Is my floor sufficient for a 260 gallon?

[Flippers4pups]

I sistered my joists, not for the weight, but to keep the tank from bouncing. Living room has a large span. Helps with twisting as well.

 

[Beau_B]

Eh... it's not a lot of safety factor.

Quick calculation is 260*8.3 = 2158lbs, rounded up to 2400 for ease, then let's say 1/2 is on this 2x8, that's 1200 over a 6' span gives 200plf (pounds per lineal foot). That's the upper limit for spruce/fir/hem #1. You would be better with doubled 2x6 actually... definitely doubled 2x8.

I'm fudging some of this, as I'm not an engineer and I don't have all the info for your situation, but I'm calculating this as though it were a header in residential construction.

It is probably ok, but if you have the option, I would do it a little differently.

If you already built it (is that it painted white in the photo?) then you could reinforce it a couple different ways... adding another 2x8, adding plywood, create an i-joist by adding a bottom cord... or everyone's favorite... steel!

 

[BeejReef]

Not a structural engineer here either, but that looks pretty good.

Ground floor - check
Near load bearing - check
additional supports added - check

I don't think you're overburdening the joists, even though they're not 2x10's, simply bc of the short span they have to support before you've added support. I would check on it after the seasons change to make sure your new foundation elements haven't sunken into the ground more.

I guess you can never know for sure, but I'd say good job! Looks like conscientious work to me. It's certainly more than many do and their tanks are ok.

 

[Tuffloud1]

Eh... it's not a lot of safety factor.

Quick calculation is 260*8.3 = 2158lbs, rounded up to 2400 for ease, then let's say 1/2 is on this 2x8, that's 1200 over a 6' span gives 200plf (pounds per lineal foot). That's the upper limit for spruce/fir/hem #1. You would be better with doubled 2x6 actually... definitely doubled 2x8.

I'm fudging some of this, as I'm not an engineer and I don't have all the info for your situation, but I'm calculating this as though it were a header in residential construction.

It is probably ok, but if you have the option, I would do it a little differently.

If you already built it (is that it painted white in the photo?) then you could reinforce it a couple different ways... adding another 2x8, adding plywood, create an i-joist by adding a bottom cord... or everyone's favorite... steel!

I already built it into my wall. Here are some more pictures.

I’m open to any suggestions to make it even safer but without having to tear everything apart.

 

[Beau_B]

Based on the last photo, if that's the 2x8 in question it appears there's plenty of space so the easiest is just slap another on with some glue and fasteners. It ideally would rest on the jacks in the same manner you have the primary, but may not be necessary. If you have the means to cut the vertical 2x4 down without making a complete mess, go for it. If you don't mind narrowing the opening slightly, adding jacks externally of the existing wall would work too... hard to explain.

I'm assuming you don't want an intermediate support so that you can get a sump in and out.

Edit to add... which side is the new bearing beam under?

 

[Tuffloud1]

Based on the last photo, if that's the 2x8 in question it appears there's plenty of space so the easiest is just slap another on with some glue and fasteners. It ideally would rest on the jacks in the same manner you have the primary, but may not be necessary. If you have the means to cut the vertical 2x4 down without making a complete mess, go for it. If you don't mind narrowing the opening slightly, adding jacks externally of the existing wall would work too... hard to explain.

I'm assuming you don't want an intermediate support so that you can get a sump in and out.

Edit to add... which side is the new bearing beam under?

I used a 2x8 based on forums where RocketEngineer recommended 2x8 for my span/size without center support.

Really, I have done all the finish work already and was hoping that I built everything well.

In that last photo, that corner with the 2x4s and 1x4 sandwiched are all glued/screwed together and glued/screwed to the 2x8.

 

[Beau_B]

As noted, it's just somewhere approaching the limit, not over.

It is likely fine. If it's an issue it would be over the course of years and the 2x8 wouldn't fail suddenly.

The plywood top adds strength too, which I can't easily calculate.

The rigidity of the aquarium itself plays a role too, it's not inclined to generate a sag.

If you can't sleep at night, just stuff a strut under it mid-span with no fastening. If in time (months, years) it requires a hammer to take out, you'll know things moved and can reinforce it then.

 

[Tuffloud1]

As noted, it's just somewhere approaching the limit, not over.

It is likely fine. If it's an issue it would be over the course of years and the 2x8 wouldn't fail suddenly.

The plywood top adds strength too, which I can't easily calculate.

The rigidity of the aquarium itself plays a role too, it's not inclined to generate a sag.

If you can't sleep at night, just stuff a strut under it mid-span with no fastening. If in time (months, years) it requires a hammer to take out, you'll know things moved and can reinforce it then.

Is there a way to attach something across the 2x8 to reduce deflection without having to cut anything out?

Everything keeps me up at night when it comes to these kinds of projects!

 

[Beau_B]

Given that it's all tidied up with the tank in place...

If it were me, at this stage, I would take 3/4 plywood, something paint grade, not OSB, and laminate it on with glue and fasteners. As a bonus it would give a nice finished surface. The shear strength of the ply would give it quite a bit of added strength. I would need to look up a chart to tell you how much... but a lot.

PS, the reason that's not the first suggestion is that's $40 sheet of plywood instead of an $8 stick of wood. But... you're down the river now. Can use the left-over for shelving!

 

[Tuffloud1]

Given that it's all tidied up with the tank in place...

If it were me, at this stage, I would take 3/4 plywood, something paint grade, not OSB, and laminate it on with glue and fasteners. As a bonus it would give a nice finished surface. The shear strength of the ply would give it quite a bit of added strength. I would need to look up a chart to tell you how much... but a lot.

PS, the reason that's not the first suggestion is that's $40 sheet of plywood instead of an $8 stick of wood. But... you're down the river now. Can use the left-over for shelving!

And that would work without covering the ends of the 2x8 that are actually over the legs?

Does it matter that the 2x8 is painted? Will glue work as well on the painted surface?

 

[Beau_B]

And that would work without covering the ends of the 2x8 that are actually over the legs?

Does it matter that the 2x8 is painted? Will glue work as well on the painted surface?

The paint shouldn't bother it assuming it's still clean and well bonded. You can scuff it up with some 80-120 grit if you like. The shortened length shouldn't really be a concern either, it's not load transfer that is the concern, it's deflection as you pointed out.

Again, I'm not saying what you have will fail if you do nothing. Just suggesting it's nearing the design load limit based on quick/crude math (2x8, 6ft span). That piece you have is nice and clean, perhaps structural grade, I can't say. You're also going a shorter distance... many factors at play. In the end, I got the sense you wanted a larger margin.

I agree with the previous contributor that some 99% stands are incredibly over built. In the end, the span charts and load calculations are all out there. It's just math.

 

[Tuffloud1]

I filled the tank up to 7 inches from the top.

I took measurements in a couple spots in the middle of the 2x8.

I measured from the floor to the top of the plywood top.

Here are the results when the tank was empty and when it was 7 inches short of being full.

 

[motortrendz]

Absolutely fine. You could build another house on that. Haha. You could have just doubled up the joists and bolted through to secure them and support the load that way but this way there will be no give at all. Good job.

 

[Tuffloud1]

Absolutely fine. You could build another house on that. Haha. You could have just doubled up the joists and bolted through to secure them and support the load that way but this way there will be no give at all. Good job.

Thanks, could you also take a look at my concern with my 2x8 stand with no center support on the back side?

I’d appreciate any feedback.

 

[vetteguy53081]

the type of bracing you did tells me YES

 

[motortrendz]

Thanks, could you also take a look at my concern with my 2x8 stand with no center support on the back side?

I’d appreciate any feedback.

I dont see what the question was sorry. What is the concern? That it has a slight bow?

 

[Tuffloud1]

I dont see what the question was sorry. What is the concern? That it has a slight bow?

Yeah, I was under the impression from everything I read prior regarding top framing of stands with no center bracing that a 2x8 over a 6 foot span is good to go.

I used a premium piece of 2x8 with 0 knots and built a stand into the walls of my house.

Looks like I have between 1/16” and 1/8 deflection when filled.

 

[motortrendz]

Yeah, I was under the impression from everything I read prior regarding top framing of stands with no center bracing that a 2x8 over a 6 foot span is good to go.

I used a premium piece of 2x8 with 0 knots and built a stand into the walls of my house.

Looks like I have between 1/16” and 1/8 deflection when filled.

Wood is always gonna have some give. If your concerned you can put a sheet of plywood over the top with a thin piece of foam.

 

[motortrendz]

Or if your really concerned you can double up the 2x8. But youd have to drill holes and use 3/8" bolts every 12in to carry the weight. But I think that's overkill.

 

[Tuffloud1]

Wood is always gonna have some give. If your concerned you can put a sheet of plywood over the top with a thin piece of foam.

Yeah I already have 3/4 plywood over the top and 1/2 inch foam.

I guess I get confused because so many people say so many different things on what an acceptable amount of deflection is.

Some say 0 deflection or you risk the tank failing. Others say no more than 1/16 inch and so on.