decision. This will give you the chance to get rid of draughts and sort airtightness, then insulate. You'll then have a much better feel and knowledge of house the house behaves (and costs), making it easier to come to a well informed decision. By then there might even be a new government grant scheme in place. Who knows.

IIRC Building regs calls for either concrete or inert layer. I've ended up with both - concrete where I had excess pumped for foundations and inert where I just couldn't find the energy to do a lean mix myself. BC happy with both.

Wow, okay, so lots for me to digest here! Much appreciated. One question that does immediately arise from both or your comments, @markocosic and @Nickfromwales is gravity fed DHW. In your views, have I overlooked this as a valid option? At least this decouples DHW from cold mains feed and can be supplemented by pump/s where necessary? Thanks.

Clearly I need to do a bit more research to understand the MIs specifiying non-modulating boiler as the preference for a well functioning thermal store. It does take me a little bit by surprise. My limited understanding is that modulation has primarily been introduced to reduce boiler cycling, which is the main source of inefficiency in the boiler. I can only surmise that the thermal store as part of the system helps to reduce cycling. Aligned to this I guess is the question about how much the modulating boiler would actually add to this system efficiency wise as I suspect that looking at designing CH return temps to ensure the boiler is condensing may yield similar, if not better, results overall. For me, the biggest concern around this is over-sizing the boiler as seems to be a common affliction here in the UK and will significantly affect energy consumption and efficiency of the system. From reading a number of threads on various forums, it does seem like thermal store v unvented is a bit like marmite. Lots of passion either way. In our last place we had an unvented system installed. The installer was an idiot who didn't seem to understand even the fundamentals of unvented systems, so we embarked on a period of rectifying the problems. The original install was worse than the gravity vented system we replaced, and once all resolved, it just about performed as the gravity system. The only benefit we saw was when showering without anything else drawing off water (should have just put a pump in). This was even with 22mm mains supply and above required pressure. No, I didn't skimp on any part of the UCV install rectification - it cost me a packet in the end - much of it down the drain. I don't necessarily think that UVC is simpler than the thermal store approach and I don't have to have G3 or get it serviced every year, or have a G3 in when something goes wrong. Yes, I know there are some claimed disadvantages to thermal stores such as standing loss, and draw off temperature reduction but from what I can see, the standing losses apply just as well to UVC and the thermal store manufacturers provide pretty good data to estimate the temperature loss in relation to draw off volume. I agree, but I've now run a couple of calculators from manufacturers both of which suggest 210l thanks for our house. It's interesting that the stores I've identified only go up to 250l for my planned configuration. I appreciate this suggestion, but again I've now read multiple manuals and articles by different thermal store manufacturers, all of which recommend draw off temps of around 50 - 52 but one even as high as 55. 48 is not much below this, and I can obviously adjust down to this no problem. ? Thanks, will do TBH, I'd prefer to avoid anything like this that contravenes the regs. I'd be happy to look at a buffer tank if we do have a problem before the mains upgrade.

There was an article on this in one of the nationals during lockdown telling everyone they'd laid their decking the wrong way up/wrong way down; it's as @Onoff says, grooves go down.

Thanks, will be avoiding 22mm feeds. I perhaps should have elaborated further on the figures I gave earlier. It's an existing property and currently the only tap that can provide a good indication of flow is teed off from the incoming main inside the house, running about 20 meters to an outside tap on the side of the garage. Only tap available internally gives a rubbish flow. In addition, our main is 15mm lead pipe which we know is at least 25m to the road. When I get round to doing the landscaping, I'm going to be digging up a row of hedges and when I do this I'm probably going to upgrade the mains as it currently runs more or less under the hedges. This should improve our flow rates. (I know that I should do this now but budget wise it really has to wait). The measured 22l/min is not far off the theoretical 27l/min I anticipate a 15mm main can deliver (at current pressure), but may I've got that wrong? I'm not expecting 18-19l right right but want a DHW system that's capable of it. I'm aware of the variations in both DCW and DHW temps and the relationship between these and flow rates from combi boilers, but the blended calc figures are very helpful, thanks. Blended output of the thermal store I've identified is set to 50 degrees C at manufacture but is adjustable. The figures for volume of DHW delivery by the thermal store are calculated at 43 degrees C. I think I've now arrived at an initial configuration for boiler and thermal store. Noting @PeterW's comment about heat exchanger, I've found an indirect store from Advance Appliances using coil heat exhangers. It's also one of the better performing from a heat loss perspective. Looking at boilers, Baxi 800 is at the top of my list right now as it fits the MIs for the Advance thermal store: non-modulating, 24kW if I settle on 210l cylinder. It's also IPX5D so can be installed fine in the bathroom including zone 2. As an aside from the DHW, my only concern relates to the boiler heat output. I recognise I've got to look at things differently when using a thermal store, but with my house heat loss calcs calling for 7kW, I'm wondering whether at 24kW I won't be over sized and this might cost me? (The 24kW is recommended by Advance for recovery rate on the 210l tank).

Here you have hit the nail on the head. I'm designing, and ultimately I'm liable, yet I have some high standards to obtain that don't involve too much compromise! ? SWMBO requires ready and instant access to hot water at the kitchen sink and basins for regular use (I do too as in our last place hot water supply to the kitchen sink was terrible, you could go and have a cup of tea waiting). I've also got to ensure we can run 2 showers, a bath, the washing machine and dishwasher simultaneously, together with the odd basin without a drop in flow or temperature and it's got to recover immediately so anyone left waiting in the queue for any of those facilities doesn't have to wait. I'm sure these requirements aren't too unusual...are they? ? Joking aside, I'm looking for a comfort/environmental/efficiency balance. Capex/Opex is again a balance here, however, right now the Capex required for ASHP on this project is too high, even after self install over MCS/RHI route. We're a family of four and we do get through a lot of hot water. Fabric energy efficiency is relatively good with a calculated required heat input of just over 7kW plus DHW. From a water use perspective, I'm looking to reduce dead-leg wastage as far as possible, while also reducing overall volume of water consumption. I will be fitting flow reducers to outlets, especially the showers (x3). With our respective routines there's likely to be simultaneous use of 2 showers on a relatively regular basis, but it's mostly going to be like one shower plus washing machine and dishwasher and maybe a basin. Bath will be used daily, twice daily 2 or 3 times a week, but filling time isn't a priority and it's unlikey to affect showering. By my reckoning a DHW flow capability of up to 18 - 19 l/m is going to service us fine. I've been investigating options today and changed my mind about the system configuration. I've identified 2 potential spaces where I could fit in a cylinder, both spaces resolving the potential dead-legs and avoiding hot water recirculation. One of them is right in the middle of the house and can be integrated into an airing cupboard, which my wife has said she'd really like. If I installed a 210l thermal store here, I could go either heat only or system boiler rather than combi. This way I'd also retain the backup of immersion heater. As for future proofing, I'm a little cynical here. I've worked in the tech industry since the mid 90s and don't think you can really 'future proof' any development. I'm making the decision based upon now and will review in 7 - 10 years, or if things move really fast, maybe even 5 years. If we're still here..otherwise it'll be a different project ☺️

Thanks for the suggestions, and makes a lot of sense. Interestingly, Emmeti make a suggestion to run HRC through their manifolds and simply t-ing off to the individual outlets from there. I'm not sure if this is the best of both worlds, or the worst. They also recommend max 12m 15mm pipe from manifold to outlet. Having measured a little more, if I run the supply pipe diagonally across the house (just about possible as I have a service void under the ceiling joists), I can get a run from boiler to kitchen sink and ensuite shower down to about 17m.