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Thin Wall Plate - Ideas?


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#1 jamiehamy

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Posted 20 March 2016 - 07:55 PM

Hi folks, just looking for some ideas. I due to changing the thickness of insulation on the warm roof build up, the ICF wallhead is sitting too high to give me the right fall for the terrace.

Without a wallplate, the joists will sit at the right fall, but once I put a wall plate in, it goes to less than 1/80 (targetting 1/60).

If I put a 25mm wallplate we will just about manage as long as I am clever with the decking. Is there anything else I can use that is thinner and will do the job?

It's posi joists sitting onto the ICF core.

Thanks, Jamie

#2 tonyshouse

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Posted 20 March 2016 - 08:55 PM

Miss out the wall plate, use noggins between joists?

#3 jamiehamy

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Posted 20 March 2016 - 09:13 PM

Is the permissable? I'll be putting in noggins/dwangs anyway (it's the top chord of the posi's, so that's the standard detail) - I thought the wallplate was for the timber to bear on rather than concrete (for some reason) - does it not matter? If we can bear direct on the concrete, then that's perfect. :)

#4 PeterW

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Posted 20 March 2016 - 10:01 PM

YOu may have to find a way to hold down the joist ends onto the concrete to the satisfaction of BC - normally the wall plate is rag bolted to the concrete to secure it from lifting and the joist are then attached to it.

#5 tonyshouse

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Posted 20 March 2016 - 10:05 PM

Holding down straps for flat roofs should hold down joists, typically twisted straps are used

#6 jamiehamy

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Posted 20 March 2016 - 10:10 PM

That should be fine - I'll put dwangs between and a timber runner along the top to be resin fixed down into the concrete - there will be drain outlets on either side - maybe one in the middle too. . A balustrade will be fixed to that eventually anyway.

We're off for the long weekend and were going to have a rest but this might just be the opportunity to finish the structural part of all the roofs..then onto insulation and EPDM...

Thanks all, as ever,

Jamie

#7 ProDave

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Posted 20 March 2016 - 10:24 PM

Am I missing something obvious.

If the fall is too low, then raise the other end, i.e. a thicker wall plate at the high end?

#8 jamiehamy

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Posted 20 March 2016 - 10:31 PM

Can't do that - as this is a terrace and if we raise the other end, then the floor will be too high and we'll have to step up onto the terrace from inside the first floor.

#9 tony51

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Posted 21 March 2016 - 11:09 AM

This shows a disadvantage of posi joists. If conventional timber joists are used, they can be notched at the ends if they are too high.