ToughButterCup

Erm, which basis?

Some would say that. But it needs to be made explicit, it seems. Its flush against the wall-plate. The gap you can see in the photo is 50mm Here's the plan annotated by the designer

Hmmmm. Thats what I think too. But .... It would be good to know what standard practice is (and therefore isn't)

OK, I accept that. And they did indeed include trimmable ends. But they are saying the trimmable end is calculated from the inside of the wall-plate. My contention (on the basis of the previous order) is that the end is calculated based on the total width of the room.

The plot thickens. In summary: the question revolves around the trimmable ends. We agreed that since our wall is uneven, that 50mm trimmable ends should be provided. The core question is, from what datum point? To explain, I need to take you back to our flat roof joists ordered from the same company. I ordered the flat roof joists based on the widest part of the space to be covered. 1979mm. Those joists were also to be provided with trimmable ends. The joists arrived, I checked them and all is well. Each joist-end will need to be trimmed a bit in some cases, more in others. The trimmable end allowance is 70mm each side. The wall-plate is 47mm each side. More than enough to allow the joist top chord to sit happily on the wall-plate So in ordering the next set of joists (for the first floor in the house), I go through the same process, and ask for trimmable ends. I check the first design, find a couple things need to be changed, send the plan back annotated with the 'worst case' width. The designer dutifully notes those dimensions on the plan (in red) , and confirms by email that the joists will include 50mm trimmable ends. At this stage I think I have ordered a set of joists, just like the last lot: joists which, with when their trimmable ends are suitably docked, will slot in neatly in between the wall-plate faces. Talking to the designer this morning he says that it is not normal to provide trimmable ends and that many customers would object to trimming joists to size. And anyway the trimmable ends are calculated from the absolute width of the span minus the wall-plate. Not the total width of the (in this case) room. In other words: 50 mm measured from where? The total width of the room or the width of the room minus both wall-plates? My contention is that the previous order with the same company and same designer measured the trimmable end from the walls themselves - not the wall-plates, and that this second order would be the same. If you reply to this post, please tell it like it is, not what you think I may want to hear.

Thanks. Thought of that.... too high. Need one of these bad boys with an anti-slip tread

Its the hopping operation that's dangerous to me. Unsupported, my knees will on some occasions give way. It would almost be better if they gave way every single time. I take the point about fastening the ladder to the trestle; in addition I need the equivalent of a sawn-off Zimmer frame at the top. Now there's an idea........ anyone got a spare Zimmer?

Gottda face it, my knees are shot. They're has-been-knees, dead knees; I know a dead knee when I see one and I can see two of them now (well it's early). Getting up and down from the trestles (as opposed to a scaffold - there's progress for ya!) I wobble like a jelly, not having the courage at the top of the steps to press hard with just one knee. How do I safely get up on to a trestle? Yes: I know use a ladder: but how do you fix the ladder solidly so that transitioning from the ladder to the planking is safe and steady? I need a handrail-grab-thingy....

I'd rather that happened than you not post. Having the lower chord of a POSI 'free' (that is tied to the joist hanger, not the wall) is counter- intuitive And your advice is exactly right. I usually try to explore the scope and severity of a problem before attempting to solve it. A useful strategy, sometimes. But as you say, inappropriate here. Domestic Client - inexpert , CDM 2015 and all that, Sometimes a Can Do attitude gets in the way.

It already is : 120 Thunderbolts into 200 concrete.

I quadruple checked. It's OK. Design approved by the supplier company

Nice idea, but it's me we're talking about, not an experienced chippy - that would make a 100 by 220 wallplate and 200 long Thunderbolts....

Yes, Russell, I think it is a (photographic) 'angle thing' . I'm not sure what a pole plate is, but the POSI joist is a good few ml lower than the wall plate (sometimes called rim joist). So the bottom chord of the POSI is 'free' - to the extent that the joist hangers will allow it to swing.

The money will be nice. But having peace of mind nicer....

It's the standard way.... Good, hefty cross-braces ; or - as we did - use up all the spare 4 by 2. God what a waste that was.

Bosch laser innit? I must have re-measured all the spans five or six times, And once with Debbie checking my measurements table (Nearly wrote measurements there before remembering what field day @Onoff would have )

55 or so. Every one exactly 100mm short.

Surprisingly, not me. The supplier's rep was quite open and frank about it: he's even been honest enough to transfer my annotation ( 'This dimension is the internal wall dimension, not taking into account the 50mm timber bearer' ) on his initial plan. BCO pointed out that since there are no POSI Joist guidelines equivalent to the TRADA ones, he can't advise on whether its possible to compensate for the error. Looks like the suppliers will need to replace them. Pity - it'll be costly.

The span at that point is 3646, and the joist supports the first floor.

If I cant take a joke, I shouldn't have started should I? So, folks, what I can I do about that then? Booked a call from the BCO, architect sucking his teeth, suppliers humming and haa-ing.

The price of the raw material is not the only cost to take into account; the biggest annoyance (on our build) was the cost of mishandling the blocks. In other words - the couldn't-give-a-stuff-itis It matters if other blocks are used as a cutting surface , so when the builder uses those blocks there are so many cuts on it that the block bursts. It matters if there is only one supplier: we used more than we thought we would, and instead of just popping down to the BM, you have to arrange a palletised delivery. Despite being repeatedly asked, our builder seemed to take delight it tell us we needed more blocks five minutes before they disappeared off site. It matters if the blocks are laid without care and subsequently, instead of relaying, bashed into place with a piece of 3 by 2 - and so fractured, causing the inevitable burst. Ask about delivery lead time. Its getting longer..... On balance, those carelessnesses added nearly 5% to the raw price. By the way, just been to a local Durisol build. An appreciable number of (as yet unused) blocks were 5mm more 'out' . QA, it seems is becoming an issue. They should not have left the factory.

Elegant. Of the techniques suggested, yours, Ed (the Scottish one) , appeals the most. I'll try the others too just for reference. The post on your blog about checking your laser has got me thinking too. Thanks.

Hmmm. Yes, temporarily just for accuracy. Your point about splitting them made me think though. I might just have to prop them in place and then fix with hangers and nails.

Wallplates are nearly all up now. ?? Can I screw the joists to the wallplate before I attach the joist hanger? I ask because I'm doing it on my own and I think I may be able to fix the joists more accurately by screwing them first and fitting the joist hanger after I am satisfied with the position of the joist.

Finish the bathroom ..........?