Floor Joist Bracing/Blocking with Pex Radiant

josephny

I'm hoping someone has experience and can recommend how to best block or brace floor joists (3x10, 16" OC) that will have pex in Uponor tracks (2 per joist bay) installed on the subfloor's underside.

Thanks very much!

STEVEusaPA

Use 2x8's, flush to the bottom of the joists, and that gives you about 2" to slide the pex & track thru.
If you can run the pex/track before the blocking, even easier.

josephny

Youngplumber said:

You want a brace for what? 

Bracing the floor joists are a good thing, as well as required under certain circumstances.

josephny

STEVEusaPA said:

Use 2x8's, flush to the bottom of the joists, and that gives you about 2" to slide the pex & track thru.
If you can run the pex/track before the blocking, even easier.

That is a fabulous idea!

Thank you.

STEVEusaPA

Also, the metal diagonal ones, installed afterwards are good, and easy.

JUGHNE

Young plumber; floor joist bracing helps in preventing floor deflection. With diagonal cross bracing when you step on one joist part of your weight is transferred to the joist on either side of the one you are on. So instead of just stepping on one joist you are putting your weight on 3 of them.

ChrisJ

Youngplumber said:

@JUGHNE I thought that was what was being discussed.

The things we rip out all the time.

At first I thought they were asking about bracing the joists becuse of the holes being drilled. 

The same guys that rip out blocking probably also cut joists and leave them hanging.

ChrisJ

Youngplumber said:

@ChrisJ if you say so.

Which is more important a unnecessary over engineered "brace" or a toilet?

Squeak the flooring or no vent? 

Over engineering is the same as no engineering. 

My house built in the 1860s has blocking on all joists.

It most certainly isn't over engineered.  Just because you do not know what it is or why is there doesn't mean it's ok to remove.  Blocking is incredibly important.

@STEVEusaPA gave excellent advise.  

KC_Jones

Youngplumber said:

@ChrisJ if you say so.

Which is more important a unnecessary over engineered "brace" or a toilet?

Squeak the flooring or no vent? 

Over engineering is the same as no engineering. 

It’s not over engineering.

Just  because you don’t understand something doesn’t mean it’s wrong or over engineered, it means you don’t understand.

If it’s in the way you either work around it, or redesign it to get structure back that you remove.  Blocking and bracing is an integral part of the structure, as Chris pointed out, for a very long time.

You’d be better off learning instead of bashing.

ChrisJ

Youngplumber said:

@ChrisJ your house being built during the in the cival war era doesn't mean the blocking saved it. Nor is it more necessary than gravity fed piping. There are times when it has to go. 

You completely missed the point.  I have a very very early stick framed house that even then they understood what and why they were doing it.

I grew up in a family of carpenters and none of them would accept what you're saying.  I'm sorry.

You don't just rip framing out without making adjustments.   Would you cut studs without building a header too?!?

Blocking besides transferring load also helps keep joists straight and vertical.

Gordy

Proper bridging installation is code, and has purpose. As stated earlier it transfers loading from one joist to the next. 

Also full dimensional blocking does not perform the same as 1x or metal bridging, and is more prone to squeak.

it is excepted that some plumbing, and hvac operations require removal in certain areas.

josephny

Gordy said:

Proper bridging installation is code, and has purpose. As stated earlier it transfers loading from one joist to the next. 

Also full dimensional blocking does not perform the same as 1x or metal bridging, and is more prone to squeak.

it is excepted that some plumbing, and hvac operations require removal in certain areas.

Gordy: Could you please expand on what you mean by "full dimensional blocking does not perform the same as 1x or metal bridging, and is more prone to squeak?"

I have 16' spans of 3x10 Doug Fit 16" OC in a reno I'm currently doing myself (and I do not claim to be an expert at anything whatsoever -- I'm eager to learn). I really like the idea of using 2x8 flush with the bottom of the joists to make pex and plates easier to install at the top of the 3x10.

If I understand what you're saying, even if I used 2x10 ("full dimensional blocking?"), it would not be as effective as 1x or metal bridging. Is that correct? Would increasing the number of 2x8 blocks help or is the physics just not there to stabilize any particular joist?

Thank you!

ChrisJ

josephny said:

Proper bridging installation is code, and has purpose. As stated earlier it transfers loading from one joist to the next. 

Also full dimensional blocking does not perform the same as 1x or metal bridging, and is more prone to squeak.

it is excepted that some plumbing, and hvac operations require removal in certain areas.

Gordy: Could you please expand on what you mean by "full dimensional blocking does not perform the same as 1x or metal bridging, and is more prone to squeak?" I have 16' spans of 3x10 Doug Fit 16" OC in a reno I'm currently doing myself (and I do not claim to be an expert at anything whatsoever -- I'm eager to learn). I really like the idea of using 2x8 flush with the bottom of the joists to make pex and plates easier to install at the top of the 3x10. If I understand what you're saying, even if I used 2x10 ("full dimensional blocking?"), it would not be as effective as 1x or metal bridging. Is that correct? Would increasing the number of 2x8 blocks help or is the physics just not there to stabilize any particular joist? Thank you!

I'm not sure what was meant by that either.

My father used full size blocking (2x12) in his own house and there's a lot of it.  He also glued the subfloor down.  He was a carpenter for 50 years.

When I was in school for carpentry they told us full size blocking was nice but not required and that cross bracing was sufficient.

Gordy

Bridging transfers loads in two ways. lateral loading and point loading.

Properly installed bridging is installed from the top before sub deck is installed with bottoms not fastened. Then install sub deck. Then nail bottoms with no load on deck.

If joists are cupped, and you can’t get the blocking tight to the joists on both sides squeak city....

JUGHNE

I can't explain it but I am thinking that the diagonal bracing may be stronger than the blocks because of the triangle effect of the diagonal.

When I was installing HVAC I was frowned upon for removing the bridging for 6" round pipe runs....at least a dozen per house.
But everyone wanted a "clean and flat" ceiling for SR in the basement so everything had to fit between joists coming from the central drop soffit for main duct.
The same GC though, would not build a 2 x 6 plumbing wall for washer box, main stack etc. It upset his plan too much and heaven forbid he might have to order a pre-hung door for 2x6 wall rather than the standard 2x4.

josephny

Gordy said:

Bridging transfers loads in two ways. lateral loading and point loading.

Properly installed bridging is installed from the top before sub deck is installed with bottoms not fastened. Then install sub deck. Then nail bottoms with no load on deck.

If joists are cupped, and you can’t get the blocking tight to the joists on both sides squeak city....

Got it.

What would you say about installing 2x8 blocking aligned with the bottom of the 3x10 after the subfloor is on?

Great and strong, not perfect, acceptable, effective, ineffective, crappy?

JUGHNE

Did your floor joists have any bridging before you started this project?
You really have 3" x 10" FJ? That sounds pretty stout already.
If we use the standard 2 x 10 (1 1/2" x 9 1/2") for 16' span it is pretty bouncy without bracing.

josephny

The house had 4' of standing water in the decayed basement for years when I bought it and had rotten 3x10 for the first floor.

The 2nd and 3rd floors has wall studs and floor joists that look as good as the day they were installed (100 years ago).

I replaced the damaged foundation and installed new (true size) 3x10x20' (so much beefier that 2x10!).

Gordy

In your case the blocking is about only option since bridging would be to hard to install and fasten correctly. Metal bridging fastens on top of joist.

JUGHNE

IIRC, there was some metal bridging that could go in after the fact. Don't know if fastened to the side of the FJ near the top or was some drive in point on the end.
If fastened it could be installed before the pex and the lower part fastened later.

STEVEusaPA

The metal bridging always goes in after framing and sub floor plywood, actually so does the blocking.
Because it’s 3x, I’d go with the metal after the pex and plates.

Gordy

https://youtu.be/55tUFdUsOYU

Gordy

https://youtu.be/bmeZcNn-1zU

Gordy

If anyone has priced lumber lately...go with metal. Much easier just install it upside down use screws, and a driver. May need to pick up a handy right angle attachment.

TAG

I was always told that was for dimensional lumber so it dried correctly ...

I use engineered products now ,,,have for years ... even the studs. no cross on the floors

My current project had them installed in the one older floor we did not remove --- no problem with placing the tracks. You can see them here.

Gordy

No it’s not so the lumber drys correctly. TJIs, and BCIs claim it’s not needed. However codes would trump manufacturers claims.

Bridging would still enhance those joist assemblies.