kxi

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  1. I had a brief tour shortly after they started re-excavating, around 2000. A story cited was the sandstone cutting into Lime Street station was being dug at the same time, and at one point the labourers working on the cutting unexpectedly broke through into a dimly lit underground chamber filled with toiling diggers (the in-progress Williamson Tunnels) and fled believing they had uncovered Hell and its dammed minions.
  2. Also worth considering that in the not too distant future there might be some large EV batteries in there periodically. Who knows what chemistry these might have in future, but no doubt there will be guidance / regulations on fire safety relating to EV parking. I suspect for now we'd have a 'no EV under there' rule until the world understands the risks better.
  3. @scottishjohn Yes the plan is for 150mm of either phenolic or kingspan quadcore panels on the soffit, should give about 0.12U. I had wondered about something like a mist system, but needs more investigation. As per it may be a really good alarm system(s) might be more effective. I did once live in a flat where a mattress was set alight in an abandoned flat below, and the first I noticed was the floor under my sunday morning feet starting to heat up. This early warning won't be available with 200mm of concrete.
  4. Thanks all of the comments. Thinking about it today, I think there's flaw that in our case means we can't use the structural topping to lay the UFH pipe. The planks are laid on the bottom flange of asymmetric steel beams in a 'slim floor' style, in order to save height. e.g. (based on shallow-floor designs such as https://www.steelconstruction.info/Floor_systems#Shallow_floors) Since the structural topping doesn't in our case go over the top of the steel beams, the UFH pipes can't go through the beams (without complexity). However, if anyone is ever interested in UFH pipes in hollowcore topping, it does appear that it is (or at least was) tacitly supported by US and Canadian building codes: http://www.healthyheating.com/Concrete-codes-radiant-heating/Concrete-codes-radiant-heating.htm#.XZpJr0ZKhhF The middle one was what i was thinking of. @scottishjohn The ICF floor style is neat and something I would have looked into, but in our case this floor is over an agricultural-use ground floor, which could have vehicles, workshops, storage, etc in and I am very concerned about the effects of a fire down there on the house above. Any EPS in the floor soffit I would expect to last hardly any time before melting. In the EKONECT and quad-deck examples it looks like the EPS in the floor doesn't provide any structural aspect, as that's all handled by the cast/pre-cast concrete, i.e. the EPS melting might not affect overall floor integrity. I suspect had I looked into these in more detail 8 months ago, we might have made a different choice, but we are on course with the hollowcore now.
  5. Our design has a first floor of hollowcore planks (about 150mm thick) with a structural concrete topping (minimum thickness 50mm I think), and we are looking to add UFH. Naively, it seems to me simplest, thinnest, lightest, and perhaps cheapest to have the UFH pipe laid in this structural topping and then make the topping the required thickness above the pipes (60mm?). As opposed to having; hollowcore, 50mm structural topping, then a separate (60mm?) screed with UFH over the top of that. As I understand it, a structural topping over hollowcore is partly to create a smooth level surface, but also sometimes to create a composite floor with the precast planks, which is stronger. My concern is that having UFH pipes in this topping would somehow adversely affect this structural aspect. I know there is general acceptance (on this forum at least) of UFH in structural ground slabs, such as in MBC builds, but what about as part of hollowcore floors? This is one for the SE, but would be keen to hear people's views.
  6. Idealcombi futura, aluminium window with PUR thermal break. Available inwards or outwards opening. Alu clad uPVC can get higher performance than timber (with the right version) if top performance is what you are after. E.g. the foam-filled energyline 91 P from gaulhofer (via ecowin)
  7. For ultra-dense, there's structural thermal breaks like: Farrat https://www.farrat.com/structural-thermal-break-connections Armatherm https://www.armatherm.com/thermal-break-materials/ Which presumably you could just use a few blocks of and fill the spaces between with standard non-dense insulation. I assume expensive though.
  8. Here's a list of prices compiled from BH public posting https://docs.google.com/spreadsheets/d/10mPQ-4HnTuUbiKmQVn3fPPoVkxDMPgRFNvaji4R8USg/edit?usp=sharing Apologies anyone if I've made a mistake on your prices or missed you out. I wasn't hugely systematic. I'm surprised not to see any Green Building Store ones. As @craig says, a simple m2 hides a lot of detail that affects price e.g. ratio of fixed vs opening windows, doors, cills, coated glass, non-rectangular, airtightness level of the model, etc. I suspect the mysterious discount factor also distorts things. @lizzie I'd previously had you at £390/m2 - was that just for alu UPVC and you went for alu timber at £566/m2 in the end? From https://forum.buildhub.org.uk/topic/1820-alu-clad-timber-or-pvc/?do=findComment&comment=26286
  9. If longevity is what you are after, there's also foam glass aggregate / gravel e.g. geocell, technpor, glapor, etc. Made from recycled glass. It needs to be much much thicker than foam to achieve same U values, but I'd imagine it would then stay inert and drainable for a very long time. @Snowbeetle used it on their barn floor and it seemed eminently self-buildable and very appealing.
  10. @worldwidewebs "I think the total floor area of the barn is something like 600m2, although the current plans show some of this to be demolished to fit in with the Class Q limit" AKAIK there is nothing in Class Q that would necessarily require the unconverted portion to be demolished, though of course you might want to in order to gain some other kind of improvement like more windows. Our conversion under class Q is mixed use residential and agricultural, and while the planners initially questioned this, a single letter convinced them it was ok. The unconverted portion would still have to remain in agricultural use though. Your implication is that this barn is part of an existing farm with other buildings and so I assume the unconverted portion could remain 'with them' as part of a working unit. Would need to check this all with someone though. Personally I'd want to remain as much built structure as possible, as once it comes down, less likely planners would allow you to put something back up.
  11. After much consideration, the build method we'll be using for the conversion is 'big shed'. In that we'll be: - Adding a new steel frame internal to the existing walls - Which supports a new precast concrete plank first floor - Then wrapping the roof, new walls, and potentially the underside of the new first floor in Kingspan KS1000rw insulated panels - 150mm quadcore. Bearing in mind the house is mainly single storey up in the air - The panels fixed onto timber purlins for the roof, and off metal inline purlins for the walls - Internally, the external wall panels & purlins hidden by PB/fermacell board covering the 'cavity', also board between the ceiling timber purlins to cover the underside of the roof panels Why this? Naively, it seems like a simple & relatively cheap way to achieve a high-insulation (0.12U), thermal bridge free, airtight shell. Though the idea came about from trying to think of the thinnest roof possible without use of exotics like areogel (which for a 360m2 roof was out of the question) since we are very height constrained on the north side. Decrement delay issue noted. @scottishjohn We also wanted a highly fire resistant first floor (hence the concrete) with large spans, due to the ground floor space underneath being agricultural use. This leads to a steel frame, which the kingspan panels go with. Frame & panels can then be constructed as a single package. In terms of precedent, we have heard of a couple of similar residential examples, and I expect more will appear due to Class Q permitted development, and obviously there are lots of offices & workshops that use this approach, often as part of bigger sheds. Various issues to work through, but making progress. For example we've found the north-south steel roof beams are thick enough to have 100mm holes cut to allow radial MVHR ducting, which gets it out of the way.
  12. Thanks all, very helpful.
  13. At the stage where we need window detailing, so to decide on outwards or inwards opening. Pros and cons of inwards opening seem to be: Pros Can have external shutters/blinds - may be a good hedge if solar gain ends up being more of a problem than anticipated Can have external insect mesh - seems unnecessary in SE England, but maybe more so in future? Easier to clean Allegedly less likely to slam in the wind Can more easily wrap insulation around outside of frame Greater range of high-performance windows Allegedly more likely to be airtight (products being equal) Cons Theoretically worse in wet climates since wind tries to push the window open when stormy, and the crucial external seal between frame & glass is a continually flexing & accessible one, i.e. more liable to wear out or get damaged Harder to have internal blinds and shutters, but not impossible as you just don't put them in the reveal Can't put stuff on window cill if you want to open them, but can use the tilt and turn for ventilation anyway Impinges on internal space if fully open Can't as easily sit on windowsill with the window fully open (maybe you shouldn't) But how valid is point 1 of the cons? Seems lots of people here have inwards opening, has anyone ever experienced issues with the weather? Or anticipate a shorter lifespan due to seal damage? Replacing the seal should in theory be possible, but likely as not in 20 years time the specific carefully designed strip won't be available?
  14. We had quotes from Leroc and Bison on 300m2 of 150mm hollowcore, max 6m spans. Roughly £50/m2 and £57/m2, supply and fix, including passive fall arrest. Price does not include structural topping (to be supplied by others).
  15. @TerryE Isn't the conversion of a barn to dwelling likely to be at least in part 5%, as per VAT notice 708? (I hope it is) https://www.gov.uk/government/publications/vat-notice-708-buildings-and-construction/vat-notice-708-buildings-and-construction Summarised: https://www.charltonbaker.co.uk/news-blog/detail/reduced-rate-of-vat-and-barn-conversions Also, if the barn conversion is under Class Q Permitted development (which I assume it is unless you go for full planning) then one would need to make a 'prior approval' application to the council. Whether one then needs to also get a certificate of lawful development in addition is debatable. Our council never suggested this was necessary and our planning consultant didn't think it necessary either, however a planning lawyer did later suggest there was in theory a case for one, though AFAIK not one that has ever actually applied to any class Q conversion in reality (but don't take my word for it). I would be surprised if anyone getting Class Q barn conversions also got an LDC, but it would be interesting to hear from others using Class Q.