Timber awning construction joints

Feb 15, 2007 5 Replies
J

Question about joints for an awning over an outside door:



The sloping slated roof will be supported by a timber structure shaped like so:



I I x I x I x I x I x I H H H H H H B I S I S I S I S I S I



Hope that's clear (!)



I is 75x50 bolted to the wall x, H & S also 75x 50 B is the horizontal 92x75 horizontal timber running the length of the awning. x supports slating laths & the slates



What type of joint should be used:


  1. at the junction of I and H - is a simple mortice/tenon joint OK & if so what is its recommended size?


  1. at junction of I and S - S here is angled. Options seem to be to (a) rebate I to hold S (b) mortice/tenon (c) just screw or bolt S to I?



I've looked at quite a few porches/awnings, but have yet to find one with enough exposed to allow me work out how joints were made at these positions. Any information most gratefully received. TIA



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A

Mortice and tenon with wood pegs through tenon,use a good quality waterproof wood glue.

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some good pictures here of porch construction may help your design

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T

I suppose it depends on what tools/equipment you have. Personally I would assemble it first, then bolt the whole thing to the wall - having pre drilled the wall plate & wall.

I'd rebate or half lap the joints and screw through from the rear with a healthy dollop of PU adhesive.

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S

You can't beat a good "R flap"

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A

Tip for dowelling joints: drill the hole for the dowel very slightly undersize so it has to be bashed in, but also drill the hole in the central tenon slightly higher up in the mortice joint than common sense would suggest, so that when you bash the dowel in it pulls the tenon down hard into the mortice slot. You need to gauge the amount of offset in the hole carefully else the dowel simply won't go through.

Andy.

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