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The Ecotrus system - why I chose it As promised, here's a few more details on the light gauge steel system that I used, and in particular why I chose it. Unlike Gus, this isn't something I'm familiar with - the vast majority of any previous building work that I've done has been with timber, and if I could have done this conversion using wholly timber, I would have happily done so. My key issue was the span, combined with my desire to do as much of the work myself as possible. Our house is essentially a square box, and it's approx 8600mm from wall plate to wall plate. There are no supporting walls at first floor level and so the existing roof was supported entirely by a typical Fink truss structure. I therefore kept going round the loop of how to bridge the span without needing the conventional approach of two RSJs at loft floor level and probably another at the ridge. I realise I'm not a structural engineer and there are probably a lot of possibilities which simply didn't occur to me here, but I did do a fair amount of research and cycled through considerations such as: Posi-joists: theoretically possible with the span, albeit would have been very deep. I also couldn't find any clear details, despite speaking to a few manufacturers, as how they could sit on the wall plates and be tapered on their top chord to fit within the roof slope. Timber I-joists: again, theoretically possible with the span, albeit right at the upper limit. Simpson Strong-Tie used to have a system to allow you to cut the necessary taper on the I-joists to fit within the roof slope, but it appears to have been discontinued now. Regardless, for the span I needed, this wasn't a particularly cost effective option and still didn't resolve what to do at the ridge. Glulams: as above, and much heavier to move as well. RSJs: probably the most conventional and likely the cheapest option overall. However, not something I felt confident managing or directing on my own, and would have required a crane to get them into position. If I'm honest, the main barrier here was probably my fear factor of operating well outside my comfort zone, plus the difficulty of finding a reliable contractor who was willing to take on the structural steel elements only. Telebeam: similar to EcoTrus, but relatively expensive and still didn't resolve what to do at the ridge. Various other combinations of building supporting walls at first floor level (too disruptive to the rest of my family, who I've been desperately trying to keep onside!) and trying to span between them. In summary, the EcoTrus system was the only one I came across which seemed to offer the required span, the freedom for me to install it myself and was backed up with a design service, structural calculations and LABC/NHBC Stage 1 pre-approval and LABC Partner Authority assessment. To be clear, I'm not saying it was the only option or even the right one, but it solved the problem that was front and centre for me. Being able to say 'I did it' has been a big part of this for me. How does it work? I found the system pretty logical. One day, a lot of steel turns up at your front door - in our case, 117 individual pieces of light gauge steel. The main components are the floor joists, rafters, gusset plates, ceiling joists and the dormer faces/cheeks. The latter are the only bits that turn up semi-assembled: we had three panels which made up the front of the dormer and two further panels for the cheeks. In advance of receiving the steel, you're provided with the assembly drawings and some standard guidance as to how put it together, starting with the floor joists. We removed the bottom three rows of tiles on both sides, fixed ropes to both ends of the joists and then lifted both simultaneously (with the back rope being rigged over a higher part of the scaffold) so that the joist ended up suspended mid-air at roughly loft floor height and in line with the relevant truss bay. Each one was then pulled in and slid through the roof until it was resting on the wall plates on both sides (with 45mm packers already in place). This was by far the most physical bit; each joist only weighed approximately 35kg, but the length made them awkward to handle. We managed it with three people and got them all in within four hours. There are two 250mm C-section joists per truss, fixed back to back through the truss at 600mm centres top and bottom with 5.5mm Tek screws. Then came the rafters; again slid into the right place using the same technique and with two 165mm C-sections either side of each truss. They were connected to the floor joists initially with a 16mm bolt, later reinforced with the same Tek screw pattern through the truss. Starting with the rafters at either end, the idea is that you then pivot each rafter on the 16mm bolt to lift them up to the underside of the existing felt until they are a specified distance above the floor joists. Once fixed, you string a line between them and use that as your reference point for all the remaining rafters. This sounded straightforward, but we ran into issues with our trusses not being true - once I had the rafters at either end fixed into place, it was impossible to get some of the intermediary ones pushed up to the same height because their corresponding trusses and/or the roof battens in that area were sitting lower. Ultimately, I had to strip that side of the roof to get them all in plane, which was fine for me as we had a tin roof scaffold and because I was planning to re-roof anyway, but would have caused a lot more issues if I had wanted to keep the existing tiles. Then you add the gusset plates - effectively reinforcing ribs which replace the need for a ridge beam - to the tops of the rafters and in line with your strings. Next comes the dormer face and cheek panels; I had messed up here and not allowed a sufficient gap in the scaffold to pull them through. The largest one was 2200mm by 3000mm and weighed about 120kg. The scaffolder was really helpful and sent a couple of his team round to adjust the scaffold and then help to haul up the panels, which we did with a scaffold hoist and some ropes to stabilise, effectively sliding them up the back of the house. They sit directly on top of the floor joists, more or less directly over the inner leaf of the back wall of the house. Once in position and squared up, you then install the dormer ceiling joists between the gusset plates and an L-bracket which is pre-fixed to the back of the dormer panels. Notwithstanding the issues with the rafters, it was a straightforward process - quite repetitive (driving Tek screws gets boring very quickly), but logical and sequential in its nature. The below photo shows where we had go to after ten days with two people working full-time (and obviously using the system for the first time). I'm conscious of length, so I'll end this post here and I'll cover the roof windows framing and some of the system idiosyncrasies next time.

Nickfromwales has given you the right steer here. That braided section right at the connector is exactly the spot where I see these flexis let go later on, so replace it while it is on your mind. It is a cheap part and it is worth it to not have that worry hanging over you.

It certainly seems to be a nice bit of kit and very straightforward to use. Proof of the pudding will come in time though… I’ll add my thoughts once it’s been installed for a while :) Yup… they were virtually free, so it seems daft not to consider using them, but otherwise you’re right… not particularly cheap. I am… might change my mind in the future though, if/when I have to pay someone else to work on it 😬

Oh that Atios Smartcore looks good. Not seen it before. I'm not building atm so haven't been paying a huge amount of attention to new products recently but had previously ruled out DALI due to the lack of interfaces I wanted to use. That Smartcore may change my view. My main thought on the Hager Klik is cost. It's obviously a huge timesaver in the right place. If you have them anyway and can use them in your layout (without making access worse) then I don't see why not. Obviously using DALI may put off normal domestic electricians from touching the system but guess you are comfortable with that.

Our build is moving on nicely. We should be watertight some time in December 🤞🥳 We’re reviewing our lighting strategy. Current plan is for all (or most) lighting to be DALI-2, controlled via an Atios Smartcore and Home Assistant. We have quite a few Hager Klik-7 marshalling boxes (more than enough for the whole house) and am thinking that this could be a neat way to run the lighting. We also already have the Smartcore (so I could have a play around with it before committing) and a lot of DALI kit… presence detectors, drivers & luminaires. There are plenty of convenient accessible spaces to house the boxes. So… just looking for a sense check really. Any downsides of using the Klik system? We installed a load in our factory/office some years ago (albeit not the DALI version) and without wishing to tempt fate have had zero issues. Made installation a doddle too 👍 Thanks :)

Just out of curiosity. Do you always adopt such a shit tone with people? My question was regarding whether the nails of the restraining straps will interfere with the chipboard flooring. I didn't want a jumped SE making snide comments.

On the UFH question, yes, I'd run the loops under the shower area as well. It's one of the best bits of a wet room, the floor dries off quickly after use and it never feels cold underfoot. A few things to plan for in your case though. Watch the cover over the pipe where you drop the slab. Once you've recessed for the tray and then deeper again for the waste, you lose a lot of depth, so check you'll still have at least 50mm of concrete over the pipe in the recessed area. Keep the loops well clear of the waste and gully position so nobody breaks out onto them later, and take photos of the layout with a tape measure in shot before the pour. You don't need a separate zone for it. In a 250mm slab it'll just sit at the same temperature as the rest of the room, which is what you want. For the formers, Gone West's insulation blocks are the way I'd go too. I'd add a bit of foam adhesive under them as well as weight on top so nothing floats, and sleeve the waste in a short length of larger pipe so you've got some play to set the final height to the tray. Then tank the whole recess properly before the screed or tray goes in.

Thanks Nick. I will do that. I have hand rails, but adding the bracing underneath makes sense.

No I don't think so - the roof plan is a straightforward box with the exception of a small mini gable on the front and that wasn't included in the steel system, so this structure is purely a pitched roof plane joined to a big flat roof dormer at the rear. I'll get the full details of the EcoTrus system up later and would welcome your views. Ultimately it's all backed up by the structural calcs, but I've no doubt it's probably over-engineered for what it is - there are essentially only three or four versions of it designed to fit all scenarios, so I guess what they save in bulk manufacturing makes up for some designs being over the top for the problem they're actually trying to solve.

Varnish it with a decent satin or matt product, and relax. I fitted an oak (iirc) untreated table exactly as you intend here for my SiL over 10 years ago. I think it got waxed maybe, but was ‘bare’ wood. Still looks good today with bath & shower present, small room, just has signs of life but zero ill effects. Storm in a teacup afaic, so keep it simple. Mask the top where the sink meets it and set it down into a ring of clear CT1, job done.

I had the first Isoquick slab laid in England sixteen years ago and I had a similar problem in the wet room. I filled all the areas, where I didn't want the concrete, with blocks of the Peripor insulation. For the waste pipes this meant surrounding the pipes with Peripor which I removed after laying the concrete. That allowed the height of the waste pipes to be adjusted to suit the shower tray. The gaps around the pipes were then filled later.

Lol. They’ll be used by everyone the second they're installed 🙄. Do this and then add some handrails. It doesn’t cost much and then you’re “safe enough”. Nobody inspects these until someone is seriously injured, then they get inspected to feck I assure you.

That's not a bad call regard leak alerts

tetris has hit on the real risk here. In my experience the basin waste and the flexible tap connectors inside these adapted units are one of the most common sources of slow hidden leaks, and a fully sealed up unit means you never see the first signs. I would keep the trap and pipework easy to get at and check the flexis once a year, that matters more than which finish you pick for the top.

Good call going wall to wall this time. That weir effect you described with leaks under the cupboards is exactly how slow leaks stay hidden for months, so removing it is the biggest leak prevention win in this whole job. While the floor is up I would drop a cheap battery water alarm under the washing machine and the softener. They cost a few pounds and they are the cheapest early warning you can fit.

How did you build that awesome custom bunkbed? Thinking of doing the same for my kids.

@flanagaj I’ve made myself up a simple pulley system (effectively block & tackle but only two single pulleys in my case as I’m only lifting a couple of packs of shingle at a time). 2 x pulley: https://amzn.eu/d/05AWFkQ0

Thank you for reading some of my posts, much appreciated, some are lengthy not least and a bit ranty! Ok to be a bit pedantic, you say this was an earlier photo. The use of one bolt at the rafter ceiling joist connection is not common practice, I would look for two. Looking at your roof, it's of modest size, the loads are relatively small, cuts you a fair bit of slack. The thing that made me wonder is this. Looking at your photo it all looks over engineered for CF. Now while EcoTrus and their SE's may not have the depth of knowledge and industry experience that I might have, My Masters thesis was testing top hat CF purlins for example, I kind of know a bit about this. I wonder why does this look over Engineered, is there another part of the roof that we can't see from the photos that would explain why I'm seeing what I'm seeing? But in the round, I really like what you are doing here!

Nah, dry fit. The ply, yes, glued. Going to do the walls first but while I wait for the tiles to arrive made sense to get these cut and ready. Onwards and upwards!

The top plates raise a structural analytical question. The structural behaviour explanation is lengthy, I've kind of given up on trying to explain a lot of this to you. You just cart on and react after the fact, get ahead of the game! If you still have concerns then go back to the posi joist designer and ask if their design accounts for full load on the adjacent long span and minimum load on the short span. When you analyse this the forces change. It may be your posi joist designer has not taken into account this load case, or that their software has an error in it! Or you may have moved the supporting walls below without asking anyone! You don't have to move them much to invalidate the design. Next time you chat with your SE ask them about my comments.

Hi @Gus Potter, thanks for reading - I've taken a lot from your previous posts on here. Interested to know which bits concern you about the technical connections? I'll post some proper detail on how the whole system goes together next; worth saying that some of those photos were taken before all the required fixings were in. But in short, it's 16mm bolts at all connections between the main members and then a lot of 5.5mm Tek screws at 600mm centres. And I mean a lot!

Post a drawing of what you intend to get best feedback.

Difference is I think you've stuck yours down

Slightly different floor build than yours, but we used offcuts of insulation cut to the size I needed and a few very long nails to hold it all in place and the some concrete blocks on top to stop it floating off during the concrete pour. When I was ready broke out the insulation, did the drainage conections and back filled with concrete as needed.

Great to see folk embracing light gauge steel (LGS). I have a background in this. When doing my training I wrote many structural calculations that underpins the likes of the software that one of the biggest CF building suppliers in the UK and Australia may use and / or their Engineers. There is a place and time for using LGS. If you hit the sweet spot it can be a very elegant and cost effective solution. I've had a glance at your photos. Some elements such as the connections look technically ropey, could be improved! It looks a bit over engineered but lacking on and understanding of connection design behaviour. The thing that strikes me most is the cost of fabrication, lots of cutting back flanges and so on. In the round though I think what you have done is great!