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Sagging to storage cabinet questions

Posted by littleblu87 (My Page) on
Sat, Jul 7, 12 at 2:13

I need help determining whether a bookcase/storage cabinet is sagging and whether the it's being made worse by the solution my grandfather came up with.

So the bookcase/storage cabinet is about 8-10 years old and made from thick, heavy, particle board or composite board. It's from Sauder and it's one of their higher end products. The top of the unit had maybe 20-40 pounds of weight on it for over a year. In December, I did not notice the top sagging at all (this is something I would definitely notice). By May, my grandfather claims it was sagging so he put in something he rigged up that will keep the top from sagging. It's basically a bunch of blocks he inserted under the shelf to prop it up and maybe apply enough pressure to push the top shelf to try to reverse the sagging. Everything on the top shelf has been removed.

When my grandfather removed the blocks for 16 hrs, I did not notice the shelf sagging at all. Wouldn't this shelf have started sagging once the blocks were removed, even though the items on that top shelf had been removed?

How likely is it that 20-35 pounds of weight would've caused noticeable sagging within a 5 month period? The shelf should be rated for 35-50 pounds of weight. My guess is it's 50 pounds, the manual doesn't provide info on this.

The inside of this storage cabinet has a center vertical shelf that goes from the bottom to 3/4 up where a horizontal shelf sits upon it. Then there's about 8 inches or so of space between that horizontal shelf and the top. The blocks are placed in that space to keep the top shelf from sagging. It would seem to me that if the blocks are simply placed in there to prop up the top shelf, then it's no big deal. But if the blocks are placed in there to apply upwards pressure to the top shelf, that the blocks would also apply a downwards pressure to the center vertical shelf. That would then place pressure in the middle of the bottom horizontal "floor" of the cabinet, which could lead to sagging to the "floor" of the cabinet. Would that assumption be correct?

Follow-Up Postings:

RE: Sagging to storage cabinet questions

check out the sagulator, it will calculate the amount of sag based on weight,dimensions, and material.

Here is a link that might be useful: sagulator

RE: Sagging to storage cabinet questions

Just by what you've said, I think your grandfather needed attention.

Check the sagulator, but you'll need to know what the shelves are really made of.

and yes, once he took the blocks out, it should have ... sagged .. back to where it was. Wood or particle board (whatever) doesn't heal.

RE: Sagging to storage cabinet questions

Can you post a picture of the cabinet with and without your grandfather's "fix".

Also ... place a straight piece of something (iron bar, 2x4, whatever, across the top and see if it's really sagging.

That weight MIGHT cause sagging, depending on how the bookcase was built and where the weight was placed.

And yes, if you are propping up the top, t6he force would be transferred to the bottom, which might sag.

RE: Sagging to storage cabinet questions

Depending on the material it may not take a 'set' form loading short term.

No load, no sag.
Loaded, sag.

Adding blocking to trasfer the weight to a lower shelf is a common method or reducing the loaded span of an upper shelf.
It is wy many wide shelves already have a vertical divider under them.

Depending on loading the transfer of force to the lower shelf may be enough to sag THAT shelf, or can provide enough additional stiffness to solve the problem.

"Particle board" is not noted for good shelf strength.
I have some utility book cases that use particle board, and the shelves are all 1.25 inches thick with only a 30 inch span.
They sag if loaded up with larger hardback books, not so badly with paperbacks.

If left loaded long enough and sagging the shelves MAY take a set that will not disappear when the weight is removed.

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