Damp proofing - rising damp
There are four forms of damp which affect property:
1. Water leaks from plumbing.
2. Penetrating damp.
3. Rising damp.
4. Condensation damp.
All these forms of damp can cause significant damage to your property and should be rectified immediately.
Plumbing leaks can cause serious damage. A weeping joint on this copper pipe within this timber stud wall was initially suspected as damp tracking from the outside walls by the client.
The client thought this "Penetrating damp” was "rising damp" but a look on the outside revealed that the property was in need of some replacement bricks and re-pointing.
In our experience we find that many of the properties we inspect with damp problems have had damp proof courses injected yet the damp problem remains, to the annoyance of the homeowner and the frustration of the contractor. We offer a guaranteed solution to your damp problems at a sensible price.
Many people think this is rising damp however this is condensation damp and the black spot mould is Aspergillus niger.
Damp proof courses are often buried below plaster, which renders them ineffective, as the damp simply rises in the plaster and tracks back into the wall above the damp proof course. Removal of the plaster to above the damp proof course usually solves the problem –however, it is important to consider the effects of moisture evaporating from the exposed brickwork below the damp proof course as this will condense on the back of the skirting boards putting them at risk of fungal attack i.e. Wet or Dry Rot.
All too often when a solid floor becomes cracked or uneven due to settlement or old age it is overlaid with a concrete screed or more commonly asphalt as a damp proof membrane. The floor becomes dry but the problems arise when the existing timber skirting boards, door casings and staircases are left in situ. These timbers are then trapped in the damp substrate and are susceptible to fungal decay (wet or dry rot).
The moisture can rise through the timbers into the plaster and is often mistaken for rising damp. We have come across situations where the skirting boards have decayed and as a result a new damp proof course had been installed along with new skirting boards. The wall to floor joint was not repaired and the new skirting boards were decaying again!
A contractor misdiagnosed damp in this property as rising damp and injected a new damp proof course. This did not cure the problem as the damp was rising through debris, left in the cavity by the workman who had fitted the French doors. The cavities were cleaned out and the problem solved. The injected damp proof course had not been required and has left the customer out of pocket!
So as you can see there are several potential solutions to your damp problems.
Often a new damp proof is not required - we use our knowledge and experience to solve your problems.
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Wet rot is a result of timbers being subjected to moisture over a period of time. The moisture content for wet rot is usually above 28-30%.
Causes of wet rot can be numerous but it is always as a result of exposure to high moisture. It is always important to correctly diagnose the source of the moisture to eradicate the problem.
Typical Wet Rot damage
Floor joists decaying due to being in constant contact with damp brick walls.
This floor joist is covered in fungus. This is the fruiting body of the wet rot Coniophora puteana (more commonly known as cellar fungus)
This floor joist had been replaced and is already decayed - the screw driver was inserted by hand!
There are several types of timber decay - Brown Rot, White Rot, Wet Rot and Dry Rot.
All destroy timber but the most important thing is knowing whether the rot is Wet Rot or Dry Rot.
Whatever the diagnosis simply replacing the affected timber is pointless unless rectifying the cause as the new timber will rot as can be seen above.
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Dry Rot (Serpula lacrymans)
True Dry Rot is also known as Serpula lacrymans and is the most destructive of the fungal growths. By the time it is discovered it has usually caused severe damage to hidden timbers. For its complete eradication and control specialist knowledge and products are required. Failure to understand the seriousness of this problem could cost even the most competent DIY person substantial funds when calling in the "professionals" to "finish the job"
We therefore recommend you contact us immediately you suspect Dry Rot may be present.
Dry Rot spores are omnipresent i.e. they are everywhere all of the time and like any plant seed will only grow when conditions are right for them.
Dry rot needs food and water - the food is in the timber and the water can be from anywhere - even condensation as shown here.
Dry Rot Spore Dust indicates a bigger problem - out of sight...
This red ochre dust is produced by the true dry rot sporophore which is under the floor. Many people simply vacuum this dust unaware as to what lies below!
Dry Rot Sporophore (fruiting body)
Sporophores like this one produce the dust as shown above. The spores are like pollen in that they are produced so as to germinate and establish in other areas of the building therefore spreading the dry rot.
Dry Rot Mycelium growing between the vinyl floor tiles and the floor boards.
When the vinyl tiles are removed the dry rot mycelium is found to have spread on the top surface of the floor boards.
Typical cuboidal cracking as the Dry Rot eats through the timber.
By the time the dry rot has passed through the timber it takes on this cuboidal appearance. At this point the timber has lost its structural integrity and is no longer able to carry weight.
Dry Rot Hyphae growing on the back of a skirting board.
The front of this skirting board still looks normal however the back is covered in dry rot hyphae. As it grows in to the timber one of the by-products of the decay process is water! This is one of the reasons it is able to spread over considerable distances.
Dry Rot Mycelium growing on floor joists.
Mycelium grows like a skin and comes in various colours - grey/fawn/yellow/white are the most common. If you look closely you will find droplets of water within it.
Dry Rot Mycelium will grow across and through masonry in search of timber
Dry Rot can grow from one building to another if left untreated, even through a row of terraced houses.
Dry Rot Mycelium growing on masonry, electrical cables and the electricity meter back board.
Mycelium will grow across anything searching for food (timber).
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Woodworm is a general term used when timbers are infested with wood boring insects.
There are many different species but they all destroy timber to various degrees.
You may well have seen the tell tale signs that wood boring insects are present - small holes on the surface of the timber or some fine saw dust in the vicinity which is known as frass.
The holes seen on the timber surface are exit holes. These holes are made by the adult beetle. When the adults emerge from the timber their sole purpose is to mate. After mating the eggs are laid on the timber and the adult beetles die. The eggs hatch into tiny grubs which tunnel into the timber. Once inside they continue to tunnel as they feed on the nutrients within. This carries on for several years depending on the species until the grub evolves into an adult beetle and emerges from the timber to start the cycle all over again.
When timbers are subsequently treated the insecticide only coats the surface with minimal penetration.
The insecticide has no effect until the beetle emerges and ingests the poison as it eats its way out. Emergence holes will continue to be noticed for the same number of years after treatment, as the life cycle of the relevant species. In the case of the common furniture beetle this is approximately 3 years. For death watch beetle it is 6 years or longer.
Once treated new eggs laid on the timber may hatch but the grub will also die as it ingests the insecticide as it tries to enter the timber.
Common Furniture Beetle (Anobium punctatum)
Approximately 85% of all woodworm infestation is by the common furniture beetle - hence the name!
Wood boring Weevil (Euophryum confine and Pentarthrum huttoni)
The damage caused by this species of woodworm is usually severe and is only found in timbers with very high moisture content. These timbers are already decaying so it is important to seek professional help to prevent further damage to your property.
Bark Borer (Ernobius mollis) on the left looks similar to common furniture beetle on the right. Note how the holes are only in the bark!
There are several species of wood boring insects more commonly known as "woodworm". They can be difficult to identify which is why it is important to have a professional opinion.
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Wall ties were introduced into buildings in conjunction with cavity walls. The earliest wall ties were bricks placed across the two leaves of masonry (known as brick ties) or sometimes pieces of slate.
Later various types of steel ties were introduced including some “home made” varieties.
The original ties did not have a protective coating to protect them from corrosion.
Quite often these earlier ties were made from heavy gauge steel.
A common type is known as the “fish tail” so called because of the shape at the ends which are bedded in the wall. These larger ties are very destructive when they corrode because de-lamination and expansion occurs and the stresses induced to the surrounding masonry cause cracking and wall de-stabilisation.
Over time the wall ties evolved into a much lighter weight wire tie. The most common was the butterfly type (so called because of its shape). These ties were galvanised to protect the steel wire from corroding.
At the time a lot of buildings were constructed using what is known as black ash mortar.
When these walls are subject to water penetration the moisture is absorbed into the black ash mortar and a mild sulphuric acid forms which destroys the galvanised coating.
In the early stages this is observed as a white powder on the galvanised surface of the wall tie. This is called oxidation and is known as primary corrosion.
After some time as corrosion continues into the steel and the colour turns to orange/brown which we know as rust. This is secondary corrosion and will result in total failure of the wall tie.
If you find a wall tie in this condition it is reasonable to assume that all ties on the same elevation with the same exposure to the weather will be in the same condition.
Walls suffering from wall tie failure have been known to collapse with serious consequences.
The modern wall ties are made from stainless steel.
In properties which need a new wall tie system installing various types and methods are available.
Corroded Wall Ties long past their useful lives!
As they corrode they de-laminate (expand) up to 5 times their original size!
Wall ties are important to the structural stability of your home and should be replaced before degrading to this condition.
As can be seen from the photographs above the stresses produced during de-lamination can crack the surrounding brickwork. Now multiply that by the number of wall ties in your property and the structural damage can be very significant - and expensive.
Wall Tie failure in this property was so severe that this section of wall had to be taken down and re-built!
In some cases it is necessary to install "lateral restraints" through the masonry and into the timber floor joists as part of the overall structural repair works.
"Crack Stitching" using stainless steel rods and special resins and cementitious grouts can also be required.
The condition of the wall ties in a property is generally unknown until the tell tale cracks appear or the walls start to bulge. By this time expensive repair works like those shown above may be necessary.
A wall tie condition survey could indicate the early signs of failure, and the essential works would be much less - possibly just the installation of a new stainless steel wall tie system.
Please remember that a survey may also confirm that no work is necessary.
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