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newshound newshound is offline
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Default Repairing timber shed uprights - fish plates?

On 24/07/2018 16:42, wrote:
On 24/07/2018 16:08, newshound wrote:
On 24/07/2018 15:15,
wrote:
I have a large shed with 6" x 3" timber uprights resting on a stub
block wall. The bottom 2-3 feet of the posts is rotten so I want to
splice-in some new timber. I can't think how to cut a decent lap
joint in the bottom end of the remaining upright so I'm tempted to
butt join the timber and add steel plates (fish plates?) on each side
- at a guess these would be around 150 wide 450 long and a few mm thick.

Suggestions welcomed for how to cut a lap joint on the bottom of a
bit of timber that's waggling in the breeze, or for a source of
suitable steel plates.


A bit fiddly, but can't you make the basic cuts for a lap joint with a
circular saw? And square off with a panel saw. Then put coach bolts
through it.


Tough to do with the timber hanging down from the roof structure, which
it will be once I saw off the rotten bit. I suppose I could cut a sort
of half lap joint (zillions of half-depth cuts with a circ saw, then
cleaned-up with a chisel) while the rotten bit is still attached and
providing a little bit of anchorage, then saw off the end. Hmm, perhaps
I could first attach some sacrificial timber over the rot and fix it to
the wall to a provide temporary anchorage.


I was assuming you have a circ saw with a 3 inch cut, that lets you cut
a lap either 6 inches wide and 1.5 inches deep, or 3 inches wide and 3
inches deep although I would do the longitudinal cut from both sides in
each case. The devil is in the detail of access and how much support
remains from the rotten bit. As you say, temporary supports are another
option.

The alternative butt joint that you describe will not be very strong in
bending. If one (or two) sides of the shed are supported against a wall
then this could provide bracing against wind loads so that the uprights
are just in compression.