Crawl Space Support

[icedgxe]

Question for any engineers or contractors out there. am upgrading to a new tank and have some floor support questions. The tank is an IM SR120 that will sit perpendicular to the floor joists (engineered I beam) and the back of the tank will be against an exterior wall. I’m not so much concerned that the floor can’t support the tank, but being in a tall crawl space, there is a little shake that will happen when walking around the tank etc. I see this in the current SR80 in the other room. I’d like it to be solid and reduce the movement. If I want to add two jack posts underneath, would digging below the first line (which I believe is 10-12in in my area), filling with gravel and setting a footer on that be a sufficient base? Also, what is the correct way to support an engineered I beam? My thought was two posts with a 2x10 or 2x12 spanning the joists. Any help is greatly appreciated.

 

[icedgxe]

 

[BrokenReefer]

Are you in a frost environment? If so you’d likely need to dig closer to the frost line (though I’m not sure given it’s under the conditioned space) or use wider pillow blocks to support the load.

 

[icedgxe]

Are you in a frost environment? If so you’d likely need to dig closer to the frost line (though I’m not sure given it’s under the conditioned space) or use wider pillow blocks to support the load.

I’m in central NC, so the frost line is roughly 10” according to what I’ve read.

 

[hoffmeyerz]

I am not an engineer but I own and run a hardwood flooring business and am a licensed residential builder. As you first mentioned you do not need to do anything in terms of weight support based on the placement you describe. Those joists are used because the have a greater span distance allowing for fewer supports needed underneath. The drawback is that the greater span distances show more deflection. Deflection is not a bad thing, if something can't bend, it breaks!
You can dig for a footer as you described but that's overkill. Remember, your not looking for weight bearing but to just add enough support to reduce deflection. You can run a 4x4 across the joists supported by jack stands sitting on a piece of treated 2x12.
I would be careful though, taking the deflection out in an area will not eliminate it, it will just show up somewhere else. If you completely stiffen the area you MAY find issues like cracks in corners somewhere else.

 

[icedgxe]

I am not an engineer but I own and run a hardwood flooring business and am a licensed residential builder. As you first mentioned you do not need to do anything in terms of weight support based on the placement you describe. Those joists are used because the have a greater span distance allowing for fewer supports needed underneath. The drawback is that the greater span distances show more deflection. Deflection is not a bad thing, if something can't bend, it breaks!
You can dig for a footer as you described but that's overkill. Remember, your not looking for weight bearing but to just add enough support to reduce deflection. You can run a 4x4 across the joists supported by jack stands sitting on a piece of treated 2x12.
I would be careful though, taking the deflection out in an area will not eliminate it, it will just show up somewhere else. If you completely stiffen the area you MAY find issues like cracks in corners somewhere else.

That makes sense. If I were to go the route you describe, would I have to be concerned with frost heave?

 

[The Roaming Reefer]

How long has the tank been set up? If you filled it recently, I would recommend draining as much water as possible to reduce deflection before doing anything to stiffen the I-joists.
That said, you could screw a strong back to the underside of the floor joists either mid-span or 8 feet from the wall. Then laminate either side of the joists with 1/2 inch ply.
One note, if that’s the exterior wall, there should be 2x “squash blocks” on both sides of the I-joists to handle supporting the structure.

 

[hoffmeyerz]

That makes sense. If I were to go the route you describe, would I have to be concerned with frost heave?

No, not only is that space insulated but with HVAC running through the space as well it should never get cold enough for that to be a concern.
I live in Michigan with a 4' crawl, placed my 75 gal tank and 20ish gal sump along exterior wall and even though it's sitting parallel with the joists I have no issues.

 

[icedgxe]

How long has the tank been set up? If you filled it recently, I would recommend draining as much water as possible to reduce deflection before doing anything to stiffen the I-joists.
That said, you could screw a strong back to the underside of the floor joists either mid-span or 8 feet from the wall. Then laminate either side of the joists with 1/2 inch ply.
One note, if that’s the exterior wall, there should be 2x “squash blocks” on both sides of the I-joists to handle supporting the structure.

This tank isn’t up yet. Still hasn’t shipped lol. I’m just trying to be proactive just in case.

 

[The Roaming Reefer]

This tank isn’t up yet. Still hasn’t shipped lol. I’m just trying to be proactive just in case.

Got ya. Just check that there are vertical 2x4 blocks on either side of your joists where they sit on top of the wall. They should be there tank or not.

 

[icedgxe]

Got ya. Just check that there are vertical 2x4 blocks on either side of your joists where they sit on top of the wall. They should be there tank or not.

I’ll get under there and take a look.

 

[icedgxe]

How long has the tank been set up? If you filled it recently, I would recommend draining as much water as possible to reduce deflection before doing anything to stiffen the I-joists.
That said, you could screw a strong back to the underside of the floor joists either mid-span or 8 feet from the wall. Then laminate either side of the joists with 1/2 inch ply.
One note, if that’s the exterior wall, there should be 2x “squash blocks” on both sides othe I-joists to handle supporting the structure.

How long has the tank been set up? If you filled it recently, I would recommend draining as much water as possible to reduce deflection before doing anything to stiffen the I-joists.
That said, you could screw a strong back to the underside of the floor joists either mid-span or 8 feet from the wall. Then laminate either side of the joists with 1/2 inch ply.
One note, if that’s the exterior wall, there should be 2x “squash blocks” on both sides of the I-joists to handle supporting the structure.

A couple of questions.

Are squashblocks supposed to be installed beside every joist?

Should the stongback span the joists matching width of the tank or across the whole width of the room?

What do you mean by laminating with plywood?

 

[The Roaming Reefer]

A couple of questions.

Are squashblocks supposed to be installed beside every joist?

They should be installed anywhere there is a structural load from above. I-joists aren’t intended to support an exterior wall, roof etc. It’s tough for me to tell just from the one picture if they’re there or not

Should the stongback span the joists matching width of the tank or across the whole width of the room?

The more you span with the strong back the better. The aim is to distribute the load across as many joists as possible.

What do you mean by laminating with plywood?

Rip plywood to the width of the I joist. Glue and nail it to the sides of the joist. You should be nailing it into the LVL on the top and bottom of the joist. This helps to stiffen the joist to prevent sagging

 

[icedgxe]

They should be installed anywhere there is a structural load from above. I-joists aren’t intended to support an exterior wall, roof etc. It’s tough for me to tell just from the one picture if they’re there or not

The more you span with the strong back the better. The aim is to distribute the load across as many joists as possible.

Rip plywood to the width of the I joist. Glue and nail it to the sides of the joist. You should be nailing it into the LVL on the top and bottom of the joist. This helps to stiffen the joist to prevent sagging

Thanks for the information!

 

[icedgxe]

They should be installed anywhere there is a structural load from above. I-joists aren’t intended to support an exterior wall, roof etc. It’s tough for me to tell just from the one picture if they’re there or not

The more you span with the strong back the better. The aim is to distribute the load across as many joists as possible.

Rip plywood to the width of the I joist. Glue and nail it to the sides of the joist. You should be nailing it into the LVL on the top and bottom of the joist. This helps to stiffen the joist to prevent sagging

I have a question on the squash blocks. Everything I’ve read says they should be 1/16th of an inch taller than the joist. Does that still hold true even though I would be adding them now afterwards?

 

[The Roaming Reefer]

I have a question on the squash blocks. Everything I’ve read says they should be 1/16th of an inch taller than the joist. Does that still hold true even though I would be adding them now afterwards?

I would cut them exact now. You risk popping nails/screws in the Sheetrock above if you try to force taller blocks in. They are supposed to be a little taller than the joists when the framing is being done before the subfloor is installed.
Exact cut blocks will still carry the load, the joists will have some stress but not much more than what they’re currently under.

 

[icedgxe]

I would cut them exact now. You risk popping nails/screws in the Sheetrock above if you try to force taller blocks in. They are supposed to be a little taller than the joists when the framing is being done before the subfloor is installed.
Exact cut blocks will still carry the load, the joists will have some stress but not much more than what they’re currently under.

Thanks! That’s what I was thinking as well. Then hammer them into the flange using an 8d nail. Would you recommend any liquid nails as well to reduce chance of squeaks? Sorry for all the questions.

 

[The Roaming Reefer]

Thanks! That’s what I was thinking as well. Then hammer them into the flange using an 8d nail. Would you recommend any liquid nails as well to reduce chance of squeaks? Sorry for all the questions.

I usually use pl400 but any subfloor glue will work. You can use 3 inch construction screws if you don’t want to hand nail/can’t fit a nail gun between the joists

 

[icedgxe]

I usually use pl400 but any subfloor glue will work. You can use 3 inch construction screws if you don’t want to hand nail/can’t fit a nail gun between the joists

Thank you very much!

 

[icedgxe]

I usually use pl400 but any subfloor glue will work. You can use 3 inch construction screws if you don’t want to hand nail/can’t fit a nail gun between the joists

Would you glue where the block meets the flange of the I joist or top and bottom where it meets the subfloor and bottom sill?