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We have most of the steelwork up in our wraparound extension and loft conversion. 1905 mid-terrace, solid wall construction. We have picture frame steels sucking heat into the ground and steels bearing on to (and/or supporting) cold brick walls. I'm looking to minimise the impact of cold bridging. The wraparound is brick and block with mineral wool cavity, pitched vented roof. The loft conversion is timber, vented cold roof (unfortunately necessary). Priority 1 is to avoid condensation, priory 2 to reduce heat loss. No cold steel near bathrooms, but plenty near the kitchen in the wraparound. The builder suggested PIR or mineral wool around the beams, but I worry if we insulate without a vapour barrier against the steels it will worsen interstitial condensation? I wonder if spray foam is a sensible way to do this, cutting the cold bridge with a continuous vapour barrier I can tape against other membranes. I've sent the horror stories but get the impression the issue is where critical ventilation e.g. cold roof is compromised by the spray foam. Other relevant measures are: -internally insulating solid walls (planning on vapour-open with thermactive plus wood fibre). -windows uprated -We'll be getting as airtight as reasonably possible -MVHR system fitted which I will control based on internal humidity Grateful for any thoughts- couldn't see similar in the forum surprisingly

Jointly awarded the Nobel Prize in Physics 2022 "for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science". Clearly not an expert in climate science then. Then there's: Alexis Carrel - Awarded the Nobel Prize in Physiology or Medicine 1912 "in recognition of his work on vascular sutures and the transplantation of blood vessels and organs". Believed in telepathy and eugenics. Richard Smalley - Jointly awarded the Nobel Prize for Chemistry 1996 "for their discovery of fullerenes" Believed that evolution could not have occurred. There are others...

A very good point. Since maintaining vapour-permiability will be essential following my current renovation, I'll be inscribing that, together with a few other key points, on a metal plate that will be screwed next to my MVHR unit for posterity - it may be worth considering. In theory I shouldn't need to do that here in France because a mandatory 'house manual' is now required as part of the conveyancing process. It has to include, in detail (product names, technical characteristics, serial numbers, etc.), all the materials and equipment related to insulation, thermal performance, energy use & generation, etc., from initial build (if built after the law came in) through all subsequent modifications. It must also contain instruction manuals, servicing requirements & maintenance details - for example the need to use vapour-permiable paints.

An insulated concrete slab is better if you need a radon membrane, as beam & block can create voids where the gas will accumulate. Radon gas is a silent killer.

According to ChatGPT... "No — there’s no credible evidence that John F. Clauser is paid by the American Petroleum Institute (API)."

Well it is. Apart from the fact im on the border of zone 1 and 2 for windriven rain. The good news its rendered externally, base coat of render, but never recieved the final coat. 50 years ago. Its fine, but looks terrible. My current thinking is to use hardie plank or similar rather than try to do a render top coat, whick will give me, hardie plank, air gap, good render, inner leaf, before we get to insulation. So, done well, no water should ever get into the cavity.

Sorry, you just clump it all in one sentence, can only respond to what I read. But as I said a well designed ASHP system is suitable for any property. But also not mentioned a piss poor design, can be be very bad in any property new or old.

I didn't actually say it cost a fortune to install a heat pump in a new build - where did I say that ? And the poor don't generally live in new builds. We are talking about older properties and going around ripping out existing central heating to replace it with heat pumps at great TOTAL cost to the tax payer. Think victorian terraces of flats and high rise buildings, cheek by jowl, little parking, no gardens. When someone from government (Millipede) arrives and says 'I am here to help you' - run for your life as fast as you can. The history of centrally planned economies is not good for anyone.

Condensation occurring on the cavity face of the outer masonry leaf is irrelevant. There is a much greater amount of liquid water at this point following periods of wind driven rain. As part of the certification process (BBA for example) cavity wall insulation, built-in or retrofit, is tested to ensure it does not allow water from wind driven rain to cross the cavity, this water should still drain down the ‘cavity’ face of the outer masonry. Again not condensation related. Adding cavity insulation does not move the dew point ‘inwards’. Condensation, if it does occur, will still be on the inner face of the outer masonry leaf and may be considered as inconsequential.

Sorry this statement alone is just utter nonsense. A heat pump is suitable for any property, when correct designed. Why does it cost a fortune to install a heat pump in a new build? You already have to install low temp heating system to comply with BR. A 35 deg system isn't even going to much of a cost premium. If I can buy a new heat pump for £2100, a large organisation will buy for half that! Scotland banned gas boilers a while ago and whole building industry came to a standstill - not. ASHP, no gas standing charge, a single zone system, without hydraulic seperation, SCoP of 4 plus easily. Cheaper for the house holder, get over it.

You seem not to understand the point I made. You cannot in one breath push for and bring about the destruction of the UKs indigineous fossil fuel industry (in the name of CO2 emmissions and climate emergency) AND then bemoan the low levels of UK energy security because of the need to import fossil fuels. You cannot claim the lack of UK indigineous fossil fuel industry (which you have acted to destroy) as a reason to destroy all fossil fuel use. There is only 1 reason there - you want to destroy use of fossil fuels in the UK to achieve net zero - it is 1 reason, there is no 2nd reason regarding energy security. You are using tautology and not recognising it. Smoke and mirrors. We are going to be using fossil fuels for many decades to come whatever is done. The UK cannot go net zero in any short timescale, so we will be happily burning gas for many more decades, like it or not. Energy security has many solutions including building gas & oil storage facilities, building nuclear power stations (large & small), building clean coal solutions. Batteries will eventually play a role. etc. Mr Millipede has just announced a new package of mad policies to ban gas boilers in new builds and spend a fortune installing heat pumps for the poor (who often live in accommodation for which they are unsuitable). Fortunately there is no industry capacity to achieve his policies on the scale he proposes, and thankfully he will be out of power within 3.5 years now. IMO, the country does not need mad crusading zealots leading us into self destruction like Chicken Licken.

My view, is do due diligence on anything you read. Who is writing it, what is their background - where is the money coming from, that allows the research and pays the bills. If you can't easily find these details ask yourself why not! Most likely it's going to filed in the nonsense pile or pile of, most likely sponsored, by some organisation with a view to spin.

The reason that some people put heaters in bathrooms is that after a shower, you are wet & naked and Evaporative Cooling takes place. If this is a problem, it's better to use infrared heaters/panels. You certainly don't need any UFH, either wet and electric upstairs in a Passive House.

In before someone says "scientists thought global cooling was a thing in the 70's! How do you explain that?!"

Yeh, it seems way too late to be considering changes like that. The amount of extra cost and time that making that sort of change adds (especially if there are other similar changes) will really add up and get your project way off track. That sort of change will likely require new drawings, other calculation changes. Does the extra weight mean bigger foundations, etc? Aside from the impact of making changes at this stage, DIY installation of B&B is an awful lot more (heavy) work than whatever radon membrane work you are thinking of. I'd assume you'd get a concrete crew in to pour the slab. If not then maybe it balances out but I very much doubt it would once you factor in the cost of changing drawings/delay/etc and installing the beams is not a one man job.

John, your experience is showing, admire, one sentence only! Take John's advice and see how it pans out. The builder may just chuck in the towel. At the end of the day they knew there was a cable somewhere, the depth is a bit of a moot point.

If you are still weighing up what floor system to use, then it’s a good job it’s raining as you are not ready yet. you need all of this completely ironed out first. Just as a few examples, before you start you need the numbers of all the local muck away Lorries in your phone, not one bloke you spoke to but 3-4 of them, if the stuff is piling up and the lad you spoke to can’t do today then you just phone the next. the same with a concrete pump, have two lined up, talk to both talk about access and anything else. go to the local concrete company and open up an account. Dumper hire, if a dumper breaks down do you know a company who will drop one off the next morning. all this stuff can turn a simple job into a disaster get very good at disaster management, have a plan for every eventuality.

Our builder went through the villages main power cable 1 week into our build, several houses on emergancy gennies, half the village without power all day, and about 4 days of 24 hour work to resolve. Architects assured us builder was responsible, and had insurance for this... And when I gently confronted him on the day, he crossly assured me his wife wasn't getting a new car this year... Thank fully he managed to prove the cable wasn't laid to the drawings, and we never heard about it again. Its a shitty situation, but if there is a doubt check before you dig is common sense... And a professional will know there are ways of checking. However.... Disputing and falling out over (say...) £5k bill on a £150k build will come back to bite you one way or another....but if it's £5k off a £15 bill..... So you need to judge the situation pragmaticly

Hiya @Julestools interesting thread and good questions. The following is a bit of back to basics, for the less initiated, maybe new folk to Build Hub. This is a very rough run down but intended to introduce folk to something that may be less familiar. When we insulate walls we want to make sure that any water that condenses in the wall can be expelled outwards or inwards before it causes any damage. When you cook or breath out you expel "water gas". This does no harm. The harm arises when the water gas turns to a liquid.. water droplets. Mould, dry rot, wet rot, most bugs / fungie need liquid water. At the bottom of a wall we often see damage due to freezing water (spalling of bricks / render) when it becomes excessive. For the water gas to turn to a liquid it needs to hit what we call the dew point. This varies depending on how much water gas is in the air and the air temperature. For example if you live in the tropics the warmer air can hold much more water gas, lower the air temperature a little and you get heavy rain. In the UK it works the same way, but a bit less dramatic... but the UK weather is it's own animal, I'm not covering this just now. If you have a 1970's brick cavity wall to start with with say 15mm of plaster on the inside and roughcast on the outside then the dew point is likely on the inside of the outer leaf of masonry, the obvious cold surface. The cavities are often drafty so lots of water gas will get vented. You can analyse this but in most UK weather conditions the water gas condenses on the inside of the outer leaf of masonry. Any condensation was designed to run down the inside of the outer leaf. In actual fact in the 1970's there was no condensation "analysis" as we now know it.. it just worked! These houses were designed based on the knowledge at the time and proven to work in most cases. If left alone they will continue to perform as originally designed, although not meet our modern insulation expectations. Cavities at the time had residual air circulation. But now we want to make them warmer! To get a handle on this it's often a good idea to research what the designer at the time was thinking and what knowledge they had at their disposal. I love this stuff! Miss Marple! @Julestools "The cavities were filled with a mineral wool type fluff in the 90's." That has two immediate knock on effects. The natural / residual air circulation in the cavity is blocked off. The cavity insulation moved the dew point inwards, so you no longer have the really cold surface of the inside of the outer leaf of wall acting as the dew point surface. The cavity wall insulation installers often sold this as they say the insulation will "wick" the water away safely downwards and not come inwards! Make of that statement what you will as adults. @Julestools " I'd love to hear your thoughts and knowledge on this approach to internallly insulating cavity walls." You are fortunate not to have any timber ( floor joists say) near the bottom of the wall. If so it becomes very tricky as the ends of the joists are more prone to getting wet. For all, BE VERY CAREFUL IF YOU HAVE TIMBER IN THE WALL! You want to improve the U value of the wall. You insulate on the inside. You shift the dew point further inwards. Qualitively, if you improve it a lot you will shift the dew point further inwards, maybe even to the inside of the inner leaf or in it. Don't forget.. the calculations in the design codes are theoretical.. we need to apply common sense, this is most important! Given the above lets take a pragmatic view. The first objective is to control the humidity in the house. Bathrooms and shower rooms need extra ventilation.. we know that. Next question is... we can select breathable insulation.. but the critical areas are bathrooms, kitchens. Folk paint them and tile walls. Say you sell the house or some really "keen" BC officer pulls you up as they say someone may use the wrong paint on the walls.. it's a fair question. Putting my SE hat on.. it is important! In some ways I think your are over thinking this! The first objective is if you are going to create excessive water gas then you need to expel that as soon as you can, but you need to have a certain humidity in the house to stop your sinuces playing up. A house that is too dry is a nightmare! In the round, if you are air tight, particularly in the wet areas, have good room ventilation then it may work. If you have ANY timber in the dew point zone then that is trouble. Yes to be CLEAR if you insulate on the inside you WILL shift the dew point inwards. Look to see what you could damage if you do this. To summarise. There is no point in trying to model the whole house, you'll drive yourself nuts! Just have a think about how a basic wall might work the way you are proposing, be conservative at this stage. Make sure you have no timber in places where water may condense. Make sure you can stop moist air by way of ventilation getting into the walls in the first place. I'm a desinger and SE in my day job.. there is a place for calculations and a time for pragmatism when dealing with older structures. @Julestools hope this helps, check you are spending your cash in the best way! It may be that you are not seeing the woods for the trees? To make a point.. if someone paints the walls with the wrong paint then all you efforts are moot.

I think we probable have space for a 25,000L tank, no idea about putting it underground or overground (wombling free). It wouldn't be ideal but if it was the difference between getting something through and not we would go for it if it was an option and just work round it I would imagine.

We had a similar issue where contractors hit a mains water pipe, they got a fine and cost the repair. Bottom line they are the professional, they are the ones that made a mistake, or had an unavoidable incident, it's their issue to sort out, they are or should be insured for such events, if they aren't that isn't your concern or problem. Don't get involved, anyone comes and starts asking or telling you stuff is your issue, pass the contractors details to them. It's not your issue to question, it's the contractors - getting involved just gets you in the middle of stuff you need not be in the middle off. Tell the contractor to deal with it - it's the issue.

or even if a system was installed. otoh the bco may look at it and say the requirement is excessive as long as the appliance can reach the building... but you would not take a chance on that. Have you space to put a big water tank underground. or 10 x IBC linked ?

None? We have 3 story passiveClass house in NN7. Lived in it for 8 years now. We have no heating on the top two floors. The master bedroom en-suite has a 60W towel rail on a Zigbee-enabled fused spur which automatically turns on overnight for about 6 hours in the heating months. We have an electric oil-filled rad in the hall well that outputs about 1kW and the CH system turns on as necessary in the cheapest (typically) 4-6 hrs on the Agile tariff in the winter months. This tops up the upper floors. Our master bedroom is about the coldest in the house and its at ~ 20°C ATM. It the house as constructed is truly energy efficient then you won't get a 10-15 payback on the installation costs of fancy solutions that you'll never use. E.g. that hall rad costs us maybe £100 p.a. and does the job. Do the math.

I'd be cautious too, because I've heard a lot of guff from mini-pile sales-people, thus start from a position of some suspicion. ie I have been given amazing claims that felt exaggerated to me. It was at an exhibition aimed at the public, not the industry. (To be clear, I've used big piles many times, but never these little ones, which may supply a less distributed resistance and be more liable to ground movement, especially in clay. 3.7m span between screws is quite a long way. Piling engineer response was basically that he believes the spacing is correct but if they wanted extra steel, then stirrups could be placed . Says who? That isn't good enough. How do we know the accuracy of the conversation and result? It needs to be on a drawing or in writing from their SE., and if it has already been assessed then that is an easy thing to confirm and will be approved by the bco. That seems to be plenty of reinforcement.. that isn't the issue really, so it should be resolvable. I don't like the generic look of the drawing btw.. 'piles to suits conditions' is not site specific.

Science is a process. Over time, through repeated experimentation, testing, review and criticism it develops explanations of reality, often based in mathematics, that best fit the currently available evidence. If new evidence is gathered and/or better explanations are developed, then the consensus best explanation of reality eventually changes. Opinions are subjective personal judgements. Individual scientists may hold them, but that doesn't turn opinions into science, nor science into opinions.