|
The ingredients for
rot to start in timbers are timber,
fungal spores and water.
Excluding any one of these from the
'mix' prevents rot from occurring. In
properties there are many timbers and spores everywhere; this leaves the one
controllable ingredient as water. Unfortunately
we place many timbers in areas of buildings where they are susceptible to
moisture ingress. This is
particularly so in ground floors, roofs and in areas where we use water, such as
bathrooms and kitchens. Any timbers that come in
prolonged contact with water will eventually rot.
Wet
Rot
Where spores can germinate the usual
result is decay to timber by wet rot. This
is a localised fungal infection only to those areas of the timber that are damp. Wet rots are not aggressive fungi and will die when moisture is removed
from their environment. Treatments
for wet rot usually rely on physical exclusion of moisture and the removal and
replacement of
decayed timbers. Chemical
treatments are not usually required, but are employed to provide protection to
new timber materials or where fungal growth has been particularly heavy. They
would also be used as a stop-gap measure if a rotted, but still serviceable,
timber had to remain in place.
Dry
Rot
A different more aggressive fungal
attack is that of dry rot. This
always starts in wet timbers, but can continue to grow with a restricted
moisture supply, spreading extensively through masonry to attack any timbers it
meets. Severe structural damage to
timbers in buildings can result and specialist treatments are always required.
Assessment
Like assessing insect attack to
timbers, our work to deal with timber rot always starts with a visit to site to
inspect the problem. Testing usually involves the probing of potentially
affected timbers with a sharp screw driver and visual identification of any
fungal growths. Any "give" in the timbers indicates softening usually
caused by fungal decay. In well decayed timbers a screw driver can be driven
into the rotten timber core, or sections of timber easily split away from the
timber's surface. Treatment
depends on the rot type, its location and the structural requirements of the
remedial repairs. The initial
treatment must always allow for the exclusion of water from the timber, or the
isolation of the timber from further moisture source with a physical
barrier. Chemical treatments are
employed to help new timbers or remaining timbers withstand levels of residual
moisture, which otherwise might continue to allow further decay.
Treatment
Use of fungicidal treatments is
governed by Acts of Parliament (law) and Health and Safety Regulations. This requires specialist knowledge. Timber replacement must follow existing Building Regulations and
guidelines to make sure that the timbers can perform structurally to
specification.
Where treatment is
recommended/required, then this is usually a combination of liquid and paste or
gel compounds of boron (a naturally occurring mineral). We also sometimes use a fungicidal micro-emulsifiable solution (FMEC), otherwise
known as polyphase or iodo-propynyl butyl carbamate, where circumstances allow
or dictate. However, most of the treatments we carry out are with boron, which
is a natural fungicide in the right concentration.
Treatments for wet and especially dry
rot attack are not straight forward as they may involve extensive rebuilding of
structural building components. After treatments Health and Safety regulations
require
the minimum of 8 hours to elapse and surfaces to be dry before re-entry to a
treated area and its reinstatement to habitable use. There are a some fungicides
now available where a 1 hour re-entry has been granted, but this is still
dependant on the timber being dry as well. Drying out is unlikely to be that
fast unless it is forced. We prefer to consider the 8 hour "rule" as
being the one to apply.
Recent
reformulation of timber treatment fluids now means that they are virtually odour
free. Some slight smell may be noticed immediately after treatment, but this
quickly declines with drying and improved ventilation.
|
