Jeremy Harris

I agree, let it sit for at least a year. I went around filling minor settlement/shrinkage cracks too soon, and now have to go around again re-doing them sometime.

I've not heard anything about them using aerogel, but it would seem a reasonably good application for it, as the high cost wouldn't be such an issue given the relatively small amount of insulation needed around the heat cell.

I've seen it used for basement waterproofing, as a layer applied on the outside of a basement wall. IIRC, the stuff used was either Bentonite or something that looked very similar and was sprayed on to the membrane on the outside of the walls. The stuff has been used for decades for waterproofing, arguably it's been used for hundreds, maybe thousands, of years, given that the use of clay that expands when it gets wet, to form a water proof barrier, has so many applications in civil engineering.

In essence it's the same principle that has been used for waterproofing in a range of situations for many years; using something that swells and becomes an aquatard. Canals used puddled clay as an aquatard layer, which works on the same principle. Boreholes and wells are sealed around their casings with a similar material, usually Bentonite, a form of refined clay that swells a lot to form an aquatard around the casing, to prevent surface water from running down the sides and contaminating a clean aquifer, or to stop pressurised underground liquids from being able to reach the surface around the outside of a well casing. Bentonite or similar expanding clays can also used to waterproof basement walls, by putting a layer of the stuff around the outside, before the backfill.

How much experience do you have with casting concrete walls, though? Have you built enough over the years to be able to state definitively that water bars (something you knew nothing at all about until this morning) are not a useful way of allowing a non-monolithic pour to be watertight?

No, it's used on any vertical concrete wall that's built in more than one pour and that's required to be watertight. Ideally, walls that need to be watertight would be done in a single monolithic pour, but where that isn't possible a water bar is a standard detail, one that's been in use for many years now.

Water bars are a standard detail in any vertical concrete pour where there is more than a single pour and a requirement for the wall to be watertight.

That fits exactly with the conversations I had with our DNO about the pole and cables crossing our plot. There was nothing recorded at the Land Registry and the DNO's view was that the original wayleave hadn't been carried over to either us, or the chap we bought the plot from (who wasn't even aware of the big underground cable crossing the plot).

Possibly, but it wouldn't be as effective as toxins that specifically target plants, plus it would pose a risk to beneficial organisms in the underlying soil. Unfortunately, persistent weedkillers have all been found to be too harmful to the environment, and I'm not aware of any that can legally be used now.

The only thing I hate about Jeye's Fluid is the nasty persistent smell of the cresol and phenol in the stuff. I used to use a power washer to clean the paths here too, but it's really slow when compared to brushing some bleach over it and just hosing it off. The other snag with using the pressure washer on sandstone is that I've found it tends to damage the surface of the sandstone paving, although it's fine on the drive pavers.

No, it's fine, the only slight risk is the same as that from handling bleach. Just chuck a couple of table spoons of calcium hypochlorite into a bucket of water, stir well, then brush it over the blocks. If you want to mix up a litre of concentrated bleach, then chuck about 4 or 5 tablespoonfuls of the stuff into a litre bottle and shake it very well to get it too dissolve and you will end up with a solution that's pretty much the same as unthickened household bleach.

Are they cheaper than hypochlorite though? I bought a 5kg drum of hypochlorite about 4 years ago. I still have about 4.9kg of the stuff left. I reckon there will still be some left when I shuffle off this mortal coil, at the rate it gets used for cleaning the patio and paths. 5kg of calcium hypochlorite granules will make approximately 166 litres of normal household concentration bleach. Last time I bought some I paid around £20 for a 5kg drum from a local swimming pool supply company. That works out at about £0.12/litre of concentrated bleach solution, so it's a pretty cheap way to clean stuff.

No, they are obliged to offer you a connection, although they can charge whatever it reasonably costs them to do this. Their charges are regulated, though, and they can only charge you for work that only they, specifically, can do, so in practice there is almost always scope for negotiation over connection charges.

Probably not worth bothering about, just run a brush over it and carry on. If you really want to get rid of it then washing with a mild bleach solution as @ProDave suggests would be as good as anything. I clean our sandstone patio with mild bleach once a year, works a treat and if hosed off with loads of water doesn't seem to cause any harm to the garden. I don't actually use liquid bleach, but just a spoonful of calcium hypochlorite ("pool shock") in a bucket of water

Looks about right to me. It's a shame that the building regs mandated figures are so high, especially in your case where the disparity between the floor area-mandated rate and the sensible ventilation rate is so great. I think you could probably rely on having the MVHR running at a higher than normal level in order to achieve BR compliance, through, then wind it down to something more sensible as others have done. This might mean you could accept duct velocities of around 2.5m/s in order to achieve the BR rates, secure in the knowledge that in reality you'd be running at a lot lower flow rate pretty much all the time.

The poles and cables up to the meter are owned by the DNO. The electricity supplier is just an agency that buys electricity and sells it, they don't normally own any of the infrastructure, with the exception of meters. A wayleave or easement is normally required for any equipment that is owned by another entity and which is placed on, over, or under private land. A landowner may or may not have the right to prohibit the placing of equipment over, on or under their land, depending on the particular circumstances, but utility companies in general (including DNOs) are reluctant to invoke any legal right they may have, as it often results in higher costs for them in getting that legal right imposed. Getting a wayleave is cheaper, quicker and simpler for them, and generally DNOs won't have the lawful authority to run an LV cable over or under private land, anyway.

You'll probably find that figure dominates the others given in building regs, as it usually does. It will also over-ventilate the house by a fair bit, as 177m³ at the typical PHPP ACH of 0.3 would mean a whole house ventilation rate of around 15l/s, and the ~0.4 ACH figure we run ours at would give you around 20l/s.

The floor area figure used is the internal floor area of all floors in the house added together. I thought you'd posted earlier that your floor area was 177m², hence the use of 177 in the sum, but I may have got that wrong. Edited to add: Just realised I have got the floor area wrong. I saw 177m³ and misread it as 177m². If the internal floor area is 310m² then the total supply (or extract) rate needs to be 0.3 x 310 = 93l/s

I agree with the above, about negotiating with the DNO, as it's exactly what we did. We didn't mind having the pole in the front corner of our plot, and knew that the DNO would have had a real problem if we decided to tell them to just remove it, as it carries a 3 phase supply over our neighbours lake, so couldn't be run underground. During my discussion with the DNO they confirmed that it's pretty common for there to be no wayleave or easement in place, and I was told by SSE (our DNO) that they believe that many older agreements were lost when the distribution network was privatised; apparently records weren't always transferred and this was compounded by the Land Registry often failing to record agreements that were originally in old sets of deeds and conveyances. In our case I think we got a pretty good deal. The DNO agreed to move their pole and underground cable that crossed our plot at no charge. I agreed to pay to have an overhead cable supplying a neighbours house, that was running along the front of our plot, relocated underground, alongside other services that were going in a trench around our plot anyway (I just agreed to pay for the cost of the cable and the alterations to our neighbour's connection). We also gained easy access to a big supply cable that now feeds our house, which meant that I gained G59/3 approval for up to 12 kWp for any microgeneration we might have (I asked for 6.25 kWp and they volunteered up to 12 kWp). We ended up with no overhead cables crossing our land at all, and a pole in a location in the corner of the plot where it's out of the way, so all around I think things worked out pretty well. The only problem with the DNO was that they were very, very slow. We had to pay them upfront in full for the work we'd agreed to, and yet they delayed carrying it out for four months, causing us to delay the build by around a month.

At guess I'd say that a TIG welded stainless tray probably wouldn't cost more than a decent shower tray. Not a lot of work in folding and welding one up, and the plate cost would be somewhere around £200/m² at a guess, less if you have a local metal factor who takes cash for small quantities...

Pretty common to have no wayleave or easement. I've experienced this three times in places we've owned, including our present house. I managed to negotiate with the DNO on the basis that their existing pole and underground cable was crossing our land without authority, and had part of the cost of putting a new pole in place and running overhead cables underground absorbed by them, on the condition that we agree to a wayleave with them.

Two points, AFAIK you cannot get 125mm semi-rigid duct, it only comes as 75mm OD, or 51mm x 114mm oval. Probably best to use double runs of either for the kitchen, just to be sure of getting enough flow on boost extract. The second point is that you need to meet the 0.3l/s per m² floor area requirement in building regs, which means that the total extract (or supply) needs to be 177 x 0.3 = 53.1l/s as the background ventilation level. The sum of all the extracts, or the sum of all the supplies (should be exactly the same number for a balanced system) needs to be at least 53.1l/s. Also, ideally you should aim to keep the flow velocity below 2.5m/s in the ducts if you can, as that's about the threshold where duct flow noise starts to be heard (in practice I've found you can go a bit above this without any noticeable noise, though). For those runs where you're getting up to around 2.8m/s - 3.2m/s I'd be inclined to double up the 75mm duct runs, to reduce the velocity a bit.

Sorry, I meant 30mm in the sense of Re, i.e. the thickness of the door being L. Should have written "thick" rather than "wide", but my brain was still in Re equation mode, and thinking of the view perpendicular to the direction of air flow.

Me too. I think these schemes are really taking advantage of those who don't know when their peak rate demand is or what impact that may have on using battery storage. I can load shift some things in the house, like heating, hot water boost charging, the washing machine and charging my car, so these are on during the off-peak period in winter, when we're not generating much from the PV array. Having said that my car has been charging for most of today at the equivalent of about 20mph only from excess PV - it's really clear and bright today, probably the best total generation day we've had so far this year. I can't load shift the evening peak from cooking, no matter what, so we'd always need enough battery capacity, and inverter power, to meet that peak demand.

Not in building regs specifically, although they do give a total house ventilation rate, which is 0.3l/s per m² of floor area. IIRC, PHPP normally gives a ventilation rate that's around 0.3 air changes per hour, which is a bit lower than I found to be comfortable (we run ours at just over 0.4 ACH). I think if you aim to be able to run the background ventilation at around 0.4 ACH, with the capacity to be able to boost this to around 1 ACH or more, then you should be around the right ball park. It ends up being a matter of choosing an MVHR from any given range that's the best fit, anyway, and we ended up with a bit more ventilation capacity than needed just because the next model down was really a bit too small.