In article , Christian
McArdle wrote:
I simply don't see how this would work for me. Where do you hide the
8" (200mm) beam? I only have 100mm to play with and need a continuous
floor with the conventional joist length being a centre supported 8m.

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A D B E C

You're planning to put your joists from A-B and B-C and holding up the
roof some other way. Most loft conversions I designed in my earlier
life had serious steel beams at D and E spanning from party wall to
party/flank wall: these supported the floor joists which now only have
span D-B and B-E also the dwarf partitions that help hold up the roof.

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Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
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