Jeremy Harris

We went through a lot of hoops over visibility splays, despite being on an unclassified single track lane that gets maybe a dozen vehicle movements a day, if that. I found that the problem was that they seem to do everything by some arcane formula and are incapable of applying common sense. In the end I suggested that I move the entrance to an impossible location (impossible when on the ground looking at it, as it went up a 1:4 slope) and that caused the highways chap to actually come out to the site. He took one look at our initially proposed entrance (right on a sharp bend) declared that it was safer than my new "impossible" proposal and withdrew all requirements for any visibility splay at all. Whilst grateful that the chap applied common sense in the end, I was just a bit peeved at all the hoops I'd had to jump though. I'd explained several times that the traffic level was very low, and, because of the narrowness of the lane traffic was forced to travel at low speed, but because they had the lane listed as being in a 30 mph zone they insisted on applying their standard rules for that speed.

To fit a 22mm copper pipe to 25mm MDPE (both have virtually the same bore) then you need an MDPE to copper adapter, like this: https://www.screwfix.com/p/jg-speedfit-ug602b-mdpe-copper-adaptor-25mm-x-22mm/49708 (not a recommendation, just the first hit on the Screwfix site) MDPE only accepts plastic inserts. If you wish to use HEP2O rather than copper (I thought you wanted to use copper, from the reference to copper compression joints?) then the guidance is the same as for copper, you choose the size based on the expected flow rate. Main supply pipes feeding several other pipes should be in 22mm, pipes only supplying a basin tap, sink, toilet cistern etc can be 15mm (or even smaller for some of them, where a faster warm up time for hot water is required).

Interesting, as that's pretty much the decrement delay for a brick and block wall with a 200mm cavity, filled with rockwool. SIPs, with a PUR core and a single brick skin seems to come out to a lot shorter time when I calculate it. What's your wall build up, out of interest?

I'm not sure they are mistakes (with the exception of the Legionella risk from the internal rainwater storage tanks, which really does worry me a lot), more choices that don't seem to align very well with their tight budget and ecological aims. Some choices seem OK, like the timber frame and hempcrete, some just seemed a bit odd, like the large (and expensive) thermal store and the inefficient (and expensive) heat recovery system. I'm guessing that they had professional guidance when choosing systems to incorporate in their home, just because I gained the impression from watching the programme that neither of them knew a great deal about building when they started work, yet at that point they had already chosen big and expensive systems for the house, despite being on an extremely tight budget. This leads me to question how sound the professional advice they received was.

I've long since given up expecting die hard activists, of any particular flavour, to be logical. It seems that disinformation and selective eyesight are prerequisites for many of them. Nothing wrong with this, as long as we take the time to understand where they are coming from and why they hold the views they do. What does annoy me is those who ignore hard evidence, or worse still, choose to try and ignore the well-proven laws of physics. For some strange reason the first law of thermodynamics/the law of conservation of energy often seems to attract more crackpot views than pretty much any other. YouTube is an interesting hunting ground for spotting nutters who seem intent on trying to prove that the first law is wrong.

We had a condition requiring that all external finishes, materials etc had to be approved before commencement. In our case the condition specified samples of every material used had to be provided to the planning officer. I spent a day driving around collecting samples from suppliers, then drove to the planning office, carrying a large pile of the stuff. I was barred from entering the building, on health and safety grounds, despite me having the decision notice in my hand stating I had to provide samples. I ended up standing outside (in the pouring rain) talking to the planning officer on the 'phone. He chose not to come out in the rain to look at the samples, so asked me to send him photos. When I pointed out that he already had sample photos in our design and access statement he just said he'd sign off the condition based on those. A frustrating day spent driving around 100 miles that was just completely pointless; he could have looked at our D&A statement and told me that I didn't need to provide samples, but I guess that wouldn't have been as satisfying as making me waste my time...

Have you had a look at standard concrete pipe and rectangular manhole rings?

I think the cost they roughly agreed at the end included £100k for the plot, so they were saying that the build cost was between £100k and £200k. If I had to guess I'd say they may have been closer to £200k than £100k, but can understand them not wanting to make the cost public, given that they had received financial assistance from their families.

The simple answer is yes, the decrement delay with the typical low heat capacity foam insulation used in SIPs panels will be pretty short. As @ProDave has written, though, timber frame can have many different types of insulation, so can be designed to have pretty much any U value and decrement delay you wish. Airtightness can be designed in, too, to save work in having to do a lot of sealing work afterwards.

A bit like me not being an electrician (but having 40+ year old qualifications) and being able to rock up in Screwfix and get an Electricfix card.

I'm not at all critical of either their aims or the amount of effort they put in, it seemed clear that they worked damned hard to build that house, and all credit to them for that. What bugs me is that they were on a very tight budget, yet seem to have been persuaded to spend large sums of money on elements that don't seem to match their stated goals at all. For example, why install a very expensive, bulky and heavy, 2,500 litre thermal store? A family of four just won't need anything like this capacity, and they could have saved a lot of money, and gained some useful space, by fitting something better matched to their requirement. Someone must have convinced them that this was a good idea on their limited budget. In contrast, the timber/hempcrete construction method looked to be a pretty good choice, as it matched their requirements and budget well; it was probably the best way to build the sort of house they wanted, for the money they had,IMHO. Wood stoves are always going to be controversial, as despite there being hard evidence that they cause harmful air pollution, and aren't sustainable here in the UK (unless you happen to also own around the 15 acres or so of woodland needed to sustain a single stove), fitting one is still a matter of personal choice, a bit like choosing to drive a diesel car, perhaps. The Ventive heat recovery system is both very expensive and inefficient, so seems another odd choice for anyone on a tight budget. The apparent absence of normal airtightness detailing also made me wonder whether it was even worth fitting heat recovery ventilation, especially a system like the Ventive, that is highly dependent on natural convection to work. The internal 2,000 litre internal rainwater harvesting system really gave me the willies, though. The idea of storing 2,000 litres of water at room temperature, in vented tanks inside the house, then using that to flush toilets, creating an aerosol of fine droplets into the air every time, doesn't seem to fit in with their desire for the house to be healthy to me. Rainwater harvesting is fine, but it seems essential to keep the storage tanks as cool as possible, as the last thing you need is to create an environment that's near-ideal for the growth of harmful bacteria inside the house. There's normally a requirement to run Legionella control measures on any water system that stores water between 20°C and 45°C, as Legionella thrive between these temperatures. If the tanks are kept below 20°C then Legionella will remain dormant, which is one reason why a lot of rainwater harvesting systems use external, or better still, buried, tanks. With tanks up in the roof space, it seems very probable that they will sit above 20°C, so will provide an ideal environment for bacterial growth. The tanks looked to be 1,000 litre IBCs, so they couldn't have been heated to 60°C periodically. I guess they must be just living with the risk.

It's a standard detail for the Kore passive slab, and any other I'd have thought. Here's the Kore info on their range of passive slabs; all include a Radon barrier as standard; it's shown in every section drawing: KORE-Passive-Slab-Design-Guide.pdf

Yes, as I wrote, they fit a Radon barrier and sump as standard when installing a slab in a Radon area.

I'd guess that the horizontal tie is also preventing outward spread, too, by restraining the purlins from moving apart under the load from the roof. It might be possible to design an alternative method of providing both intermediate support for the purlins and ties to stop spread, but this would need to be done by an SE, as it's not really a DIY proposition (although the actual work may well be).

It seemed pretty clear that this couple had been led by the nose by whoever was advising them, and they just didn't question whether or not the advice they were getting was sensible for their house and budget. Their "eco awareness" seemed pretty flawed, with so many contradictions that I had to conclude that they really didn't know what was harmful for the environment, and their health, and what wasn't. It was a pity, as their tight budget could have been used to build a house with a significantly lower through life environmental impact if they'd taken the time to properly research what would best fit their requirements and budget. Their build costs were around the same as ours, yet I strongly suspect the environmental impact of their house is a lot greater, may two or three times greater, perhaps.

Passive slabs are often installed with a Radon sump and barrier. Our guys came with all the parts to install the Radon sump etc, but didn't fit them because I told them there was no need here, as we're on sedimentary rock. A Radon barrier and sump is only usually needed if the ground has igneous rock beneath, most commonly granite, which will usually contain fairly high levels of radioactive material.

The MVHR used is a Ventive Windhive, up to 72% efficient at best, which is pretty grim, pretty much any other MVHR will run at 80%, many will run at around 85%. However, given the pretty dire airtightness (apparent from just the shots showing the absence of decent sealing anywhere) the efficiency of the Windhive almost certainly doesn't make much difference, so the thing is most probably a bit of a white elephant (or should that be Dalek?). Why a family of four needs a 2,500 litre thermal store, in a house that apparently has a gas boiler, is a bit beyond me. It may well better utilise the heat from their solar thermal system, but still seems a heck of an overkill to me, especially for a house being built on a really tight budget.

We have a passive slab on clay. We dug out ~200mm below the levelled area where our house sits and filled it with compacted MOT3. I did get the clay assessed, and it turned out to be hard gault, with a near-zero risk of movement with moisture change, so not all clay presents a heave risk. Chalk is damned good in terms of both max allowable bearing stress and drainage, so would seem ideal for a pretty simple passive slab foundation.

Same here re: the preheat buffer tank, @TerryE. When I installed it I assumed it would be more useful than it is, but we've stopped using the ASHP to heat the buffer tank solely for hot water preheat now; it only provides preheat if the ASHP has been running the UFH overnight, and that preheat is then only used to shave about 1 kWh or so off the first shower energy use. With hindsight I've have been better to have put the Sunamp in the ground floor cupboard where the buffer sits, as it would have been a lot easier to install downstairs.

The ventilation requirement was intended for timber suspended floors, and I have heard of one case where it's been lifted for a concrete suspended floor, with the undercroft being filled with loose insulation (IIRC I think it was Leca). 175mm of PIR will give just over double the downward heat loss when it's 0°C outside as the 300mm of EPS under a passive slab laid on to ground at around 8°C (there's no particular need for passive slab insulation to be below ground level).

You can easily fit normal MVHR vents through the roof if you wish, there are several roof mounting vent designs available, some of which look quite discreet. You will need to space them apart, though, to make sure the fresh air intake is a couple of metres away from the exhaust.

Could the space under the floor not be filled with insulation, with the vents closed off? The other thing that puzzles me is that a ground bearing slab places far less load on the underlying ground than strip foundations, so on weak ground I can't quite understand why something that's the foundation equivalent of stiletto heels, in terms of the point loads applied to the underlying ground, can be viewed as being better. I can understand the flood risk concern, but that's just a matter of setting the finished floor level above the flood risk level (something we were obliged to do as a planning condition, with our slab).

I watched tonight's programme with a growing level of disbelief that anyone could be suckered into filling a house with so much completely pointless "eco junk". It seemed a triumph of ignoring simple physics in favour of buying into sales hype for expensive, and largely ineffective, technological measures, when a far, far simpler, fabric first approach would have obviated the need for daft extravagances like a 2500 litre thermal store. The house had obvious major airtightness problems, with a total absence of sealing around doors and windows, and even around the wall to roof junction, let alone all the myriad of penetrations through the walls. The couple were on a tight budget, but opted to spend a massive amount of money on pointless stuff, and neglected to pay any attention, or any expenditure, on the things tht would have really reduced the house energy use. The final straw was seeing that they had a non-room sealed wood burning stove (which just illustrated how thermally poor the house is), with a very inefficient (and expensive) heat recovery system.

I'm afraid I really struggle to see any advantage in using beam and block. Thermally, it's poor, as no matter how much insulation you install, there is always going to be a higher heat loss than a ground bearing slab with the same insulation, just because the air in the undercroft will be cold in cold weather, colder than the ground by a fair amount. What's the rational behind anyone using beam and block, as I'm genuinely puzzled?

My worst adventure with explosives (wasn't my idea, it was another club member's) was when the septic tank at the caving club filled up. Usually when this happened, the duty officer for that weekend would round up some "volunteers", and dig the thing out (not nice, as it was almost always one giant, smelly, fatberg). Digging it out meant donning wetsuits and wellies, lifting off the concrete railway sleepers that formed the lid, and climbing down into the semi-solid goo to shovel it out into barrows. This particular weekend, the tank overflowed, the truck was called to suck it out and quickly discovered that the contents were too solid, so needed loosening up. Hoses had been tried, to no avail, so an enterprising member (from Wolverhampton, who, by coincidence, was called Roger) came up with the idea of using a bit of bang to loosen up the contents. A small charge (around 4ozs of plastic blasting gel) was poked into the bottom of a pipe, together with an electric det. The pipe was pushed down to the bottom of the morass, everyone moved away and Roger connected his exploder and blew the charge. There was a satisfying bang, followed very quickly with what looked like a geyser, extending upwards for a couple of hundred feet. Needless to say, this was a **it geyser, and what goes up, must come down. Unfortunately, there was a stiff breeze blowing, so the area where it came down was the car park, where there were around 30 or so members cars... Worst of all, the bang hadn't had the desired effect at all, all it did was blow a hole a couple of feet wide in the middle, so members had to spend the rest of the day hand digging out the pit, then hosing down all the cars.