# Is This Strong Enough?



## TromboneAl (Jan 31, 2012)

Quick question: I'm almost done making this support for a platform bed (queen-sized mattress). The wood is clear fir, 2x4s and 4x4s. The 4x4s are 16.5 inches long.

You can see how I joined the rails to the legs. They are glued and screwed. 3/4 inch plywood will be screwed on the top, and a full panel will be glued and screwed onto the end part. My wife and I weigh under 160 each.

Is this strong enough, or do I need to add triangular shear supports?

Thanks!

- Al


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## cabinetman (Jul 5, 2007)

Your frame doesn't have a center support like your drawing shows. Queen size is 60"x80",how are you cutting the plywood, and supporting the seam? If you screw, or glue and screw the plywood for the top, that should eliminate racking. You may get some movement between the legs and the rails, but it may be only minimal.













 







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## TromboneAl (Jan 31, 2012)

Thanks for the welcome.

Yes, I eliminated the center support when I went to 3/4 inch plywood. I cut the two sheets of plywood as you'd expect (61 x 48 and 61 x 34.5) , and I plan to not support the seam at all. I'll see if any sway or bounce is noticeable, but I doubt it. If there is too much bounce, I'll support the seam with more plywood glued on underneath.









So you're saying I don't need to reinforce the corners, which is what I think as well.


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## Dominick (May 2, 2011)

I was going to say something regarding the bounce factor,:laughing: but decided I'll keep my mouth shut. I agree with c'man


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## bigcouger (Jan 4, 2012)

You are going to need that center suppoet for the long run best doing now than regreting later


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## Chaincarver Steve (Jul 30, 2011)

You really do need a center support running from side to side with a fifth leg in the center. Else it WILL sag. Maybe not today. Maybe not tomorrow. But soon. And for the rest of your lives.


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## Chaincarver Steve (Jul 30, 2011)

You may be able to get by without a center leg if you're using a single box spring. But if your bed use two separate box springs you definitely ned the fifth leg. But I think you'll need that center support beam regardless.


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## TromboneAl (Jan 31, 2012)

Chaincarver Steve said:


> You really do need a center support running from side to side with a fifth leg in the center. Else it WILL sag. Maybe not today. Maybe not tomorrow. But soon. And for the rest of your lives.


I'd be surprised. I put the narrower sheet of plywood across two 2x4s that were apart the same amount as the side rails. I then stood on it at the center, and bounced up and down. The sheet hardly budged. And when sleeping (etc.  ) there will be a very thick mattress on top of the the plywood.

But maybe you're right -- I'll know tomorrow. 

If I do need more support, it won't be difficult to remove the plywood and add another 2x4 -- though I think I'd run it from head to foot.

But if the legs aren't secure, I'd risk that the entire thing would collapse and I'd have to start over. But I sure don't see that happening.

Thanks for the input!


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## Chaincarver Steve (Jul 30, 2011)

By the way, the "maybe not today..."stuff was there in an attempt to be funny. It's from some old movie.

Anyway, do what works. But if you add a center support, side to side would be more rigid than head to toe.


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## dat (Nov 11, 2010)

Dominick said:


> I was going to say something regarding the bounce factor,:laughing: but decided I'll keep my mouth shut. I agree with c'man


:thumbsup:


I would say it needs a center support too, sure wouldn't want the bed to fail at a bad time


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## TromboneAl (Jan 31, 2012)

This is with all my weight in the center, not distributed, on the narrower plywood, with no support from the head and foot rails.


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## Chaincarver Steve (Jul 30, 2011)

There's reasons all queen and king-sized bed frames have a center support (hint: it's not for looks). One is for support. The other is to prevent the sides from bowing and allowing the bed to fall through. Your plywood may prevent the falling through but over time I doubt it'll completely prevent sagging. A bed that sags towards the middle is incredibly annoying. I know. Been there.


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## Chaincarver Steve (Jul 30, 2011)

TromboneAl said:


> This is with all my weight in the center, not distributed, on the narrower plywood, with no support from the head and foot rails.
> View attachment 37221


Now add the weight of the box spring(s), mattress and your wife. This is some pretty heavy plywood you have there though. Will you cover the entire thing in a single sheet? If not, where will the seam be? The seam (if any) will be the weakest point and will need support.

EDIT: I see you did mention a seam and said you do not plan to support it. Oh well, I tried. Personally, I think you're asking for trouble.


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## TromboneAl (Jan 31, 2012)

All done. Thanks for the tips, but there's no way that an additional support or leg is necessary. Perhaps you just have to be here. When we lie on the bed, or even jump on it, you can't feel any give. It's just as if the mattress were on the floor.

I even decided to leave some space between the two pieces of plywood, so that I could get more air flow. We live where it's very humid, and this whole project was done to replace the drawers frame that was under the bed until now. The drawers got slightly moldy from the humidity, and we couldn't keep anything in them. 

Here are some final pictures.

Thanks again for the help.


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## Chaincarver Steve (Jul 30, 2011)

Well, you're the one there in person. So you would know better than anyone how solid it is. I'm glad to see that you have the seam running side to side. That's the strongest option because the span is shorter. I wasn't trying to give you a hard time, by the way. It looks nice. Sweet dreams!


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## Tom5151 (Nov 21, 2008)

TromboneAl said:


> All done. Thanks for the tips, but there's no way that an additional support or leg is necessary. Perhaps you just have to be here. When we lie on the bed, or even jump on it, you can't feel any give. It's just as if the mattress were on the floor.
> 
> I even decided to leave some space between the two pieces of plywood, so that I could get more air flow. We live where it's very humid, and this whole project was done to replace the drawers frame that was under the bed until now. The drawers got slightly moldy from the humidity, and we couldn't keep anything in them.
> 
> ...


Nice job. How did you end up fastening your trim to the plywood? I see the fasteners you used but was curious if you have a dado on the trim that the ply fits into. Can't tell from the pic.

Thanks


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## TromboneAl (Jan 31, 2012)

Tom5151 said:


> Nice job. How did you end up fastening your trim to the plywood? I see the fasteners you used but was curious if you have a dado on the trim that the ply fits into. Can't tell from the pic.
> 
> Thanks


I can't take any credit for it, but there was a rabbet at the bottom of the headboard and the "footboard." So those fit right over the ends of the plywood. In addition there are two L brackets on each side. Larger L bracket attached the headboard and footboard with the sides. All that stuff was part of the original bed.



> I wasn't trying to give you a hard time, by the way.


I understand -- no problem. Actually, the seam had to go from side-to-side -- the only reason for the seam was that I couldn't buy any plywood that was 82 inches long. 

------------------------

This will be a great forum for my occasional carpentry questions, but if you don't see me around, it's only because I already have too many hobbies, and probably won't do much woodworking.


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## mackem (May 20, 2007)

Welcome to the forum Al :thumbsup:. You've made a very
nice bed there, and thanks for the pics. :yes:


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## johnnie52 (Feb 16, 2009)

Its a real nice looking bed. However, looking at the "mattress" I have to ask. Is this a sleep comfort "air" mattress of some kind?

The guys are right about needing support at the seam. In time it is going to show sagging no matter how strong it seems right now, plus you have weakened the plywood by cutting all those holes.


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## Poodle Head Mikey (Jan 21, 2012)

*Ahhhhh . . . Casablanca fan eh?*

Ahhhhh . . . Casablanca fan eh?

PHM
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Chaincarver Steve said:


> . . . . You really do need a center support running from side to side with a fifth leg in the center. Else it WILL sag. Maybe not today. Maybe not tomorrow . . . . But soon. And for the rest of your lives.


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## BigJoe16 (Feb 20, 2012)

I have always said if its worth doing, its worth over doing, and if you think it might not be strong enough then make it alot stronger


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