Joining timber for stair treads

[henlan77]

I just stumbled across these forums and find it a fantastic resource - well done.

I have some nice lengths of 200 x 40mm blackbutt that I wish to use as stair treads. Each tread needs to be 300mm deep, so I'll need to rip some of the boards in half and join the 100mm length to the 200mm length. Make sense?

What is the best method to join the lengths to make a really solid tread? The stairs are 900mm wide and will only be supported at each end. I'm worried that an inferior joint will seperate or flex. The stairs are not visible from behind or below.

Thanks in advance.

[rod1949]

There are several options ie. dowels, biscuts, feathered, fingered or butt jointed with cleats underneath.

If you are inexperienced and don't have or don't want to get the tools/equipment for the first 4 options then butt joints with cleats would be your easiest.

[AlexS]

Good butt joints using a quality glue (eg Titebond I or II) will be fine by themselves, but you may want to use dowells or biscuits to help align the boards. I wouldn't use cleats, as differential movement between the cleats & treads is likely to cause splitting.

Haven't used blackbutt, but some hardwoods have a bit of a problem with glues, so as soon as you've planed the join, clean it with metho and glue up as soon as the metho has dried. Clamp nice & tight, and don't remove the clamps too soon.

[silentC]

In fact, ordinary woodworking glue and some decent clamps is all you really need. I worked in a staircase joinery in Sydney back in the 80's and we used to glue up treads for kite winders (the large kite-shaped treads that you see in 90 degree bends on a staircase) with ordinary PVA. You can use biscuits or dowels for alignment if you like, but they don't add a lot of strength to the joint. Cleats will provide reinforcement if you want to be sure. Once the tread is wedged in its housing, it wont go anywhere.

[rrich]

Timber does not like to be joined end grain to end grain. It is just the nature of timber fibers.

A stair tread is a critical item that should not fail under any circumstances.

Keeping the above in mind, here is something that you could try. A series of reinforced lap joints to end to end join the timber. I would not run the grain of the tread front to back but rather left to right. The exposed grain in the front to back configuration would probably cause problems later on. (Catching your toe on the edge of the step could cause the edge of the tread to start to break away.

What I would do is to make up a series of pieces using lap joints to make the necessary width (900mm long by 40mm wide?). Then cut a dado the length of each piece on the underneath side of the timber. The dado should be a snug fit for plywood. (10mm ply?) Glue 50mm to 75mm wide strips of plywood into the dado. You could fit the risers into an appropriate dado. Finally assemble the 900mm by 40mm strips into the treads by edge to edge gluing.

Make the plywood fit exactly between the stringers. When installing the treads, glue the plywood to the stringers. If possible put a screw through the stringer into the plywood underneath the tread. This should give you a stair that should last many years without squeaks.

[silentC]

I've used blackbutt and it glues up fine with ordinary yellow glue.

On the cleats, if you're going to use them, they need to be fitted with slotted screw holes or in a sliding dovetail so that the tread can expand and contract.

[silentC]

Timber does not like to be joined end grain to end grain.Rich I think you've misread him. The treads are to be 300mm deep, not wide. He wants to edge join a 200m wide strip and a 100m wide strip to make up the 300mm.

[henlan77]

Thanks for the advice guys, much appreciated. I will buy a few more sets of clamps and some decent glue.

Just interested that no one mentioned epoxy. I was under the impression that it was one of the strongest glues available, but maybe it is overkill for stair treads?

[rod1949]

You will find that most decent wood glues are stronger than the timber. The glue dosen't break its the timber that breaks

[silentC]

Ordinary woodworking glues aren't noted for their gap filling capabilities, so if you are gluing in situations where you can't guarantee a nice void-free interface between the two surfaces, then you need to use something else. Most woodworking glue isn't all that water-resistant either (although there are some available that are), so for external or marine applications epoxy is used a lot.

For your situation, it's unnecessary though because you are going to make sure your mating surfaces are smooth and flat before glue up :)

The glue Alex recommended is the bees knees.

[glock40sw]

G'day All.
Only this week we have started glue laminating Australian Hardwoods.
We have done GIBK, BBT, S/Gum, Tallowood all with Titebond Ultimate III.
So far I've used 40 litres of the stuff. We are laminating 50x25 on the 50mm faces to make 300x50 for step treads etc.

So, just use Titebond adhesive for your steps and it will be no problem.