How to seal bearing beams on a walkway?

[Nötegårdsgubben]

I am thinking of constructing a boardwalk with longitudinal 34 mm planks, approximately seven meters long.

Underneath, it's slightly swampy ground, and I plan to gravel up at points, lay concrete blocks, and a light joist to have something to screw the planks into.

But how closely should the joists be spaced? I want it to feel stable when you walk on it, but does that mean I have to stick to 60 cm on center, or what margin do I have?

The gain from moving from 60 to, say, 90 cm would just be to avoid 3-4 support points, so economically it's only a couple of hundred kronor, and in terms of labor probably only a few individual hours. Still, I'm curious about how to think about this.

I understand that it might be simpler with solid beams and crosswise planks, but right now I prefer not to do that.

 

[fribygg]

In a footbridge, you can probably tolerate a certain amount of sway, so you can probably use cc90.

 

[ArneTW]

You could be more generous with the studs and use larger dimensions...

I assume you are "laying" the studs down?

/ATW

 

[fribygg]

You could be more generous with the battens and use larger dimensions...

I assume you "lay" down the battens?

/ATW

Laying the battens on the slab removes almost all load-bearing ability, so that seems silly.

 

[ArneTW]

Placing the joists on the slab removes almost all the load-bearing capacity, so it seems foolish.

Well.

It depends on how wide the plank is going to be...

If it's, for example, 2-4 boards wide and you place your joists on 2 leca blocks, the free span for the joist is 10-20 cm.

So I don't know how much load-bearing capacity the joist needs?

/ATW

 

[Nötegårdsgubben]

You could be more generous with the studs and use larger dimensions...

I assume you're "laying" the studs down?

Yes, that makes sense and would shorten the span to "edge to edge" on the blocks rather than 60–4.5.

It will probably be a mix of that and what @fribygg wrote. A slightly larger span, but not overly large so you'd want to add extra support points as soon as you're done...

 

[fribygg]

I would have probably chosen to build it like a regular dock. use telegraph poles and transverse 34 mm decking, but of course, you can frame on the telegraph pole with transverse 2"x4" and lay the decking lengthwise.

 

[z_bumbi]

Regardless of cc, screw cross braces between the boards in the middle between the support points to make it sturdier. You're not stepping on one board but all the boards are loaded more or less simultaneously. A piece of regel works as a brace.