Recommended joist spacing?

[Birds]

My new benchwork is nearing completion but I have another question before I add decking.

What joist spacing would people recommend for a 6' x 14' layout with 1/2" B/C grade plywood decking?  There will be four sheets of plywood (three at four feet wide, and one at 2 feet wide).

Right now I have joists spaced 18" on center with a total of 11 joists.  (This includes two joists at each end, and two keeper joist fixed to the legs.)

Thanks,

Chris 

[Jumijo]

 

I spaced mine 24" on center.

Jim 

[marxalot]

I used 1" x 4"s, 16" to 18" on center and can Modock around on top the table if need be.

Jim

[chuck]

1x4's 16"-18"

1x3's 14"-16" 

[Sturgeon-Phish]

24" on center is fine for 1/2 on 2x4's.  Keeps the sheeting waste in check.

 Jim 

[Sturgeon-Phish]

What size joists?

[Birds]

I knew I forgot to include something!!

The joists are 1" x 3" cut to 6 foot lengths.

Thanks for the replies so far!

Chris 

[Sturgeon-Phish]

16" OC.  Screws and glue are the way to go IMHO 

Jim 

[c50truck]

Chris,

Your spacing should be fine, The B/C plywood is probably not a sawdust core or three layer ply. I suspect it is 4 ply or better. I always space the joist with 1x4 at 16" on center. Just like building a house, your home is only as good as it's foundations.

Rod L.

 

[riverrailfan]

I knew I forgot to include something!!

The joists are 1" x 3" cut to 6 foot lengths.

Thanks for the replies so far!

Chris 

 

16" OC but I would double up at the seams where the plywood meets to have something to screw to.

 

My 8x12 is 24" OC with 2x4's with 1/2" plywood

[Birds]

Thanks guys!

I was able to get the 16" OC spacing with the number of joists I have.  I am considering adding a few more joists to bring the spacing down to 14" OC to give myself a bit more of a margin.

The span of the 1x3 joists between the two L girder webs is below the maximum span length for 1x3 that Linn Westcott shares in his book "How to Build Model Railroad Benchwork", but the support points are a slight bit beyond the recommended 1/5 and 4/5 points that he mentions.  So I am thinking that bringing the joist spacing down to 14" OC might be a good compensation in the long run even if it is overkill.

Chris

[laz 57]

16 inches on center with 2X4s.  If I want to get on top it will hold my weight.  Also used homosote easier to put screws into.

laz57

[Anonymous]

16 inches on center with 2X4s.  If I want to get on top it will hold my weight.  Also used homosote easier to put screws into.

laz57

Homosote also helps reduce, not eliminate, noise.

Speaking of noise... I have 1/4 ply on 1 x 4 and FasTrack is noisy when running dirrectly on directly on the ply, but when the train is on the elevated sections the noise reduces to just about nothing.  For the new layout and the big layout I am going with 1x4 with 2 inch foam core (between the 'joists'), then homosote for the subroad bed (unless I find some old ceiling tiles laying around the rental property in Pittsburgh), then cork road bed, then the track (either FasTrack or Gargraves/Ross - leaning heavily toward the Gargraves/Ross with balast).

[Jumijo]

I measured mine last night - 16" on center 2x4s. I had previously stated 24" on center. My mistake.

Jim 

[Anonymous]

I measured mine last night - 16" on center 2x4s. I had previously stated 24" on center. My mistake.

Jim 

No problem, everyone is entitled to one mistake per year... looks like you've used your quota!

[Birds]

I was able to get the joists installed at 14" OC, and with joists at the points where seams of the plywood will fall.

There was only one problem with the install - a screw sheared inside a joist and I can't back it out.  I was even using a manual screw driver!  It's a tad wobbly on one side if you wiggle it, but the pressure will be pressing it into the frame.  I will probably anchor it down with a 1" L bracket.

I had a couple joists that were high.  They were planed down even with the ones next to it.

Thank you for all the comments and suggestions.

More pictures on Sunday.

Chris