Strapping?

Celtic

I'm getting ready to start a renov. on my 1st. flr bath....I want to sister up the 2x8 joists for added support for the tub, tile, etc.

Looking up at the 1st flr joists from the basement, there is this metal strapping in place..sort of forming an "X" between 2 adjacent joists.
What is this for?
Why?
This house was built in 1950...I don't think much consideration was given to hurricanes and that sort of event.

Can I just cut this strapping out and sister up as planned ...abandoning the strapping?
I don't see what purpose it serves...other than to be in my way

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JumboJack

I "think" they where used like a block would be used.To keep the joists from twisting...

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in texas with framing and cornish people will do it for 3.00 a foot. What do yall think about that? Just laber

Celtic

I could understand that IF they had done the same on the 2nd floor...

...UNLESS of course, the strapping was there to prevent twisting while working the joists on a cement/cinder block wall...

The 2nd flr joists could have been nailed to 1st flr walls/framing and such to prevent the twisting and falling/domino effect.


The place is balloon construction.

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Meetre

my thoughts exactly, fancy blocking used back then, if you cut it, you may want to replace it with wood blocking when you are done sistering joists.

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steves

Does it look like this ?

http://www.strongtie.com/products/CFS/TB-LTB.asp

If so you can replace it with blocking or strapping on the bottom of the joists.

Celtic

Very similar..probably a thinner steel.


I *could*...but why?
Is it really necessary considering I will be doubling up the 2x8s ?

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Gus Dering

Metal bridging or solid blocking placed midspan adds stiffness to a joist when a load is applied to one or two joists. In order for them to deflect a significant amount the bottom of the joist needs to twist to one side or the other. The metal bridging you need to remove keeps the bottom of the joist stacked with the top so the joist will perform to it's highest load rating.

All that said, cut it out of your way, throw in the new joist and block the bay if you want. If not don't loose any sleep over it.

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neolitic

Put in the bridging.
Then don't lose any sleep.

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(Sorry....it seems there really are dumb questions)

Celtic

I did the math on what I need as far as joists go [I can almost count to five by myself now]....

...and should have just enough scrap to block each bay twice...which is one more than the strapping



Thanks guys.

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KennMacMoragh

If the buildings been there for 60 years, I think it's safe to just cut them and forget about it. The joists have done all the twisting and cupping they are going to do. Unless it makes you feel better, go ahead and put some new blocks in.

Celtic

It's that or toss the scrap...

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loneframer

I have thrown in the towel on metal strap bridging. In addition to preventing "splaying" of the joists, properly installed X bridging will allow load sharing between the joists. As joists shrink over time, metal bridging loses it's tension and is useless for load sharing. If 1x3 or 4 wood X bridging is properly installed, as the joists shrink, they actually get tighter and stiffen the floor, removing "bounce". Metal strap is also notorious for annoying squeeks in the floor, which is ultimately caused by their failure to loadshare.

wallmaxx

People used to think that bridging (blocks or strapping) reduced floor bounce when the spans were close to the code limits.

The last apartment I did, the engineer said to my face - bridging is only good for adding squeaks to your floor system.

knucklehead

You will have to do solid bridging to replace the old because you won't be able to nail the top of "X" bridging, unless you take out the subfloor. I would put some back if you can . It can't hurt. Even if it is not as tall as the joists. It will help keep those double joists tight together

knucklehead

What do engineers know?

I think it helps, personally. I lived in a house that had a 16' span with a bounce when the kids were running around. I put solid blocks in and it got rid of the bounce.

Celtic

I can actually remove the sub floor.
It doesn't really affect me.
I have to lay a new sub floor and was just going to pile it on the existing floor before slapping down some DenseShield.

The saddle/threshold into the bath is probably about 1" - 2" higher than the hallway.

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loneframer

I have retrofitted wood X-bridging. Once they are cut to fit, lay the piece flat to the joist and nail or staple the top through the short point of the bevel. Then fold it over to the opposing joist, persuade it up tight and fasten. This is not the best way, but it works well if done correctly.

knucklehead

So you forgot to put it in before you put the plywood down?


I guess that would work, Aren't the metal ones made specifically for 16" centers?

Celtic

Nothing has been forgotten as nothing has been installed yet.
The room is demo'ed and that's it.

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Gus Dering

He was razzin Loneframer with that comment.
It's not always about you.

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