Thread: Building a window seat/bench

I'm assuming you are putting a 90x38 along the wall, and another one along the front of the seat as a rail, and the mdf will bridge the two, with 90x38 legs spaced along the front.

Whenever I need to answer a question like this, I usually put together a mock up and try it out. Get a length of 90x38, set it on two bricks 1250 apart and see how much it bends. The MDF won't add much strength, so you can ignore that.

I'd be aiming for around 600mm spacing, but you can also strengthen it by doubling the rail, either side by side, or one on top of the other at right angles.

Here's a garden seat I made last year for a customer. Its made from 75x16 tallowwood from memory, but the front of back rails supporting the seat are doubled to 75x32. It holds me and my brother, both over 100kgs.

Usually a pine 90 x 38 stud is a vertical timber member. It is not graded to be used as a horizontal member unless it's a noggin between studs. The maximum 'span' of a noggin is usually 600mm but that is not load bearing. It is a stiffener for the vertical studs which are load bearing.
I would advise getting hold of a span table and use hardwoods above f17 of around 90 x 45 min or Oregan of similar size.

I'd prefer a 90 x 45 on edge but a 90 x 35 0n edge might do , make sure you use a piece of pine without any knots or pith. And put an upright in midway.

Thanks for the advice guys. I'll have a think about alternatives ways to support that span. Perhaps a verticle sheet of 16mm MDF spaced at 600mm apart and also acting as a divider will offer enough support for the seat. What do you think?

Simon, do you know where I can get a span table? That would be handy for sure.

Thanks again.

Steve