Rotten Floor Joist. Help

FreeBear

shap101 said: Would I get away with keeping the breeze blocks in place and just replacing the end 25m of the joist ( one side in the wall the other on top of the blocksv) . 

No. It is a bodge.

Without a proper foundation for the blockwork and appropriate DPC, the floor will drop again at some point in the future, and without a DPC, the joist will rot.

Do it properly, and it will not need doing again.

shap101

Thanks again to you all. Just got back from the builders merchants who didn't have any joists In stock and couldn't / wouldn't recommend a suitable replacement .  
The joist measures 50mm x 100mm,  will try wickes tommorow. 
Just a bit less stressed as atleast its supported now 

shap101

A quick question would this do the job   had a look a wickes online and they don't seem to stock size I need) (50mmx100). 

https://msstimber.co.uk/products/4x2-treated-c16-regularised-carcassing-kiln-dried-timber?variant=14650576601145&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=CjwKCAjw97P5BRBQEiwAGflV6RXOtwJicnQ2B_ajbFSAbXZKgK08ynP59FoKt398VUovv7nEqySs-RoCty4QAvD_BwE

maisie_cat

Are there any sleeper walls? We had the same problem, although we fixed it before flooring. We cut the rotten joist back to a sleeper wall, replaced the rotten element and sistered some timbers to either side. Check the airbricks if there are any, plastic laminate won't help matters as the original floors would have been pine probably, so breathable

shap101

Mickey666 said:

Yes, that's the stuff.

I'm not sure what sort of 'builders merchant' wouldn't have any 4x2 inch C16 pressure treated 4x2 PAR timber though - 4x2, 6x2 and 8x2 timbers are staples of the building trade!  Wickes is not really what I would call a builder's merchant, more of a DIY store.  I would look for your nearest Jewson or Ridgeons branch instead.

Just a note about timber sizing.  The original floor joists might well be 50x100 (or 4x2 in old money ) but that's probably a 'swan' size and the joist will be quite rough.  These days, 'sawn' sizes - ie as if comes out of the mill - are less available because the norm is not for all timbers to be planed smooth - hence 'PAR' meaning 'Planed All Round'.  This will take off a few mm off the 'sawn' dimensions so that a '4x2' joist PAR joist will actually measure about 97x47mm.

This is neither here nor there in new construction but is more important when repairing an existing joist in the way you're doing.  The height of the joist is not particularly critical but the width ideally should exactly match the joist being repaired.

A decent builders merchant should be able to cut wood to size and some may even stock 'sawn' timber, though that's becoming rarer these days because of H&S considerations - splinters etc! 

Just remember to brush on some preservative to any cut surfaces because the pressure treatment is relatively thin.

Thanks again.  

Just rechecked the width if tge wood abs it comes up as 54mm not too sure how I measured ot incorrectly before.  

I see what you mean a out being as close as possible due to the need to " sister ' them,  will call a few merchants to see if they stock or are able to cut to the right size.   

jackieblack

Mickey666 said:

I'm not sure what sort of 'builders merchant' wouldn't have any 4x2 inch C16 pressure treated 4x2 PAR timber though - 4x2, 6x2 and 8x2 timbers are staples of the building trade!  Wickes is not really what I would call a builder's merchant, more of a DIY store.  I would look for your nearest Jewson or Ridgeons branch instead.

Local Jewson told me last week that they have been struggling to get timber since the lockdown and current stocks are lower than usual with some usually readily available sizes/lengths sold out/unavailable 

shap101

Struggling to find the correct 55mm timber, everyone has the standard 2x4 but nothing else suitable. 
Would I get away with using a standard 2x4 but only connected to one side or won't this be strong enough. 

FreeBear

Width of the timber won't matter too much - just use some thin strips of ply to fill the space.

shap101

Quick update. Was able to get the joist sorted today and with the spare wood and screws sorted the one next to it as well . 
Took me the whole day (8-6) , quite awkward and my knees are shot from crawling under the boards but worth it. 
Not perfect but 1000% better than it was and safe now. 
Thanks again to all who took the time out to respond especially Mickley666 for the full breakdown. 
Now off to bed. 


.