SimonD

One length of cavity wall has 2 spirit levels somewhere. One quite used and one almost brand new that replaced the former and only lasted a couple of days in use. To this day the most bemusing is how I managed to bury a pair of metal roofing shears somewhere in the roof.

which invalidates the experience how exactly? ?

Having recently done my own windows, and mainly on my own, I'd would say it depends entirely on access and space around your house. With my installation it was such that I couldn't use any of the commonly available lifting equipment e.g. telehandler, spider crane, tracked lift, glazing robot, or a genie type lift (I hired one of these thinking it could work). I had to make my own lifts using Kwikstage scaffolding and an Elephant chain hoist using a hired in 4 pad suction lifter. I used Hird for my equipment hire who were very easy to deal with and much cheaper than GGR who I found wanted to over-sell equipment (and operator) and were a bureaucratic nightmare for a self-builder!

Even better I hope is a picture I found using the same solution to a roof almost identical in design to yours. In this one, they've decided to simply cantilever the ladder to be held by the roof deck.

Two ideas, just to throw them out. 1st is to modify your noggings for the overhang by ripping a firring strip at the same angle as the rafters and then you frame what are called gable ladders which provide you with the overhang - the gable ladder rests on the firring and is fixed to the rafter. With only 200mm overhang you might actually get away with it simply screwed or bolted to your final rafter and cantilevered without support if you're using 18mm plywood or osb roof deck. 2nd is to make the asymmetry a feature by create some boxing at the corner so the low soffit extends out beyond the wall to the same extent as the high soffit and then you have a box that brings the soffit round the corner and then up vertically to meet the higher soffit. Hope that makes sense.

Circular saw with connected extractor or jigsaw with long blade. I've used both the standard cross-cut and ripping blades on the circular saw with no problems but I'm using a Festool HK85 which is a bit of a beast - no real clogging problems even without extractor. On the jigsaw I used Bosch T1044DP blades the fibres do fill the teeth but you've just got to intermittently draw back the blade. If using an extractor stock up on dust bags, they fill up like there's no tomorrow! Can't believe how many bags I've filled up but the remains are great for lighting fires ? I've been cutting 140mm and 60mm thick boards.

Don't worry about it too much, it's not going to cause you any damage or harm to your room. To explain: Many people think that 'breathable' equates to vapour permeability and vapour diffusion but in the the case of woodfibre, this isn't the benefit as you do install a VCL to the inside of the woodfibre buildup. But this vcl needs to be one that is compatible with the properties of woodfibre. Why? This is because the value of woodfibre is its capillary and hygroscopic capability that can absorb and take moisture through the envelope and out of the building, but it can also work in the opposite way to prevent overly dry air in the building during winter for example. This is why these buildups use osb or even clt as the vcl. If you add an impermeable or non hygroscopic/capillary material to the buildup this process is short circuited. So where and when do you get best bang for buck with wood fibre? In well insulated and airtight buildings with low air change rate, preferrably 0.5 ach and below. Also, in terms of decrement delay, the significant benefit comes not from the flexible wood fibre but the denser boards installed to the external side of the frame. In your example case, there is a minor reduction of risk in that if your vcl and pir layer is breached or incomplete in any way, any excess moisture coming through due to vapour diffusion in this case, will be buffered by the flexi wood fibre whereas a mineral wool could not do this. However, given your situation and buildup, it is more cost effective and practical simply to use a mineral wool. HTH

It's simply the buildup using PIR to the inside of the woodfibre. It makes no sense. Beware professionals has become my motto following the self-build journey. Many RIBA and RICS peeps don't really understand how woodfibre actually works, why the usual recommend buildup other than it's supposed to be breathable, and then many of then don't even understand the full meaning of that term either. Sorry, I've been jaded The good news on that one is that historically hygroscopic/capillary insulation materials like wood fibre, sheepswool, cellulose etc. have had their stated u-values down-rated due to the assumption that when they absord moisture they also insulate less well. Unfortunately this doesn't take into account that their behaviour in absorbing and releasing moisture tends to generate heat, and also that up to a point the moisture doesn't affect their thermal performance. You'll likely get better performance out of them than predicted, whereas it's frightfully common for insulation systems like PIR not to perform as predicted, but that doesn't always help with BC unfortunately. Sensible decision with the buildup. Decrement delay is an interesting one for me. I designed my house for good decrement delay and it really works to a point when you have nice sinusoidal temperature curves through night and day. Last summer when we had the heat wave, the house, even the upstairs timber frame, maintained a nice cool temperature compared to outdoors. However, on day three of relentless heat, it seemed to just become saturated with heat and gave up. Suddenly the indoor temp shot up to just above outdoor temp. and then took some time to settle back down again.

I'm finding the same thing with awaited phone calls and emails from suppliers and manufacturers, sales and technical departments alike!

Dead right, seems to be permanent affliction nowadays ? Ta!

A sudden veer in design from an area of the house not having a room to now having a room has caused me a bit of a headache. One partition wall is going to run parallel to the joists and fall approx. 150mm from a joist. The partition wall is going to be a simple stud wall 38 x 89 mm cls with plasterboard and some osb behind. The subfloor is 18mm osb at 400cc and I have noggings at 1.6m intervals that sit on sleeper walls. The joists are 47 x 145. I'm seriously not in the mood to take up a new subfloor that's fully glued down and filled with insulation to add double joists below. Can I get away with simply building the wall as is, or could I perhaps double up a couple of cls studs on the vertical like double joists laid on top of the floor (essentially so they span between the noggins) and build the wall on top of that? Any other sensible thoughts? Now I really do sympathise with builders who hate customers who change their minds part way through a piece of work!

I have to say I think that buildup is very weird as you've got layers of incompatible materials, thus you actually lose a lot of the benefit of the woodfibre board. Who designed this because it would be much better to have designed the buildup with the flexible woodfibre between rafters and then woodfibre boards on top of the rafters. This would give you the benefit of the materials, plus extra decrement delay and better hygrothermal performance of the envelope. However, if you're still looking for alternative supplier, you could try Ty Mawr who sell the Schneider Holtz woodfibre products, or as has been suggested above, Pavatex Pavaflex. You could also try Hunton - huntonfiber.co.uk - a Norwegian company. Good luck

I'd suggest finding a specialist broker, I'm not sure your standard self-build underwriter would know what to do with this one as a collapse of tunnel could be rather expensive to fix.

They're not wrong. A lot of poor understanding of timber frame out there in England. Where we live I struggled to find a timber/builders merchant that even stocked 38 x 140mm cls so I had to buy it by the pallet. One of my bugbears is poor storage of timber even by suppliers so you can end up with saturated stock for your frame, which is a no-no for a good quality frame (and good internal finish). This is so often overlooked that I recommend if you do go down this route, you make sure the moisture content of the wood is checked before installation - do this yourself or make sure your chippy has the means to do it and does it! However, like @the_r_sole says, find the right engineer (ours specialized in timber and steel frames) and a good chippy with the knowledge and you'll be good to go.

No they don't. There are plenty of very large commercial projects using what I explained was a traditional fully supported standing seam roof. There are plenty of published details. I personally have a copy of the Federation of Traditional Metal Roofing Contractors Guide to Good Practice because I've installed this type of roof. The fully supported traditional standing seam roof is used both for commercial and domestic purposes and has been for decades, if not more than 100 years, more widely outside of the UK. As I think I said, we're talking different products designed for different build systems. For a domestic project, you're unlikely to get any supplier to sell you the systems used for this kind of commercial project, because it's not worth their while due to the normal size of project.I spoke to a few for my current project and the closest I got from one of them was an indication that I might get some offcuts from an airport development. Typically the commercial standing seam roofs I think you are refering to have a much higher upstand, but you'll find they're similar thicknesses to slightly thicker at about 0.7 - 1.2mm. They tend to have a narrower cover at about 400mm or just over IIRC. They also often consist of a sandwich construction with double layers of steel- corrugated below as a structural deck, insulation, and then the standing seam (e.g. Kingspan). I've come across one traditional standing seam product by Euroclad (basically Tata Steel Colourcoat Urban), that can apparently be installed just on battens, but in this case, I'd be concerned maintenance access would be severely compromised. The fundamental fact is that the OP asked whether sarking boards and breather membrane were satisfactory for supporting a traditional standing seam roof and the answer is that yes they are. Sarking boards are actually preferred to osb and plywood as a substrate because they provide better through ventilation to the back of the metal. Plywood is the popular installers choice because it has good pull out strength for nails which reduces installation time and osb is third because of reduced fixing pull out strength, so you either have to increase the number of fixings or use screws instead of nails in high wind uplift areas.

I'm not sure of you're talking cross purposes here. The issue with the hip on a traditional fully supported standing seam roof isn't as described above because you would simply form shorter trays from the coil to account for the effective roof length. Indeed, this would also be done if you were ordering prefabricated standing seam sheets as you'd pull the required measurements off the as built roof. You wouldn't experience the same wastage compared to a standard length corrogated metal roof sheet, nor would you experience problems cutting each tray to fit the angle of the hip ridge - this is bread and butter for a standing seam contractor and is very easy to do. On traditional stending seam, there is not overlap. The coils are sold in certain widths which can be specified, the most commog being a cover between seams of 430mm, 530mm and 600mm, with corresponding coild widths of 500, 600 and 670 for 25mm standing seams. Not on a traditional standing seam roof. This requires the metal to be fully supported. However, I do wonder about the necessity of this buildup I think the roofers could easily have left out the 9mm osb and first layer of breather membrane unless they were worried about wind wash on the insulation where membrane would be sensible. Otherwise, it's absolutely the correct buildup with 18mm supporting osb and membrane under the steel roof. This is not correct, you're talking different a different roof finish compared to a standing seam roof which does require support, unless the OP has got the terms confused?

Assuming you'll be using traditional sarking boards at 22mm thickness these are fine for a standing seam roof. Just make sure that if you do go for the standing seam you use a marginally thinner sarking board at the eaves for the eaves flashing. With traditional standing seam it's often the labour that's expensive and this will depend on the number of penetrations in the roof and its shape. If it's a simple rectangular shape, it's a really straight forward and quick process. You can even buy ready fabricated trays that clip together saving even more on labour. I've installed both and love both materials, but I think my personal preference does now lean towards the metal.

Give Promain a call. They have lots of anti slip paints and will be able to tell you which is best suited to osb. Here's their pages for wood floor anti-slip paints; https://www.promain.co.uk/anti-slip-paints-and-coatings/anti-slip-coatings-for-wooden-flooring.html

The flat and lean-to roofs are pretty easy, the gabled extension may or may not be. As you've illustrated the design, it has a fully vaulted design which really needs the input of a structural engineer first as there are various options as to how to tie the trusses - this will have most impact on the cost. You could use a steel or glulam frame which tie the trusses at the ridge, or you can use ridged or cable ties. Steel portal frame may be the cheapest option as it could be as little as a few grand, but as already mentioned above, it depends on the details.

I've used loads of stainless in various widths and it is very malleable. If you wanted, ping me a pm with your address and I'll pop a few meters of offcuts, probably 75 or 100mm width, in the post for you to see how it works. If it's too wide you can actually cut it with scissors. I use Robinson wire cloth, better prices than the Amazon link. https://www.robinsonwirecloth.co.uk/online-shop/Soffit-insect-mesh-stainless-steel-30m-roll-p49612077

The 60% rule came in a couple of years ago. If a supplier is supplying and fitting a qualifying energy savings measure, like a heat pump, and lets say charges a total of £10,000 ex vat. If the supplier has to pay more than 60% of that to buy the products and materials then the vat charged needs to be apportioned between materials and labour. Materials gets charged at 20% and the labour at 5%. If the total materials is below 60% of the total charged, then the supplier can charge at the lower threshold of 5%. This is warning bell no 1 with your quote. If he hasn't done his own heat loss calcs and merely relied on an incorrect epc, that's warning no. 2. He really needs to do this himself and also carefully design the heating system for a heat pump. Just chucking in a heat pump is unlikely to yield promising results. It looks like your existing radiators are being kept in the new system? That is not a good sign either.

I should probably also add that if the quote doesn’t exceed the 60% vat rule the whole supply should be 5 % vat.

Nibe is a leading Swedish manufacturer of heat pumps so no worries there. However, I would check your supplier as I don't think they have treated your installation correctly for VAT purposes as they've quoted you a flat 20% whereas I believe it should be apportioned between materials and labour with different VAT rates. Not a good start for a potential contractor as Nibe actually provides guidance for this on its very own website. https://www.gov.uk/government/publications/vat-changes-to-the-reduced-rate-for-energy-saving-materials-2019/vat-changes-to-the-reduced-rate-for-energy-saving-materials-2019 https://www.gov.uk/guidance/vat-on-energy-saving-materials-and-heating-equipment-notice-7086#para2-9 Also, has the company provided you with their own heat loss calcs? That would be useful so you can verify the claimed reduction in heating costs and RHI and of course the sizing of the heat pump. At least it'll be neat and tidy they say...

Our planner wanted a chimney too. I wonder what it is about planners and chimneys. On our house the addition of a chimney made the house look like a ferry sailing off to sea. I've built the house without the chimney but if there are ever any questions I can show them that the structure has the base for the chimney so we can add it on in the future. Nothing in the planning rules to say by when you have to finish the build. Anyway, could you do something similar to avoid the chimney yourself? Just an idea like ?

Okay, so I'm slowly progressing with this, along with all the other things to juggle while building on your own. Can someone point me in the direction of manufacturers/suppliers for a 300l accumulator suitable for external installation as I'm going to really struggle to get this inside but have an ideal place outside where the mains comes into the house. And also the same for thermal a large 300l thermal store with a secondary return? Internet search algorithms seem to have decided I don't need anything bigger than 250l! MTIA