Joists in the en-suite….

[jayc89]

Started on our en-suite, lifted the boards to find this concoction of joists. Where it juts out looks to be where an old fireplace might have been. No idea what’s going on with the dropped flooring where the hearth once was… I can’t figure out how the centre part of the joists are actually supported and given I plan to fit a bath and tile this room I want to know it’s right. The floor was springy with the boards down so I was expecting to add some noggins, but not unearth this can of worms… 

[jayc89]

[Redbeard]

Can't see v well, but is the dropped floor where the hearthstone was?

[markc]

I would say the dropped area was a hearth stone

[jayc89]

I’ll take some better pics tomorrow. The dropped area is certainly where if expect a hearth to originally be, but I have no idea why it’s dropped nor why there would be floorboards in its place now…. 

[joe90]

Is this ground floor or first floor?, if ground floor i would be tempted to rip the lot out as you need “solid” to tile onto with new moisture proof chipboard. If first floor then remove floorboards or see what joists you have throughout. 

[Adsibob]

What type of bath you installing, cast iron, steel or plastic? And what about its maximum capacity?

Edited December 3, 2023 by Adsibob

[jayc89]

2 hours ago, joe90 said:

Is this ground floor or first floor?, if ground floor i would be tempted to rip the lot out as you need “solid” to tile onto with new moisture proof chipboard. If first floor then remove floorboards or see what joists you have throughout. 

 

First floor I lifted a couple of boards from one side and the rest of the joists look "normal". I'll remove the lot regardless. I have some 22mm Caberfloor I could use... 

 

29 minutes ago, Adsibob said:

What type of bath you installing, cast iron, steel or plastic? And what about its maximum capacity?

 

Acrylic, 102kg with a 205L capacity

[joe90]

40 minutes ago, jayc89 said:

I have some 22mm Caberfloor I could use... 

👍

40 minutes ago, jayc89 said:

Acrylic, 102kg with a 205L capacity

It’s the water it holds that is heavier than the bath itself (unless cast iron).

[Adsibob]

Keep in mind what size floor tiles you’ll be installing. If small to medium, a bit of floor deflection every time you fill the bath won’t be an issue. If however you are going with large format floor tiles, the deflection could cause one or two of them to crack.

[jayc89]

10 hours ago, Adsibob said:

Keep in mind what size floor tiles you’ll be installing. If small to medium, a bit of floor deflection every time you fill the bath won’t be an issue. If however you are going with large format floor tiles, the deflection could cause one or two of them to crack.

 

We're still undecided on the tile format, it's likely to be large... 

The room's are pretty tall, nearly 3m, approx. 200mm taller than the rest of the first floor rooms (no idea why...), I was considering running some 8x2 timbers across the existing joists, fixed with truss clips and noggins, to bring it up to a similar height to the other first floor rooms. Span is approx 4.2m. But I assume deflection will still depend on the joists below these new timbers. 

 

If finished with 22mm P5, glued and screwed, would that add the required rigidity for tiling? 

[joe90]

4 minutes ago, jayc89 said:

But I assume deflection will still depend on the joists below these new timbers. 

No, the new timbers are bigger than existing so will not deflect as the current ones may do. Not sure of span tables for these but 8 x 2 sound very good especially if sistered to the existing.

[jayc89]

7 minutes ago, joe90 said:

No, the new timbers are bigger than existing so will not deflect as the current ones may do. Not sure of span tables for these but 8 x 2 sound very good especially if sistered to the existing.

 

If I was to replace the joists I think I'd need to go with 9x2 to satisfy current building regs, but given I'm overlaying on top of existing, I'm hoping 8x2 would be OK, and I'm only really going that large to raise the floor to where I want it (also gives me somewhat of a service void for my waste pipe too!)

Would a truss clip at each end of the new timbers, plus noggins in between, say at 600 centres, perhaps 400 beneath the area to be tiled (room to be split into wardrobe and ensuite), be suitable? 

[jayc89]

This is what I'm thinking. 

 

Dark lines are existing joists, running left to right, spanning approx 4m. 

Lighter lines are proposed new 8x2 timbers, running top to bottom, spanning approx 4.2m.

 

I was thinking of just using truss clips at each end of the new timbers and noggins in between, but I could use clips at each intersection. Would noggins be a better solution mid-span?

 

 

[joe90]

3 hours ago, jayc89 said:

This is what I'm thinking. 

I “think” this looks sound (but I am no SE) especially if every cross is skew nailed, screwed or bracketed to bond old to new.

[jayc89]

Made a start on this yesterday. Some of the centre cross overs have gaps up to 10-15mm, so much so the nail holes in the truss clips have nothing to grab onto! I've managed to get 6x clips in each new timber so far, 3x at end each, it's the central joists that seem to have dropped - shall I just pack those ones out with some timber shims and D4? 

 

 

[joe90]

What about packing and lowering the truss clips so some nails are in the old joists?

[jayc89]

22 minutes ago, joe90 said:

What about packing and lowering the truss clips so some nails are in the old joists?

 

Pack and glue, let that set and then offer the clips up to the bottom of the shims? Should work, will check the nail holes in the side of the clips will have something in the new timbers to grab onto. 

Will get some pics up tonight.