Q Are white & brown rots both wet & dry rots?

A There are many different fungi that come under the umbrella title 'wet rot'; some of these are brown rots and some are white rots. There is however only one true dry rot (Serpula lacrymans) and this is a brown rot.

Hope this answers your question

Q I have bought a flat in a Victorian house built about 1890 that has a large, complex roof. The flat has a glass lantern roof approx 2.5m long and 1m high, with 4 glass panels on each side. It's much too high up for me to inspect closely, but I can see that the wooden frame is badly rotten. I've been told it would cost £1000's to replace, and possibly even £1000's to put the scaffolding up. I've been advised to leave it alone, wait & see if it breaks in a storm and then claim on the insurance. But would the insurance be likely to pay out if the frame was already rotten? Is it possible to repair parts of the rotten frame in situ without having to replace the entire thing?

Q What are the indications of wet rot?

A There are many different types of wet rot so the answer to your question is not straight forward. Some wet rots are what is termed 'a brown rot' which demonstrate shrinking and splitting of the timber along and across the grain causing cuboidal cracking and the wood to become darker. Others types of wet rot are termed white rots which cause the timber to become fibrous and lighter in colour. Sorry not to be more explicit but the answer you will appreciate is huge.

A Wet rot is a group of fungi that are either a brown rot or white rot. In common with all fungi it requires moisture for germination to take place and to sustain life. So as with all wood rotting fungi the primary cause of wet rot is moisture. If wood is kept 'dry' - below 18% moisture content - it will not decay.

Q I bought a 300 year old timber framed grade II listed cottage 6 months back. Since moving in I have been taking a much closer look at the beams and discovered several patches of what I believe to be dry rot. What is the best course of action for me to take now? I did have a full structural survey and no mention was made of the beams other than "you may want to get a timber expert to look at the beams" which I did not. Should I request the building surveyor to come back and take another look (free of charge) or should I find an expert to come and take a look?

A I would suggest that you get the surveyor back and get his opinion. It may not be dry rot and you could be worrying needlessly. He did put you on notice that something might be wrong by suggesting you get a specialist to look but you did not take his advice so you would be on your own here unless what you are now seeing is very obvious. A timber treatment company will almost certainly find a reason to carry out some form of treatment as this is how they earn their living so be warned.

Q I currently pay over £200 a year to insure my house against attack by wood rotting fungi. I took over the premiums when I bought the house (an old house built in 1864) some 5 years ago.  The insurer has just sold the business and I am being offered the same deal by the new owner. I also pay £1000 a year for home insurance. Can I get the risk of wood rotting fungi covered under a normal buildings policy and will it be cheaper?

A I am aware of these policies and to be honest it is my opinion that they are not all they are cracked up to be - especially with regard to wood rotting fungi. It is almost certain that a condition of your policy is that the property must be maintained in a dry weather proof condition at all times. Wood rotting fungi will only develop in damp conditions and therefore the only way your property will develop a fungal outbreak is if you do not maintain the property i.e. let overflows run, allow roof leaks, do not repair damaged or leaking gutters etc. If wet or dry rot develops there has to be a cause which WILL BE a so called lack of maintenance thus you would not have complied with the terms of the policy and no claim would be paid. In other words save your money, maintain your property and you will not have a problem.

It is not possible to put wood rotting fungi or wood boring beetles onto a normal buildings policy. Dry rot is regarded as a consequential loss if an unseen leak has occurred and is normally not covered but this depends how the policy was written. We are aware of many cases where an ex gratia payment has been made by the insurance company.

Q I had a company out to give me a quote for treating some woodworm. They confirmed I have a small area (approx 1/2 of kitchen floor) affected. In the process they discovered I also have wet rot in some of my floor joists and they need to be replaced. The cause is leaking pipes under the bathroom & also the fact that some of the joists have been resting on wet masonry. I'm unsure if the masonry is simply wet because of the leak or if there is an additional cause. They have quoted me a substantial sum for replacing the joists with treated ones and replacing the floorboards. They didn't mention anything about needing to improve the subfloor ventilation so I'm not sure if this is an issue. I have another specialist firm coming out to quote but don't imagine they will be much cheaper. As I am about to start building work I ran the problem passed my builder who says he can replace the joists & sections of floor affected at a fraction of the cost (he's carried out this type of work before). I am also having a new bathroom & kitchen installed; the pipe work will be renewed & re-routed so this should solve the problem of the leak. My questions are
1. Do I have to improve sub floor ventilation? I have a semi bungalow (approx 1930s) that currently has 4 louvre style air bricks measuring 9" x 6", 2 at the front of the property & 2 at the rear. There aren't any on the side. I have a couple of stairs at the front so it's not possible to have 1 under the front door.
2. Will the builder have to use specially treated joists? If so what should they be?
3. Can wet rot develop into dry rot?
4. Once areas affected by woodworm & wet rot have been replaced,
a) Will any type of fungicidal treatment need to be applied?
b) Should entire subfloor level be sprayed with insecticide? (Bore holes only present at sub floor level)

A Thank you for your many questions. I answer below your questions in the order raised:

1. You can never have too much sub-floor ventilation. We would expect there to be more vents than two in the front and rear. We would expect there to be one every 1.5 metres of exterior walls if all floors inside are suspended timber floors. It sounds like, but we cannot be certain without seeing, that the wet rot was caused by timber in direct contact with damp sub floor masonry - not the lack of ventilation.

2. The builder does not have to use specially treated timber but industrially pre treated timber is the best and probably worth the small additional cost (labour will be the same)

3. Wet rot does not change into dry rot. They are totally different fungi with similar but different requirements.

4. a) It is not possible to apply by surface application an effective treatment that will prevent future fungal decay. Do not let yourself be talked into this. If you keep the timbers dry and well ventilated no wood rotting fungi can develop.

4. b) A sub floor area is open/interconnected and it is therefore possible that woodworm is present in other areas as well. Is it possible to crawl underneath to check? Only spray all floors if it is justified.

Hope the above is of assistance to you.

Q I live in a ground floor flat in a Victorian country house. We discovered that a spur off the main water intake in the main entrance hall was leaking and appeared to have done so for a period of a few months. The valve has been replaced and the cupboard housing the water intake has dried out quickly. I have been noticing a smell in my flat and I can't locate the source. It is only noticeable for a few minutes at a time and generally when first entering a room. Obviously the leaking water has gone somewhere and I worry that it is under my flat. Now that the leak has been repaired how can I discover if wet rot is the cause of the smell and what should be done about it?

A Wet rot as a general rule does not smell. Dry rot however has a very distinct 'mushroom' smell, especially when disturbed, similar to that experienced when opening a sealed box of mushrooms. You will have to raise floorboards and check under the floor with a torch and mirror to see if you have a problem but will you know what to look for and where? Experiencing a smell upon entering a room is common and as you quickly acclimatise the smell is no longer noticeable. The smell you are experiencing could just be a musty smell percolating up from the damp oversite beneath the floors or it could be a musty smell caused by mould present in your flat as a result of condensation which could be occurring but is unseen. The current cold weather (January) will cause condensation to form more readily in properties. Make certain that the sub floor ventilation is good which would disperse odour and aid the oversite drying process which is likely to take years.