Wall/Ledger Plate Concerns - Adding another below and lateral stress

[ToastyToes]

Hi all,
Builder installed a new suspended floor for my bathroom. Victorian, double solid brick wall. Detached.

He used an M12 unbranded threaded rod to secure the wall plate to the wall. 4 bolts go through the wall and are bolted to a steel plate on the outside of the house. At a later date I installed another other 4 M12 bolts with resin about 8" into the wall.

Around 500KG dead weight:

• 250KG water cylinder
• 80KG shower tray and bedding, glass.
  
• Toilet
• 40KG vanity unit and sink
• 55KG empty bath
• Plus studs wall, cement boards, flooring etc.

I'm concerned the wall plate is taking a hell of a lot of weight. Its only a 7x2 with some M12 bolts. I'm also concerned if over time the wood goes bad, then the whole bathroom will come down and could kill someone.

I was wondering what I can do to add more support to the wall plate? I was thinking of bolting another wall plate directly below the existing one so it will efficiently be ~16 bolts supporting the floor.

I'm also concerned that the wall plate could be pushing out on the wall and could cause a wall bulge in the future. Is this possible with wall plates?

Here is a photo of the current install.

Thanks all. Some advice from experience will be nice.

 

[^woody^]

Jesus. If you put in any more bolts and timber the floor will be fine but your foundations will be sinking.

 

[ToastyToes]

Jesus. If you put in any more bolts and timber the floor will be fine but your foundations will be sinking.

Please don't make me more paranoid then I already am...... are you joking?

 

[Notch7]

shear capacity of M12 bolt = 63Kn x 8 = 500kn (I think you will be ok!)

of course there are other factors and maybe a pro on here will give more accurate information, but Im sure you are fine.

you are thinking about the wall plate i the wrong way -it wont push the wall out for the simple reason it is locked at each end with nailed joists hangers, which have a reasonable resistance laterally. Also because the wall plate is joined rigidly to the joist ends it cant twist.

The wall plate and joists act as a buttress to the external wall and actually increase strength not reduce it.

 

[ToastyToes]

shear capacity of M12 bolt = 63Kn x 8 = 500kn (I think you will be ok!)

of course there are other factors and maybe a pro on here will give more accurate information, but Im sure you are fine.

you are thinking about the wall plate i the wrong way -it wont push the wall out for the simple reason it is locked at each end with nailed joists hangers, which have a reasonable resistance laterally. Also because the wall plate is joined rigidly to the joist ends it cant twist.

The wall plate and joists act as a buttress to the external wall and actually increase strength not reduce it.

Thanks Notch.
Understood the example but the other end of the joists are sitting in the web of an RSJ by about 100mm, so technically if the wall wanted to bulge, it could.

Although the plasterboard along the RSJ would make it quite evident that there is movement.

 

[^woody^]

if the wall wanted to bulge, it could

And what forces are going to make this wall bulge?

 

[ToastyToes]

And what forces are going to make this wall bulge?

Well I have a bulge on another wall in the house which is quite a few inches due to the loft conversion (25 year old DIY loft).

Although this new bathroom suspended floor is level, if it was slightly leaning towards the wall, then the pressure of the entire floor would lean on the wall, if that makes sense?

Even if the floor is level, I'm thinking the weight of the wall pushing down on the wall could cause a bulge, similar to this but lower down the wall... between ground floor and first floor.

 

[^woody^]

You might want to avoid American sites for advice.

But having said that, look at which way the joists are spanning.

 

[Notch7]

Even if the floor is level, I'm thinking the weight of the wall pushing down on the wall could cause a bulge, similar to this but lower down the wall... between ground floor and first floor.

Actually your image indicates the opposite

 

[ToastyToes]

Actually your image indicates the opposite

Yes it does because the joists are tied to the wall... I'm just worried that because where the joists sit in the web of the RSJ and aren't secured from moved towards the wall, they could over time move in that direction.

 

[^woody^]

Yes it does because the joists are tied to the wall... I'm just worried that because where the joists sit in the web of the RSJ and aren't secured from moved towards the wall, they could over time move in that direction.

Again what is going to move the joists sideways?

Refer to Newton's 1st law

 

[Leofric]

I'm also concerned if over time the wood goes bad, then the whole bathroom will come down and could kill someone.

I suppose you could say that about any timber first floor

 

[^woody^]

There does not seem to be many reports of these killer floors from houses from Edwardian, Victorian, Georgian or even Tudor times in the papers. Unless it's all hushed up.

 

[tony1851]

Yes it does because the joists are tied to the wall... I'm just worried that because where the joists sit in the web of the RSJ and aren't secured from moved towards the wall, they could over time move in that direction.

There is no reason why the joists should 'move over time' to the extent where they come off the flange of the steel beam.
The biggest problem in bathrooms is potential leakage from wastes which can over time cause rot and weaken the joists. But even then, there is a large amount of 'redundancy' in the established sizing of timber joists which allows for a degree of degredation over time.

 

[ToastyToes]

There is no reason why the joists should 'move over time' to the extent where they come off the flange of the steel beam.
The biggest problem in bathrooms is potential leakage from wastes which can over time cause rot and weaken the joists. But even then, there is a large amount of 'redundancy' in the established sizing of timber joists which allows for a degree of degredation over time.

Thanks for your response. He used 7x2 joists at 300 centres. I wish we used 7x3. It'd just about OK with regs.

Building inspector requested we double the joists under the bath so we installed 7x3 half way directly under the bath too which sit in the web of the steel.

I also made it very clear to trades not to drill or notch the bathroom joists, hence why the pipes run under the ledger plate and the waste runs with the joists.