We've just discovered some dry rot in the house whilst renovating the en-suite (ground floor, in the extension, with a flat fibreglass roof). We've knocked off all the plaster and render from the block walls and plan to treat them with some cuprinol dry rot stuff, and we're replacing all the wood from the room. However, when we took down the ceiling plasterboard, we found that the rot had touched the ends of two of the joists (about 60cm worth, from ends towards the middle).
As we've not long purchased the house, cash is kind of tight - we've got access to some acro-props if need be - can anyone recommend what the best thing to do here is? We're edging towards splicing in two new joist ends.
Sorry but as you've removed the ceiling anyway I'd seriously recommend removing the joist and burning it and any other wood within 3 feet. I know this sounds traumatic and expensive but the spores will be well spread around and it's better to fix it all now than have to come back later. That said if you've got the props and can do the work yourself joists aren't expensive.
In my experience, there is only ONE way to treat *true* dry rot - and that is to be drastic.
Very briefly:
Remove and replace ALL timber within the infection area and upto 3 feet (1metre) away from the last signs of the infection and burn it - even if its not showing signs of dry rot.
Hack off ALL the render and plaster within the area stated above and dispose of it carefully (try not to drop it around the house).
Properly treat ALL the wall on the exposed parts with the correct chemical solution. Treat ALL new timber again with the proper solution. Mix a dry rot killer with the render and then re-render the exposed walls. Ensure that all ventillation grills are open to ensure a good airflow.
Bear in mind that *true* dry-rot fungus will spread through brickwork, stonework, render etc to infect timber far from the original site if not treated properly.
Again, in my experience, if the infection is fairly serious, I would advise that you contact a specialist firm to carry out the chemical kill procedure for you, as they have the expertise to do the job properly and will usually give a guarantee on the work they have done - the added bonus is that the will correctly identify the rot.
With regards to my statement of *true* dry rot - there is wet-rot fungus that looks similar to dry rot and the simple cure for this is just to eradicate the incoming moisture and the job is done - after replacing the rotten timber.
As a matter of interest, I have seen new floors and windows replaced in a house where the dry rot had not been properly treated, and these lasted all of two years before needing to be done again - it was expensive as the rot had progressed to other areas as well.
Thanks everyone for all the replies. We've already removed and burned all the wood from the room - the problems set in we think when the roof leaked and was replaced - but it was apparently wet for a very long time (we weren't the owners then). As far as the dry rot is concerned, there were no fruiting bodies, and no sign of any red spores. However, the skirts had "cubed" and there was mycelium on the plaster, leading up to the joists (hidden behind tiles). The main affected areas were around the shower cubicle. We've gutted the room and will be refitting it very soon. I do plan to coat all blockwork and all new wood in the appropriate chemicals, and probably use plasterboard on the walls.
We're just trying to decide now whether to splice in new joists or to just rip out the two affected (and one on either side of these) - as well as the 2x4 that they're resting on, oh and the fascia board as well.
Besides a roof leak. Just a thought; that dampness isn't in part due to lack of a proper vapour barrier, on the warm side of the walls/ceilings, thereby allowing house moisture to condense inside the structure and cause rot?
As long as you do deal with the damp, there is no need to chemicalise anything. If you dont address the damp, nothing you do will prevent re-rot, but chemicals can delay it.
IIRC copper is effective against plant lifeforms, so you can treat it with copper sulphate in emulsion paint if you want.
thats the logical thing, if its easier than replacing the whole joist. Add joist hanger and bolt new section on.
You dont need acro props, just cut wood to the right length and jam it in to prop it. If youre going to pull it about, it could slip and fall, so a good idea to attach prop to joist in case it moves.
Rots are caused by damp, dry rot included. (The name is a bit misleading.) So the most important thing is to fix the source(s) of water.
I dont know all the dimesnsions, but I'm tempted to say it might be sufficient on a small roof to simply fit some load spreading noggins and leave it at that. Depends
You are being too pessimistic "burning it and any other wood within 3 feet" is not necessary. The source of damp and any infected wood should be removed and perhaps some poison should be spread in the area. I wonder if extra long joist hangers are available for this situation
Anna
~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|
Isn't this confusing wet rot with dry rot. Dry rot brings its own moisture in from its roots just like ivy, hence the name. Wet rot can only survive in damp and will die when the moisture goes.
I found my dry rot specimen thriving in a thin void where cement render and bricks had separated due to poor adhesion, and growing from next door through a crack in the brick work. Conditions were desert dry but it had almost reached my ceiling joists.. After cuprinol dry rot treatment it hasn't reappeared since 1989 so I hope its gone.
Dry is called dry because it leaves a superficially dry powdery residue rather than wet rot which leads to sponginness and superficially damp appearances.
I believe I read this as the recommendation of the Agony Uncle on
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some years ago. The problem with poison is you may miss some of the rot and then it will return. As their ceiling is down I'd still replace. Joists are only about £6/metre after all - I expect the poison will be of similar cost.
Spores from the fruiting bodies of another infestation, blowing around as dust. It's probably pointless trying to avoid the spores as there will be enough infestations around that the spores will get everywhere anyway. The trick is not to have the right situation for them to germinate anywhere.
Bringing infested timber in to the house would be another route, but that's probably relatively rare.
I found only one tiny bit in mine. A small piece of wood (probably less than 1"x1"x2") screwed to the wall under the bath had obviously been kept damp by water leaking between the bath and the wall. It caught dry rot. The hyphae grew out of it across the wall like a 2-dimentional tree. However, they are blind and had set off in a direction where there was no timber for some distance. They had used up all the cellulose in the small wooden block without finding another source of cellulose, so the dry rot died by itself. There was no evidence this growth ever produced a fruiting body (which would have left the spores around as a brown dust for a few feet radius).
I saw some large infestations some 25 years ago when I was first looking to buy a house. I started by looking at houses which were in a bad state (read cheap). In a poor photo (there was no photo, but imagine a poor photo), one had what might have looked like a shag-pile lined celler, but was actually a dry rot lined celler, with hyphae looking like small tree trunks coming up through the ground floor and heading off into the first floor. (I didn't buy it, and actually I didn't dare walk around much of it. I had this terrible urge to have a shower as soon as I got back home, as though it might infest me;-)
Great until the spores spread the rot around a little.
Yep - there is a need, the mycelium can and does spread under the render.
Dry rot actually sucks the moisture out of what it is infecting - so even if you cure the damp you've still got to kill the mycelium.
Fair enough on that one.
Nope, exactly right, after spraying the brickwork.
See elsewhere above.
Nope, just retired from a building maintenance environment where as a chippie and a general formeman I had the dubious honour of working on well over fifty houses infected with various levels of dry rot.
See eslewhere above
The damp was fixed in the original area - but someone (not I) took the decison that the rot wasn't bad enough to go the whole hog.
Talking to the tech-reps (not salesmen) and the bodies that actually did the spraying along with a few experts NOT connected with the dry-rot companies - we had a whole department of these hanging on 'coat-hangers' just waiting for us to call on their services.
I've yet to see a dehumidifier completely dry a room where there is a constant dampness and not hermetically sealed.
dry rot spores in landfill are not a problem. By the time you remove a roomful of rotten wood, the spores are all over the place already. It is not the spores that are the prime problem, it is damp.
all plant life does that. All plant life can not take up sufficient moisture to survive when its environment is too dry. This is qiute basic stuff.
no
So you did work for companies that did the kind of treatment you advocate?
replaced
looks like it wasnt
a tech rep is not a salesman? Rep means representative.
who obviously also have heavy financial incentives, ie a very biased viewpoint
impartial expert advice is available.
Strange, I've not seen them have any problem. One of the risks of dehumidifiers is that people can be tempted to get a cheaper non humidistatic one and end up drying everything to a crisp.
I was wondering how dry is dry enough here? Thinking of situations where very dry conditions (I have 18" thick rubble filled walls) are difficult to achieve (at least in a timely manner).
Also, timber is not often all that dry esp. when new (even the kiln dried stuff) - thinking here of patching the effected area might introduce moisture, at least temporarily.
In those types of situations is it not prudent to use a chemical approach also to prevent reoccurence?
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