Jeremy Harris

I may be lucky, but I've never, ever, seen a fire, or the possible start of a fire, caused by arcing. I've seen loads of arcing damage, but 99% of the time this was secondary to an overload condition, something like a plug heating up, allowing the socket spring contacts to deform, so causing some arcing before the circuit naturally self-limited and went open circuit. I've certainly seen arcing in switches, usually it just makes the switch defective, either permanently on or off, or just damages it mechanically so it stops working. All these things look messy, but how many actually cause fires, so needing houses to be fitted/retrofitted with hundreds of pounds worth of (somewhat dubious it seems) AFDDs? I get the feeling that this is a solution looking for a problem, that's being promoted by the manufacturers of the solution as a "must have". There are a few other examples of the regs going a bit OTT in recent years, and I'm beginning to wonder if the IET are really doing a proper, validated, risk assessment before mandating that certain devices must be installed. I should make it clear that I'm all in favour of RCDs etc, but I can't help thinking that banning ring finals, for example, would give a better safety benefit than mandating that AFDDs be fitted.

Polyethylene is very resistant to most solvents. I have 5 litre PE cans here containing toluene, isopropyl alcohol, methanol, monoethylene glycol, methylene chloride, plus a few others, and all are fine. Offhand I think that only solvents like benzine, and maybe napthalene and a few other polycyclic aromatic solvents, slightly degrade PE by tending to harden it.

An application we dealt with a few weeks ago was for a certificate of lawfulness for a mobile home that had been on an isolated site for around 15 years or so, with no form of consent. I drove up to look at it and take some photos for my colleagues, and it was very obvious that it had been carefully hidden by shrubs and trees, It was a few tens of metres off a fairly well-used byeway, yet unless you'd spotted it on Google Earth and then gone looking the chances are no one would ever see it. In their submission, part of the evidence for the length of time it had been there were receipts for two replacement mobile homes, delivered to the location, so the one I looked at was actually the third one that had been there. I doubt that there was any way to prove that it had been deliberately hidden, given the nature of the wooded land around it, but it seemed to me that some effort had been taken to make sure it stayed out of sight. If you deliberately hide an unlawful development than it remains unlawful, as demonstrated by the chap that built a wall of straw bales around the outside of his unlawful development and failed to gain a certificate of lawfulness because it was deliberately hidden, I believe.

I used glass bricks to make an internal, high level, window, that lets a bit of light into one of our bathrooms from the hall. Not only were they relatively cheap, but they are also pretty good at keeping noise out. They let a surprisingly large amount of light in. The window I built is four bricks wide and three bricks high. You really need to use the thin stainless steel strengthening rods in the joints, though, to give the window enough strength.

I don't know of any building-type sealant that will adhere to polyethylene, it has far to low a surface energy to enable most adhesives that set to ever adhere to it for long. Some non-setting mastics do adhere to it well though. These are most commonly used to adhere polyethylene rain screens to the inside frame of car doors. This stuff used to be sold on rolls, with a backing tape, and was generically referred to as dum dum. I can't for the life of me find dum dum anywhere, but this seems to be similar, but in strips, rather than a roll, and a bit expensive: https://www.frost.co.uk/eastwood-flexible-strip-caulk-dum-dum-replacement/ This stuff seems similar, but I'm not 100% certain that dum dum was butyl, so I can't say for sure that it would work the same way: https://www.ebay.co.uk/itm/BOLT-ON-PANEL-SEALER-BUTYL-TAPE-ROLL-STRIP-SEALANT-HEADLIGHTS-CARS-VANS-SEALANT-/251426750877?pt=LH_DefaultDomain_3&hash=item3a8a33c19d I was sure that Sika used to make something like this, but right now I'm struggling to find it.

My desk is a corner one, that's 950mm deep at the deeper end and 600mm deep at the shallower end. The deeper corner is ideal for placing a fairly large monitor, there's just room to fit two 24" monitors, side by side, in the angle of the corner OK, with both being at a good viewing angle when sat looking in to the corner. I can fit the small PC behind the monitors, right in the apex of the corner, which keeps it out of the way. Another handy space saving device is to fit a keyboard drawer. I find this invaluable, as I can just slide the keyboard and mouse away under the desktop when I'm not using them, leaving enough clear desk space to do paperwork. Not sure I'd want a window in front of me, but being able to look out from one side might be nice. Perhaps a curved corner desk arrangement that allows you to sit facing the apex of the corner, with a view out to one side through the window? I've not sat at a curved fronted desk before, but have to say I really like it as an idea. It's a lot easier to hide all the clutter associated with a desk top PC, deep in the corner space.

I can't be sure, but advice I've read suggests taking them at least ¼ mile away is enough to prevent them finding their way back. I'm taking them about ½ mile away, and across the other side of the village stream, so to get back they'd have a fair old hike. I could set up one of the UV marker boxes by the trap, so that all the trapped mice leave UV visible footprints, then go and look to see if any are making their way across the bridge opposite our drive (that's the only bridge over the stream they could use to get back).

I reckon that cat would transform from a 15 W heat output one one to a 30 W version after a few weeks on munching on my mouse population...

One thing I missed out on our build was putting an insect/rodent barrier in the cavity behind the garage cladding. On the house we used catering pack sized stainless steel scouring pads, unrolled a bit, a suggestion from someone on Ebuild. I've just got around to doing the garage, and awkward job, but it has to be done as we have a massive mouse infestation in the loft space (more on getting rid of mice later). As an experiment, I bought a roll of stainless steel wire wool, intended for use as motorcycle silencer packing. The stuff I bought came from this eBay seller: https://www.ebay.co.uk/itm/10m-x-3-Wire-Wool-Wrap-For-Exhaust-Silencers-Stainless-Steel-T304-High-Grade/111442420150?epid=2008975940&hash=item19f27c61b6:g:Or4AAOSwq7JUKXI~ It seems ideal for using as an insect/rodent barrier, as, before it's compressed, it's about 100mm wide and maybe 50mm thick. It will nicely fill a 25mm deep cavity, and is a tight enough fit to stay firmly wedges in place. Stainless wire wool has been tested as being an effective rodent barrier, too, so it should help keep the mice out. FWIW, I found where the mice were both getting in and where they were nesting, by using this stuff, together with a UV torch: https://www.ebay.co.uk/itm/UV-Tracking-Blocks-In-Mouse-Boxes-Mice-Poison-Mouse-Killer-Mouse-Poison/392274391592?hash=item5b55603228:m:mzwkxA-6QRVHAcyGaBL5S0w This works well, and their tiny footprints glow brightly in the dark when illuminated with a UV torch (it was like something out of CSI wandering around with the UV torch tracing their footsteps). Getting rid of the mice once they have established somewhere as a home seems difficult. I've been catching between 2 and 8 a night for well over a week now, with no sign of the numbers abating (they really do breed like mice, it seems). So far I've refrained from killing them, and have been live-trapping them and releasing them about ½ a mile away (guidance I've read suggests they need to be released at least ¼ mile away to prevent them returning). For those interested in live trapping mice without buying an expensive collection of traps, then I can recommend making a simple walk-the-plank trap, fitted to the top of a tall bucket, with a lid fitted around the pivoting plank to prevent the mice from jumping out. There needs to be a ramp up to the plank and the plank needs to be counterbalanced so that it always resets. I used a small magnet and a screw to hold the plank steady, only allowing it to tip the mouse into the bucket when the weight near the baited end is about 12g (about the weight of an AAA battery). It helps to add a small drop of cooking oil in the bottom of the bucket, making sure the base and sides are well coated. The oil stops the mice jumping (a great help when you are trying to lift out a bucket containing 8 fairly frantic mice and relocate them). For those not fussed about killing mice, then filling the bucket with a few inches of water will drown them.

Missed this earlier. Trickle ventilation shouldn't be anything near 2 ACH, probably more like about 0.2 to 0.3 ACH at a rough guess. We ventilate our house at about 0.45 ACH and find that keeps the air nice and fresh, but the heat loss penalty for that ventilation rate is small, as about 85% to 90% of the heat is recovered by the MVHR system.

Not my experience, unless the thing hasn't been turned on for ages and has got a bit dusty. I still have one here that I used to try and speed up the drying of the plaster, as we had water running down the windows for a couple of weeks afterwards. I'll dig it out and try it to see if there's any smell.

We used two very good local guys. They took fifteen days in total to board and skim a total wall and ceiling area of 460m². Their price (labour only, as they weren't VAT registered) was £5,100. Some of the work was a bit more difficult than normal, as the hall ceiling is vaulted and around 6.5m high, and the bedroom ceilings are also vaulted, but only about 4m high. This added maybe 10% on to the costs, at a guess. In terms of price per m², then that works out at about £11/m², at 2014 prices. I recently chatted with the chap that did our plastering and he's inundated with work, is now VAT registered and so is charging a bit more. We are in an area where things tend to cost a bit more, anyway. It's getting hard to find anyone who will work for less than about £200/day, and good people are a fair bit more than that now.

This is where a fan heater works well, as they heat up the air quickly, and even though the structure will carry on absorbing heat for a long time, the warmer air makes the room feel more comfortable. This is just the solution that @SteamyTea prefers, as it's an effective way to heat up a relatively small space to a comfortable temperature pretty quickly. In my old workshop (a single skinned, brick built, uninsulated, garage) a 2 kW fan heater was enough to get that up to a comfortable temperature within about 20 minutes or so.

Best estimate is that the heating requirement for a ∆T of 20°C will be a bit higher, at 428 W, allowing for typical thermal bridging and ventilation heat losses. The slightly better floor insulation is offset by the fact it's a suspended floor, plus the window area is slightly greater than I'd assumed (door area's the same as I'd used)., That's for doors and windows with a U value of 1.2 W/m²∙K, about as good as any DG window is likely to be.

It is a specific SIP issue in the context of this thread, though, as the OP is planning to build with SIPs, so needs to check and make sure that the wall-floor detail is properly designed. My comments were not directed at you, but to the OP, and anyone else that is using SIPs that is not aware of this potential issue. The reason for highlighting this is that it was clear from the thread on Ebuild that there were some people designing foundation details for use with SIPs that were not aware of the potential problem. You used an SE (same one I used) that is very familiar with the potential issues, so designed them out, but that doesn't, by any means, imply that all SEs are as clued up about this (the evidence presented in that other thread suggests that few were).

Our power floated concrete floor went down before the house went up. The door thresholds didn't need to be rebated into the slab, as we just bought Part M compliant doors, that had shallow thresholds that were compliant. We did need to cut small sections out of the 200mm thick upstand insulation where the door thresholds went, though, (before the slab was poured) to ensure adequate support for their outer edge (they all sit wholly within the insulation of the walls, to minimise thermal bridging). One thing you may wish to consider is allowing for mat wells inside the external doors. We have found that a Part M compliant door opens with only a small clearance over the floor, not enough for conventional door mats. We get around this by using very thin super-absorbent mats, which work well, but out of preference I wish we'd made a rebate in the floor to allow a proper doormat to be let into it. We couldn't do this afterwards by cutting out a recess, as we have the UFH pipes within the floor. I can't seem to find the thread, but there's one here that shows a timber mould being used to shutter a rebate for a shower tray, that might give some ideas as to how to go about it.

Thanks, that seems entirely sensible to me, as that EPS upstand should significantly reduce the potential problem. I also think you're right about the way loads are better able to be transferred through the OSB web of the I beam from one member to another, with the web being able to take significant loads in shear. I beams are different to SIPs in this respect, as the SIP manufacturers are usually fairly clear that the foam core should not be relied upon to take sustained shear loads (sustained being, I think a key point, as I believe their concern may be about long term creep and possible delamination of the skin - core bond). That's why they usually seem to require that both edges of the panel have adequate structural support at the base, as the skins are bearing the vertical load (which is unlike pretty much any other timber frame construction method). I'd guess that there maybe other ways to transfer the load from the outer skin to a point inboard of it, so allowing insulation to lie under the outer part of the panel, but it's still a detail that needs care to work through.

Not just a SIP issue at all, but still one that applies to SIPs when used with a passive slab, as it does to other timber frame construction methods on a passive slab. The example I quoted of @PeterStarck's build, which uses foam-filled I beams has potentially the same issue at the sole plate, which is why I speculated as to how this might have been overcome. I can't recall the detail, but think he used an external insulation layer to address it, much the same as Kingspan agreed was a good solution for SIPs in this particular type of construction. Other solutions are to use insulated load bearing materials, like foamglas, to reduce thermal bridging (pretty sure this may be a standard detail from some SIPs suppliers). As long as the floor-wall detail is designed carefully then I can't see there's any problem, but there are certainly examples of some SIPs builds where this detail has been poorly thought through. It's a potential issue that came up in a thread on Ebuild, where examples were given of wall-floor junctions for SIPs construction that were potentially iffy, in that thermal bridging just hadn't been adequately dealt with in the design. The same is true for early timber frame builds - who can forget the disasters from early English timber frame builds in the 1970s and 80s that rotted out due to a failure to understand interstitial condensation risk. A former colleague bought one of these 1970's timber frame houses, built by Barretts, IIRC, and ended up having to have the external walls replaced after a few years due to rot. The problem was that they had built the walls with the sole plate bearing on a cold foundation and had failed to provide adequate vapour control.

Some of those points are interesting in themselves, as they raise questions as to how different local authorities view things. For example, here we have no pavements, or protected areas for pedestrians, we actively discourage external lighting, and have virtually no street lights (and are removing what few there were, as a part of the AONB drive to gain Dark Skies status). Everyone in the village just carries a torch when they go out in the evening (need to, as it's literally pitch black outside here on a cloudy night). There is an acceptance here that private cars are still pretty much essential, as although we have two bus services (one run by the county bus company, the other a community run minibus) neither are that frequent. A recent application I looked at near here was for a single dwelling on a hilltop, at the end of an unmade byeway (a pretty rough chalk/gravel track that cars can just about get up) and a bit over a mile from the nearest tarmacked road. I strongly suspect that it will get approval, as there has been temporary accommodation up there for years, albeit related to agricultural work. Likewise there have been several barn conversions in the open countryside, or outside any defined development boundary around here. One just outside our village looks very likely to get approval, as the existing listed barn is on the verge of collapse, so converting it will give it a new lease of life. One of the nicest I've seen in recent years was the conversion of a small old chalk cob barn into a 2 bedroom cottage. The roof had gone and the chalk cob was collapsing badly, but by allowing it to be converted to a cottage, albeit with a timber extension to allow for enough living space, it now looks much as it did 100 or so years ago, when it was still in use. The flip side seems to be that gaining PP to squeeze in a house into a tight plot within the development boundary does seem to be getting more challenging. Some of that may be because the street scene within a conservation area, and AONB, seems to carry significant weight as a planning consideration, and some relates to requirements for vehicle access, particularly enough parking, together with the turning space needed so that cars can always enter and leave in forward gear. The latter policy seems to be one that is fairly strongly applied here, and caused me some challenges in making enough space on our tight and steeply sloping plot.

Not really, it varies on several factors, not least being the heat capacity and thermal conductivity of the type of construction. A low heat capacity structure will respond very differently to dynamic changes, particularly in the external layer, than a high heat capacity structure, for example. @PeterStarck's build uses an I beam portal frame on a passive slab, so he also had to ensure the detailing was right around the floor - wall junction. This may have been easier, as I beams are probably better able to transfer vertical loads from the outer member to the inner one via the OSB web, so reducing the load that the outer member applies to any supporting structure. I can't recall offhand how he did this, but have a feeling that the outboard side of his frame bears on an EPS upstand, a bit like ours. Perhaps he could give some input if I have this wrong.

Place the 140mm stud on the passive slab ring beam and add external insulation. A 140mm stud wall will almost certainly need more insulation added, both to get the wall insulation up to a reasonable value and to mitigate thermal bridging through the studs, so the external insulation layer can just extend down over the floor - wall junction and mitigate any thermal bridging at the base, too.

I had three quotes for a 6m x 4m timber framed garage, clad with larch, with the timbers visible at the front. Prices for the basic structure, less roofing and cladding, varied from £8,800 for Douglas Fir to £15,400 for oak, from three suppliers, two local and one near Bristol. I had to amend our planning consent because the original approval included the frame being on display at the front, and when we switched to a house-type timber frame the appearance changed slightly. IIRC, the cost of our insulated timber frame garage was a couple of thousand less than that for the Douglas Fir version.

The key thing is that SIPs wall panels have the vertical structural loads spread equally between the inner and outer OSB skins, so need these loads to be taken equally into the foundation. A timber frame can be designed to place all the vertical loads towards the inside face of the frame, so alleviating the need for any support under the outer face. The thermal bridging issue is just one of how best to keep both SIPs skins adequately supported, without creating a thermal path from inside to outside through the supporting structure. There are options available to do this, it just needs a bit of careful detailing, that's all. A 140mm timber frame will need additional insulation just to meet building regs, so adding this on the outside removes the problem. The same can be done with SIPs, and this was the option I wanted to use when we were originally going to have a SIPs build (we only didn't because the SIPs builder's prices were higher than we would have liked, and they were really slow to respond at the time).

The main difference is that a timber frame (like our twin stud) can be designed so that all the structural loads are taken on the inside member, with no load on the outboard one. In our case the inboard stud bears on 100mm of concrete and the outer stud bears on a 200mm wide bit of EPS. SIPs is different, in that both the inside and outside skins are equally loaded, so both edges of the sole plate need to bear on something load bearing, like concrete. You can't easily use the same sort of thermal bridge free passive slab that we have with SIPs, so care needs to be taken to design the detail at the base to both support both side of the SIPs panel and also to ensure that there's no thermal bridge at this point. It can be done, just needs a bit of careful detailing to get it right. Adding external insulation at the sole plate is one solution (there are others). There was a thread about this on Ebuild, where Kingspan SIPs got involved, where the issue was discussed in depth, as it was clear that this particular potential gotcha hadn't been thought about in terms of dynamic interstitial condensation risk. A design can look OK on a static condensation risk analysis, as this may not accurately model the sort of dynamic changes that can drive water vapour in from outside, towards a region that may be below the local dewpoint. This then needs a significant heat input, to an area that may well be normally cool, to evaporate moisture out again. In the debate on Ebuild, Kingspan agreed that adding a layer of insulation around the perimeter, would adequately mitigate the risk. The dynamic risk does depend a fair bit on other elements of the design, including the type of external rainshield skin used.

Welcome. As @ProDave has said, £1200/m² is achievable, but likely to be a bit tight, especially for a relatively expensive build system like SIPs, I think. When interfacing SIPs panels to a passive slab there is some critical detailing to get absolutely spot-on at the sole plate/foundation interface, as SIPs panels need support on both the inner and outer faces (as the skins are load bearing) and this creates a bit of a challenge to get a thermal-bridge free junction (can be done, just needs care to make sure there's no dynamic interstitial condensation risk at the sole plate from rapid external temperature and humidity variation). To complete within 7 months and come in under £1200/m² will mean some long working days of hard work, as you will need to do a fair bit of work yourself to keep the cost down. As a guide, our build was a passive slab and frame package, where I did most of the work internally, after the house was wind and watertight (that process was quick, 4 days for the foundations, 4 1/2 days of frame erection to rain proof). I had just taken early retirement, so could be on-site every working day. Leaving out the time spent dealing with problems that weren't directly associated with the build itself, I spent about 3 years of full time effort on the build, and it came in at about £1380/m². Much of the prolonged build time was because it took me much longer to do things than it would have taken a decent trades person. At a guess I'd say that most jobs took me around three or four times longer to do many jobs, really just because I had to learn new skills, plus working on my own was much slower, especially when moving heavy or awkward stuff.