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About Olf

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  1. Do you have enough space in the soffits to extend the runs so they finish the recommended 1.5m apart? If not, check the 'combined grille' idea.
  2. I was after the same, though it appeared that high water table prevents from building any soakaway and so war with Thames Water to connect to existing rain sewer is on. I'd recommend you dig a control hole, that answers many of your questions. Using it for percolation test will give rough idea of volume ( and so cost) of soakaway to start with. Or - like in my case - possibility of having one at all. To answer the question it is yes and no. Yes, as there are companies doing just that, but not sure what methodology they use. I suspect it is based on HR Wallingford tools, so something not publicly available and requiring some skills to do the calculations. I'd believe there are consultancies using the same method without selling any product, but still the effort may be more costly than building 'standard' soakaway capable of capturing all the rainwater, and adding water harvesting system as a bonus
  3. Exactly, and that what angers me. They just lough in the face: they prefer to supply large developers with standard stock and/or with increased price of raw material try to encourage to cancel an order than would be now at small markup or even loss. I've had these problems throughout the build, with noticable similar case when Tarmac called 3h before sheduled delivery to fill foundations to say that they 'ran of cement' - which was just smoking pile of bs. My biggest problem is lack of communication: if they said it is another 8-10 weeks, I would put all the resources in a backup plan. But if it may show up any day, but they just don't have an idea what is happening on their own backyard, then I'm not so happy to pay SE £££ and risk having 2 sets of lintels, in case Catnic shows up.
  4. Make sure that you can actually order that. When I was searching few suppliers were interested in a small private project, and when it came to order no one was, all their output being sucked by major developers. Ended up with standard beam and block with PIR on top and worse U than wanted and planned.
  5. Catnic thermally broken heavy duty lintel for 150mm cavity spanning 3600mm wide French door ordered at beginning of May, as the very fist thing. Was quoted 4 weeks delivery, which was comfortable. End of June (already past the scheduled date), checking for update, answer: not made yet, shortage of steel. Couple of more updates, one pointing to the week beginning 19th of July (as in now). Fresh update: not made, no steel to roll it. I'm not going to speculate what really is going on, but need to start with plan B, as the walls are now erected and only the section over the doors is missing, builders were pi$$ed and left for another job, making me *&^%$£. Because of cavity width (not 100mm, so building merchants don't have anything available), span (more than 2m, so building merchants don't have anything available) and my desire to have it possibly not thermally bridged, I'm thinking about 2 separate lintels for each leaf, using RSJs (as these need 'only' cutting to length). Any other ideas? Do I need to involve SE, or will it be enough to get steel merchant to provide figures just to demonstrate that load capacities are equal or better than the limits already calculated for Catnic lintel?
  6. That's what I'm planning to use, if that helps
  7. I used Iko Bitument paint. K Kaps look cool, but could not find any stock and probably they make sense when dealing with 10s or 100s of beams and time saving is measureable.
  8. Multifinish, concrete blocks, insulation boards please We may find the prices possibly dropping: few weeks ago I had to buy OSB urgently (collapsing foundation trenches), rented a van, sprinted to B&Q and paid £29 a board. 3 days later doing order for roof boards I was hit with £39 price - 1/3 hike! But now it stays. I suspect some materials got 'future increases' included on the wave of panic buying, with all the desperate ones served and shortage of labour, stock will have to be shifted so the price adjust. Though OSB doesn't have best before date, otherwise there would be soon pallets given away, like with plaster...
  9. On one end of the extension (at the existing building wall) the roof joists are suspended from an RSJ, that creates a new challange: junction of the beam and the wall. With the load imposed by the beam I'm worried that any membrane I'd try to use to form 'Tony tray' would be thinned to the point of becoming permeable, defeating the whole point. The other issue comes from the small size of section of the wall requiring this treatment - that effectively makes it a 3D 'cup' around the RSJ end to be formed. That got me thinking about using joist seals, has anybody tried that route? Actually '3D' aspect should also show at the ends of standard 'Tony tray' - would you fold & wrap the membrane at the end of the wall, or for simplicity just leave this one junction potentially leaking?
  10. I'd exercise an option to have 1st floor addition full width, by rotating the 1st floor bathroom 90 deg and extending slightly the bedroom, so it still have access to light (maybe even incease the size of the window).That will allow to blend with the roof better (less flat roof)and possibly address the issue they have with the form of it (with imho is ugly too). You mentioned future dormer roof, that would give you an option to go beyond existing rear wall with its depth (subject to planning and headroom available, maybe do some sketches now?) Do you need both bath and shower? Not concerning planning I'd also ditch the bifold idea - I assume flat roof joists sit on the walls, for 3 panel bifolds you would still need and extra steel above. For negligible effect of bifolds in 3m wide opening you'll spend a lot to make it work and more than 95% of time open one panel only. It doesn't seem that you have some lovely views there neither.
  11. In normal times I'd just go for stock OSB/3 T&G boards, but with current problems with sourcing anything I'm considering all possible options. I put to sleep idea of using P5 chipboards (for now...), but trying to find what is wrong with square edge OSB: with joists at 400 mm centres, 1200 mm wide boards of the bottom layer should always meet over the joist (75 wide, so at least 34 mm support each) and any buckling that could still try to happen will never be visible, and should be reduced once the sandwich is sqeezed with the fixings. With top it should be even easier, with rigid insulation boards providing flat surface, OSB boards will only be providing extra lateral stifness (and load distribution of anything pressing from above), so lack of interconnection should not matter much. Should it? Additional question: going square edge, what gap between the boards is sensible to allow for any expansion? EDPM on top, so quite forgiving.
  12. Why not? As temperatures inside and outside get equal, heat recovery part gets less and less significant and the ventilation can be achieved by simply opening windows. If the intake is above sunlit surface of the roof, locally the air can get pretty hot so if you sick this in using MVHR is against you. Plus any gains through the attic (which does get very hot). As mentioned before, your best strategy is to reduce unwanted gains first and then fight the rest with aircon.
  13. Well there is a rainwater sewer right under the extension the builders 'found it' and have fun repairing, but in BC's words we can only connect there when all the other options fail. Possibly again, if I can show calculations that green roof and rainwater harvesting limit the output massively, may be a good bargaining chip.
  14. When visiting to sign off footings trenches, the BC was a bit shocked how much clay was there and requested percolation test rather than stock hole for soakaway. On top of that all the new roofs served will be total of 120 m2, so with insufficient absorbing rate the hole could get bigger than the area available. However, we're planning a green roof on the extension (40 m2) and the remaining 80 m2 will be going through a surface rainwater harvesting system (2 or 3 IBCs). As much as plain soakaway calculation process is covered in BRE Digest 365, is there a similar source showing how to calculate either reduction of necessary capacity when slowing/delaying rainwater runoff, or adjustments to the parameters taken for BRE soakaway calculations (effectively achieving the same)? I can see some companies selling products that promise exactly this (eg https://suds-solutions.co.uk/rain-activ/), so there must be a way of either convincing or dazzling BC to approve reduced soakaway volume.
  15. Agree, apologies for messing up. I must have felt subconciously that something is wrong, as somehow enabled strikethrough I don't think 'passive thermal inductor' is possible, as that would enable an oscillator, and step further is a generator. Phase change produces kind of Zener diode effect. Possibly for radiant heat only, as it is pure electromagnetism, the solution would be easier to find - but that's way out of scope of the forum