Dry rot on joist ends

mazears · Posted: Tue Nov 03, 2009 7:54 pm Post Subject: Dry rot on joist ends

I have dry rot on at the ends of 3 floor/ceiling joists (also on the internal wooden lintel) They seem quite crumbly and soft. I have some dry rot water based treatment (one for wood/one for mortar).What would be the best course of action? A builder friend advised to prop the joists then cut the bad ends off 6ins. He said to put joist hangers on inside of the good joists either side of the 3 to be cut,and hang a new piece wood across.Then attach the 3 cut ones to the new piece with a further 3 joist hangers. Would this be acceptable?

Kitchen ceiling joists

noseall · Posted: Tue Nov 03, 2009 8:21 pm Post Subject:

How much rot damage is there to the joist ends?

Are you sure it is dry rot?

mazears · Posted: Tue Nov 03, 2009 8:49 pm Post Subject:

The 1st (towards left) of the 3 bad joists seems to be the worst. You can see where i've hollowed it out. I've had a screwdriver in it and it breaks away probably 2in deep from bottom end. I could maybe break it all away if i tried. Other two can be chipped away from bottom end but not half as bad. All 3 joists rest on the inside brick although at present they are just sitting in mid air and not on the brick-hence a slight spring in upstairs bathroom. Right hand side of the lintel is extremely rotten also. I posted a question in this forum previously and was advised it was dry rot as opposed to wet rot. Was hoping i could simply paint on the dry rot treatment but think 1 or all 3 may need cutting off?

gregers · Posted: Tue Nov 03, 2009 9:02 pm Post Subject:

the preservation industry will state that any evidence of dry rot will need to be removed.
1m in all directions where feasible.past the last found evidence.
i think you will have to cut out a lot more then you think,then maybe do a trimmer/trimming situation using the jiffys where needed.
the masonary will need to be drilled and sprayed with a masonary fungcide(dry rot fluid).
any timbers left i would surface treat with something like probor 20,which is a deep penertrating paste/gel.

why not phone up a treatment specalist to advise and see how much it will cost to treat and gaurantee (peace of mind).

also bear in mind,THAT IF IT IS DRY ROT,because it is close to the timber lintol then it may be in there as well,think you need to investigate a lot furthur.

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mazears · Posted: Tue Nov 03, 2009 9:21 pm Post Subject:

I was intending taking out the timber lintel and replacing with concrete one. Bricks above and around this area need removing and securing again (maybe i can discard these bricks and use others if they are a potential problem with the dry rot? I bought a suitable timber treatment and a treatment for masonary from permagard (5litres of each that you paint on). Sounds like the joist hanger scenario is ok but you recommend i cut 1m off each joist end? Sounds alot as kitchen is only 2m wide

stuart45 · Posted: Tue Nov 03, 2009 9:27 pm Post Subject:

You also need to find out what caused the timber to get damp and correct the problem.

gregers · Posted: Tue Nov 03, 2009 9:31 pm Post Subject:

i defo think you need to gain advice from a reputable preservation company to give you the advice thats needed,painting on the solution is about as much use as a chocolate fire gaurd imo,you need a decent hand pump at least to make sure you are getting the solution into the building fabric painting it onto the timber will be ok to a point,but it will need to be done at least a couple of times.

what i have suggested was/is what we used to advise customers,wether that has changed i do not know,take a look on google and read up on the info about dry rot.

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mazears · Posted: Tue Nov 03, 2009 9:34 pm Post Subject:

The damp is either from the bad external rendering or from bath directly above. Property has been empty along time and had no ventilation