RSJ box frame - is this a valid approach?

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hi all,

I just want to validate my thinking about installing a box frame, having spoken to my builder.

the extension floor slab and bricks up to DPC are nearly in place. the builder suggested we prop the floor joists in the existing kitchen and prop the outer wall using strong boys. they then want to demolish the rear wall to open up the existing kitchen, remove several rows of bricks from the footings, to make place for the bottom beam, install the box frame and THEN start building the extension walls.

needles to say, this means the house will be propped for a few days, without an actual wall to protect us from anything (weather, thieves etc.) and I'm a bit concerned.

what I would suggest is that we build the extension walls first (no roof) and then remove the outer wall. would this work? we need to remove 4 rows of bricks from above the foundation, lower the beam (end to end), install the columns and the top beam and encase it in concrete (bottom), dry pack it (top).

is there a "correct" order in which to do this? would my approach work?

thanks
 
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I am not a builder or qualified in any way for this but...
what is his reasoning?
is it access? maybe the steels need space to be installed?

Many extensions seem to be built by building an OSB/Ply wall for security?
 
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He did propose a plywood temporary wall, I can’t see how that would prevent anyone from getting access to the property. I can literally smash it into pieces by kicking it twice.

As for the beams, it might be access, but I don’t see why it wouldn’t work with the walls in place.
 
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Goalpost not an option due to the foundation and structural engineer wanted one. Entire! rear wall goes, so no lateral support at all.
 
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I can literally smash it into pieces by kicking it twice.
I'll see your "kicking ply twice" and raise you a kicking glass once.

Build a temporary wall. But don't use the ply you mention, use normal ply I doubt anyone can kick normal ply and break it. I'll put 50p on it.
 
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Your bits of steel will be a lot easier to put in place with a forklift or telehandler if there isn't a new extension in the way :)
 
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The way I see it, since the top/bottom beams are 6m long, they will need to be placed on the ground, next to the foundation, BEFORE the ceiling/wall is propped.

With one acro every 90cm, you won’t be able to squeeze a 3m rsj between, let alone a 6m one.
 
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Your paying your builder to build this for you so you have to trust he knows what he's doing, your in for a very difficult build if your going to be questioning your builder every 5 minutes with some bloke on the Internet said it should be done like this.
 

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