Joists 100mm short of a picnic. Trying to maintain my sense of humour....

[PeterW]

Thicker wall plate may work but I expect BCO would want it bolted not screwed so the whole lot would have to come off and start again.

 

If the supplier has measured and they have it wrong then however much it seems harsh, it’s their issue to resolve. 

 

(Sorry @recoveringacademic missed your call earlier ..!)

[Russell griffiths]

1 hour ago, recoveringacademic said:

 

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. 

Is that a standard detail ?

i thought the hanger worked by having full contact. 

Anybody. 

[ToughButterCup]

39 minutes ago, Tennentslager said:

Swap the wall plate for one 50mm thicker each side...they pay.

Maybe...?

 

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....

[ToughButterCup]

8 minutes ago, Russell griffiths said:

[...]

i thought the hanger worked by having full contact. 

[...]

 

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

[ToughButterCup]

27 minutes ago, PeterW said:

Thicker wall plate may work but I expect BCO would want it bolted [...]

 

It already is : 120 Thunderbolts into 200 concrete.

[PeterW]

3 minutes ago, recoveringacademic said:

 

It already is : 120 Thunderbolts into 200 concrete.

 

Sorry, meant that if you joined two 50mm joists together to make 100mm, BCO would want them through bolted to each other which would mean the plate coming off. 

[mvincentd]

1 hour ago, recoveringacademic said:

 

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. 

I'm no expert but I would respectfully encourage you to closely examine the suppliers fitting plan for the posijoists to rule out any misinterpretation.  I hope my concern is ill founded given all your hard work fitting the wall plate.

IF you mean your posijoists are designed to be top hung surely you should have more length on the top chord, but they don't look like they are anyway to me?  Are there joist hangers in the case of top hung?

I do actually have some posi's where they are in hangers that are 'free' at the bottom but the hangers are bespoke, much heavier gauge and coach bolted.

My SE and Crendon (posijoists) were quite specific that its the lower wall plate of the two (image attached) doing the work, and the upper one is relatively speaking just a filler.  Hence the bottom of hangers match bottom of wall plates and the 'excess' height of the posijoist protrudes above top of hanger (in my case to match top of concrete). 

Regarding the 100mm short issue, I don't think you should even begin to put your own thinking cap on.....Posi's are an engineered solution and the supplier needs to warrant the integrity of the solution so the answer surely MUST come from them...to that end I don't see bco wanting to stick their neck out.

[mvincentd]

52 minutes ago, recoveringacademic said:

 

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

sorry missed this while typing my essay!

[ToughButterCup]

8 hours ago, mvincentd said:

sorry missed this while typing my essay!

 

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

9 hours ago, mvincentd said:

[...]

I don't think you should even begin to put your own thinking cap on.....Posi's are an engineered solution and the supplier needs to warrant the integrity of the solution so the answer surely MUST come from them...to that end I don't see bco wanting to stick their neck out.

 

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.

[scottishjohn]

13 hours ago, Tennentslager said:

Swap the wall plate for one 50mm thicker each side...they pay.

Maybe...?

that sounds like easiest way --you even got templates for drilling 

or double up + a few more concrete fixings  to be sure - it would be my solution if i was paying 

Edited November 27, 2018 by scottishjohn

[joe90]

I still say it’s the suppliers problem, why should you have to make more work because they cocked up?, simply tell them you want what you ordered, joists THAT FIT.

[jack]

35 minutes ago, joe90 said:

I still say it’s the suppliers problem, why should you have to make more work because they cocked up?, simply tell them you want what you ordered, joists THAT FIT.

 

Agreed.

 

The only reason to be doing anything other than demanding the correct joists is if that will delay you and you can come up with an alternative that reduces the delay.

[Jeremy Harris]

There's no way I'd be faffing around with doubled up wall plates (which will inevitably then be working at a much higher than designed shear stress) for a problem that's someone else's error.  I don't even think that the doubled up wall plate solution would be acceptable with the present depth of the timber used - at the very least it would need an SEs input to confirm that it's OK, as ideally wall plates should be as thin as commensurate with getting adequate joist hanger fixings in, as that minimises the peak shear stress they see from the total floor load.

[the_r_sole]

.

Edited September 26, 2019 by the_r_sole

[ToughButterCup]

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.

 

 

[the_r_sole]

.

Edited September 26, 2019 by the_r_sole

[ToughButterCup]

4 minutes ago, the_r_sole said:

you asked for trimmable ends, they said they'd give you them - whether or not it's normal practice isn't anything to do with it

 

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_r_sole]

.

Edited September 26, 2019 by the_r_sole

[jack]

23 minutes ago, recoveringacademic said:

... he says that it is not normal to provide trimmable ends and that many customers would object to trimming joists to size.

 

And yet they accepted an order from you on this basis, just like last time. They're taking the piss.

 

Does the diagram that was annotated (and agreed) have arrows showing what the dimensions relate to? I'd have thought would be the end of any conversation on this point.

[ToughButterCup]

1 minute ago, the_r_sole said:

[...]

so it just looks like they are back tracking after a mistake and are going to ask you to pay again.

 

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

[jack]

6 minutes ago, recoveringacademic said:

But they are saying the trimmable end is calculated from the inside of the wall-plate. 

 

Even if what they say is true, you'd expect to have been supplied with joists at least as long as the distance between the wall plates, plus some amount for trimming (hence "trimmable").

 

What's the other end of the joist doing in the first photo? Is it against the far wall or the wall plate? Either way, I can't see that there's a trimmable portion, no matter what they think the measurement should be based on. 

[JamieL]

In fact on that basis you'd expect to be supplied with joists 100mm too long if they wanted the dimension to the inside of the wall plates and you supplied the dimension to the outside of the wall plates.

[ToughButterCup]

1 minute ago, jack said:

 

Even if what they say is true, you'd expect to have been supplied with joists at least as long as the distance between the wall plates, plus some amount for trimming (hence "trimmable").[...]

 

Some would say that. But it needs to be made explicit, it seems.

2 minutes ago, jack said:

[...]

What's the other end of the joist doing in the first photo? Is it against the far wall or the wall plate?

[...]

 

Its flush against the wall-plate. The gap you can see in the photo is 50mm

 

Here's the  plan annotated by the designer

 

 

[ToughButterCup]

2 minutes ago, JamieL said:

In fact on that basis you'd expect to be supplied with joists 100mm too long if they wanted the dimension to the inside of the wall plates and you supplied the dimension to the outside of the wall plates.

 

Erm, which basis?

[JamieL]

On this basis:

57 minutes ago, recoveringacademic said:

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.

You provided a larger dimension than they were expecting.

 

Anyway that is irrelevant as your diagram above is perfectly clear. You have told them that the width of the room is 3646 (in block 1 for example) and they have decided to provide joists that are 3560. Which is obviously going to be too short.

 

Edited November 27, 2018 by JamieL