Damp Information
Timber Problems
Other than in rare cases, timber problems are found in older properties and it is not very common to find an attack of woodworm in the timber floor of houses built after 1950. Although it can be found when a new hardwood planked floor is brought in already infested when the timber is purchased from the merchant. Or if there has been a leak. But usually it is houses built in the 19th century that seem to have had the greatest infestations, probably from common furniture beetle (Anobium punctatum) This particular insect has been a serious problem in the last 100 years due to it’s main attraction to sap-wood, the reason being that most of the floorboards and often the sub-timbers are cut from the outer edge of the tree, that stores large amounts of starch, a food that the larvae of the insect thrives on especially Pine. But they also like old plywood, particularly that used as a backing for furniture and this is because the glue used to bind the various layers is made from blood albumen of animals and is very nutritious. Most old meter boards have had to be replaced due to this problem. There are lots of other wood boring insects in the UK as well, but the problem has subsided since the change in building materials and tongued and grooved flooring for purposes of fire check. It’s still pine but the insect cant get under it, and of course houses built after the fifties were constructed with solid ground floors.
Wet rot (Coniofera Puteana)
Also known as the cellar fungus. Wet rot can infect hard or softwood depending on the circumstances. In older buildings it tends to be found at the front and back of ground floor rooms due to the timbers in these areas being in direct contact with wet bricks or brick sleeper walls that are prone to rising damp. Main timbers called bearer plates were often embedded within the brickwork just above the ground with the joists being placed in the opposite direction so as to form the framework to nail the floorboards onto. In time moisture in the lower footings becomes absorbed, usually in the underside of the bearer plate, which becomes attacked by the wet rot fungus so the timber shrinks over the years causing the floor to become springy and often resulting in a gap appearing between the skirting board and the floor. But this type of fungus is not malignant, and if new timbers are replaced upon damp proof course material and are insulated from the sleeper walls, wet rot will not return. There is another type of wet rot that is quite deceiving to look at, and is caused by ingress of humidity. This can be general and affect the whole ground floor area, and is usually caused by a combination of a particularly damp oversite (Ground), and insufficient ventilation. Early signs are distortion and a hollowness forming to the underside of the joists, the rot taking place inside the wood and it’s only when the timber is opened up that the true extent of the damage is revealed. Another lesser-known wet rot is called string rot. (Asterostroma spp). Often found where bottoms of door frames and skirting boards are prone to receive moisture forced up through the edges of new solid floors. The wood rots along the grain and when disturbed comes apart like a mash of damp straws, as opposed to the cuboidal cracking in ordinary wet rot. Again, non malignant and is cured by replacement of new wood upon some form of insulation from the damp. Or ideally get rid of the damp. Something easier said than done.
Dry rot (Serpula lackrymans)
Now we come on to the fungal problem that is malignant. A mushroom that thrives in damp houses. Used to live in the forest till man came along and began constructing things with timber, and has now been found in mines boats and of course buildings. Being a mushroom it likes the dark, feeds on decaying matter and has developed certain aids that help it to survive once initial germination has become consolidated, and although there is quite a lot of it about, it is quite difficult to cultivate deliberately in the lab, with conditions needing to be optimum. The part that looks more like your typical mushroom is called a sporophore or fruiting body, and I have it on good authority that this is edible, however I have never been tempted to have a fry up on site and am prepared to accept the word of one of the lecturers at the Buckingham College of Further Education. This is produced when the plant reaches maturity and will then release up to a million spores per minute into the atmosphere. But because they are so small they remain invisible to the human eye and the only time they are seen is where an outbreak has occurred in a place where there is lack of ventilation and no air movement, in which case spores build up into piles of rust coloured dust layers, sometimes very pungent and because the local air becomes thick with them, can be smelled and literally tasted on the tongue. I also suspect that the spores can be harmful to people with certain respiratory conditions such as Emphysema or Asthma.
The biggest danger with this fungi is the deceitful way in which it thrives, so that significant damage has occurred often as much as five years before its discovery, and being a plant that does not need sunlight, it remains concealed within the structure of a timber floor or behind a skirting board or panel. It is only when that panel gradually becomes like melted paint or someone falls through the floor, you realise something is not right. Dry rot begins by the alighting of a minute airborne spore, upon a piece of timber that has a moisture content of between 16-20%. All being well and bad, a tiny tail develops and anchors itself into the pore of the bare wood, and just like any other young seedling, begins to extract the goodness from within. In this case it is both solignin, which binds the cells of the wood together, and the cellulose, which forms the building blocks. With wet rot it is only the cellulose that becomes consumed where as with dry rot it is both. Also the dry rot damage produces larger cuboidal cracking. What makes it malignant is its ability to spread by sending out tendrils not just to search for other moisture sources but to actually transport moisture to other dry timber so as to provide its own survival ecology, even penetrating through bricks and mortar to do so, and although when remedial treatment begins and the main source of water is cut off from the plant, extended vegetation can still continue to survive if enough background moisture is present, such as soft damp brickwork or plaster. But of course the original source must be rectified, such as a blocked gutter or other defect mentioned earlier. Germination conditions can also occur after a flood or other escape of water whereby damp timbers affected, pass through that optimum moisture content mentioned, during the slow drying out process. This has been known to occur many years later in cases of severe flooding.
Treatment is not a DIY job and should only be tackled by an experienced preservation company of long establishment. I have personally attended at first hand re-infection of dry rot in cases of original serious outbreak quite a few times, due to treatment being inadequate by the specialist company, but unfortunately long after they had disappeared into the murk.
