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Posi joists on internal walls


willbish

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Wondering on the collective opinion, what is the better way to support posi-joists on internal blockwork walls?

 

The two options, as far as I can see

-Bear the bottom chord directly on the block work or

-Use a JHM type hanger

 

Any structural advantages to either method? Will be trying to minimise any movement/deflection

 

Bearing directly onto the block work is easier and cheaper and length of joists less critical

Using hangers feels the more superior way to do it but I'm not sure why!

 

Just to add the block work walls will continue up another story so there will be plenty of weight bearing down

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3 minutes ago, Russell griffiths said:

I would say built in as well

the only down side is the length of joist, will you be able to handle a full length that goes from outer wall to outer wall

The internal block walls are not intermediary supports. They are supporting the ends of the joists

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  • 2 weeks later...

@Big Neil with ICF the walls will be propped, usually from the inside, to ensure alignment during concrete placement.

If you are intending to cast your joist ends into the concrete core all your joists will need to be propped as well. This could get very crowded!

 

The other issue is ensuring no concrete leaks where your joists penetrate the inner leaf of the ICF.

I've only seen a handful of ICF builds, they all have fixed joists after the concrete has been poured.

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  • 3 weeks later...
On 08/11/2018 at 07:06, willbish said:

If you are intending to cast your joist ends into the concrete core all your joists will need to be propped as well. This could get very crowded!

 

Was thinking of placing them after the first pour which would be to joist bearing height, then the props for the first part could be taken away anyway. Metal end caps for the end of the joists - jobs-a-goodun.

 

 

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12 minutes ago, Big Neil said:

 

Was thinking of placing them after the first pour which would be to joist bearing height, then the props for the first part could be taken away anyway. Metal end caps for the end of the joists - jobs-a-goodun.

 

 

You would need to insure your concrete pour was accurate to within 3-5 mm over the length of the wall, or your joists would all be out of level, you would then need to cut every block you put on next to accommodate the joist in the way. 

I really don’t see what benefit this method would have over the standard fixing method of a pole plate bolted to the wall and joist hangers. 

The canadians and the yanks have been doing it like this for years, can’t see any reason to change it. 

 

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Look up FOX blocks on YouTube, they seam to have more vids than anybody else. 

You can do it a few ways

you put your pole plate,ledger board, rim joist, call it what you like, in position, screwed to the wall with temporary fixings, mark out your joist layout, work out where your fixing bolts go and drill holes in pole plate, remove pole plate and cut a large hole in your icf in the location of the bolts, fit a membrane of some description to the back of the timber, put timber back up with bolts projecting into the holes you cut, when you pour your concrete it will flow into the holes you cut and surround the bolts, it will end up with concrete pads projecting out to the back of the timber adding the support you wouldn’t get from the insulation layer. 

I will be doing mine in a months time, I will try and remember to take a few pics. 

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Thanks for all the answers. I'll look at FOX blocks later. 

 

Unlikely i'll be able to get down your way before Christmas, but thanks very much for the offer. Just trying to arrange a site visit for a thermomur build somewhere up near me in Manc-land at the moment, so should be interesting to see.

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