Dry Rot - What's the real advice?

[asenath]

Sorry if I'm repeating other posts - have read through lots but just wanted to check situation out

1903 House - in Hull - awaiting survey re possible secondary flooding fron floods in city in 2006.

Last year flooded down pipe between my property and neighbours caused water to enter property - more their side than ours. Duly sorted & gutters cleaned - no further incidences.

Informed this morning neighbours have dry rot - invited in and I have it too. We did remove a "mushroom" from the corner of ceiling last year - did not grow back - problem solved so I thought - how wrong was I?
Neighbours asked if their specialist could have a look inside - his card announces him to be a damp proof specialist - triton chemicals approved contractor - advised ceiling between ground & first floor would need to be removed to assess damage and all the plaster in extensive area removed as well.

So I took part of the ceiling down myself - not sure whether husband was best pleased with this! Found grey - brown tendrils everywhere & reaching extensively outwards but no other mushroom structures. Some whitish tendril and "puffy" substance in stair tread underneath. Floor above this is a bit bouncy also and it appears that skirting boards are also starting to seperate somewhat. Doesn't smell pleasant either!

FRom what I've read most companies want to treat with chemicals - would like to aviod this as some people here have respiratory probs. One even said they didn't do chemicals on their site but went on to suggest I would need it as I had a very serious problem causing horrendous damage to the house.

The damaged wood will obvioulsy need replacing but it is really necesarry to replace all surrounding area of wood & plaster of up to a metre away from where the last tendril reaches? Fair enough if this is the case but I can't help thinking that the companies have some invested interest in departing me from my cash at a rapid rate!

And would secondary flooding have any influence on the situation?

 

[MdB]

"his card announces him to be a damp proof salesman- triton chemicals approved contractor"

There - corrected that for you.

<complete non expert view>
I would treat everything that you have been told with a certain scepticism. Our expert here on the forum hasn't been around for a while but from what I remember, wood that has been damp, rotted and lost its structural strength needs to be replaced. Wood that is still strong and is now dry isn't a problem. Spraying can't reach everywhere and is pointless on dry wood and often does more damage exposing the wood for spraying than it protects. The important thing is that the damp problem has been fixed as damp wood will rot whilst dry wood won't.

Hopefully others here will correct me if I have got any of the above wrong.

<what I would do>
Read up as much as possible on the problem and then pay to get an independent damp expert in who doesn't get a kick back from damp proofing companies. Free "experts" from damp proof companies are not free as the solutions they provide are expensive and can wreck your house in the process.

 

[Jon Maine]

There are lots of brown rots mainly wet but only the one dry rot, Serpula lacrymans ( dead mans tears )

Heavy cuboidal cracking within the timbers is a brown rot feature. the white (with possibly yellow or lilac hints) mycelium can penetrate concrete a metre thick which is why it is called dry rot as it can form a conduit to carry water so it can infect dry wood away from the original damp source which wet rot's don't do.

The fruiting body usually in the corner of a wall or ceiling starts yellow-ochre and ends up rusty red when mature.

Eliminate the cause of damp, ideally remove all infected timber and burn and replace . You can irrigate the wall with special anti fungicidal chemicals.

Does not necessarily sound like dry rot from your description. Do you have a picture of the fruiting body?

 

[asenath]

Hi Thanks for your replies

Def have the cuboidal cracking in the floordboards. The mycelium is brown / greyish - does this mean it's dead? The fruiting body was yellow - turning red with a white outside ring to it. Also noted that a fine red dust settled about as well. This was all removed and never returned. The source of water has been sorted.

Don't have any central heating and the house if well ventilated through airbricks & open cast fires in all rooms even the bedrooms

I presume as the wood is drying out this is when the woods have started to seperate and dip enough for both houses to notice? Sorry if I'm asking silly questions.

Do we really need to take everything back a metre from where the last mycelium is? It's pretty extensive any way - will need a whole new staircase (hoping the other are ok) - really don't want to be having to go futrther than need be.

Thanks

 

[Jon Maine]

That sounds more likely from that description.

The standard advice is to remove all affected timber if you can and either burn or it can be treated in a kiln as if the temperature reaches 40 degrees throughout it will be sterilsed. A metre or half a metre beyond is the standard advice.

However, remove the source of damp and it will be dormant, it will just sit there for decades waiting for moisture again but as long as it is dry you will have no problem.

Maybe if you want to go down that route you could install some sort of moisture level sensor in the wall at the troublesome spot
so you are a step ahead.

Have a good poke around on the net there is a lot of advice, I wouldn't allow your arm to be twisted but something needs to be done even if its only a strategy to monitor it.

 

[Penners]

Jon has given you very knowledgeable advice, which would allow you to deal with the problem without using any chemicals.

In following that advice, I think my only small worry would be the possibility of the rot reappearing in the event of any dampness re-entering the wood. Vigilance is obviously the best policy against this, but if you did decide that you want to try and kill the rot, then I understand that the least toxic treatment is to use a borate liquid. Here's a typical example: http://www.greenspec.co.uk/html/product-pages/probor.php

Such materials are available to spray, paint, or smear on as a gel.

I add the same disclaimer to the above as MdB did - I'm no kind of expert.

 

[skier-hughes]

I'd also add that you want to keep in close contact with your neighbours as to what work is being done.
I'm assuming you are semi detached, so in theory, if your neighbours decide to use a chemical damp proofing company, they should tell you of any works involving your shared wall........ but.......

 

[Matt Green]

Original poster: your dry rot is dead. Repair the damaged timber and don't lose any sleep. Resist all urges to buy chemical treatments to kill something that is dead.

DEAR ANYONE READING THIS THREAD:

There is no need to burn dry rot infected timber. It is a mushroom: not biohazardous waste.

DO NOT UNDER ANY CIRCUMSTANCES irrigate a wall for dry rot.

There is no need to cut back any more timber than is not fit for purpose.

It will not be 'become dormant' once dry. It. Will. Be. Dead. Quite, quite, dead. No more. An ex-mushroom. It dies without water. If the timber gets wet again, dry rot spores may develop there, but: they would have done that anyway, old outbreak or not.


M

 

[Flyfisher]

Thanks Matt, glad to see you're still around.

Is it fair to assume that dry rot spores are (more or less) everywhere, ready to germinate (fruit?) when conditions are right?

Presumably there are no effective treatments to kill the actual spores?

I didn't quite understand your point about "never irrigating a wall for dry rot" - why would anyone even think of doing such a thing?

 

[asenath]

Thanks for all your advice! So glad I found this forum.

Feeling a whole lot better about the issue now - have printed all this off & some excellent articles from Matt Green to share with the neighbours!

I for one will not be going down the chemical route now - and I'll be ready for the all companies who are going to try to sell me the rubbish. I did think it was rather strange pumping a whole load moisture into an area that was trying to dry - didn't sound very logical to me!

Someone even told me today that I was looking at thousands & thousands of pounds to sort out and the spores would be a risk to everyone's health - talk about scaremongering.

So again - thanks everyone - I may even sleep tonight!

 

[Jon Maine]

It will not be 'become dormant' once dry. It. Will. Be. Dead. Quite, quite, dead. No more. An ex-mushroom. It dies without water. If the timber gets wet again, dry rot spores may develop there, but: they would have done that anyway, old outbreak or not.


M

Dry in a house = 14% approx water content in wood.
Dry Rot thrives above 20% in the right temperatures and does not like ventilation much.
Masonry takes approximately 1 month to dry an inch of wall.

You do not wave a magic wand and make it dry over night, and as it starts to dry out a saturated wall may seem dry but could easily still be wet enough to sustain the fungus for a considerable time and has been recorded as many months and into consecutive years before it dies. That is the idea of treatment and removal of infected material, to help arrest the spread whilst drying occurs.

Constant monitoring is the key and if it stays dry for a year or more it probably is all dead. However the spores will be present for decades and could start the cycle again the next time it gets wet as they indeed did the last time. ( the spores are virtually everywhere anyway )

This is another reason why the standard advice suggests treatment of the area.

You will note my suggestion is constant monitoring and no treatment is a definate option. However the onus of the decision should be with the person in the situation after receiving the balanced argument. I have successfully treated several outbreaks by drying and monitoring. Where it was more difficult to dry so easily and inspect I have also removed infected timber and treated the surrounding wood.

 

[Penners]

Thanks Matt, glad to see you're still around.

Seconded. Welcome back, Matt.

 

[Matt Green]

Dry Rot thrives above 20% in the right temperatures

Thrives? It can survive above 20%, it 'thrives' at a higher moisture content than that (the figure depending on the researcher you read, several put the optimal growth conditions at 30%ish for room temperatures).

However, remove the source of damp and it will be dormant, it will just sit there for decades waiting for moisture again but as long as it is dry you will have no problem.

It will die. The concept that a fungus can survive in a drying wall without a food source (wood) for decades is insane.

This is another reason why the standard advice suggests treatment of the area.

The 'standard' treatment advise has been developed by an industry with a desire to sell 'treatments'. You can treat a dry rot outbreak successfully without irrigating a wall or cutting out sound timber 'as a precaution'. Isolate any timbers from the wet masonry and/or spray a fungicide on the mycellium to kill off any vegetative growth by all means, but that type of treatment was not what you were advocating. Drying and monitoring is not the only path you can take, noted and I never suggested otherwise, but the alternatives you highlight are not a responsible way to treat a period property (i.e: they are unneccessary damage to the fabric).

Monitoring the damage once the water source has been eliminated is best way to deal with dry rot. There are alternative ways that involve masonry biocides and intervention into the building fabric which might be appropriate in some cases. Removing sound timber and drilling into walls of a period building to deliver fungicide are indefensible techniques.

M

 

[Jon Maine]

Well,

I think we will have to agree to disagree. If you must insist on bringing up the same sentence again which I incorrectly wrote and then clarified later (the spores will remain in situ dormant) carry on and be petty. I believe your approach could be dangerous advice to many people as every situation is different with possibly more than once source or even type of damp problem. If led to believe unblocking that gutter will kill the dry rot when there is also a cracked tile or a severe condensation problem your advice would be very wrong. I suggest you consider these other options whilst commenting. I fully agree it is only to easy to get "an expert" to quote for all sorts of remedial work which could be a total waste. On the other hand one needs the full picture before making rash statements. In my experience I have found the obvious cause of dampness is not always the only one.

My advice to anyone else reading this forum is that I have taken 25 years of working on old buildings to form the views I have many of which agree with Matt but common sense says keep a close eye on the drying process and the demise of the mycelium. Do not take it as read that you have knocked it on the head after the first attempt.

I think Matts approach does not take into account how long things take to dry. Yes he is right it will die. Dampness in old buildings can sometimes not be easy to control for many reasons and the research I have had to rely upon clearly states the rot remains active above 20% moisture content and probably most prolific at around 30% but hit 40% and again it is to wet for it to operate( again all reliant upon ventilation, heat and possibly other external factors).

What I am saying is be very careful because this rot did not end up with a latin name which essentially translates that it is enough to make a "dead man cry" for no good reason. If it were so easy to extinguish perhaps a different name would have been appropriate.

Anyway here is a question Matt which I have often wondered about which perhaps you can answer. Is the mycelium constructed to take moisture in only one direction? Could it reach a secondary source of dampness, then after the first damp problem becomes dry then take moisture back through the mycelium to the site of the initial out break?

Although when I tried to grow mushrooms in my cellar I could not make it work........ :lol:

 

[asenath]

Ok so now I'm confused?! :shock:

There seems to be brown / black/ grey tendils emanating from one area in the corner which is the outside wall, I did take a bit more of the ceiling down and there are grey whitish tendils also but not as many as there is the brown and this seems to be at the far ends of the tendril reach - if that makes sense?

The smell cetainly has lifted since moving removing the ceiling. There is a faint smell but that I believe is from the sub space beneath the house and the entry point under the stairs. It's certainly not strong neither is it when the trap door is lifted.

I removed the wood surround nr the window - one side came away although did not crumble - the other side seems solid with no give in the wood. Nr the staircase there is a ledge - the wood there seems to have shrunk from the wall - the wood appears solid - no cracking or giving - chipped at the space behind it - this appears clear with no tenrdils etc to see. To be honest not quite sure if the gap has always been there but the previous owners had papered along it to cover it - and I've uncovered it in my ever increasing paranoia!

I too wonder about Jon's question - can the rot find another source of moisture if not completely dead- and start a new out break from there? I just worry that if we remove as much of the wood that we can and where we can see we may miss something that still remains alive and ready to go again!

 

[Matt Green]

If you are talking about the spores, they will remain viable for decades, yes, absolutely, but not the mycelium or the sporophores. The spores surviving is a moot point though- as you say they are everywhere, the trick is to give them nowhere to germinate and that takes 30%+ moisture content.

I note that you studiously avoid issue that the cure may cause more damage to the building than the fungus, but given you are going to roll out the old "I bin doin' this f' 25 year, lad" argument I will admit defeat as I cannot match that and you cannot learn anything from me because I am just too green... My only recourse would be to flex academic muscle, but you could easily deride that with the "experience int' real world, lad" counterargument and it would be checkmate again.

I should come back to this forum in 15 years time when my points will apparently carry more weight. Ah, well. Onward:

Anyway here is a question Matt which I have often wondered about which perhaps you can answer. Is the mycelium constructed to take moisture in only one direction? Could it reach a secondary source of dampness, then after the first damp problem becomes dry then take moisture back through the mycelium to the site of the initial out break?

That's a real can-of-worms question. Interesting though.

Think about it from an plant (fungi) energy point of view. There is two way movement of water through dry rot mycelium (Coggins' research Uni Liverpool PhD thesis and papers from it), but even supplied with water the mycelium in the original source could not continue decaying timber despite having water pumped back to it because the timber there would be too dry. In order to achieve that, the fungus would have to extrude the water and wet the timber up to a moisture content that decay could occur. There is no evidence that the fungus can do this, despite a few inferrences that it can in textbooks that give Serpula Lacrymans: Fundamental Biology and Control Strategies by Jennings and Bravery as the reference. That book never makes the claim but has been quoted as doing so a few times in other works where authors haven't chacked their sources accurately.

From the fungus' point of view, massive re-allocation of water like that is a lot of energy for not a lot of gain. From experience: it lets the mycelium at the original source die back and produces new mycelium at the second source. There is some EH research looking at this in more detail in progress at Birkberk College.


M.

 

[Schoolmarm]

So in the case of a person who is worried that treating one cause of damp, will not ensure that all causes of damp have been removed the only safe solution is to remove ALL the wood in the house. Just in case some more damp is present.


Is that right?


Matt please flex your academic muscles for us laydees

 

[Matt Green]

So in the case of a person who is worried that treating one cause of damp, will not ensure that all causes of damp have been removed the only safe solution is to remove ALL the wood in the house. Just in case some more damp is present. Is that right?

For the overly paranoid, yes. By extension of that argument: if you suffer with veruccas, chopping off both your feet will mean you are never troubled by them again.

Apply common sense, don't lose sight of the actual problem, relax, engage kettle, open biscuits.


M

 

[skier-hughes]

, relax, engage kettle, open biscuits.
M

I'm going to do that, I have a couple of choc hob nobs left

 

[skier-hughes]

All the hob nobs have gone