saveasteading

I too have tested very small bits of insulation on a fire. I justify this as being best for the planet overall....a few fumes and a lot of knowledge. Polystyrene burns and melts and drips and spreads Polyurethane , whichever letters, was similar. (presumably I have not seen the more resistant one) PIR burned but went out when the heat source was removed. then burned to nothing when back in....lots of black smoke. Fibreglass makes a little smoke (from the glue?) and turns to sand mineral wool , the light insulation type, as for fibreglass mineral wool as fire barrier just sits in the fire. sheeps' wool, stinks and somehow disappears but doesn't burn as such. mdf/cellulose board....not tested

Thanks ADLIan . Would it have been PU that was a previous issue, and PUR is more fire resistant?

Hi, welcome. You get about 10% at most off the warrant application fee if you use certified designers. Our project is being submitted this week, is by a Chartered Engineer (me) and Chartered Architect, but not registered in the system as working in England. It would have cost about £2,000 each and a lot of effort to get on the registry. I will report on how it goes. If I was the building inspector I would look at the qualifications, at a few details to spot check information and design knowledge, and approve it. But they are entitled to send it out to as many consultants to check as they like. I did I don't have any problems with being checked, but it takes time, and there is always more than one way to do something. I did 3 projects in Scotland but before the registry , and it was much more a matter of trust than in England. The local builders say they have seldom seen a BCO. That is understandable in Highland Region as they could be on the road 95% of the time due to distances. Some on Buildhub say that they simply send reports and photos, which the BCO may or may not look at. I guess it mostly comes down to trust and confidence. It is that in England too, where perhaps 5 visits cover the project and it isn't by spot-check but invitation. So you will save 'much time and effort' mostly by having a good design. If you are not a building designer then you need someone who is, as the BCO only checks bits and pieces, and doesn't do the design for you. Cross fingers for us please, and good luck for your project.

Non-scientifically: The samples I have seen look very different. PUR looks like the white foam you see in packaging for delivery protection. PIR looks like a denser 'Crunchy' bar. I recall having a client's insurer panicking about 20 years ago, because there had been nasty fires where PUR was blamed. If I remember correctly, it drips as it burns, and so spreads fire quickly. It was then withdrawn from use in commercial composite steel panels, although still used in agricultural sheds. I have been involved in picking up the pieces in 2 fires. one was made much worse by polystyrene insulation in the roof, from a very different era. the other was a nasty fire on the outside face one of our own completed steel buildings: arson/vandals setting fire to a huge pile of bagged sawdust stacked against the metal wall. The paint on the steel cladding was burnt off, and the fibreglass cavity turned to sand. The screw fixings lost their heads and washers but stayed fixed. There was no structural damage or distortion. So I had the chance to discuss with the fire officer. He was amazed that the wall stood up to the heat and delighted that the insulation just disappeared. He said they were ready for the fire to enter the building. I told him it was designed as a fire barrier wall, (fibreglass to stay in place 15 minutes before failing) but his opinion was that they seldom worked so this was great. Went on to discuss PIR filled composite cladding. Off the record they hated it and were scared of it falling off the walls, so they never went near it. So, I think the fire service knew of problems with PIR but couldn't prevent its use. I asked if I could quote how impressed they were with our wall, and he said no: they are not allowed to comment on commercial products. If we had used rock-wool instead of fibreglass I wonder how it would have performed. Not as much difference as is implied I feel, unless it was the special fire resisting variety. Grenfell: I recall reading that the sample sent for fire testing had an added sheet of cement board that was never made part of the product. That would make it manufacturer specific. the other manufacturers' products would have behaved in the same way, but had not made the same claim. How to stop it happening again? Nobody was in overall charge. The old position of Borough Engineer would have been that person, but there was none such. Would they have spotted the problem? Probably yes I would say, as they would have had the authority to have it all designed and proven, and not changed without approval from the top. But the other parties would have complained about bureaucracy and interference. Anyway, there is no such role any longer as accountants and 'executives' took control of the councils.

Piling is favourite. Don't hesitate to contact several companies as they have different kit, processes and overheads. I would phone and ask for their Estimator or Sales Engineer, who might be the same person. If it really doesn't suit them they will likely give you another suggestion. Also there are driven precast, driven in-situ, bored in-situ, and gravel piles to consider. If other neighbours wanted the same at the same time, then it could help the cost a great deal, in the arriving ('mobilising') and tidying up costs. Watch for the exclusions. They will want and need good access, hard standings, water, and someone else to clear up the leftover concrete. then you have to cut back the heads of the concrete too. If I had to guess I would say the best value will be from either a small, local piling contractor, or a driven pre-cast specialist. Precast can include tidying the tops off and installing beams to your plan, and I would suggest getting a price for that.

Does that mean that you forego reclaiming VAT on the remainder of the works? Oh, and congratulations. Was there a moment of joy that it was done, or was it just another stage?

Clearly Gus and others have done this in real life. Theory is great but everything changes when a big concrete wagon turns up. The pressure to pour in 30 minutes, the force of the concrete pushing most things away, the groundworkers start shovelling like mad and standing on the wrong places and your bits of eps and diagonal bars end in the wrong place. Therefore I suggest a timber boxout for each pipe, held with a few spikes, and laid when there is calm and a chance to check it. And the pipe that is in the boxout should be closed off with a polythene bag and sticky tape or string, so it doesn't fill with concrete. For all the above, double the risk if the weather is foul. Miserable people with hoods up, mud on the site, water getting in the concrete. Design and manage with bad weather in mind, and it doesn't rain. The diagonal bars are very important, but the groundworkers don't understand, never will and will not put them in (or may even take them out if they are not tied.) (Because they know better than any Engineer). Therefore this is a diy (or commercially, senior management) job , with tying wire to secure the bars to the main mesh.

I have been referred by BH correspondents to some excellent documents, especially by Historic Scotland, and subsequently quoted in government docs. They are saying that solid walls, if thick, provide better insulation than theory would allow, and any sort of gap and inner lining helps even more. They give figures for real life tests, and they vary a lot, but normally better than the U value calculators would give. This is unless the wind whips through it naturally or you are made to put in vents. To trees in rock, add rowan, which catches and grows on cliff faces. It would move elsewhere if it could, but it doesn't have a choice and seems to grow anywhere that other trees don't. Also keeps witches away.

When done, and the demo wood has been used, we will have any amount of abandoned branches in the nearby felled commercial forests, but it is probably too tarry for the only wood in the burner. There is a little area of woodland but it isn't far off being natural so don't want to touch that, including the fallen trees that are full of oozy life. Any advice on pollarding? If we were to plant soon, what trees should we use? Sand underneath for 1-2 m then probably rock.

It seems to keep the sheep cosier than a layer of fibreglass would. But I see what you did there: R = Ram U = Ewe λ = lamb I have found some stuff on converting wool, and it would seem to need an awful lot of washing, to get rid of manure, lanolin, weeds etc.so perhaps not as 'green' as it might seem. Maybe try washing a fleece in the cement mixer next summer.

Civil Engineer with capitals please, as many a groundworker has decided to hijack the term.

I am familiar with the substantial air gap at the interface of a bottom cleat for metal cladding (disregarding the old detail of not facing it at all. Our detail had a flexible mastic under it, but there were still noticeable gaps. Best found by looking out from dark to light. Tape was the answer if it was too wide for mastic. ( a long timber or steel onto concrete will have gaps even if in tolerance), and you hope it stays there permanently. We will be doing this properly! No air test required so all the more reason to look for the gaps as we go along.

I mean the output pages. There are lots of histograms and pie charts telling you where you are using notional electricity, including cooling and heat exchangers. I can't remember if there is even any allowance for where you are in the country. Your assessor should be able to copy it all to you. It is genuinely interesting, though annoying.

I need convincing on that! anything I have looked at would never pay back the capital. Even running the cold intake past the waste involves a lot of rerouting. es sticky tape and mastic. Comes cheap by the box. With a new 'stick' construction ( now 1/5th of the job) there are lots of potential gaps, at the base especially. Do people place the bottom string onto mastic before fixing to the footings?

I have been involved with SAP/EPC (as a targeted building designer) since the very first talks by BRE. Along with most others present I left at half time when they couldn't explain where any numbers came from. I think it was rushed through before it was ready, like Breeam and air tests, because it was a money-maker. Lots of approximate assumptions were included. Then once the programmes were written there was little desire to change them. The professional assessors can't change the formulae in the core programme, so you chuck in some numbers and tick boxes and out comes a rating. We bought the core programme and played with it to see where the anomalies were, which was fun but annoying. There were lots of tick box items which didn't make any sense to us, and I think the experts learnt which give the best outcome. For your own interest you can insist on the dozen or so back pages of the assessment. There you will see the assumed power consumption when your ashp goes into cooling mode for three months for the Highland summer, and the power used by heat recovery. Then deduct that manually for an academic A++

Shiny layer is ok straight off the cooking foil roll but fades over time? Is it the shinyness or the aluminiumness? It appears to me that a silvery barrier will add about £300 to the project cost. It all adds up but that seems ok. Up for suggestions of where better to invest the money. I'm more likely to be a bit overdone and tough.

I agree not a big problem but it is ugly and could start to spall the bricks esp in frost.

and yet BRE say use 0.18 for a 22mm air gap in a wall and 0.44m if it has a shiny layer. Instinctively I think this feels about right, because aluminium absolutely does reflect a lot. Build quality et al are much further down the line and are not in the warrant application. For now I want to put in a reasonably accurate heat loss proposal, that is fairly mainstream and uncontroversial. But I really don't want to change it later, so am deciding on fundamentals like PIR or mineral wool. shiny membrane or not. It isn't easy as the standards for a change of use are rather high, not that we wish to cut corners anyway, and there are lots of constraints due to the existing geometry and structure. I'll see if I can summarise the points you mention. The surface area is huge. back to shiny: we are fitting out a roof area as site office, with PIR between the rafters and lined with a shiny membrane. With Infrared heating I think we will get quite a lot of that bouncing back in, and it will be a bit like being the turkey in the foil. Will report on this when done.

No thanks. has calculus in it. Care to summarise?

Good point. Plus wind blowing it back to the wall.

At the right hand side you have a gravel bed at the bottom which will take the water lower, then it drains away. Less water will reach it anyway as there is a lot of brick to absorb the rain. Under the door it is paving slabs and no gravel, and all the rain hitting the glass runs straight down. Check that the paving runs properly away from the house, all the way from the wall. Golf ball test. Check if rain running off the door sill is dripping onto the ground or running backwards and down the wall. it is all below the dpc and you seem to have ventilation, so prob not along term worry, but better if it didn't look like that. Guessing that this wall faces the prevailing wind so south-westish.

If it doesn't show any signs of decay then all is well....for the moment. Better left out in the air so it can dry intermittently than encased in any screen, so the best thing you can do is progress.

No. the concentrated load needs to be spread efficiently. An ordinary block is likely to crack and then concentrate the load directly below. Why would you want to not have a padstone? Tell us please. If the geometry has gone wrong then you can make it on site perfectly well, but ask the Engineer to give you new dimensions. needs high quality concrete, I would put some reinforcement in it because, why not? You can also buy all sizes of padstone bricks and blocks, and build to suit. Basically it is made from structural concrete without the usual fillers that keep costs down. Assuming someone has designed this for you, ask them for a revised detail if you have to.

Today I will mostly be doing the same again, trying frametherm in the U value calcs, adding in the effect of heat loss through the rafters and studs, and finding a way to get better numbers. 1. pass all the tests to prove it to the BCO 2. actually get what is best for the building and bills in the long term. Perhaps these are in reverse order. Question. Please excuse the avoidance of jargon and scientific precision, and I am thinking here only of keeping heat inside. We 'know' that a shiny layer helps insulation, by reflecting the radiation, but only when it faces an air gap. Theoretical U value for the gap jumps from .18 to .44 if I remember correctly. BUT does that not depend on the aspect? Heat (radiation) from inside travels through plasterboard, hits metallic layer on inside face and it is reabsorbed back into the plasterboard and the membrane itself No help and no hindrance OR hits the shiny stuff on the other side of the gap and bounces back into the gap. Warms the air and helps the insulation level. Then the reverse occurs at the outside...let's say PIR is left 50 short of the sarking. to provide a ventilated space. Then the reflection is again inwards, to no advantage. and anyway the air gap is ventilated so the effect of the gap is low or nil.. Which could bring us onto multifoil, which is not in our recipe, so I won't go there. Red pens out as necessary.

Yes primitive isn't it? Sarking is standard in Scotland. 150 or 225mm boards still available in quantity at merchants, £20/m2, pressure treated.. But mostly used for maintenance. Osb is normally cheaper, and is certainly quicker. Contrary to the understanding of some, not all Scotland has any more severe weather than the rest of the UK, but it is simply a sensible thing to do for UK weather generally. I don't think our steading would still be standing after 120 years if it didn't have it. Did the people who wrote the BS consider the differences? Nuff said. The slates are impermeable until they break, but at least have double cover unlike modern tiles. The gaps are very permeable.