Joist hangers to support new flat roof?

18 May 2011
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United Kingdom
I am presently replacing an old concrete roof on a lean to style extension. I was hoping to use masonry joist hangers into the existing external wall to support the new joists or would a timber wall plate with hangers be better? Should I use firings or simply have the hanger/plate raised slightly to give a 1/60 drop for the 3.6M length? thanks in advance.
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Bolt a timber plate to the wall and secure the joists with jiffy joist hangers.

Use furring strips on top as sloping the joists creates a ceiling anomaly.

Don't forget insulation. Use the 'warm deck' method as this is simple to install and reliable.
Thank you noseall - for the advice and the quick reply!
Joists are 50x200 at 600 centres although may drop to 500. Would you recommend another 50x200 as the timber plate?
Best wishes
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A little more information from another post.
Without wishing to contradict any of above posts, may we make a couple of further suggestions.
Use STANDARD timber to timber 225mm long joist hangers in preference to jiffy. Couple of coppers more, but much better.
Nail every hole with sheradised 30x3.7 square twisted nails.
If you screw plate to wall before bolting, then use Through Bolts. Do not use raw bolts rag bolts, shield bolts, call them what you like, as these all need a bigger diameter hole in brickwork than your fixing hole in timber plate. Through bolts, the anchor is same size as bolt. Rattle drill straight through timber and brickwork in one hit, push bolt in and tighten.
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Always use same size plate as joists.
If fall is from house to flank, use firrings, if from front to back or back to front, use reducing rips. As nose has said keep level ceiling.
600 centres :?: Depending on what decking you are useing :?: Would suggest 400 centres. Set your joists for 2400 sheets. Check you have sufficent storey height before roofing in.

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