Need to replace a couple of joists...

[Screech20]

Hey guys.

Currently doing the bathroom, and although I expected the floor to be wet from the bodged up shower, i didn't expect it to be this bad.

As you can see from the (hopefully) attached photo, the joists have rotted right up to the supporting sole plate, which means it needs cutting back leaving the to the right of it unsupported.
Unfortunately replacing up to the next support isn't much of an option.

What I'm hoping to do, if you guys agree it's a good idea, is to run a row of bricks off the slab, about where you see my level, to create a new support.
I would obviously need to use a dpc and a treated timber sole plate.

Does that sound like a sensible/doing idea?


Cheers

 

[vinn]

Your bathroom is on the ground floor?
Please step back and take a photo of the whole floor from right to left.
Thats not the sole plate - is it a 4x plate sitting on the concrete? Is it rotted?
The two affected joists go under the wall/partition to the right - where do they finish?
The partition (is it an in-fill to a previous opening) is built off the raised floor.
How is this raised floor ventilated?

The fungal affected joists could be cut back and chemically treated. Or, depending on the span, could be replaced entirely.
New joists could be introduced and packed up below the partition.

 

[Screech20]

Sorry I was thinking about it while typing but forgot to give that info!

Yes it's on ground floor, it's a 1930's bungalow.

It's timber suspended floor with vents around the perimeter.

Yes it's 4x2, wasn't too sure what to call it, maybe a mid span support?
It runs all the way from front to back. It's not rotten, and there is a dpc under them (there are more of them under the floors)
The wall the the right is the bathroom wall, all the non load bearing walls are built off the boards like that.

I'd rather cut them back over replacing the whole span, due to access under the floor in the next room.

Cheers

 

[geraldthehamster]

Is it just the two joists we can see that are affected? If the timber is sound where your level is, and sound to the left of the photo, then I'd be inclined to let the affected wood dry out and sister another timber alongside, spanning from sound timber to sound timber. Either drill and bolt or use plenty of good screws.

Cheers
Richard

 

[Screech20]

Yes it is just the 2. The one with the chisel sticking out of it is the worst one, and lost quite a bit of material by poking around at it.
It is sound to both left and right, and actually, about a meter to the left is where it starts, in a pocket of the cavity wall, sitting on a sole plate(?),
So I could pocket the new sister joists in the same way, and bolt/screw as you say?

Cheers

 

[KenGMac]

Screech2

Suggest that before you cut the damaged joists out you provide a very tight fitting support below the joists roughly below where the spirit level is in the image posted, this support only needs to extend about 100.mm each side of the two joists to be cut away.

Why? because, if the partition wall is resting on the joists to be cut, and if the partition wall moves then you will be faced with more problems? the floor plate appears to stop, unsupported just before the brickwork wall that has been removed? this could leave the lower area of the Partition to fail if the supporting joists are removed

Also, as a precaution, suggest you place a length of a DPC material under this bearer, as for the fixings to use my preference would be bolts, drill a hole that is a good tight fit for the bolt, the less movement the better.

Did the original floor bounce? or move? if so then introduce more "Sole Plates" to stop the bounce.

Finally suggest you get a hold of anti-rot timber spray and use liberally on all exposed timber as a precaution to kill off any rogue fungal spores.

Ken.

 

[vinn]

OP,
It might be easier to slide new joists in to rest in new wall pockets,
rather than bolting-on between the bearing plate & the wall to the left.
But its a site decision.

If you do bolt-on then pack up at the bolting on position and run a couple of noggins to prevent any movement.
Whatever, you must cut out all fungal infected wood.
Never sister next to decayed timber or you will swiftly have two rotting joists instead of one.

 

[Screech20]

That's for the replies guys. A little confused with what to do now.

This is thevother end:


Which for me is easy enough to get a new joist next to the old ones, pack up as required and fix down.

I then want to bolt the new to the old? (How big bolts? Every 300mm or so?)

Then cut out the wet rotted section?

Cheers

 

[Screech20]

Ok so I had an idea. Please bear with...

After having a quick look under the floor in the hall this morning, I noticed the lounge wall is also sitting on the floorboards, (which I didn't think it did) and there is also another joist mid span support under it.
So I think I can replace the rotten joists up to this point, but I'll need to do it in 2 sections, as there's no physical way of getting 3.4m under there.

So looking at the sketch below, (very rough I know, it's all I had to hand in my van!) I think it's how I can achieve it.



Black lines = Walls
Blue lines = mid span supports
Green lines = affected joists
Yellow lines = part 1 of replacement
Pink lines = part 2 of replacement

 

[bernardgreen]

as there's no physical way of getting 3.4m under there.

May not be the solution for you but nothing is impossible, This was a replacement for a water damaged joist. A hole in the wall was less work tha removing partition walls and floorboards.

 

[Screech20]

That method did cross my mind before I knew how long I needed them to be, but unfortunately I don't have for the room on the outside either.
There's a 6' driveway then a 8'wall.

Cheers

 

[geraldthehamster]

Perhaps I've misunderstood, but surely it's only the metre or less visible in your picture that's damaged? If those two joists are sound where the level is, and sound at the left of the picture, I'd just bolt new timbers alongside that section. As long as they attach to a foot of sound timber each side. It's only a short section. Unless the rot is more widespread, which I don't think you've said it is, why are you wanting to replace vast lengths of joist?

Cheers
Richard

 

[Screech20]

No, no misunderstanding.

I was up for sistering the joists, but then someone else said I shouldn't do that.

But now I've thought about it, it's not that much more hassle to do as per my last 'sketch', for my peace of mind if nothing else.

They are only short, but there is going to be a fair bit of weight with the bath.


Cheers

 

[geraldthehamster]

Up to you but I think this is unnecessary hassle. I'd just do the pink lines in your diagram, stopping short of the walls, bolt together and if you're still worried pack up underneath as ree suggests. Sorry, not ree. Vinn

Cheers
Richard

 

[Screech20]

I hear you. So once all bolted and packed up, (with some kind of dpc?) then cut out the rotten bits?


Cheers