Are We Seeing More Dry Rot Outbreaks ?


Our office gets a wide spectrum of calls throughout the year on all of the remedial services we provide, from our flagship bread and butter Damp Proof Courses and re-plastering (DPC) installs right up to basement conversions. Thrown somewhere in between in no particular order would be Paid pre-purchase, damp, timber and condensation surveys, below ground waterproofing for lateral moisture, timber treatments, renovation, condensation, and ventilation.

This year however and in particular since September we have seen a 70% increase in the number of enquiries and surveys for suspected Dry Rot (surpula lacrymans) to give it the Latin name.

Asking around the industry more and more companies say they are seeing the same worrying shift too. So why is this happening? please read on.

After returning to their holiday home this couple discovered Dry Rot had been living there.
After returning to their holiday home this couple discovered Dry Rot had been living there.

The couple who owned this property in France locked it up when they came back to England after their break with all the shutters closed, and when they returned months later they found an outbreak of Dry Rot that affected the supporting beams and the outbreak was in the walls too. The repair bill was €80,000.00 and their insurance did not cover this.

What Is Happening Then?

So why (you ask) have we seen such a sudden shift this year and is it just a one-off? We asked Damp Sam from All Dry Damp Proofing for his thoughts on the matter.

He told us that, “dry rot spoors are in the air all around us and there are billions floating around but for them to germinate the conditions have to be just right” (like Goldie Locks porridge).

The conditions needed would include high humidity, a lack of adequate ventilation and a source of moisture with wet timber thrown in too. For the germination process to start the timbers have to have a moisture content of around 28% and if the rot is to thrive the optimum moisture content would be 35-40% and you could get this in many ways. leaking gutters due to vegetation or damage. damaged flashings around chimneys and valleys and leaking pipes in out of the way places such as subfloors. in a lot of cases, the ventilation to the subfloors is missing or blocked because the occupiers feel draughts.

In this picture dry rot strands can be seen along with some mycelium feeding on the sugars in the timber. We fixed the Sheffield property
In this picture, dry rot strands can be seen along with some mycelium feeding on the sugars in the timber. We fixed the Sheffield property

So What Has Happened This Year Damp Sam?

This year we have had a very humid summer and it was noted that in between the hot spells there was a lot of heavy rain which pushed up the humidity levels above average. With the temperature being hot, then when it rains the water quickly evaporates leaving the atmosphere very humid adding moisture to the air and the temperature is still hot. If we then add to this the defective gutters, valleys etc then the conditions are then perfect for Mr. D Rot to move in.

What Should I Look For? (how can I tell if I have Dry Rot)?

Ok so there could be a number of clues and this would depend on how long (mature) the dry rot has been growing.

1.There may be a fusty, pungent, mushroom smell emanating from somewhere. Women and children may notice this first as they have a better sense of smell overall.

2. You may start to see a red or rust coloured dust around a certain area. These are spore dust and come from the fruiting body that would probably be mature.

3 cuboidal decay of timbers, the timbers may start to decay and skirting boards may look blurred. When prodded they will be soft and brittle.

4 A white mycelium that could look like cotton wool or a flat grey mycelium that looks like a mushroom skin and can be peeled.

5 Last but not least the fruiting body, this can look like something off Dr. Who and maybe a red or dark brown plate-shaped fungus that has grown in a dark corner.

Fruiting Body of Dry Rot (Sheffield)
Fruiting Body of Dry Rot (Sheffield)

What do I do if I think I have Dry Rot

You should contact your nearest qualified competent remedial treatment company. if you are in England contact the Property Care Association (PCA) where you can do a postcode search for your nearest members. They will come out and confirm what type of rot you have. There are lots of wet rots brown and white but only one Dry Rot.

Once the Dry Rot has been identified the surveyor will look for the source of moisture and tell you why the outbreak has occurred. This may have to be done on the second survey though.

The Second Survey

This is usually a paid survey and will involve invasive methods. Timbers may need taking up and test patches cut and drilled into the walls. this is to find the extent of the outbreak. The surveyor will need to do this so a more accurate quote can be given to what will be needed to treat the problem. The longer the rot has been in place the further the fungus will spread to find timber food sources. the fungus will grow through inert materials such as masonry and concrete and this is where damage can be caused as well as in structural timbers.

How Can I Make Sure I don’t Get Dry Rot

Sadly there is no way of saying it will not happen because if the conditions are right the fungus will germinate and move in.

What you can do though is be on your guard and keep an eye out for signs such as:-

1 blocked and leaking rainwater goods. look for green algae on brickwork and ask why is that there, where is water dripping from or splashing back onto.

2 defective pointing, missing roof slates and poor flashing around chimneys.

3 blocked air bricks and vents.

4 burst or leaking pipes internally, look for watermarks on ceilings, note frequently drops in pressure on the boiler. listen in the house when its quiet for unusual noises like hissing and dripping that just wasn’t there before.

5 be vigilant and know your property, look at it from all elevations and if something doesn’t look right search on google or youtube because someone out there will have the answer.

Thank you for taking the time to read this and get to the bottom of the article, we hope it has been useful to you.

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Wet and Dry Rot living in harmony in Sheffield near Barnsley




2 comments on “Are We Seeing More Dry Rot Outbreaks ?


Hi. I have a ground floor with very cold outside walls which get condensation on them . If I stuck dry lining over the walls would this stop the condensation forming .

    Simon Cooper Post author

    Good Morning Martin,
    it is possible that insulating the walls would stop condensation forming on those particular surfaces, but it sounds like your property may have high humidity so you would need to address that issue too or the condensation will just form on other cold surfaces like windows or absorb into the furniture/bedding etc.
    We do damp & condensation survey and reports to identify and diagnose the problem. it may be you don’t have the correct extractor fans in the kitchen or bathroom. some people like to have fish tanks which are a source of moisture. other issues can be cellars with standing water or even suspended timber floors with standing water in the subfloor. the correct ventilation would need putting in which could be a positive input ventilation (unit), passyfier vents, alternating fans.
    there are lots of solutions but the key is to have the problem diagnosed correctly rather than trying this, then trying that by the local builders. This tends to be what landlords do in my personal opinion but if they paid for the correct solution in the first place they would save money and a large turnover of tenants.
    if you go to the Property Care Association (PCA) website you can do a postcode search for your nearest qualified member who would be able to carry out the survey and provide a report.
    Hope this helps. Happy Easter

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