Strengthen joists.

[amoreex]

Hello!
I am working on our laundry room/mudroom.
The room is 2.2x3.9 meters.
The floor joists are 45x220 and run along the long side.
So, 3.9 span.
Currently, it is cc60.
And since we are going to have tiles, I need to have cc30. Or at least reinforce it!

I've asked around a bit among acquaintances and many of them have just inserted blocking between existing joists at cc30. To reinforce it that way,

I'm unsure if I can add another joist in between to get cc30.

Is it wrong to just use blocking?
Or is that sufficient?
Should one glue the blocking or just screw with e.g., 100mm screws?
Will use 45x220 lumber in that case.

Then there will be floorboards on top that are glued and screwed.
So I think it should be pretty stable?

Today, you can feel a bit of bounce in the joists.
In the past, you could also feel vibrations. But I think it has to do with the existing floorboards only being poorly glued to the joists and not in tongue and groove.

Thanks in advance!

 

[Tompafix]

Hi!
I'm working on our laundry room/utility entrance.
The room is 2.2x3.9 meters.
The floor joists are 45x220 and span the long side.
So that's 3.9 meters span.
Currently, it’s cc60.
And since we are going to have tiles, I need cc30. Or at least reinforce it!

I've asked around a bit among acquaintances and many of them have just blocked between existing joists at cc 30 for reinforcement.

I am unsure if I can fit an additional joist to lie between them to get cc30.

Is it crazy to just block?
Or is that enough?
Should you glue the blocks or just screw them with, for example, 100mm screws?
In that case, I will use 45x220 timber.

Then there will be floor paneling on top that will be glued and screwed.
So I think it should be quite stable?

Today, you feel a little bounce in the joists.
Previously, you could feel vibrations too. But I think it has to do with the existing floor paneling being only poorly glued to the joists and not in tongue and groove.

Thanks in advance!

How are the joists currently positioned in the space (picture?) and can you access to screw on the sides? You'll have quite a few blocks to screw in if you’re just going to block. At least use 120mm screws, and glue never hurts.

 

[AXS]

Is it insulated?

You can also smack on a regel on every existing regel to make it more stable, it doesn't need to be 220.

 

[amoreex]

How are the joists positioned in the space today (picture?) Can you screw into the sides? There will be quite a few noggings to screw in if you are just going to add noggings. Use at least 120mm screws and glue never hurts.

Not the best picture.
But you can see the direction at least.


Yes, it will be about 30-40 of them...
For the outer ones, I'll have to use joist hangers.
But for the others, I can offset them slightly.

Oh, you need more than 100?
I thought doubling the thickness of the material. But of course, you're screwing into the end grain, and that's weaker.

 

[amoreex]

Is it insulated?

You can also add an additional beam to each existing beam to make it more stable; it doesn't need to be 220.

yes, it's the ground floor. With 220mm insulation and a crawl space underneath.
What do you mean by adding to each existing one?

 

[Tompafix]

It will of course be more stable than today if you add bridging between the joists and are careful with the gluing of the chipboard. But you will only get more integration from the existing joists that are there today. They will still have the same span that they have today. So preferably you should add joists in between that have the same support as those that are there. Also, a couple of rows of bridging to increase integration even more. You could also reinforce the current floor structure from underneath in the crawl space and thus get a shorter span than you have today.

 

[AXS]

yes it is the bottom floor. With 220mm insulation and a crawl space underneath. What do you mean by attaching to each existing one?

Check here: https://www.byggahus.se/forum/threads/foerstaerka-golvbjaelklag-med-kortlingar.224383/#post-1865712

 

[amoreex]

Check this out: [link]

now I get it!
So maybe increasing from 45mm thick to 90mm thick?

 

[AXS]

now I understand!
So maybe increase from 45mm thick to 90mm thick?

Exactly!

The advantage as I see it is that the fastening at each end won't be as critical. But not as strong as cc30 and the insulation won't fit.

If you add noggings, it's important that they are pieces all the way from wall to wall. It should be like a "whole" stud in the opposite direction from your current studs.

 

[amoreex]

Update!
I lifted the insulation and the subfloor boards (if that's the right word?)

and I see that I can definitely insert a joist there..
I see the foundation wall.
And between the wall, it's 385mm.
So I can reach it on the other side too.

The question is whether it's possible to tilt down the joist and then lift it back up?

Some of the other joists are already spliced with joist connectors.
So maybe I can do something similar?
And then add additional short pieces where it's spliced?

I think this should be a better option than just adding short pieces?
Because I would be adding more joists.

Then, of course, add short pieces between the joists. But maybe not as tightly.

That way you can just split the insulation, and it will fit!
The same goes for the subfloor boards, you can just cut them to fit!

However, in the first section where I filmed, there is a floor drain.
I'll have to come up with a solution around that because we can't have a joist in the way there.

 

[Gabbe1]

I would have installed the chipboard flooring according to all the rules of the art and then applied self-leveling compound with reinforcement mesh.

 

[amoreex]

I would have installed chipboard flooring according to all the rules and then used leveling compound with a reinforcing mesh.

yes, that will be done..
But according to GVK, the span is too long and needs to be reduced to cc30

 

[amoreex]

Hope you can watch the movies too.
And understand how I filmed and so on!

 

[Tompafix]

You should definitely attach studs to the foundation wall if you can. If you place it diagonally in the space, there should be no problem getting them in place. Avoid splicing them as it takes a lot to get a good joint.
Then add some bracing rows, and it will be rigid and good.

 

[amoreex]

You should definitely attach studs to the foundation wall if you can. Thinking if you set it diagonally in the space, it shouldn't be a problem to get them in place. Avoid splicing them as it requires a lot to make a good splice. Then some rows of nogging and it will be solid and good.

Yes, I think I'll try to do that!
However, in certain places, I will have to attach the studs to the nogging.
For example, where the floor drain is in the way.
But that's not the end of the world, right?
After all, it's resting on the foundation wall on one side anyway.
And then extra noggings there to distribute the load to the other studs.