Rotten joist and sill beam repair advice

[Angush]

Hello
After taking up a floorboard over a springy section of floor I have found 3 partially rotten joists ( last 4 inches or so) and most rotten of all the beam they sit on (i believe called a sill beam?).

I am thinking to use bower beams to rectify and repair the joist ends. Any advice appreciated.

With regard to the sill beam, is this just a case of replacing the piece of timber and fixing it into the bricks below somehow? Then joists will need to be fixed to this?

Thanks all

 

[Angush]

I should add this is ground floor

 

[Angush]

More investigating. Slightly more worrying.
Dry rot?

 

[Deleted member 174758]

More investigating. Slightly more worrying.
Dry rot?

Dry rot generally has white to yellow/orange fungal blooms and even fruiting bodies. Very distinctive musty smell, too. Wet rot or maybe boring beetle, perhaps (difficult to discern on a phone screen in a bouncy van). Are there any flight exit holes 2 to 3mm in diameter? Is the timber wet? At least it looks like you've found the reason for your crowned floor

Sill beam/wall plate, whatever you want to call it, it should be replaced with treated timber which has a DPM between it and the masonry (1000 gauge Visqueen). Joists should be propped rotted ends cut away and treated with Cuprinol or similar and sistering joist ends installed (same cross section as original) with a minimum of 1 metre overlap and two or three M12 coach bolts, dog washers, etc to fix to existing. If both ends of a joist are rotted just replace it

 

[Angush]

Hi Job and knock .
Your helpful comments on a couple of my posts have been incredibly useful!

Thanks again and apologies if you keep seeing me crop up!

All the best and thanks again .
Angus

 

[m0t]

I had to do the same job in my small downstairs office about 6 years ago.

I was advised to do different things on different online forums so I'm not sure if I did it 'right' in the end.

My sill plate had completely rotten away for about 2 metres. I cut it at the point where it was still solid and painted the cut end with treatment. I laid a DPC down on a mortar bed then laid quarry tiles accross the top instead of replacing the wood.

I then cut the joist ends about 750mm from the end and then bolted new ends on using toothed washers.

I painted the joist ends with cuprinol, wrapped them in plastic and then replaced the bricks between the joists.

 

[Angush]

Sounds like a similar fix and likely outlast you! Well done !

 

[tell80]

OP,
In the crawl space, lack of through ventilation can be a cause of dry rot - examine any air bricks in your front and rear elevations - are they clean, how many?
Knee walls should have honeycombed brickwork to aid through ventilation.
The skirting on the return wall should be removed and checked for rot.
The last remaining floor board should be lifted and also checked for damage.
No wood debris should be left under the floor.