Cross bracing floor joists

[The Evil Twin]

Hey folks, looking for some product advice.
The back story is that my parents are getting new floors throughout. Carpet is going away and LVP in. Plus, the kitchens and bathrooms will be getting new stone tile. They asked the contractor about the bounce in the floor in the great room and bedroom. They said they can install cross braces (metal) under all the floors. Wood blocking won't work due to the HVAC and electric running through some of the bays. I'm guessing 2x2 wood would not be strong enough and it might still take up too much space or split with framing nails.
Anyway, the price add was (IMO) ridiculous. So, I'm probably going to do it. Thing is, I'm having trouble finding the cross braces for an EXISTING floor. It seems they are all installed before the sub floor?!? At least that's what the photos seem to imply (see below). Or, do you just bend the ear on the upper end to nail into the side of the joist like you would on the lower end? I don't like the idea of nail-less, and the one product I did find that nails to the side of the joist top and bottom is $27 each! (www.homedepot.com/p/Retrofit-Dimensional-RDC-2x10-16-Joist-Hanger-x-Brace-2-in-x-10-in-x-16-in-18-Gauge-Galvanized-Steel-Measurement-RDC-2X10-16/322001890)

 

[skeets]

In every old home I have been in the cross ties were 1x4s with ends cut to fit and nailed in place

 

[pigdoc]

Disclaimer: I've never done what you are attempting (retrofitting floor joist X-braces).

I've seen some pretty crappy X-bracing jobs done with scrap 1-by...And, they tend to squeak.

From your image, it looks like you could cut off the top ends of the metal braces (part with two nails through it), with a tin snips. Then, nail braces to the SIDE of each joist near the top using that part that has 3 nail holes in it. Looks like you can bend that part to match the angle you need. Going to be a struggle to swing a hammer up in there, but a compact air nailer should fit...

And, while you're at it under there, keep a sharp eye out for weak or cracked joists that could be sistered.

Before the new flooring goes down, I'd spend a day to tighten up any squeaks in the subflooring by just nailing it down better in those spots....Maybe use ring shank nails for that...

-Paul

 

[fried1765]

Disclaimer: I've never done what you are attempting (retrofitting floor joist X-braces).

I've seen some pretty crappy X-bracing jobs done with scrap 1-by...And, they tend to squeak.

From your image, it looks like you could cut off the top ends of the metal braces (part with two nails through it), with a tin snips. Then, nail braces to the SIDE of each joist near the top using that part that has 3 nail holes in it. Looks like you can bend that part to match the angle you need. Going to be a struggle to swing a hammer up in there, but a compact air nailer should fit...

And, while you're at it under there, keep a sharp eye out for weak or cracked joists that could be sistered.

Before the new flooring goes down, I'd spend a day to tighten up any squeaks in the subflooring by just nailing it down better in those spots....Maybe use ring shank nails for that...

-Paul

""Maybe use ring shank nails for that"
Nope.
Screws !

 

[GrizBota]

I’m presuming these areas with too much “bounce”/deflection have a crawl space under them and it isn’t post and beam construction? The idea of the cross bracing is to get more joists involved in resisting the deflection of an isolated load (e.g, a person walking over it). The subfloor sheeting helps do this as well, depending on how it’s attached to the joists.

The most effective way to decrease deflection is to shorten the span length of the joists, such as to install a supported cripple wall in the crawl space (if that’s the configuration). If the span length is halved, the deflection decreases by a factor of eight! That will certainly be more effective than sheet metal cross ties in decreasing deflection, if it’s feasible in the current floor system configuration.

Also, wooden cross bracing can be installed with the 2x material the flat way so a 2x6 would impact the space for utilities in the same way the 2x2 that you mention would. If it is a crawl space, there should be insulation between the joists and the utilizes mounted below the joists. Perhaps this is a basement application? It it’s unfinished, an intermediate joist support may still be feasible.

 

[The Evil Twin]

In every old home I have been in the cross ties were 1x4s with ends cut to fit and nailed in place

Space and time are an issue though. That's why I'm looking at the prefab metal.

 

[The Evil Twin]

Disclaimer: I've never done what you are attempting (retrofitting floor joist X-braces).

I've seen some pretty crappy X-bracing jobs done with scrap 1-by...And, they tend to squeak.

From your image, it looks like you could cut off the top ends of the metal braces (part with two nails through it), with a tin snips. Then, nail braces to the SIDE of each joist near the top using that part that has 3 nail holes in it. Looks like you can bend that part to match the angle you need. Going to be a struggle to swing a hammer up in there, but a compact air nailer should fit...

And, while you're at it under there, keep a sharp eye out for weak or cracked joists that could be sistered.

Before the new flooring goes down, I'd spend a day to tighten up any squeaks in the subflooring by just nailing it down better in those spots....Maybe use ring shank nails for that...

-Paul

That's what I was thinking, but did not know if it is a "legit" way to install them. I don't see why it wouldn't work, but.....I'm not a framer and never done it.
Existing wood is in great condition. Already been over it. Good point!
Another good point on the squeaks. It does not now, but I should still check after I'm done. Maybe even a few weeks after so there are some heat/ cool cycles.

 

[The Evil Twin]

I’m presuming these areas with too much “bounce”/deflection have a crawl space under them and it isn’t post and beam construction? The idea of the cross bracing is to get more joists involved in resisting the deflection of an isolated load (e.g, a person walking over it). The subfloor sheeting helps do this as well, depending on how it’s attached to the joists.

The most effective way to decrease deflection is to shorten the span length of the joists, such as to install a supported cripple wall in the crawl space (if that’s the configuration). If the span length is halved, the deflection decreases by a factor of eight! That will certainly be more effective than sheet metal cross ties in decreasing deflection, if it’s feasible in the current floor system configuration.

It's a full basement underneath. About 9' slab to joist. I thought about adding another beam under there, but if/ when someone wants to finish it that wouldn't work. It also might cause someone to shy away from buying it. Granted, it could be removed before they sell and/ or would be the next owners problem, but I don't want to go that route.
Quite honestly, if the basement were finished, this would probably not be an issue. The wall studs down there would stop the flex.

 

[Flintknapper]

I always prefer solid 'bridging' over cross bracing. If electrical needs to be run you can drill holes for that. HVAC 'ducting' is an issue but leaving out the blocks in that run could be done and then strengthen it as much as possible below the ducting.

It is easy to install and doesn't take much time. I'd rather 'over build' than find out later the floor squeaks and deflects.

Not traditional floor joists (as with a building) but you can see solid bridging (blocks) on this deck I built for my in-laws to accommodate a hot tub.

 

[GeoHorn]

Evil,…we ran into the same issues with our pier-and-beam wood floors when we wanted to install tile in the kitchen where linoleum previously existed. We were extensively warned that tile over such a flooring would eventually crack the tile regardless of what we did.

I ignored them….and installed cement-board (hardi-board type products) directly onto the linoelum…didn’t even remove the linoleum. I ran deck-screws every 8 inches down thru the cement board and linoleum and into the joists…which I did no other modifications to. We then set the 14” tile with latex-grout. That was 1997. We have never had a single cracked tile, despite a heavy granite island and large 10-seat round table installed over it….(just out of view immediately to the right of the pic)….and grandkids running, jumping with joy, and all sorts of dropped objects.

(Don’t let the DW know I posted this without her permission before her housekeeping.)

PS our house is sitting on 2X8 joists spaced 16”.… the tiled area measures 45’ x 20’. There is some solid 2x8 cross bracing… but Flintknapper offers a good solution for you on that. Even if not uniformly installed…solid wood cross bracing is so much better than X-bracing, IMO….it will also allow addt’l deck screws down into the cross braces which X- bracing would not.

 

[The Evil Twin]

Hmm.... @Flintknapper and @GeoHorn yall gave me an idea to mix the two. Boring holes for the electric to pass through is not an option because that would mean pulling the wire back from every vent register, outlet, appliance and light then re running it. That is not gonna happen. But, using the blocking in empty runs and X where I would need to avoid utilities is probably the route I could go. Duct runs are 6" or 4" off the main, so I can use a hole saw through the block and then cut it in half and block just the bottom half.

 

[North Idaho Wolfman]

Floor flex / bounce will only be eliminated if the joists are twisting on the bounce.
Have someone jump on the floor as you look / measure for twist.
Real quick and easy way to find out run a string across crossways on the joists then clip a paper clip on the string on both sides of 2 center room joists, jump up and down, now look at the paper clips, are they pulled away from the joists, then the X's will help, or any blocking for that matter.
If the paperclips haven't really moved then it's a support beam install situation.
One factor is if it's an older build and there is flooring flex in the sheets, then an added subfloor sheet glued down will really help reduce bounce.

The X brackets would work much better if they were installed before the floor sheeting was laid.
If you use them now use a structural screws to install them onto the sides of the joists, nail on the bottom will still work, but you're already installing screws so just run with those.
You can also lay blocking flat and get the the same benefit as you' re just stopping rolling / side flex, of the joists.

 

[GrizBota]

It's a full basement underneath. About 9' slab to joist. I thought about adding another beam under there, but if/ when someone wants to finish it that wouldn't work. It also might cause someone to shy away from buying it. Granted, it could be removed before they sell and/ or would be the next owners problem, but I don't want to go that route.
Quite honestly, if the basement were finished, this would probably not be an issue. The wall studs down there would stop the flex.

Sounds like an unfinished stud wall in the middle perpendicular to the floor joists could be a fix and it wouldn’t really change finishing the basement at a later date (the the new owner might have some more floor flexing if they removed it).

 

[GeoHorn]

E-Twin, I failed to mention what the Wolf reminded me… before laying down the cement-board…we painted the linoleum flooring with suitable adhesive/mastic to stick it down in addition to the deck screws.

 

[The Evil Twin]

Floor flex / bounce will only be eliminated if the joists are twisting on the bounce.
Have someone jump on the floor as you look / measure for twist.
Real quick and easy way to find out run a string across crossways on the joists then clip a paper clip on the string on both sides of 2 center room joists, jump up and down, now look at the paper clips, are they pulled away from the joists, then the X's will help, or any blocking for that matter.
If the paperclips haven't really moved then it's a support beam install situation.
One factor is if it's an older build and there is flooring flex in the sheets, then an added subfloor sheet glued down will really help reduce bounce.

The X brackets would work much better if they were installed before the floor sheeting was laid.
If you use them now use a structural screws to install them onto the sides of the joists, nail on the bottom will still work, but you're already installing screws so just run with those.
You can also lay blocking flat and get the the same benefit as you' re just stopping rolling / side flex, of the joists.

From everything I am reading, it will help with vertical flex as well as twist. The blocks/ crosses spread the load to the adjacent joist on either side.

 

[The Evil Twin]

Looks like I'll block where I can and X where utilities run. Since I have a plan, back to my original question....
do you just bend the ear on the upper end to nail into the side of the joist like you would on the lower end? Anyone know for sure?
I sent an email to their support address. I didn't expect an answer in the days leading up to a long weekend.

 

[North Idaho Wolfman]

From everything I am reading, it will help with vertical flex as well as twist. The blocks/ crosses spread the load to the adjacent joist on either side.

Yes True to some extent.
Note: I've been in houses where the metal braces vibrate and ring, think of a really badly tuned base guitar.

The X brackets would work much better if they were installed before the floor sheeting was laid.
If you use them now use a structural screws to install them onto the sides of the joists, nail on the bottom will still work, but you're already installing screws so just run with those.
You can also lay blocking flat and get the the same benefit as you' re just stopping rolling / side flex, of the joists.

Nails will just pull out of the face and be worthless.
Structural screws for this, look like drywall screws on steroids.

 

[Flintknapper]

From everything I am reading, it will help with vertical flex as well as twist. The blocks/ crosses spread the load to the adjacent joist on either side.

^^^^^

Correct.

Without pics....it is hard to say what all your options might be. But IF the wiring is run anywhere near the joist or flooring/decking you could simply 'notch' the block to accommodate it and not have to pull any wiring to run through bored holes.

I'm sure you'll come up with the best solution, you are an intelligent man.

 

[fried1765]

I always prefer solid 'bridging' over cross bracing. If electrical needs to be run you can drill holes for that. HVAC 'ducting' is an issue but leaving out the blocks in that run could be done and then strengthen it as much as possible below the ducting.

It is easy to install and doesn't take much time. I'd rather 'over build' than find out later the floor squeaks and deflects.

Not traditional floor joists (as with a building) but you can see solid bridging (blocks) on this deck I built for my in-laws to accommodate a hot tub.

View attachment 103813 View attachment 103814

Very nice.

 

[The Evil Twin]

you are in intelligent man.

Don't tell the wife. She thinks I spend so much time in the shop trying to "fix" things because I have trouble figuring stuff out