Gus Potter

Great post and lots of info, well done you! Spend time finding the right SE, that has deep knowledge, is pragmatic and understands holistic design. That means they could swap hats and be an Architect not least. An SE like this is going to cost a bit, but it will be the best money you spend! SE's like this also act as an advocate for you, will hold your hand and guide you through all the other regs and sorting out a builder etc! Try and find a local SE, not me! as I'm too far away from you to be able to come to site on short notice, not least!

Thanks mods for removing my drawings with the Client info, you have saved the day at my end! Reposted below, redacted:

Here is the roof plan. I've screen shotted it, you won't be able to read the detail but can see the shape. Each cold formed cee was a different size, but cf providers can handle it provided you give them a schedule. All for £1552.00! The schedule looks like this, but if the walls are parallel then it is much simpler as all the cees are the same length. I would explore using cold formed joists, creating the fall can be really easy!

You'll only learn this kind of nugget stuff on BH from the likes of Nick. You may think.. well I'm not going to let the floor socket "take a drink" but.. The spark may also want to change the cable rating anyway as it's not say in a wall. Electric cables are sized partly on not just the load but also if they are surrounded by insulation, or near to say UFH. Fundamentally we don't want them to heat up too much. Thus what Nick is saying also make sense when we look at the electrical design holistically, and that can save cost later on. Thus, why not adopt Nick's suggestion, as the spark will insist that the wiring up to the floor socket is to spec anyway? It's just that last nuance that Nick is bringing his experience to bear.

I appreciate your desire for level and diligence. Have you considered. If you have an existing house. How level and undulating all the other floors are? If a new house then it is going to take time to bed in, settle. To provide a bit of context. Often as an SE I'll start by designing a house to settle no more differentially by 25mm! Then refine depending on the finishes and how tolerant the structural frame is going to be in terms of differential settlement. A Swedish log cabin might shrink by 75 - 100mm! I would give the floors you have laid so far a "walk over test" not by you, but by visitors. Ask them if they notice much level or issues with flatness. Glancing light is always going to show up even tiny changes. This is building, not eye surgery!

This is really a bugbear I have with folk who are less experienced Architects, it's even more of a wtf are you doing with Architects who are set in their ways. I wear two hats, SE and Architectural designer. Design is about communication of information not least. At concept design stage if you stick on a grid it lets everyone see how the floors and things line up. On BH most folk don't have access to say CAD or more complex design packages where we can overlay floors etc. It lets us all see what goes where, get a rough handle on things and communicate well. If there is a grid we can say, say on teams, go to grid intersection 2A, and a bit to the left or 300m up on the drawing, there is no dubiety and that stop wasting time trying to identify what part of the drawings we are looking at, it avoids error and folk getting frustrated. Later when we come to the detailed design a grid is essential to allow the builder to set things out. Why not start with a grid at the beginning, grids help reduce error! Now Architect's like their drawings to look good, when I draw stuff in cad I'll change line weights, emphasise at time depending on whether I'm trying to show a Planner, a checking Engineer or how the kitchen may look to the Client. Funnily I work with quite a few highly experienced Architects, they have embraced my suggestion for putting grids on drawings! It's the future! Architects.. For pure visual presentation, just turn the grid layer off and stop being so precious.

It is. The reason behind it is that the building loses a lot of sideways stability. The steel work is also designed to stop the building falling over sideways. This is often the main challenge as an SE, not just to hold up the vertical loads but also to maintain sideways (horizontal stability). You also need to maintain your thermal breaks / mitigate thermal bridging etc. This makes the SE work harder as in the old days we just tied everything together! That all has to come together and then needs to be detailed (just as important), with the propping sequence thought through, so it's buildable by an average (hopefully) competent builder at a sensible cost. I deliberately put lots of detail on my drawings where I want to explain to the builder what is expected of them and thus by inference what they should include in their price.

Good link. My own view is that the glue, if the right glue is going to out perform the timber. If you take a structural glue, like Cascamite, invented about 1940 it's well proven. It's relatively cheep and easy to use, just keep it out your hair, arms etc! You ain't going to get it of with a bit of Fairy liquid! Sometimes I want to glue stainless steel plates together, here the glue is a bit more specialised, maybe @Alan Ambrose may chip in. Buckland mention the end grain. The critical bit is to make sure the end of the cut timber is treated. But I can tell you that 99% of the time on site the joiners cut a bit of wood / trim Gluelam and don't treat the exposed ends. And then all the theory turns to manure! It's good though to see Buckland investigating this, it can only help inform.

Always helpful Thus the rebar has to have adequate cover and be surrounded by well compacted concrete. This concrete is at the start of the next lift, well down the shutter. Very difficult to achieve. The only reason for continuous rebar between floors is if you have particular fire or disproportionate collapse requirements. Less onerous on the standard ICF build. In fact.. if you add rebar into the ends of Hollocore slabs and tie that into the external walls then you start to create a moment / partial stiffness connection. You then introduce an extra bending force into the walls, thus you need to design for that, it potentially causes problems with concrete core thickness. Disagree, a lot, not really applicable to self build when using ICF, you are mixing up platform and core lifting with ICF which is a different animal. If you give your Hollocore slabs full bearing on the ICF core (say 150mm) then this often satisfies the tying requirement on a low rise buildings, like self builds. My advice stands. Recognise that on your second ICF lift it's going to be hard (impossible actually) to get adequate concrete compaction at first floor level when you have to get the poker all the way down the base of core if there is more rebar congestion. Keep it simple, extend the Hollocore out to the external face of the core. Always check with you SE in case there are funny point loads or lateral bracing requirements. My advice is general, but intended to be practical in the first instance.

Good spot, thanks for looking at my stuff. There are three fin plates, one at each end and on in the middle marked F4. The end ones stop the angle rocking on the external leaf of masonry. The centre one halves the effective length of the steel angle. Over a 4.0m length the angle will fail, in torsion and buckling. The members marked 7 xB8 are the first floor joists that rest on the inner leaf beam. I've added more drawing to let you see what I've been up to! Remember thought these are screenshots of part of my drawings. While I'm happy to share some stuff I do I need to protect my intellectual property to some extent. It is after all my day job also. The stuff you see is only part of what is a much larger drawing set. This is big bug bear I have. Architect's nine times out of ten don't put a grid on there drawings at the concept design stage. Thus it makes it right from the get go hard for a Client to line stuff up. As I wear two hats.. I just can't see why they don't do this, it's bonkers or arrogance?

Your SE is trying to convey to you some very difficult / complex structural behaviour, in lay terms. To put this into context. Working from left to right. The first two diagrams show a Cee section. It takes about 3-5 years after graduating from uni to even get you head round this, to be able to design something buildable and cost effective. Your SE has made a pretty good go of the diagrams. Option 3 works, up to a point span wise, much depends on the span / size of the angle. Angle sections are prone to twisting. Your SE later may want to also restrain the angle in places to stop it twisting. Below is a cross section though something very similar to what you have. Buried within the insulation you'll see two bolt heads. below is a screen shot of the steel GA details. If you look closely you'll see a steel fin plate in the middle of the angle span. Here I'm shortening the effective length of the angle and stop is twisting over the doors below. The fin plate method is a small local thermal bridge, but an effective way of getting a relatively small steel angle to work. Yes there are still thermal bridges, but this is not a new build rather a retro fit into an older house. Below is the proposed rear elevation. The clear opening width is some 4.0m. The steels over the opening need to carry first floor and roof loads. I've only posted parts of some of the drawings, hope enough to give you flavour of some of the things we need to think about.

As a suggestion for granite walls call: https://masonsmortar.co.uk/ The link to their website is above. This is a completely different animal. I'm assuming as it's in the centre of your house it is an internal wall? Try and post some drawings, maybe some photographs, often most helpful and describe what you are trying to do / why and your thoughts.

Hope you are enjoying BH, we have lots of fun here. Remember there is no such thing as a stupid question! As an SE I often look at bearing lengths for say Hollo core slabs. Generally on masonry standard is 100mm, on concrete (ICF) min 75mm, I then deduce your SE is taking into account construction tolerance, hence the 80mm. That's a good sign! The bearing length is vitally important as the floor slabs often act as diaphragms that tie the house together. But now we need to look at your pour sequence. Normally we would cast the first lift up to underside of Hollo slab, set the slabs, then carry on. A standard ICF domestic core is 150mm of concrete, sometimes a bit more. Now if you have a 80mm rest on your Hollo core that technically leaves 150 - 80 = 70mm of concrete before the outside skin of insulation, and that bit is going to be very hard to compact properly as it's going to be at the bottom of the next shutter lift. Have you considered extending the Hollo core slab rest to the full thickness of the concrete core so it sits flush with the outside edge of the concrete core? Then you'll have much better tying and can foam up the Hollo cores to your hearts content as they will be easily accessible? If you really want air tightness you can seal off any gaps within the floor depth as the end of the Hollo slabs will be flush with the inside face of the outside insulating layer of ICF,, that's a tongue twister! I may have missed something here. You SE may have introduced some extra floor to floor tying rebar, hence the reason for the 80mm bearing? Can you post the details you have? To finish, good question and hope you enjoy BH, folk chipping in, but also remember that folk that come after you will learn from your posts and experience. For me, it's also my day job, I also learn from your innovation, so thanks.

Very good question, looks like you are on the ball! Below is a typical Strongback detail: If you want to make a hole for a duct in these you'll likely have to add some plating detail or the like. It all looks quite doable..if your ducts are not too large. Can you dimension up your sketch / photo and mark on the hole and diameter you need to make? Plating with ply each side with glue is an easy option if your duct is not too large a diameter. There are plenty ways of getting around this, but we are looking for the simplest and cheapest option. I say glue as if you just use nails when you calculate the forces you often need lots of nails and the nail edge and end distance just takes loads of time to detail. The nails are just used to clamp ply until the glue cures.

I can see where you are coming from. Avoid blockwork. This is so fraught with tying difficulty. It sounds like you are ok with a solid baluster wall, it's going to look ugly! You should be able to much more easily sort this using a timber solution. As an experiment put two studs up , one attached to the wall to the left of the top of the stair stringer. One in line with the nose of the last tread, line each side and glue ply to that, give it a wobble! Check your BC drawing in case a diligent (no9t pragmatic) BC officer pulls you up about future provision of a stair lift, if applicable to you.