Rotten Joist

[securespark]

I have a joist under the water cylinder that has been subject to a leak for many decades.
Can it be treated with wood hardener or is it too far gone?

 

[big-all]

wood hardener does nothing to the strength it just holds the rotten bits together in a similar way to hair spray
indeed you should remove all soft timber and start again
but wood hardner helps and lets you leave perhaps the odd 10 or 15% you cant easily remove and makes the surface firm enough to accept filler

 

[securespark]

How does one go about replacing a joist? Or can you just replace part of it?

 

[big-all]

if the rot is localize you can sister the joist over all or just the rotten part and a further perhaps 450-500mm dependant on circumstance
use toothed timber dogs/joiners and perhaps 12mm bolts
is that a floor joist or just for the water tank ??
also what is the span to the right to a supporting wall

 

[bobasd]

what floor is this?

step back an take a photo showing from left wall to right hand wall.
something is showing signs ofrot at the top of the photo - is it floorin or another joist?

replace that joist if possible by hand saw cuttin a cross cut or even cut a say 6" block out an then lift out the rest. but it depends on if thats a ceilin below attached to the joists?
the joist sittin tail in the brick pocket could be well rotted.

dont go boltin on both bolt-on an rotten joist could collapse under the cylinder weight.
or messin with hardener could result in a collapsed joist.

a cylinder of scaldin water collapsing through a bedroom ceilin could cause injurys.

 

[bernardgreen]

Had a similar problem in the cottage, decided drastic action was needed. Got this new joist in parallel to the failed one without lifting all the floor boards

 

[securespark]

Thank you fellas, much appreciate your help.
Hi b-a...
The photo is of the floor of the airing cupboard.
To the left of the cupboard (on the other side of the brick wall the joist is resting on) is the staircase. The front wall of the house is 4m from this brick wall.
Bob...
This is the first floor adjacent to the stairs. The brick supporting the joist is the end of the solid wall from downstairs. On top of it is a Paramount wall.

The thing showing rot is the bottom of the Paramount wall forming the back of the airing cupboard.

The hot water cylinder is not going back, we are having a combi fitted.

 

[bobasd]

all a bit confusin.
so the joist is spannin 4M an it runs under that office room - is that right?
an the gf ceiling p/board is pinned to the joist.

is that definitly the only rotted joist?

 

[securespark]

As far as I can see.

It was the only joist the cylinder was resting on.

Yes, the plasterboard you can see is the GF ceiling attached to the joist. The lighter patch you see is where the damp has separated the paper off the plasterboard and it has detached.

The joist span is 4m, from the brickwall you see in the picture which forms the side of the staircase to the external front wall where the computer desk is.

 

[big-all]

i personally would hack away and work out what percentage is damaged at the worst point and iff its less than 20%would just sister it across the damaged area less for strength more for a surface to secure the flooring to

 

[securespark]

Thanks everyone!

 

[big-all]

as an aside
wood doesnt fail without warning
it will sag a bit this will transfer load via flooring to timbers each side
they in turn if they cannot support the extra load will transfer in all directions
in general you can loose perhaps 30% off structural strength over a small area with no more than slight sag
many a structure is underspecked without failing
remember
regs will allow say 20% as a safety margin construction will have another say 10% margin
grading will have say another 10% margin to make sure no comeback
you can remove 25% centrally as a hole with no problem and off course notching

 

[securespark]

I'll get a chippie to look at it. Thanks!