Stair tread rebuild

[Tom Gattiker]

Good to see so many ponders here. Just stumbled over here myself.

Need to repair some stair treads at the church. The glue joints failed--do to earlier moisture problems.

Do I need to use biscuits (or dowels) for strength (I don t normally do when making panels)?

Is standrard HW store poly varnish ok or do you have to use something harder?

(the treads are 1" oak)

Thanks.

[Lee Schierer]

Biscuits or dowels are for alignment and add little if anything to a good joint in the way of strength. I would run all the board pieces across a jointer to remove the old glue and true up the edges. I would glue them with either Tite Bond II or one of the polyurethane glues. If you use the poly glue don't dampen the surface, there is plenty of moisture in the wood for curing and you will get less foaming and a stronger joint.

Finish the surface with a good quality floor finish. Polyurethane should be good for this.

[Tom Sweeney]

I thought that I've seen threads where they say that biscuits work in the same fashion as loose tennons, which would indicate to me that they do add strength. I know that some people like them & some don't - but I thought the strength issue was correct.

Not disagreeing mind you - just a newbie trying to figure stuff out. :confused:

[Tom Gattiker]

Scott,
In this case, folks are saying (and I agree) that neither a loose tennon or anything else is really needed for an edge joint. They are strong enough on their own.

More generally, I think the FWW joinery test a year or 2 back found that double biscuits are quite strong (as compared to tennons or loose tennons). Of course we'll know with greater certainty in 100 years or so.
Tom

[Lee Schierer]

I've read variying opinions regarding what if any strength biscuits add to a joint. In edge or face gluing, they add nothing as compared to the strength of the joint it self. In an end grain to face grain joint, they add some strength over a plain joint. Also the same in a miter or end grain to end grain joint, they awould add some strength. The added strength in these cases comes from increased surface area for the glue, so any material you added such as a spline or loose tenon would add the same amount of strength.

Norm is always saying how he is going to use bicuits to strengthen the joint. I'm not sure he is always correct on that account, though I respect what he has done for the woodworking community.

Use biscuits if you want to. Furniture has been made successfullly for a long time without them.