MDF or Plywood?

[Steve Creameans]

Hello all. I've researched the forums for a topic that may answer my question but didn't really see one that applys.

I am building a work table for a craft room for the wife. I plan on using 3/4" MDF supported on 3 sides (left, back, right) by a 2x2 cleat screwed to wall studs. It will be 8' long, and 22" inches wide.

My question is, am I setting my self up for some sagging since I don't plan to use a center support, or will the MDF be rigid enough at that length and width to support itself ?

Thanks for any input!

[Russ Ambrose]

give the sagulator a look...it's helped me answer similar questions

http://www.woodbin.com/calcs/sagulator.htm

[Steve Creameans]

Thats a nifty tool. Thank you!

[glenn bradley]

I can only recount my experience. . . that will, in no way, be enought support for 3/4" MDF over that span. I would add a front support and center support. I have had 2 laminated 3/4" panels sag over a span of only about 20".

[Alan Tolchinsky]

If you build some storage underneath you won't have any problem. But seriously you need some "verticles" to support that, maybe three or four.

[Bill Huber]

I am with Glenn on this, there is no way that it will not sag like mad.

It wouldn't take much to make a frame and cross supports on 24 inch centers.

[Steve Creameans]

My other option (based on my abilities and wanting this to look presentable) would be to use a piece of MDF on edge as a center support screwed in from the top of the table down. I realize I would have to do extra finish work, but I'm not real concerened about that.

What, if any, material (budget minded) would work that span resting solely on the 2x2 cleats?

[Steve Creameans]

Thank you all so far for the input.

I considered framing it, but I am in a rental house, with really nice hardwood floors so Im trying to do the least amount of damage as possible. Me with a power tool in my hand is almost stretched to the limit.

[Lee Koepke]

I used plywood for a similar condition, a maple edge band on the front, and still added a brace in the middle.

It was a 'folding table' for her laundry room. My span was 6'.

It would be hard to justify an 8' span without some kind of support.

[Greg Funk]

A torsion box built with 3/8" skins on the top and bottom and 3/8" ribs would work over that distance and is not too difficult to make. The biggest challenge will be setting up a flat enough surface to build the box on. I built some 8'x3' shelves this way for attic storage and they are very strong. I use pre-finished 3/8" 2nds that I get for $20/sht for this type of work.

Greg

[Jim O'Dell]

What if you dropped down to 1/2" MDF and built a torsion box? Should control the sag. Would be a little heavier, though. I'm still not sure about an 8' span. Maybe a triangular support in the middle going back to the wall. Wouldn't impact the floor and would give you some more support directly tied to the wall stud. Jim.

[Joe Chritz]

The rear support will help some with the span but you will need something else.

The longest shelf supports you can find (like for laundry tables) should work and still leave it open underneath.

If that won't work then you will be into a torsion box or some kind of steel support.

Joe

[Steve Creameans]

Did some research on torsion boxes and I think that's way beyond my abilities.

How do you guys feel about creating a center bookshelf 20" wide, and 12" deep? I was thinking a simple "U" shape with a center shelf to keep it from racking and sliding it under the table flush with the front edge to close it off. Then drilling down from the top to secure it.

I know that would create some more finish work but sanding is something I have some experience in.

[Steve Creameans]

If you build some storage underneath you won't have any problem. But seriously you need some "verticles" to support that, maybe three or four.

I have no clue how I missed this one...

[Peter Quinn]

MDF $28/sht...sags///9 ply birch $45/ sht..doesn't sag...use plywood? Tortion box is a nice touch for airplane wings and assembly tables, I used a home cheepo luan hollow core door for my wifes's craft table...cost $15...hollow core door is a tortion box...hollow core door?