andyscotland

In terms of a building control certificate, that depends on where you are in the UK. And as @nod says there will be sparks who are capable of doing a decent job but wouldn't for example be able to issue a Part P certificate (for English building control) due to not having paid the money/kept all the many things in date to be on the Part P register. However, you absolutely should have had an Electrical Installation Certificate with accompanying schedule of test results. There's no specific restriction on anyone issuing those - if you're competent to do the work you're competent to issue the cert. That is a fundamental requirement of BS7671 (644.1) and I would be concerned about anyone who did this kind of work without meeting that requirement.

All air contains moisture(*). What matters is the combination of how much moisture there is and how hot the air is. The warmer the air, the more moisture it can carry. If slightly warmer air is next to slightly colder air, it's easier for the moisture to stay as moisture and move to the warmer air, so everything stays in balance. Think of it like a big wedge made of toilet paper, the "cold" end is a single sheet thick, the "warm" end is several sheets thick. If you slowly pour water on the thin end, the paper will start to soak it up until it is saturated. If you pour more water on, the paper will draw it across to the thicker pile (even though that means the water is flowing upwards!). Only when all the paper is saturated will you start to see liquid water lying on top/overflowing the edges. But if slightly warmer air suddenly touches something cold, the air right next to the cold thing will be much colder and the moisture will have to condense into water. (Here imagine you rapidly press down with your finger on a wet bit of the thick toilet paper, so it is suddenly only the thickness of the "cold" end. If there is still some dry paper, you'll see it get wet. If all the paper is wet you'll see water leaking out) The moisture in the air under your house will mostly come from three places: the outside air, evaporation from the solum, and warm moist air leaking from your house. The outside air will be cold but by definition not be saturated (unless you are literally inside a rain cloud). So the air will be able to absorb some of the house moisture even as the house air cools. The solum (generally the coldest surface) then acts as a kind of buffer. If the air under the floor gets saturated (because it is cold and/or humid outside, or the house is humid inside), water will condense onto the solum and soak in making it damp. Nothing will evaporate from the solum because there is nowhere for it to go. But then on days when it is warmer/drier/you've had the windows open in the house, the air will not be saturated so the moisture in the solum will be able to evaporate. So - assuming your ventilation etc is as it should be - over time and across the seasons you will get a variation in dampness down there but it will balance itself out. * Well, not air in deserts or up mountains, but... If you use foil just below the wool, it will do very little because moisture can still get round it and will go to the places that are weakest. If you use foil across the whole loft (under the wool and over the joists) it will trap moisture at the top of the joists where they are cold and that will cause problems. You either need a fully sealed and continuous vapour barrier below the whole loft construction (e.g. between joists and ceiling) or you need to design the construction to breathe and then ventilate the loft, which is the standard detail for loft insulation in existing construction.

Condensation in buildings varies significantly over time depending on outside and inside environmental conditions (temperature & humidity) and the difference between them - and in this case also the temperature of the outside water supply and the amount of time that water is flowing/not flowing, since that will control the surface temp of the pipe. Small differences in any of those factors can be enough to make condensation appear or not at any particular moment. I'd be surprised if you'd get enough evidence over a few days/weeks to understand the long-term performance of that junction. Whereas there's plenty of evidence that the usual pipe lagging solution will work. Because the mineral wool is breathable, allowing a temperature and humidity gradient across it, so the condensation doesn't form at that interface. Big condensation issues in buildings are almost always caused by constructions that trap moist air in the wrong places.

The air under your house will also be slightly warmer than outside (because it is sheltered and being heated by the house above) and will still have humidity (from the house, and from the ground, and from the outside air). At this time of year, the water pipe itself will likely be colder when water is flowing. So you will potentially get condensation on the MDPE anywhere it is not lagged, but particularly as it gets closer to the house air as the air temperature will rise but the pipe will be the same. With your ideas (taping foil over the top / putting PIR over the top) you are allowing that condensation to form at the top of your floor surface but attempting to seal it there. Hence why your foil was wet underneath. This will eventually be bad for the flooring/structure of the house because that is not designed to be permanently damp. With the pipe lagging solution that everyone else is suggesting, you are *preventing* the warmer air from touching the pipe, so it will not condense in that area. Even if this is only a short length down to just below your joists, that is enough to stop condensation forming where it's a problem. You might still get condensation on the section below the lagging, but this will either evaporate off (due to your subfloor ventilation) or drip onto the solum and eventually evaporate from there. Neither of those is a problem - the solum is expected to be slightly damp at times and the house is designed to accommodate that.

If you've just taped that patch over the hole and there's a void below (I assume?) then the air from whatever that void is can still get to the pipe surface and if the pipe is colder than the surrounding air it will likely condense. You need to completely enclose the pipe.

You can either pack the framework up so that it starts where you expect FFL to be (which is IMO the best solution), or once you have it all installed order a door of the appropriate (shorter) height to hang above the flooring.

The British gypsum white book is also a good resource https://www.british-gypsum.com/specification/white-book-specification-selector/white-book-overview

It's worth confirming which part of the UK you are in as the rules are subtly different in each country. For example in Scotland as soon as there's any sort of toilet/shower etc the structure requires building warrant approval regardless of size. Not sure if that applies elsewhere.

Yeah as others have said dust and smoke alarms do not mix. If you are still doing works and want some temporary protection then you could consider heat alarms (which can be suitable for dusty environments) and then replace with smokes at the end of the project - however these take longer to detect a fire so may not be suitable if you are living/sleeping there. Otherwise you need to cap them (or remove them) any time the house is dusty and/or treat them as consumables if you're sleeping there during works and want peace of mind that you'll get early warning to evacuate overnight.

That does look relatively full to me. A 6 core cable will be even more rigid round bends I think. Also as @-rick- mentioned that does look like you're trying to pull them as one big lump, it will be much easier if you spread out the point where each one joins onto the one before so that you get as much of a taper as you can. The thinner cable will help to lead the following cable round the bends and so on. Possibly, it will have fewer snag points on bends and obviously will sit dead straight in the sections where your flexi is dropping - but you can potentially solve those without swapping it all out. Also the smooth conduit might actually have more friction along the length (the cable is in contact with the wall all the way, unlike flexi where 50% is on a ridge and 50% over a valley) so might not end up much different. For bending you don't need a heat gun (and can easily over melt it that way), just insert spring, rub up and down the outside with a rag a bit to gently warm it a little, then bend. Bend it slightly over the angle you want then you can ease it back to the exact angle as you fix it into place.

Plus the existing network cable? I agree with @-rick- that sounds quite a bit for 20mm with bends. It won't be helping if they're 4 core sheathed - you'll be losing space to the sheath and also that makes it more rigid around bends. If the whole run is in conduit between boxes you could use singles, starting each one staggered after the other as @-rick- said.

No, I think maybe you've missed mine 😁 Absolutely, kitchen should have a heat alarm. However, it is possible for cooking smoke to leave the kitchen (especially if an extractor hood is not in use) and depending on the layout and airflow in the house that can make it to a smoke alarm elsewhere (e.g. in a location where it is compliant/required such as a hallway or landing). With an interlinked system this can then cause a nuisance alarm on the whole system. I'd only got mentioned it because of @Redbeard commenting they'd had a lot of nuisance alarms on their newer interlinked system : one possible explanation is that the smoke alarms were in different locations to the old standalone ones, or that they were more sensitive/reliable than the old ones thus picking up kitchen smoke wafting around outside the kitchen.

Absolutely, but I've seen places where a smoke alarm has been mounted outside a kitchen but near enough to it (or further away but in the natural path of airflow from the kitchen through the house) that it triggers. I agree with a well designed system & correct selection/location of heads there shouldn't be an issue.

I believe they're being discontinued - possibly partly because AFAIK they don't meet the building regulations requirements as they're not certified to the relevant British Standard and interlink over WiFi so won't work if your router is on fire. Depending on the circumstances of your nuisance trips this would suggest perhaps: * The mains alarms were doing a better job of detecting actual smoke (burned toast etc) than the old battery ones. I'd say that's a benefit but might mean they weren't the right types or locations of alarms for your property. * They were mains powered but radio interlinked and perhaps not properly house coded (or from one of the cheaper brands) so picking up interference from elsewhere. * They were mains interlinked but with a fault in the interlink wiring causing unwanted triggers. I'd say interlinked alarms (from a decent manufacturer) have a lot of safety benefits over standalone ones in terms of detecting and more importantly waking the occupants in time to evacuate - especially if mains powered and wired interlinked. If you do occasionally get cooking smoke etc spilling out of the kitchen to the rest of the house then you can minimise impact of nuisance trips with a remote control to silence alarms next to the cooker (much easier than running around the house flapping a tea towel 🤣)

It can also help to do it as a two person operation - one applying fairly constant tension on the draw wire/cord (good job for a teenager if you have one 🤣) and one pushing the cable in at the other end. I've found that reduces the tendency for it to poke into a ridge on the bend rather than going round. Make sure both the push and pull are directly in line with the end of the conduit opening to at least eliminate the friction at those points.