Alan Ambrose

Ah, nice.

Ah, I think you can do some back-of-the-envelope calcs to satisfy yourself. If you're a CAD guy then you could do the stress analysis in Fusion or similar and get some approx results. Approx because wood, strictly speaking, is anisotropic (i.e. it has different characteristics depending on the orientation of the load to the grain) and Fusion doesn't do that. You're going to use a safety factor of 2 or more likely 3, so rough approximations all wash out. (1) Do a simple loadout calc using the quantities and densities of the various materials. That'll also give you the quantties to order. Don't sweat the detail i.e. the fixings and the light/small stuff. Add some for live load, wind load etc (standard BC values). This is a super lightweight building anyway so the numbers will all be small. (2) Maybe read the beginning chapters of an undergraduate structures book. Ignore most of the maths, but get a feel for where the shear and bending forces are and which directions. For example, the roof loads you have will 'push the eaves away from each other'. Maybe consider a metal rod or smallish beam in tension between the eaves. You're building a larger version of a shed, so you don't have to stress yourself too much, but some basic understanding of structures would help. Otherwise find someone who can help, maybe informally, so you're not on their PII. If you like, make a balsa wood or cardboard model and see how it breaks when you load it. (2) To convince yourself and maybe anyone else. Take one truss, maybe full dimensions rather than scaled. Load it approximately with the loads you calculated, maybe measure the defelection. Then stress with 3x the load and/or until it breaks. That gives you your safety factor and some confidence. p.s. (a) You can pretty much see from inspection that it'll be strong enough, maybe with a bit of attention to the joints and the eaves support I mentioned. (b) Is there a worry that any moisture ingress will destroy the MDF? As others have said - would you consider just simple treated CLS rather than I-beams?

Yeah, I was sort of aware of that (I don't know much about SAP). Seems to me that PHPP is a bit more sensible in that, if you don't put in any bridges, it probably overestimates the straight U-Value heat loss and partially compensates for the missing bridges. Have installed Therm, so will give it a go.

Thanks for that, and yes, those instructions are well written. Fusion makes some pretty temperature plots (in 3D) (see below) but doesn't do the last step of calculating total heat flow. Do you have an idea of how well the standard details match real cases? Presumably if they work for standard modern estate builds they're a 'bit high' for better insulated designs. I see from the doc that the BRE have doubled some of the numbers between SAP 2012 & 10. They say part of the rational is to encourage people to do their own calcs. Well great if that was easy. Re: windows I found that e.g. Rationel publishes U-Values and psi-values. I assume other suppliers do the same although I have not looked. How reliable are they - anyone's guess.

IF crazy expensive, it may not be too hard to have fabricated yourself. Assume folded aluminium, powder coated, PIR behind?

Sounds a bit thin for SL compound. Check on the instructions?

Versailles eat your heart out . Go for it!

Shouldn't need to change the CU I think, and can usually work either with the isolator between meter and CU (Octopus may likely have put one of these in), just switching the main CU switch and being careful, or pulling the DNO fuse as said. Last bit of electrical work I has done (on a landlords supply) the electrician worked with the 3P CU all live even though I told him I would rather he isolated it entirely and everyone would have to live without the passenger lift for an hour or two.

>>> So today I've submitted a new Outline Planning Application Congrats on your persistence. Does this have different content to the first as I think, if not, it gives them an excuse to dismiss it straight away saying 'that's already been decided'? Worth waiting 'til the Labour amendments come through and/or gaining the attention of your MP? - I'm a big proponent of transparency and calling attention to stuff that isn't right. At some time the head of planning will need to interface with the MP and will probably be a bit embarrassed about this stuff - especially as the 'sustainable transport' policy is just a simple excuse not to build.

Thanks @Duncan62 I feel I'm making some progress but it seems a hard nut to crack. It appears that most paid-for FEA software is actually a nice user interface sitting on a public domain back end e.g. Nastran. All quite expensive considering it's 'required' for SAP, PHPP etc. As @Dan F says, standard details are available if that's what you have.

Ah the second thread should be: http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11107&page=1#Item_0 FYI I'm trying a simple case with Autodesk Fusion to see how/if that works.

Sounds neat - I can see that working as heat doesn't know or care whether it's going up or down or side-to-side . A couple of related threads here: https://aecb.net/forums/topic/psi-therm-software/ https://aecb.net/forums/topic/psi-therm-software/ The Therm video is fun - reminds me that some in the world still use BTU / ft^2 / degree F !

I agree about the renders or even hand drawn. Most of us are superficial. Some of us (including planners and councillors) can't think in 3D. So, make it easy for everyone and produce the prettiest picture you can, in particular showing what it will look like from the street. So that you stand your best chance of getting it approved first time.

Nice, I want to do a steel frame building some time. It's the overgrown Meccano set thing I think.

>>> no reason to keep building the same looking houses In fact those almost certainly were not great houses, at least judging by today's standards. So, every reason to change.

Could ask Westco I guess - in principle they should know

I wouldn't mind an 'exact' value i.e. some calculations rather than someone's guess.

Sound like you have concluded the design phase .

An electric stapler with stainless steel staples is an easy way. DPC is very thin so not sure you need sealant unless the planks are bumpy. The object isn't to keep 100% of the water out, 99.7% will do. Probably fix to the slab with CT1 or similar and tuck down the edge of the slab (or start by tucking it down first). I think for the bit near the door (or all around if you prefer) the thing to search for is 'tapered timber firring / tapered fillet / wedge strip / shim' etc.

No, I mean these - v cheap - just crease at the angle between wall and slab: https://www.screwfix.com/c/building-doors/damp-proof-courses/cat850234 Not sure what you make the shallow fall thing from, but I know they have shallow angle stuff for flat roofs.

Yeah, I think this is a problem with modern meters - they don't seem to support the old economy seven thing well or at all. I think I would get the electrician back to wire the off peak to the standard supply and install one or more timeswitches for the immersion and storage heater. That way you'll be future proof and you don't have to bang your head against the wall trying to get Octopus to retrace their steps. If they have OK internet, I might make those timeswitches Heatmiser ones and add a controller box so you can control them with a mobile app - but you may think that's a step/expense too far.

Maybe some DPC strip sealed to the concrete and up the sides of the timber for 6-9 inches? Maybe something under that to create a fall away from the shed. Does that french drain fill up when it rains? Know where it drains to? Is there some fall in the concrete outside the door?

Looks a bit special. Dare to take off the caps (maybe noting position) to see what's under there? Says 'wetsco' - what's the other writing say on there? Can't see anything here, but I didn't spend much time looking: https://shop.westco.co.uk/ Best guess Google came up with was a baby manifold, but that doesn't make any sense as the dimensions of the two take-offs are different.

Assuming you get their guarantee - I'm guessing Sika want to sign off the spec & drawings and have a person on site to verify? That's it?