Rising damp and White Rot: A case study
Rising damp is a common problem that affects many homes and buildings. It occurs when moisture from the ground travels up through porous building materials, such as bricks, mortar, and timber. Moisture in timber frames that have been affected by flood water, can also be trapped behind plaster sheet, tiles and architraves. This remains sight unseen. When this moisture reaches the timber frame of a building, it can cause a number of problems, including the growth of white rot.
White rot is a type of fungal decay that can cause significant damage to timber frames. It is typically caused by the presence of moisture and can spread quickly if left untreated. In addition to weakening the timber, white rot can also have an impact on the overall structural integrity of a building. White rot will only grow in dark places as it hates sunlight. Typically, it’s found under subfloors or in roof spaces. Anywhere which is dark and damp.
Preschem was contacted by Noela, who has experienced such a situation. There had been some past renovations where a concrete slab was poured next to an existing slab internally. The problem was picked up, when the building was being investigated for another unrelated moisture issue in the kitchen and bathroom. However, the photos here are from a wall where there are no water pipes or adjoining wet areas. But this wall is about 2m from where there the other issue was picked up. The moisture has either migrated from that source or wicked up from the fresh concrete into the baseplate and lower portion of the studs. The concrete was installed internally as part of a renovation project some years back, but it’s possible that the wall was fitted to it before the concrete had properly dried. As you can see the damage is quite spectacular, and expensive to repair.
White rot fruiting body on plaster
You will note that the white rot has grown in a fan shape on the plaster. This is what’s known as a fruiting body. Other areas are wispy or fibrous in appearance, especially on the insulation and the studs and baseplate. This is mycelium and it’s searching for another suitable location, where there is moisture and timber. Like all living things, rot fungi need’s nourishment to survive. This is how it searches for its next meal.
Advanced white rot in wall cavity caused by rising damp.
The advice Preschem has given to prevent this occurring again is to first use a waterproofing membrane or damp course on the concrete. This will hopefully prevent moisture wicking into the baseplate again. Dry timber doesn’t rot, so the moisture barrier is the most important part of preventing reoccurrence. Replacing the baseplate with H3 structural timber is also advisable. Normally this level of treatment is for pine that has external exposure, such as a deck subframe. But the concern is that there could be a lingering moisture issue. Lastly, the use of No-Rot Gel on the surviving and replacement base plate, wall studs and noggins. No-Rot Gel, will sanitise any active fungal spores and offer Noela years of protection should the moisture issue return at a later date.
Preschem’s No-Rot Gel is a powerful wood preservative that is specifically designed to protect timber from fungal decay. It works by penetrating deep into the timber and killing rot and active rot spores.
To use Preschem’s No-Rot Gel, you will first need to remove any damaged or decayed timber. This may involve cutting out affected areas and replacing them with new timber. Once the affected areas have been removed, the remaining timber should be clean.
Firstly, wet the timber with water. This may sound strange as the rot was caused by moisture in the first place, but this will ensure deeper penetration of No-Rot Gel. Next, apply Preschem’s No-Rot Gel to the timber using a brush. The gel should be applied liberally, ensuring that it penetrates deep into the timber. Reapply the product within 2 hours, especially on a hot day. By reapplying it quickly, the solvent in No-Rot Gel won’t start to dry and get sticky. This will mean the second application will be better absorbed, rather than become a sticky mess on the surface.
Allow the timber to dry for several days before completing the repairs and replastering the walls.
Overall, rising damp can be a serious problem for timber frames, but with the right treatment and preventative measures, it is possible to protect your building from the damaging effects of white rot. By using products like Preschem’s No-Rot Gel and taking steps to prevent moisture from entering your building, you can ensure that your timber frames remain strong and durable for years to come.
Preschem would also like to thank Noela, for generously allowing us to publish this article and sharing her images with you.
great article
G’day! Is it possible for me to let my brother examine this article before contacting a restoration company sometime soon? His home exterior has been covered in salt dampness for almost a month now. Thanks to you, we now realize rising dampness can be eradicated by minimizing the presence of moisture.
Hi Sam,
Anyone can examine the article. In terms of rising salt damp, that’s a function of masonry in contact with and drawing moisture from the soil or rock. Figuring out how to prevent this occuring if there’s no damp course installed is not easy to remedy. Retrofiting damp course would be difficult. It appears that there are companies are using a water based siloxane creme and are injecting it into treatment holes in the masonry. I cannot comment on how effective this is, but siloxanes do offer excellent water repellency in masonry.
I would also point out that this is not the likely issue in the case in this article. It’s either from the high moisture content of the slab that was retrofitted to the home, or most likely, moisture ingress from the bathroom behind this wall. Probably from a leak in the pipe, and it’s found a way to get into this wall.