Is my floor sufficient for a 260 gallon?

[motortrendz]

I think your fine honestly. Can you add a jack stud in the back of the stand to help?

 

[Beau_B]

The initial deflection I wouldn't worry about. My suggestion was based on long term loading.

Sorry if you're getting confused by many opinions. As I mentioned earlier, the answer is in the math. Calculate the load, check your material.

 

[James77]

You'll be fine, that is very well supported.

I imagine you had fun doing that? Good job on it

 

[Tuffloud1]

I think your fine honestly. Can you add a jack stud in the back of the stand to help?

I want to avoid a center brace in the back for maintenance and fitting a 60 inch sump in.

Someone else suggested gluing/screwing 3/4 ply over the 2x8 which seems like my best option to limit deflection at this point.

 

[Tuffloud1]

The initial deflection I wouldn't worry about. My suggestion was based on long term loading.

Sorry if you're getting confused by many opinions. As I mentioned earlier, the answer is in the math. Calculate the load, check your material.

You aren’t confusing me at all. I appreciate the help.

It’s more so all the info out there regarding deflection.

As far as the math goes, I’ve tried looking at various calculators regarding loads/lumber and there is so much criteria they want you to punch in that I’m not sure I’m doing anything right.

 

[Tuffloud1]

You'll be fine, that is very well supported.

I imagine you had fun doing that? Good job on it

Ha! Yeah, I can’t think of a better way to spend a Saturday than crawling around in dirt moving bags of concrete.

 

[Beau_B]

72*28 is 14sqft. 260g x 8.3lb = 2,158lbs. That means 154psf load for the water alone. That's at least quadruple what building codes are designed for.

Something less than half the weight will be on the 2x8 (other carried by 3 walls). Let's use 1200lbs because it's easy and leaves some excess. 6ft span (I know it's a little less) is 200plf (pounds per lineal foot).

The problem you may be having is most charts are for joists with spacing and something like 30live/10dead loading with l/360 deflection which translates into the range of 50plf. Using those numbers is unacceptable.

I don't know what species would you used, but the only chart I can get my eyes on is for southern pine, which is considered a high grade structural lumber. A 2x8 single ply in 6ft span can take 335plf... so no worries. However, SPF (spruce) won't have that high rating, but it wouldn't be 30% less.

Going through a window/door header chart, everything is 2-ply because that's really the only way it's ever done. This is where it caught my attention, because if doing a 6' opening in an interior load bearing partition, IRC would have me building a 2-2x10 header... using SPF #2.

Girder charts are similar. I could go through and reverse calculate some of the loads on the chart and then compare them against your needs, but it's a bit of a guess and check maneuver.

It's evidently adequate based on what I can find. It's just approaching design limit and nearly everyone likes to shoot well beyond when supporting a box of water. Obviously lumber companies aren't sitting around coming up with charts for such loads.

This is all worth exactly what you paid for it and there's no engineer stamp.

 

[Tuffloud1]

72*28 is 14sqft. 260g x 8.3lb = 2,158lbs. That means 154psf load for the water alone. That's at least quadruple what building codes are designed for.

Something less than half the weight will be on the 2x8 (other carried by 3 walls). Let's use 1200lbs because it's easy and leaves some excess. 6ft span (I know it's a little less) is 200plf (pounds per lineal foot).

The problem you may be having is most charts are for joists with spacing and something like 30live/10dead loading with l/360 deflection which translates into the range of 50plf. Using those numbers is unacceptable.

I don't know what species would you used, but the only chart I can get my eyes on is for southern pine, which is considered a high grade structural lumber. A 2x8 single ply in 6ft span can take 335plf... so no worries. However, SPF (spruce) won't have that high rating, but it wouldn't be 30% less.

Going through a window/door header chart, everything is 2-ply because that's really the only way it's ever done. This is where it caught my attention, because if doing a 6' opening in an interior load bearing partition, IRC would have me building a 2-2x10 header... using SPF #2.

Girder charts are similar. I could go through and reverse calculate some of the loads on the chart and then compare them against your needs, but it's a bit of a guess and check maneuver.

It's evidently adequate based on what I can find. It's just approaching design limit and nearly everyone likes to shoot well beyond when supporting a box of water. Obviously lumber companies aren't sitting around coming up with charts for such loads.

This is all worth exactly what you paid for it and there's no engineer stamp.

I believe the wood was labeled as "clear" doug fir.

The "clear" meaning free of knots and bowing.

It was outrageously priced at $8.34 per foot.

 

[Tuffloud1]

I started a build thread if anyone is interested.

Large Build - Tuffloud1's 262 Gallon In-Wall Reef Build Thread

Well here it goes! I started into the reefing hobby over 5 years ago. My first and current system is 90 gallons which I built into a wall in my living room. Here it was before I moved it out of the wall to make room for the new 262 gallon going in it's place!

www.reef2reef.com

 

[Tuffloud1]

72*28 is 14sqft. 260g x 8.3lb = 2,158lbs. That means 154psf load for the water alone. That's at least quadruple what building codes are designed for.

Something less than half the weight will be on the 2x8 (other carried by 3 walls). Let's use 1200lbs because it's easy and leaves some excess. 6ft span (I know it's a little less) is 200plf (pounds per lineal foot).

The problem you may be having is most charts are for joists with spacing and something like 30live/10dead loading with l/360 deflection which translates into the range of 50plf. Using those numbers is unacceptable.

I don't know what species would you used, but the only chart I can get my eyes on is for southern pine, which is considered a high grade structural lumber. A 2x8 single ply in 6ft span can take 335plf... so no worries. However, SPF (spruce) won't have that high rating, but it wouldn't be 30% less.

Going through a window/door header chart, everything is 2-ply because that's really the only way it's ever done. This is where it caught my attention, because if doing a 6' opening in an interior load bearing partition, IRC would have me building a 2-2x10 header... using SPF #2.

Girder charts are similar. I could go through and reverse calculate some of the loads on the chart and then compare them against your needs, but it's a bit of a guess and check maneuver.

It's evidently adequate based on what I can find. It's just approaching design limit and nearly everyone likes to shoot well beyond when supporting a box of water. Obviously lumber companies aren't sitting around coming up with charts for such loads.

This is all worth exactly what you paid for it and there's no engineer stamp.

I just realized I have a piece of 3/4 ply left over from the top of the stand that will work.

If I did glue a piece to the 2x8, what should I use to screw it in?

Should use general construction screws or do I need through bolts which have a nut and washer from the back side?

How many should I use?

 

[Beau_B]

I would suggest using a polyurethane glue, such as Loctite PL premium or even Gorilla Glue.

Fasteners would typically be nails 4 or 5 vertical every 12-16" but if you want to use screws that's fine. For this most any construction screw would work. For reference GRK, Spax, Simpson, etc. offer wood specific with a star drive, looks like you have something similar already. I typically reserve through bolting for situations where there is leverage or inconsistent loading (motion).

The option of angle iron attached to underside of 2x8 could be considered as well if you are still feeling uneasy and don't like scabbing ply on. A plywood ring frame would work too. Depending on the header you built over the tank, you can transfer loads up to that. Still a number of ways to skin the cat, as they say.

To go back to loads and deflection, I believe the target when working around glass is 0% deflection, and if you look at all the stands for smaller tanks, that's what is achieved. We use the same standard when working with stone counters and with ceramic floors it's usually L/720 minimum. So when discussing whether a particular beam will carry the load... yes... absolutely, but at what tolerance? That's probably where the multitude of opinions and info comes from, not everyone is using the same considerations. The issue is not about whether the beam will fail in the sense of it breaking, but will it lack the performance to properly support the tank over time. I just read the tank weighs some 550lbs on it's own, so there's another roughly 45plf to tack on to the calculation.

 

[Tuffloud1]

I would suggest using a polyurethane glue, such as Loctite PL premium or even Gorilla Glue.

Fasteners would typically be nails 4 or 5 vertical every 12-16" but if you want to use screws that's fine. For this most any construction screw would work. For reference GRK, Spax, Simpson, etc. offer wood specific with a star drive, looks like you have something similar already. I typically reserve through bolting for situations where there is leverage or inconsistent loading (motion).

The option of angle iron attached to underside of 2x8 could be considered as well if you are still feeling uneasy and don't like scabbing ply on. A plywood ring frame would work too. Depending on the header you built over the tank, you can transfer loads up to that. Still a number of ways to skin the cat, as they say.

To go back to loads and deflection, I believe the target when working around glass is 0% deflection, and if you look at all the stands for smaller tanks, that's what is achieved. We use the same standard when working with stone counters and with ceramic floors it's usually L/720 minimum. So when discussing whether a particular beam will carry the load... yes... absolutely, but at what tolerance? That's probably where the multitude of opinions and info comes from, not everyone is using the same considerations. The issue is not about whether the beam will fail in the sense of it breaking, but will it lack the performance to properly support the tank over time. I just read the tank weighs some 550lbs on it's own, so there's another roughly 45plf to tack on to the calculation.

Do you have any links to angle iron? Not sure what thickness and how it would be fastened. I'm not familiar with this.

And I'm assuming this will work by attaching to the 2x8 between the 2 legs and not over the legs.

 

[Beau_B]

Angle iron = right angle steel. Think bed frame. Comes in various sizes 1/2" up to you name it. I'm not a steel worker so I don't know without researching what would be needed. Surely 1 1/2" would do it.

For reference regarding deflection, I keep saying things like L/720 and it occurred to me you and everyone else might not know what that means. It's the designation for allowable deflection for a given length. Code for floors is often L/240.

In you situation the L is 66" (5 1/2ft). So for L/720 it's simply 66/720 = .09 inch accepted. You're 1/16th observed is .0625, so technically what you have built appears to be exceeding L/720... the standard for tile floors.

I'm pointing this out to say again, you're probably fine as-is... just not OMG that's totally overbuilt it would hold up your car... There actually are cars that weigh the same as your tank set up, so let's keep that in consideration too. You could park a Mazda Miata there.

 

[BeejReef]

I don't see a 6' span, but it's entirely possible I'm missing something. between your load bearing wall and your new jack supports looks to be 3' max. The tank is 6' long, but it's not spanning a joist or two, it's running perpendicular to the joists and crossing over a number of them.

 

[Beau_B]

I don't see a 6' span, but it's entirely possible I'm missing something. between your load bearing wall and your new jack supports looks to be 3' max. The tank is 6' long, but it's not spanning a joist or two, it's running perpendicular to the joists and crossing over a number of them.

The discussion has moved on from the floor structure to the single 2x8 that is supporting the back of the tank. It has a 5'6" span. You can see it in the photos painted white as the ladder frame directly under the aquarium.

Speaking of moved on... I have to get back to work! To be continued if necessary.

 

[Tuffloud1]

Reporting back, I sistered on a Doug Fir 1x8 to the 2x8 by gluing with Titebond 3 and screwing a bunch of screws. Let it cure for almost 3 days.

Just filled the tank back up.

The deflection is now almost non-existent at 1/32 of an inch in the middle.

I’d say it worked.