4

I just recently setup an aquarium I had on this long glass table with dimensions of 54 x 18 inches. The glass is about a half inch thick.

My 12 gallon tank I would estimate filled at around 200 lbs. I am worried about the glass being able to support the tank.

As a precaution, I just ordered another 52 x 16 tempered piece of glass at 1/4 inch thick. I ordered it slightly smaller since the original piece has angeled edges, and I wanted it to be flush so I subtracted the angled bit from each side.

Should I worry about this amount of weight? Once i add this second piece on top, will that remedy any concern? It looks like it may be bowing every so slightly, but it could just be in my head.

glass thickness

enter image description here

d. horn
  • 41
  • 1
  • 2
  • Just for reference -- If you look online you'll see that water has a density of about 8.34 lbs/gal. So a filled 12 gallon tank would have just a tad over 100 pounds of water in it. Factor in the weight of the aquarium itself and the additional weight of the pebbles and you'll have a good idea of the total weight. (The pebbles are more dense than the water they displace so the pebble factor to add is difference between their weight and the displaced water). – Michael Karas Sep 14 '15 at 07:44
  • Is that a rimless (glass) tank? If so, it needs to be level and flat just like acrylic. – Raystafarian Sep 14 '15 at 11:15
  • Yes it is. I actually just ordered a leveling mat (Mr. Aqua Hybrid Foam Mat) and should have it tomorrow. – d. horn Sep 14 '15 at 13:56
  • 2
    If that was in my house you'd have to add 60 lbs for my dog and a few lbs for the cat because they'd both be trying to get in there. – jqning Sep 15 '15 at 02:34

2 Answers2

2

According to the tabletop glass load calculator found here, and to my slight surprise, this table top can hold about 400 pounds.

I certainly wouldn't jump up and down on it, and any scratches might compromise it to some extent.

I told the calculator the glass is tempered, 1/2" thick, 18" x 54" with supports spaced 4 feet apart. Make sure you know the glass is tempered, not annealed. If it's annealed glass, it'll hold about 100 pounds.

That 1/4" sheet you just ordered would only hold 54 pounds on its own if you swapped the sheets. If you lay it on top of the other sheet, I don't know how to calculate how much stronger that will make the table, although it certainly will add to the load the other sheet is holding up. Maybe somebody else has some expertise in the benefits (if any) of gluing (laminating) two sheets of glass like that together.

Craig Tullis
  • 5,826
  • 1
  • 17
  • 28
  • Thank you. Those specs are accurate, assuming the glass is tempered. Once I add the second piece on top it will be even more supportive, correct? I don't the relation between glass stacking and weight load. – d. horn Sep 14 '15 at 04:11
  • I edited my answer about the same time you were composing your comment. Just laying the thinner sheet on top of the other sheet, I honestly don't know. Maybe if cleaned them both and glued them together they'd share the load more cohesively (because the sheets of glass wouldn't be able to move with respect to each other)? But I just don't know for sure. – Craig Tullis Sep 14 '15 at 04:13
  • Thank you. That was my concern, I don't want to add it if it will just be useless weight. – d. horn Sep 14 '15 at 04:16
  • @d.horn That would be my concern, as well. It looks like the existing glass is okay for that load. I'm curious if you can see it bow at all? With respect to laying another sheet on top and whether that would strengthen or weak it overall, I think I would seek advice from an engineer or even from someone (a builder or installer) who specializes in large glass installations in your area. One thing we both know, though, is that it's going to be a lot like ice (like any hard, brittle sheet). The more the weight is spread out, the more weight will be safely supported. – Craig Tullis Sep 14 '15 at 04:19
  • If I use the vertical metal bar under the glass as a guide, it does seem almost a mm closer in the middle. Unfortunately I can't tell if it's from bowing or the metal bar not being perfectly level and flat and arching slightly in the middle. – d. horn Sep 14 '15 at 04:24
  • after measuring the height of the bar in the middle and left/right, it does seem to be equal throughout. Leading me to believe the mm difference is from bowing. Is that something to be concerned about? I've heard tempered glass can bow slightly without issue. – d. horn Sep 14 '15 at 04:32
  • 1
    I don't think the second piece of glass will make it significantly stronger - force on the top glass will cause it to flex and exert force on the thicker glass below since it's able to slide. If you glued the glass sheets together, then you'd likely see better support. Similar to if you fashioned a beam out of a stack of paper, it will flex easily if the pages are loose like a book and can slide over each other, but it will act more like a solid piece of wood if you glue the pages together. – Johnny Sep 14 '15 at 05:45
  • thanks. I guess I'll stick to the single pane of glass then. – d. horn Sep 14 '15 at 06:04
  • 3
    What chance is there that you could put supports under the glass at the halfway point on those "beams"? Reducing the span to 2 feet (according to the same load calculator) increases the weight it can bear to 540 pounds. – Craig Tullis Sep 14 '15 at 07:12
1

Adding a second thin sheet of glass probably won't do a lot to reinforce the first, thicker sheet. First, the weight carrying ability of a sheet of glass increases at somewhere between the square and the cube of the thickness, so a 1/2" sheet can carry between 4 and 8 times as much weight as a 1/4" sheet. Plus, the thinner sheet is more flexible, so at any given amount of bend the thicker sheet will be carrying far more of the weight.

If you could laminate the two together than you would indeed be increasing the strength, but that might be very difficult to do in the field rather than in a glass factory.

Daniel Griscom
  • 6,218
  • 33
  • 29
  • 41