Should I reinforce these floor joists?

[NetWareHead]

You could rip some 3/4" plywood and sandwich the old beams in between.
Construction adhesive along with carriage bolts & nuts would give you a strong bond.

This may be the route I take. It is alot easier to rip pieces of plywood and sandwich the joist than to try and fit an entire lenght of 2x8 up there. I suppose it would be a good idea to stagger the seams too, apply glue and then drill carriage bolts to secure everything.

Do you guys think a plywood sandwich is equal to another joist? Or is it worth to try and get a real joist up there and sister with that?

 

[crashtech]

I don't want to make an enemy of you, but when you're into something that deep, it's best to involve a professional at some level. You've made it plain that you don't know what to do, so get somebody good to look at it and tell you what needs to be done, at least. Good luck with it.

 

[Greenman]

This may be the route I take. It is alot easier to rip pieces of plywood and sandwich the joist than to try and fit an entire lenght of 2x8 up there. I suppose it would be a good idea to stagger the seams too, apply glue and then drill carriage bolts to secure everything.

Do you guys think a plywood sandwich is equal to another joist? Or is it worth to try and get a real joist up there and sister with that?

3/4" plywood glued and bolted will far surpass the strength of another joist.

 

[NetWareHead]

I don't want to make an enemy of you, but when you're into something that deep, it's best to involve a professional at some level. You've made it plain that you don't know what to do, so get somebody good to look at it and tell you what needs to be done, at least. Good luck with it.

No harm done

 

[Greenman]

I don't want to make an enemy of you, but when you're into something that deep, it's best to involve a professional at some level. You've made it plain that you don't know what to do, so get somebody good to look at it and tell you what needs to be done, at least. Good luck with it.

He has involved a professional, me. I'll grant you that pictures aren't as good as actually seeing things in person, but the issues he has are common and correctable.

 

[paperfist]

3/4" plywood glued and bolted will far surpass the strength of another joist.

So sistering 3/4 plywood to the joists for strength purposes?

My next project is to reinforce 2x6 joists on a 2nd floor to better support a bathtub. I was going to attempt to sister in another 2x6 glued and screwed and catch 2 support walls. It could be impossible as I haven't opened the floor yet.

But saying plywood is as strong as another 2x product is something I hadn't considered. I know both products are incredible strong at their 'heights' just never looked into plywood that way.

 

[Greenman]

So sistering 3/4 plywood to the joists for strength purposes?

My next project is to reinforce 2x6 joists on a 2nd floor to better support a bathtub. I was going to attempt to sister in another 2x6 glued and screwed and catch 2 support walls. It could be impossible as I haven't opened the floor yet.

But saying plywood is as strong as another 2x product is something I hadn't considered. I know both products are incredible strong at their 'heights' just never looked into plywood that way.

Plywood is very stout material, and a layer of 3/4" on each side of a joist helps a lot. Take a look truss joist. They get incredible spans out of 1/2" OSB.
LVL joists are plywood as well, and they'll take loads that would shatter an equal sized timber.

 

[NetWareHead]

Been doing a ton of reading on this and and pros and cons of using another joist vs plywood. I think I may go with the plywood sistering idea on the basis it will produce a floor that is more stable in the long run vs using a joist.

After a visit to my lumber yard, I cant tell you how much dimensional lumber I examined that had a curve to it. :\ Finding the right joist is such a pain in the ass. Now there is a way to get around this as explained to me by my buddy. "Crown" the joist with the curved end facing up towards the subfloor and then shim it upwards on the ledger sides to force it against the subfloor.

Or I could plane the curved upward side of the joist but I dont have a planer.

This just doesnt sound right to me and I feel it would make the floor prone to settling and changing later on down the road. Not to mention the point where the joist crown presses against the subfloor is going to lead to an uneven pressure point on this oint of contact. I intend to install tiles on this floor and settling is going to weaken the mortar/grout and lead to tiles popping later on.

Now I could use Ditra as the underlayment to uncouple any floorboard movement from the above tile. Ditra having its own disadvantages. Plus I want to heat this bathroom with electric radiant floor and coupling ditra with radiant floor mat is another layer of complexity that I need to research. So anyway, why not make the floor as stable as possible if I have the chance to now and hope to not need Ditra?

Plywood I feel as an engineered wood product is less prone to this and would be better in the long run. I feel that it will just "stay" and I have better luck finding straight flat sheets of plywood. Feel free to rip apart my theory if I'm wrong... Thanks.

 

[Greenman]

Been doing a ton of reading on this and and pros and cons of using another joist vs plywood. I think I may go with the plywood sistering idea on the basis it will produce a floor that is more stable in the long run vs using a joist.

After a visit to my lumber yard, I cant tell you how much dimensional lumber I examined that had a curve to it. :\ Finding the right joist is such a pain in the ass. Now there is a way to get around this as explained to me by my buddy. "Crown" the joist with the curved end facing up towards the subfloor and then shim it upwards on the ledger sides to force it against the subfloor.

Or I could plane the curved upward side of the joist but I dont have a planer.

This just doesnt sound right to me and I feel it would make the floor prone to settling and changing later on down the road. Not to mention the point where the joist crown presses against the subfloor is going to lead to an uneven pressure point on this oint of contact. I intend to install tiles on this floor and settling is going to weaken the mortar/grout and lead to tiles popping later on.

Now I could use Ditra as the underlayment to uncouple any floorboard movement from the above tile. Ditra having its own disadvantages. Plus I want to heat this bathroom with electric radiant floor and coupling ditra with radiant floor mat is another layer of complexity that I need to research. So anyway, why not make the floor as stable as possible if I have the chance to now and hope to not need Ditra?

Plywood I feel as an engineered wood product is less prone to this and would be better in the long run. I feel that it will just "stay" and I have better luck finding straight flat sheets of plywood. Feel free to rip apart my theory if I'm wrong... Thanks.

You're on the right track. I like to beef up the floor system then use level quick as my tile base. It comes out perfectly flat and level, so the tile is easy to set. With electric radiant heat in the floor I always install a second temperature sensor, as those tend to be the part of the system that fails. Your spare sensor is already there should the first go bad. Also note that most warm floor systems aren't heating systems, they just keep the floor warm, so you still may need a primary heat source.

 

[DrPizza]

You're on the right track. I like to beef up the floor system then use level quick as my tile base. It comes out perfectly flat and level, so the tile is easy to set. With electric radiant heat in the floor I always install a second temperature sensor, as those tend to be the part of the system that fails. Your spare sensor is already there should the first go bad. Also note that most warm floor systems aren't heating systems, they just keep the floor warm, so you still may need a primary heat source.

Damn! Where were you when I did my electric radiant floor heating? Well, fingers crossed that my temperature sensor never fails - that's a great idea, given that they can fail - and it would have been trivial to install a second backup sensor in case the first one ever fails.

Aren't a good number of those cuts against international building code? I'm certainly no expert on the code, but I have done a little reading when looking how to do wiring properly. However, I recall seeing that you're only allowed to cut so much out of the board, you aren't supposed to cut a certain distance from the sides of the board, and you aren't supposed to cut close to the top or bottom edges. I'm pretty sure I see cuts in those photos that go against all three of those.

Don't quote me, and this may only apply to vertical members, but I think it's 60%, and 40% for load bearing.

Long-term, it's a risky decision not to get proper inspections. I suppose every do-it-yourselfer considers themselves above such things, just like we are all great drivers, and it's the always the other guy that is the problem.

To an extent, I agree. But, I don't think that's true of every person who does their own work. Right in the OP, he has talked to some of his construction buddies, and understands sistering joists - but is asking for 2nd opinions. And, I think he got a really good 2nd opinion with the 3/4" plywood option. And, I don't think the OP sounds like someone who just purchased his first hammer and is searching for a project to tackle.

 

[crashtech]

To an extent, I agree. But, I don't think that's true of every person who does their own work. Right in the OP, he has talked to some of his construction buddies, and understands sistering joists - but is asking for 2nd opinions. And, I think he got a really good 2nd opinion with the 3/4" plywood option. And, I don't think the OP sounds like someone who just purchased his first hammer and is searching for a project to tackle.

I didn't mean that the OP was all that inexperienced. But even a somewhat experienced individual can be tripped up by something that only seems obvious after the fact. I hope that isn't the case here.

 

[NetWareHead]

Do you guys think I should remove load the floor above before sistering (and by that I mean get that big cast iron bath tub out of there)? Or should I sister the joists with the tub in there?

Also, one of my buddies told me I should jack up the floor and go about 1/8 inch every few days. I will check the floor to see if it is level already. My logic says that if the floor is already level, then I wont need to apply pressure from below using jacks.

However, if I need to jack, then I'm thinking I need to support the floor the jacks will rest on (first floor bathroom) from the basement underneath and jack up the second floor bathroom floor accordingly.

 

[NutBucket]

Aren't a good number of those cuts against international building code? I'm certainly no expert on the code, but I have done a little reading when looking how to do wiring properly. However, I recall seeing that you're only allowed to cut so much out of the board, you aren't supposed to cut a certain distance from the sides of the board, and you aren't supposed to cut close to the top or bottom edges. I'm pretty sure I see cuts in those photos that go against all three of those.

Yeah, that's about right. Most of the strength in the joist is along the top and bottom edges. Holes should be centered in the joist (best case).

 

[Greenman]

Do you guys think I should remove load the floor above before sistering (and by that I mean get that big cast iron bath tub out of there)? Or should I sister the joists with the tub in there?

Also, one of my buddies told me I should jack up the floor and go about 1/8 inch every few days. I will check the floor to see if it is level already. My logic says that if the floor is already level, then I wont need to apply pressure from below using jacks.

However, if I need to jack, then I'm thinking I need to support the floor the jacks will rest on (first floor bathroom) from the basement underneath and jack up the second floor bathroom floor accordingly.

If you're talking about trying to remove a bow in the joist, don't bother, it will just bow back down when you remove the support. Sister the bad joist, install new 3/4" plywood subfloor using good quality adhesive (solvent based). Use tongue and grove plywood or block the unsupported edges, then level the floor when you tile.
The tub shouldn't be an issue, unless the cut joist is bowing from the tub being on top of it. If that's the case just drive it up with a 2x4 from the floor below and bolt on the sister. You don't need to be fancy, cut the 2x a bit long and drive it. If it doesn't want to move, hit it harder.

 

[NetWareHead]

With electric radiant heat in the floor I always install a second temperature sensor, as those tend to be the part of the system that fails. Your spare sensor is already there should the first go bad. Also note that most warm floor systems aren't heating systems, they just keep the floor warm, so you still may need a primary heat source.

Greenman do you mind sharing the brand/model you install?? The two sensors is a great idea. Is this a primary heat source or just floor warmer?

 

[Scarpozzi]

My thoughts...

1. Those joists have been cut and are not ideal.
-Cut joists simply don't have the same load bearing capacity when notched for plumbing or electrical and can be made far weaker by the cuts themselves (ie...wood more likely to split around cuts)
2. Consider their age and type of wood
-#2 Yellow Pine is a softer wood, but will harden once aged a few years. That appears to be a harder wood, but the best way to tell is to try to drive a 16 penny nail through it.

If you don't want to replace the joists, you should consider either sistering another joist next to the ones that need it. (Taper the boards so they slide in easier) Or...consider adding additional joists between existing joists to support the floor in-case those joists fail. (so move 8" to a foot on either side and insert a new joist to off-load where possible around the plumbing)

 

[Greenman]

Greenman do you mind sharing the brand/model you install?? The two sensors is a great idea. Is this a primary heat source or just floor warmer?

I can't remember the brand name. It was wires on a backing mat that was set in thin set, then tiled over. I also used a system that was simply a coil of the heating wire that was anchored to the floor, then a layer of thinset over the top. I thought the type with the backing was a better product, but both worked. I'll see if I can dig up the name.

The last bath I put it in, the mat ran about 5" in front of the toilet. The owner left it on 24/7 because she always wanted the floor warm. After about a month of that, the wax ring softened and the seal to the toilet failed and started to leak. We had to have a little training program on proper operation.

 

[NetWareHead]

The last bath I put it in, the mat ran about 5" in front of the toilet. The owner left it on 24/7 because she always wanted the floor warm. After about a month of that, the wax ring softened and the seal to the toilet failed and started to leak. We had to have a little training program on proper operation.

My plumber uses non-wax rings specifically on radiant floors near the toilet. Nothing to melt.

 

[NetWareHead]

Update: Floor sistering and subfloor replacement done. Check out the pics here: https://goo.gl/photos/Vdmp6u9c46GLwbTJ9 Album contains newest pics towards the end (scroll to the bottom). My carpenter and I ended up sistering good joists right next to the bad ones and secured them using joist hangers at the ends. A ton of liquid nails between the joists and new 3/4 plywood subfloor. (Removed rotted old plank subfloor)

No squeaks whatsoever and floor movement eliminated. We moved the cast iron bath tub back in, leveled it and it too feels solid. Huge difference in floor quality. Getting ready to lay down some tile this coming week. Hopefully the new floor is solid enough to provide a goood foundation to new tile and not have any cracks in the grout.

 

[SparkyJJO]

Looks much better.

That one cable should not be run under the joists however. Code violation.

 

[NetWareHead]

Looks much better.

That one cable should not be run under the joists however. Code violation.

Interesting. Never thought it would be a code issue and we have another room (kitchen) with multiple electrical cables under ceiling joists. I'll ask my electrician about this

 

[Greenman]

Looks much better.

That one cable should not be run under the joists however. Code violation.

It's not a code volition unless that surface is being drywalled. I assume the ceiling is going to be dropped.

 

[SparkyJJO]

Maybe it is a local code thing. It used to be OK and was commonly done in the past, but I know around here a cable going under a joist is instantly frowned on if it is new wiring.