Repairing timber shed uprights - fish plates?

[nothanks]

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.

[newshound]

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.

[nothanks]

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.

[newshound]

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.

[dennis]

Sounds like a job for a multitool.

[newshound]

A bit slow, on 6 x 3.

[The Natural Philosopher]

Dont even startt. Do waht I did. Enormous tub of car body filler moulded to upright shape...use bit of timeber to bulk it if you must.

[Tim Lamb]

In message , [e-mail] writes

Bit of care with a decent handsaw? 3" with a jigsaw is tricky.

I would strengthen by screwing on some 25x50mm folded galvanised steel (because I have some:-) but 1"x2" angle would do. Use two lengths per join.

Alternatively the agricultural approach... butt join and then strengthen by nailing on 3"x2" either side:-)

[nothanks]

The circ saw might not manage 3" depth but I was talking about using

1.5" cross cuts (like a narrow dado cutter) to create a half housing and avoid having to try to cut vertically up a waggling piece of wood with a hand saw.

It's not the preferred solution, but should be OK if I can find long galvanized plates to sandwich the joint.

[nothanks]

Thanks, but I'd like some strength in the post, rather than just having it look OK

[nothanks]

Trying to do this with a jigsaw would be more than tricky - a waste of time!

[John Rumm]

A scarf joint would be easiest - just a long straight cut on the diagonal with a handsaw - match the same angle on the new bit, then glue up and screw through the face into the joint a couple of times.

If you want a half lap, then as you said - repeated cuts every few mm with a circular saw, then knock out the waste, and plane/chisel flat.

[The Natural Philosopher]

Oh FFS its STRONGER than wood!

[John Rumm]

also getting the 3" depth of cut could be tricky - you would have to plunge from both sides.

[tabbypurr]

When sideways displacement is acceptable, just overlapping new & old wood & putting many screws in works. When it's not, a butt join with timber pieces in lieu of fish plates is pretty easy to do.

NT

[dennis]

To make a lap joint you can take a quarter out first and then take the next quarter out. Assuming you have access to one corner and most of one

6" face. Its easy with a multitool if a bit slow. You need less access than with a circular saw or a hand saw.

Maybe one of those little chain saws in the other thread would do it better?

[nothanks]

I'd discounted a scarf joint because it's dependent on the glue and screws to resist the shear force, whereas if I shim the ends of the lap joint then I've got half the thickness supporting the load, as well as the glue and screws.

[Brian Gaff]

I'd like to use angle brackets on the bottom of shed uprights due to the rot issue too. I guess in my case finding suitable long brackets is going to be reasonably easy, but I sure as hell am not sitting on the floor in a shed in

81 degree f heat! Brian

[Brian Gaff]

The other way of course is to get some of thus Arris rail extender brackets, cut the wing bits off and use the angled piece on the timber join. Brian

[tabbypurr]

it is, but you can get plenty of strength from glue & screws if done well.

NT