Designing Buildings - User contributions [en]

Hygroscopic Salts

2019-06-25T13:19:24Z

AtlantisDamp: Created page with "= What are hygroscopic salts? = ----- In order to understand the nature of hygroscopic salts, we must first look at the term ‘hygroscopic’ which means to absorb water from t..."

= What are hygroscopic salts? =

-----
In order to understand the nature of hygroscopic salts, we must first look at the term ‘hygroscopic’ which means to absorb water from the air. Therefore, a substance which is hygroscopic is one which is able to consistently attract water from its surroundings via adsorption or absorption. There are many examples in nature of hygroscopic materials but one of the most commonly known is honey as it is primarily a sugar. Sugar is hygroscopic and in its natural state contains very little water but if the surrounding environment contains moisture it will absorb it.

Salt, like sugar, is also hygroscopic in nature and many salts such as Calcium Chloride and Sodium Hydroxide are so hygroscopic that they will dissolve in the water they absorb. Hygroscopic materials also have a tendency to over time become damp and soft when exposed to air that contains a lot of moisture. As such, the level of moisture held by these hydroscopic salts is usually proportional to the level of humidity.

== Hygroscopic Materials In Walls ==

-----
These hydroscopic materials can however lead to a number of problems, particularly in composite materials such as walls. Dampness in walls can arise from a number of problems, most notably it is as a result of inadequate ground and surface drainage, but it can also be as a result of cracks in your foundations, saturated ground- the list goes on. But, when the soluble salts within the walls become concentrated where the water has evaporated from the wall you will begin to see a ‘tide mark’. This line across the wall isn’t simply an indication that moisture is working its way up through the capillaries of the wall’s building materials. It is in fact a signifier that dampness in the wall has already evaporated to the surface.

In these instances, hygroscopic salts can have a detrimental impact on the very foundations of your home and will continue to wreak havoc, creating tide marks and dampening your wall plaster. Wall plaster in any home with hygroscopic salts which are saturated is at risk of being internally and externally dampened. The first step in addressing this issue is to locate the source of the moisture and rectify the problem. Once this has occurred you can begin to assess the damage and in most cases, it is advisable to re-plaster the affected walls.

Even if the source of the moisture is dealt with, the hygroscopic salts are likely to have retained water and will continue to give the ‘tide’ damp wall appearance. Often the appearance of the dampness will come and go depending on how dry or humid the air is that day. It is for this reason that the recommendation will always be to freshly plaster as a ‘salt retardant’ additive can be incorporated. This helps to ensure any remaining moisture is unable to evaporate and settle on the plaster surface.

To ensure that any saturated hygroscopic salts found in your wall are sufficiently sealed and your walls are damp proofed it is always advisable to use a certified damp-proof specialist who can provide the correct advice and solution for your property.--[[User:AtlantisDamp|AtlantisDamp]] 14:19, 25 Jun 2019 (BST)

[[Category:Conservation]] [[Category:Education]] [[Category:Water]]

Damp in buildings

2019-06-18T10:48:26Z

AtlantisDamp: Undo revision 136381 by Editor (talk)

[[File:Mould_growth_in_building.jpg|link=File:Mould_growth_in_building.jpg]]

= Introduction =

Excess water/moisture in all its forms (vapour, liquid, and flooding) is still the most common problem in housing. Damp in buildings may be apparent from:

* Damp patches.
* Mould growth.
* Mildew, salts, staining and tide marks.
* Damage to surface finishes, such as blistering paint and bulging plaster.
* Corrosion and decay of the building fabric.
* Slip hazards.
* Frost damage.
* Poor performance of insulation.
* Damage to equipment, or electrical failure.

Successful treatment can only be achieved if the type of damp is correctly diagnosed. The complexity of existing buildings means that damp is very often misdiagnosed, leading to future problems, cost and disruption to the occupants.

The most common causes of persistent damp in buildings are:

* Condensation (surface or interstitial).
* Rising damp.
* Penetrating damp.

= Condensation =

Condensation occurs when moist air cools below its dew point, and water condenses. This can occur as surface condensation, but also within the fabric of a building itself, as interstitial condensation. Modern surveying involves the use of accurate thermo hygrometers and thermal imaging to highlight areas of cold surfaces where gaseous water is diffusing, and condensing within pore spaces.

See Condensation and Interstitial condensation for more information.

= Rising damp =

Rising damp is caused by incorrect placing of, faults to, or the absence of a damp-proof course, and is generally only apparent up to 1 m above ground level because of the limits of capillary action to draw moisture up through porous elements of the building structure. Rising damp can be exacerbated by alterations to ground levels, flooding, leaks, and so on.

See Rising damp for more information.

= Penetrating damp =

Penetrating damp is moisture that penetrates laterally through the fabric of a building, typically as a result of leaks to pipework, damage to the building fabric which allows water to penetrate, high ground levels, blocked drains, leaky gutters, cracked masonry, broken flashings, etc.

See Penetrating damp for more information.

= Identifying damp =

When identifying damp and its causes, architects, surveyors and project managers need to consider the current condition and the expected post-construction condition of the building. There are a number of established methods for diagnosing damp:

=== Observation ===

Manual viewing is the least costly, but potentially least reliable method of diagnosis.

=== Moisture meters ===

Moisture meters can be used to confirm the observed diagnosis. In skilled hands with regular site calibration moisture meters can be a good starting point, however, depending on the complexity of the building, the materials used, its present condition and maintenance history, moisture meters can lead to misdiagnosis.

=== Laboratory techniques ===

Drilled samples and moisture contents can be subjected to techniques such as a carbide meter, oven drying and soluble salt analysis. These can be used to confirm the results of thermal imaging and thermo hygrometry.

=== Temperature and humidity measurement ===

Recording the relative humidity (RH) and temperatures in a series of rooms and outside using half hourly sampling can be an effective way of diagnosing damp.

Thermal imaging is used to accurately record the temperature of building fabric and isolate areas that are either close to, or below dew point. These areas will suffer interstitial condensation and damp. A thorough understanding of the relationship between temperature, relative humidity, and absolute humidity is essential. RH and temperature can vary wildly, yet the moisture content of the air stays the same. Good, dry air should be around 7 grams/cubic metre.

At 12 g/m3 building fabric is susceptible to interstitial condensation. This same total moisture content (TMC) can also start to raise moisture content of timber to the point where beetle attack and fungus can take hold.

= How to avoid damp - Improving air quality within the home =

There are several steps you can take to enhance the quality of the air inside your home. By carrying out these actions, you can improve your quality of life and protect your health. Steps you can take to improve air quality include preventing condensation, keeping an eye on the temperature and ensuring enough air gets inside your home.

 
 
Make sure your home is well-aired

 
One of the reasons so many people complain about poor quality air is that the buildings of today tend to be tightly sealed. This means less fresh air gets inside homes than in the past, resulting in air pollutants lingering. You can get rid of pollutants by keeping your home well-aired. Just remember that pollution from outside can also get inside. One thing you can do to reduce the amount of pollution that gets into your home is to check your local air pollution levels on a regular basis. You should also keep your windows closed when the Daily Air Quality Index is high.

 
 
Opening your windows

 
 
You should make your windows are left open for at least five minutes numerous times a day. If you ever have building work carried out on your home, find out how your home will be aired. If dust will be present, it may be wise to stay elsewhere whilst the work is being carried out. The wet and cold weather that we are so often faced with can cause serious problems with mould and damp. Damp is a cause of condensation, which itself results in fungi including mould.

 
Fighting condensation

 
 
Condensation is more likely to occur in the colder rooms of your home. You can prevent condensation by taking steps to prevent leaks and other forms of water damage, by ensuring your home remains well-aired and by drying your laundry outside whenever possible. It’s also helpful to use extractor fans when cooking or showering as these remove moisture from the air. You should also wipe your windowsills on a daily basis as this will help you reduce condensation and make sure any mould that you do find is removed immediately.

 
When to seek help

 
 
If a problem with damp or mould becomes too difficult for you to deal with, it’s a good idea to get help from a professional. If you rent your home, let your landlord know about the issue so they can put a solution in place. A large amount of the moisture found inside homes is a result of drying clothes. If it is not possible to dry your clothes outside, make sure your utility room has sufficient ventilation.

 
 
Monitoring solutions

 
 
High and low temperatures can both affect your breathing. Make sure the rooms that you use remain at a comfortable temperature and close your windows at night during the colder months of the year. Technology has made it easier for us to monitor air temperature and humidity within our homes, and there are various solutions available that will help with this.

-----
This article was originally based on [http://brebuzz.net/2016/06/20/diagnosing-the-causes-of-dampness-in-buildings/ Diagnosing the causes of dampness in buildings], published by BRE Buzz in June 2016. It has subsequently been edited by others.

--[[User:BRE_Buzz|BRE Buzz]]

--[[User:AtlantisDamp|AtlantisDamp]] 17:16, 30 May 2019 (BST)

= Related articles on Designing Buildings Wiki =

* Building damp-free cavity walls.
* Cold bridge.
* Condensation.
* Damp-proof course.
* Damp proof membrane.
* Damp proofing.
* Dew point.
* Diagnosing the causes of dampness (GR 5 revised).
* Dry rot fungus.
* Efflorescence.
* Humidity.
* Interstitial condensation.
* Moisture.
* Penetrating damp.
* Rising damp.
* Rising damp in walls - diagnosis and treatment (DG 245).
* Spalling.
* Stain.
* Structural waterproofing consultant.
* Tanking.
* Understanding dampness.
* Wall insulation and moisture risk.
* Water vapour.

[[Category:Construction_techniques]]

Damp in buildings

2019-05-30T16:16:17Z

AtlantisDamp:

Damp in buildings

2019-05-30T16:14:55Z

AtlantisDamp:

[[File:Mould_growth_in_building.jpg|link=File:Mould_growth_in_building.jpg]]

= Introduction =

Excess water/moisture in all its forms (vapour, liquid, and flooding) is still the most common problem in housing. Damp in buildings may be apparent from:

* Damp patches.
* Mould growth.
* Mildew, salts, staining and tide marks.
* Damage to surface finishes, such as blistering paint and bulging plaster.
* Corrosion and decay of the building fabric.
* Slip hazards.
* Frost damage.
* Poor performance of insulation.
* Damage to equipment, or electrical failure.

Successful treatment can only be achieved if the type of damp is correctly diagnosed. The complexity of existing buildings means that damp is very often misdiagnosed, leading to future problems, cost and disruption to the occupants.

The most common causes of persistent damp in buildings are:

* Condensation (surface or interstitial).
* Rising damp.
* Penetrating damp.

= Condensation =

Condensation occurs when moist air cools below its dew point, and water condenses. This can occur as surface condensation, but also within the fabric of a building itself, as interstitial condensation. Modern surveying involves the use of accurate thermo hygrometers and thermal imaging to highlight areas of cold surfaces where gaseous water is diffusing, and condensing within pore spaces.

See Condensation and Interstitial condensation for more information.

= Rising damp =

Rising damp is caused by incorrect placing of, faults to, or the absence of a damp-proof course, and is generally only apparent up to 1 m above ground level because of the limits of capillary action to draw moisture up through porous elements of the building structure. Rising damp can be exacerbated by alterations to ground levels, flooding, leaks, and so on.

See Rising damp for more information.

= Penetrating damp =

Penetrating damp is moisture that penetrates laterally through the fabric of a building, typically as a result of leaks to pipework, damage to the building fabric which allows water to penetrate, high ground levels, blocked drains, leaky gutters, cracked masonry, broken flashings, etc.

See Penetrating damp for more information.

= Identifying damp =

When identifying damp and its causes, architects, surveyors and project managers need to consider the current condition and the expected post-construction condition of the building. There are a number of established methods for diagnosing damp:

=== Observation ===

Manual viewing is the least costly, but potentially least reliable method of diagnosis.

=== Moisture meters ===

Moisture meters can be used to confirm the observed diagnosis. In skilled hands with regular site calibration moisture meters can be a good starting point, however, depending on the complexity of the building, the materials used, its present condition and maintenance history, moisture meters can lead to misdiagnosis.

=== Laboratory techniques ===

Drilled samples and moisture contents can be subjected to techniques such as a carbide meter, oven drying and soluble salt analysis. These can be used to confirm the results of thermal imaging and thermo hygrometry.

=== Temperature and humidity measurement ===

Recording the relative humidity (RH) and temperatures in a series of rooms and outside using half hourly sampling can be an effective way of diagnosing damp.

Thermal imaging is used to accurately record the temperature of building fabric and isolate areas that are either close to, or below dew point. These areas will suffer interstitial condensation and damp. A thorough understanding of the relationship between temperature, relative humidity, and absolute humidity is essential. RH and temperature can vary wildly, yet the moisture content of the air stays the same. Good, dry air should be around 7 grams/cubic metre.

At 12 g/m3 building fabric is susceptible to interstitial condensation. This same total moisture content (TMC) can also start to raise moisture content of timber to the point where beetle attack and fungus can take hold.

= How to avoid damp - Improving air quality within the home =

There are several steps you can take to enhance the quality of the air inside your home. By carrying out these actions, you can improve your quality of life and protect your health. Steps you can take to improve air quality include preventing condensation, keeping an eye on the temperature and ensuring enough air gets inside your home.

=== 
 
Make sure your home is well-aired ===

 
One of the reasons so many people complain about poor quality air is that the buildings of today tend to be tightly sealed. This means less fresh air gets inside homes than in the past, resulting in air pollutants lingering. You can get rid of pollutants by keeping your home well-aired. Just remember that pollution from outside can also get inside. One thing you can do to reduce the amount of pollution that gets into your home is to check your local air pollution levels on a regular basis. You should also keep your windows closed when the Daily Air Quality Index is high.

=== 
 
Opening your windows ===

 
 
You should make your windows are left open for at least five minutes numerous times a day. If you ever have building work carried out on your home, find out how your home will be aired. If dust will be present, it may be wise to stay elsewhere whilst the work is being carried out. The wet and cold weather that we are so often faced with can cause serious problems with mould and damp. Damp is a cause of condensation, which itself results in fungi including mould.

=== 
 
Fighting condensation ===

 
 
Condensation is more likely to occur in the colder rooms of your home. You can prevent condensation by taking steps to prevent leaks and other forms of water damage, by ensuring your home remains well-aired and by drying your laundry outside whenever possible. It’s also helpful to use extractor fans when cooking or showering as these remove moisture from the air. You should also wipe your windowsills on a daily basis as this will help you reduce condensation and make sure any mould that you do find is removed immediately.

=== 
 
When to seek help ===

 
 
If a problem with damp or mould becomes too difficult for you to deal with, it’s a good idea to get help from a professional. If you rent your home, let your landlord know about the issue so they can put a solution in place. A large amount of the moisture found inside homes is a result of drying clothes. If it is not possible to dry your clothes outside, make sure your utility room has sufficient ventilation.

=== 
 
Monitoring solutions ===

 
 
High and low temperatures can both affect your breathing. Make sure the rooms that you use remain at a comfortable temperature and close your windows at night during the colder months of the year. Technology has made it easier for us to monitor air temperature and humidity within our homes, and there are various solutions available that will help with this. 

-----
This article was originally based on [http://brebuzz.net/2016/06/20/diagnosing-the-causes-of-dampness-in-buildings/ Diagnosing the causes of dampness in buildings], published by BRE Buzz in June 2016. It has subsequently been edited by others.

--[[User:BRE_Buzz|BRE Buzz]]

= Related articles on Designing Buildings Wiki =

* Building damp-free cavity walls.
* Cold bridge.
* Condensation.
* Damp-proof course.
* Damp proof membrane.
* Damp proofing.
* Dew point.
* Diagnosing the causes of dampness (GR 5 revised).
* Dry rot fungus.
* Efflorescence.
* Humidity.
* Interstitial condensation.
* Moisture.
* Penetrating damp.
* Rising damp.
* Rising damp in walls - diagnosis and treatment (DG 245).
* Spalling.
* Stain.
* Structural waterproofing consultant.
* Tanking.
* Understanding dampness.
* Wall insulation and moisture risk.
* Water vapour.

--[[User:AtlantisDamp|AtlantisDamp]] 17:14, 30 May 2019 (BST)

[[Category:Construction_techniques]]

Recognising wood rot and insect damage in buildings

2019-03-20T13:39:09Z

AtlantisDamp:

--[[User:AtlantisDamp|AtlantisDamp]] 13:39, 20 Mar 2019 (BST)BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries.

[https://www.brebookshop.com/details.jsp?id=140308 Recognising wood rot and insect damage in buildings] (BR 453) 3rd edition was published by BRE on 13 January 2003. The 132 book guide was written by A F Bravery, R W Berry, J K Carey and D E Cooper.

[[File:Recognising_wood_rot_and_insect_damage_in_buildings.jpg|link=https://www.brebookshop.com/details.jsp?id=140308]]

It enables the recognition of wood destroying fungi and insects found in buildings through information in note form supported by flow charts and images. It also allows identification of harmless species that might be encountered which do not necessarily require treatment. Further, general information is given on remedial treatments.

The third edition includes guidance on types of fungal growths which, though less regularly encountered, nonetheless mislead diagnosis. It also has a short section on termites.

Since the first edition was published, there has been an increased emphasis on conservation, repair and refurbishment, and an increasing desire to avoid excessive use of remedial preservatives by adopting environmental control strategies that bring decay and insect attack under control. These strategies depend on correct diagnosis.

The book gives clear and authoritative guidance on the process of inspecting buildings for timber damage and on the identification of causal agencies.

Its contents include:

* Introduction.
* Building inspection for fungal and insect attack.
* Identification of wood rotting fungi.
* Types of fungi found in buildings.
* Key for identifying fungal growths in buildings.
* Wood rotting fungi.
* Non- wood rotting fungi.
* Algal growths.
* Chemical attack of wood.
* Identification of wood boring insects.
* Key identifying wood borers.
* Damage category A insects.
* Damage category B insects.
* Damage category C insects.
* Remedial treatment of damage by wood boring insects.
* Non wood-boring insects commonly found in buildings.
* Termites.
* Appendices.

= Different features of wood rots =

All fungal decay occurs when timber becomes wet for some time. Dry rot requires considerably more moisture for an outbreak to begin than wet rot does. Dry rot will usually occur where there has been water ingress or a leak. Unlike wet rot, dry rot can spread onto adjacent timbers via masonry.

In contrast, wet rot is more frequently seen and typically easier to treat. Wet rot is generally confined to the area where timber has become, and remains, wet.

In all cases of wood rot, it is imperative that the source of moisture is identified and prevented. The source in your home could be anything from condensation in the sub floor void, a leaking downspout persistently wetting a solid wall or a leaking radiator pipe.

= What is dry rot? =

Dry rot is a serious timber condition caused by fungal growth. It’s definitely not something you want to ignore! Having sad that, when caught early the extent of the treatment may not be as extensive as you will fear.

Its Latin name is Serpula Lacrymans, which is taken from the Latin for ‘tears’ due to the fact that water droplets – likened to tears - are often produced on the surface of the dry rot.

It is possible to confuse dry rot with some types of wet rots – specifically brown rots – due to the cuboidal cracking that can be seen. The difference with dry rot is that the cuboidal cracking is much larger. There are also other identifying features of Dry Rot, including:

· It develops on the surface of timbers and produces a mass of cotton wool like growths, (mycelium).

· Mycellium spreads by delicate hyphal threads to supply the dry rot outbreak with moisture and nutrients it gets from the timbers.

· Can be bright yellow and/or lilac in colour.

· Can penetrate mortar beds and plasterwork.

· When dry, the mycelium strands will snap.

Left untreated, it will cause the decay and degradation of any timber or cellulose based product, such as cardboard and paper, it comes into contact. As mentioned, dry rot can also travel over and behind masonry and plasterwork. This can often result in structural integrity problems if your property is affected by it.

A [https://www.petercox.com/our-services/dry-rot/treatment/ dry rot treatment] programme carried out by an experienced and qualified expert can eliminate the problem and the earlier you can [https://www.petercox.com/our-services/dry-rot/what-is-dry-rot/identify/ identify dry rot] the more simple and cost effective treatment becomes.

As dry rot is the most serious of the wood rots, it requires extensive specialist treatment. Treatment should only be carried out by our fully trained technicians, or reoccurrence is highly likely. It is absolutely imperative that the spread of the dry rot is identified to its full extent. Only then can remedial treatment be confidently undertaken. If there is failure to remove the dry rot in its entirety, a reoccurrence will likely occur.

It is crucial that the correct problem is diagnosed, as the treatments can vary dramatically. In some cases, such as dry rot, if the problem is treated incorrectly, it can reoccur, even upon the removal of all decayed timber.

= How does dry rot get into my home? =

Dry rot spores exist in the atmosphere and can literally float in through your window and travel around your home. However, they will only eve become a problem when they find themselves in the right conditions to germinate. For dry rot, these conditions involve damp timber with a Moisture Content of around 20% and that is freely accessible to air.

Furthermore, in new build houses, infected timber can be found in hardcore when used as a base for concrete floors. It can travel up to skirtings and architraves before the natural moisture present during construction had dried out.

= What to do if I think I may have wood rot issue in my home? =

It is crucial that the correct problem is diagnosed, as the treatments can vary dramatically. In some cases, such as dry rot, if the problem is treated incorrectly, it can reoccur, even upon the removal of all decayed timber.

= Related articles on Designing Buildings Wiki =

* Damp and timber report.
* Dry rot fungus.
* Insecticides Market.
* Mould growth in buildings.
* Timber preservation.
* Timber.
* Woodworm and spiders.
* Woodworm.

--[[User:AtlantisDamp|AtlantisDamp]] 13:39, 20 Mar 2019 (BST)

[[Category:Conservation]] [[Category:Publications_/_reports]]

Woodworm in buildings

2019-03-20T12:43:20Z

AtlantisDamp:

[[File:Woodworm.jpg|link=File:Woodworm.jpg]]

Woodworm infestation of untreated timber is a relatively common problem. The House Longhorn beetle was a particular problem in the UK prior to the introduction of pretreated timber in the 1960s.

The House Longhorn beetle measures up to 25 mm long when mature, and can lay up to 200 eggs on the rough surface of untreated timber. After 2-3 weeks, the larvae emerge and bore into the timber. They can be detected by the powdery deposits known as ‘frass’ left on the surface and the bore holes of around 3 mm diameter. They are attreacted to damp areas and timber with a high moisture content.

If you’ve only just noticed these holes, it’s unlikely that the structural integrity of the beam has been compromised. If you’ve only just revealed the beam, for example it was under plasterboard or a thick coat of varnish, it’s important to get the timber inspected by an expert as soon as possible, who will be able to identify the type and extent of any infestation you may have, and also let you know whether there are any structural issues to consider.

Other woodborer insects include:

* Furniture beetle: These are 6-8 mm long and lay 20-50 eggs on soft or hardwoods.
* Lyctus powder post beetle: These are 10-15 mm long and lap 70-200 eggs on the sapwood of new hardwood.
* Death Watch beetle: Around 7 mm long and lay 40-80 eggs on hardwood. Are a particular problem on oak timbers found in old churches and similar buildings.

= Is the infestation active or inactive? =

It is important to identify whether and infestation is active or inactive. Very often, tunnels and holes found in decorative beams in your home are of historical nature and the beam was left in place as the previous attack did not affect the structural integrity of the beam.

Nevertheless, it is important to identify whether the holes you have found are due to a currently active woodworm. Sometimes you may be able to see frass. This is a dust-like or gritty substance that that comes out of the holes during emergence season – normally around May to September. Occasionally you may even see the beetle. If you are lucky enough to see a beetle, try to keep it in a container until you bring in a specialist as it will help with the identification, and therefore treatment, of your wood boring insect.

If you’re not sure if the frass is fresh and you have not seen any beetles emerging, there are a couple of things to try. You could fill the holes with shoe polish and await the emergence season. If the infestation is active, you will see the shoe polish is no longer in place. Alternatively, you could wrap some newspaper around the beam, again wait for the emergence season and then check the paper for frass.

= What steps are required to successfully treat a timber infestation? =

The process for treating timber is a specialist task which includes:

* Correct identification of the infestation and its extent through looking at identifying factors such as the tunnels, the emergence holes and the frass.
* Ensure all timbers can be accessed.
* Check extent of damage by probing and drilling if required, for example treatment of Death Watch Beetle (Xestobium rufovillosum).
* Thorough cleaning down of all timbers to ensure the timber, not the frass, is treated.
* Expose built in ends of structural timbers.
* Correct and thorough application of species-specific insecticides.
* Utilising health and safety best practice for your re-entry time.

Timber can be treated:by:

* A water-based boron treatment which can be sprayed or brushed on, or injected as a gel or paste.
* Ultraviolet insect killers.
* Fumigation or fogging.
* Replacing affected wood.
* Monitoring and improving conditions to prevent re-infestation.

A specialist survey may be necessary to determine the most appropriate form of treatment.

For more information, see also: Timber preservation and Woodworm and spiders.

= Will the problem return? =

Depending on the infestation type, you may see some symptoms in the coming years due to the life cycle of the beetle and the fact that the insecticide used is a contact insecticide. This means that for treatment to be effective the life cycle must be completed as only emerging beetles or lava laid on the surface of treated timbers will be destroyed. Despite of this life cycle, which differs depending on breed, rest assured. All our timber treatments come with long term guarantees for your peace of mind.

= Find out more =

=== Related articles on Designing Buildings Wiki ===

* Adhesives.
* Ancient Woodland.
* Building preservation archive.
* Confederation of Timber Industries.
* Cross-laminated timber.
* Defects in construction.
* Domestic roofs.
* Dry rot fungus.
* European Union Timber Regulation.
* Flat roof defects.
* Flooring defects.
* Forests.
* Glulam.
* Laminated veneer lumber LVL.
* Plywood.
* Recognising wood rot and insect damage in buildings.
* Roofing defects.
* Timber.
* Timber framed buildings and fire.
* Timber preservation.
* Woodworm and spiders.

--[[User:AtlantisDamp|AtlantisDamp]] 12:41, 20 Mar 2019 (BST)

[[Category:Conservation]] [[Category:Theory]]

Woodworm in buildings

2019-03-20T12:41:08Z

AtlantisDamp: Undo revision 130775 by [[Special:Contributions/[IP address hidden]|[IP address hidden]]] ([[User talk:[IP address hidden]|talk]])

Wall tie failure

2019-03-01T14:41:56Z

AtlantisDamp:

--[[User:AtlantisDamp|AtlantisDamp]] 14:41, 01 Mar 2019 (BST)Main article: [[Defects_in_Brickwork|Defects in Brickwork]]

= Introduction =

Failure of wall ties has become a significant problem in recent years. The main cause of failures is rusting of metal ties, although there can be other causes, such as failure to properly bed the tie in the mortar joint, poor quality mortar reducing the bond between tie and mortar, or not installing the requisite number of ties.

Wall ties are used to hold the internal and external walls that make up a cavity wall together as a single unit. Over the years wall ties have been made from a variety of materials, the most common being metal that has been coated in zinc or bitumen, with stainless steel becoming more common over recent years.

Wall ties play an essential part in a property’s structural stability. Because wall ties are situated within your wall’s cavity and cannot be seen externally, it’s important to know what signs to look out for that could indicate wall tie failure. Identifying and fixing problems with your wall ties as early as possible can prevent serious damage to your property’s structure and keep the repair costs down.

The obvious danger with rusting wall ties is the possible collapse of the outer leaf of the cavity wall. Owners of properties with cavity walls should look out for signs of wall tie failure to avoid serious structural damage occurring. Other consequences include:

* The rust will have a significantly greater volume than the original metal. This expansion of the tie may cause cracking and distortion of the structure, particularly where strip ties have been used. The rust-induced expansion in strip ties can lead to secondary damage, such as a redistribution of loads, buckling and bulging of wall, and damage to the roof as the external leaf increases in height.
* The less bulky wall ties will not generally produce enough expansion to induce cracking unless the joint is abnormally thin or the mortar is very dense. Unfortunately, wire ties produced in the UK before 1981 had less rust protection than strip ties and therefore are likely to have a shorter life expectancy; a particular problem because failure can occur without the outwardly visible warning signs produced by cracking.
* Cracking will also reduce the weather resistance of the wall, which in turn accelerates the rusting process.

[[File:Rusted-wall-tie.jpg|link=File:Rusted-wall-tie.jpg]]

A wall tie from a house built in the 1920's - When placed, both sides of the wall tie would have been symmetrical in size and shape to each other. The right hand side of the tie was in the outer leaf, and has been heavily corroded since then.

= Corrosion and Rusting =

Corrosion refers to a partial or complete wearing away or a dissolving or softening of a substance by a chemical or electrochemical interaction between the metal and its environment. Rusting is a type of corrosion and it is caused by the interaction of water and iron or steel in the presence of oxygen. Rust is a hydrated iron oxide, which although solid in form, is weak and brittle.

Galvanising is a means of protecting iron or steel by coating it with zinc. The zinc protects the steel electrochemically. Of the two metals zinc is the more chemically inactive and it will slowly corrode in the preference to the steel. The thicker the original coating of zinc, the longer it will last. The zinc protection reduces in thickness but it does not undergo a chemical change. Eventually the zinc coating will disappear.

Properties built between 1935 and 1981 are most at risk of wall tie failure for a couple of reasons. Firstly, most houses built before 1935 had solid walls, and secondly, during the early years of cavity walls the wall ties were not made durable enough and frequently suffered from premature corrosion. It was in 1981 that the British Standard recognised the problem with wall ties and the zinc coating on the wire tie was tripled in thickness.

The process of rusting can accelerate due to:

* Aggressive chemicals: black ash is a product of coal mining which was sometimes added to mortar to give it a black colouring. The high sulphur content of black ash produces a weak sulphuric acid when wet for long periods. This sulphuric acid can attack a galvanised coating.
* Chloride salts, which may come from marine sands or may have been added to mortar as accelerators, can, even in small amounts, speed up corrosion.
* Carbonation: where ties are well bedded in mortar, protection against rust is provided by calcium hydroxide, which is formed as the cement hydrates. Unfortunately, as the mortar slowly carbonates this protective alkaline layer is destroyed. Carbonation will occur more quickly in permeable mortars.
* The building, or particular sections/elevations, experiencing high levels of moisture ingress because of their exposure.

The portion of the tie in the outer leaf will usually be the most severely affected because of exposure to rain penetration. However, condensation may also produce enough moisture to allow rust failure to occur.

= British Standards and Premature Failure =

In the UK during 1945, a British Standard (BS) was introduced which set out, amongst other things, a minimum thickness for the galvanising layer. The standard identified the two basic shapes of tie – vertical twist and butterfly. The standard specified that the galvanising should be twice as thick on the vertical twist as it was on the butterfly ties. Unfortunately this minimum thickness was reduced in 1968, because it was thought that the standard was excessive.

In 1981 the standard was increased and specified the same thickness for both types. The reason for this was the increasing evidence regarding performance in use and the realisation of the scale of the problem. The problem of rusting was thought at one time to be localised as it was believed that it occurred mainly in areas where a catalyst, for example black ash mortar, increased the likelihood of breakdown. It was later appreciated that the problem was more widespread and the causes more complex.

The Building Research Establishment has suggested that all steel or iron wall ties inserted prior to 1981 are at risk of (premature) failure (premature relates to the notional 60 years life of a building.) Because cavity walls tended to be first introduced in areas with high rain penetration, including salts, there can be a potent combination of age and aggressive environments.

= Stainless Steel Ties =

Stainless steel walls ties are available. Stainless steel is a ferrous alloy which contains at least 10% chromium. Since chromium is more reactive than iron, a ‘self healing’ impermeable layer of chromium oxide forms naturally on the surface of the steel. Chromium oxide is durable in a wide range of exposures and prevents the formation of rust. Where there is exposure to chlorides, for example in marine conditions, care must be taken in selecting the appropriate grade.

= Detection and Investigation =

Wall tie failure can often be identified by the horizontal cracking that results from the expansion caused by the rusting process. Unlike sulfate attack the cracks will coincide with the position of the ties (and will obviously only occur in cavity walls). However, because butterfly ties will usually not cause cracking it may be necessary to carry out investigations where the problem is suspected or anticipated.

The main signs of wall tie failure are:

Horizontal cracks in the walls – The commonest symptom of wall tie failure is the appearance of cracks in the wall. These cracks are usually horizontal and appear at the point of the internal wall tie. The cracking is usually caused by wall ties expanding due to rusting.

Bulging walls – Rusty and expanding wall ties can also cause brickwork to bulge outwards.

Collapsing walls – In extreme cases, if the problem is left to worsen, wall tie failure could eventually cause entire walls to collapse.

Ideally, strip ties should be identified before the cracking occurs. This might involve a visual inspection of the suspect ties, either by using an optical probe or by removing bricks. It should be kept in mind however, that a tie can be in good condition in the cavity but poor in the outer leaf and therefore exposure of the end embedded in the outer leaf is a sensible step.

Ties can be assessed visually for rusting. The presence of red rust, the product of the oxidation of iron, indicates severe rusting, while the presence of white deposits or a blackening of the galvanising indicates that the zinc is corroding. Measurements of zinc thickness will enable the projection of the remaining life (The Building Research Establishment give some useful guidance on this.) Metal detectors can determine the exact pattern of tie placements and can help in establishing if a defect is caused by wall tie failure.

[[File:Wall-tie-repairs.jpg|link=File:Wall-tie-repairs.jpg]]

Disguising wall tie replacement is difficult, particularly where houses are rendered. Painting will help, but it is very difficult to often match the texture of the original render. In plain brickwork, extensive repointing is usually necessary.

= What should you do? =

If you suspect that there may be a problem with your property’s wall ties, it’s important to seek advice from an expert as soon as possible to prevent the building becoming structurally unsafe.

= Find out more =

=== Related articles on Designing Buildings Wiki ===

* Brick.
* Building damp-free cavity walls.
* Cavity wall.
* Damp
* Defects in brickwork.
* Defects in stonework.
* Efflorescence.
* Interstitial condensation.
* Pattern staining and soiling in stonework.
* Penetrating damp.
* Preventing wall collapse.
* Repointing.
* Rising damp.
* Spalling.
* Wall ties.
* Weep hole.

[[Category:Regulations]] [[Category:Construction_techniques]] [[Category:Design]]

Damp and timber report

2019-01-30T16:44:35Z

AtlantisDamp: Created page with "Why You Need a Damp and Timber Report Damp, wood-rot and insect infestation can all present serious trouble for the structural integrity of a building if left untreated. Unfortu..."

Why You Need a Damp and Timber Report

Damp, wood-rot and insect infestation can all present serious trouble for the structural integrity of a building if left untreated. Unfortunately, the presence and severity of these issues may not always be immediately apparent to the untrained eye. Alarming as this may sound, problems with damp and timber can often be resolved fairly easily by a qualified professional when identified early—but you can’t fix a problem if you don’t know it’s there. For this reason, it may be worth considering getting a damp and timber report.

What is a Damp and Timber report?

A damp and timber report is a survey of a property carried out to determine whether or not damp is present, and if so what type of “damp” it is. The survey also checks timber for the presence of wood-rot or pest infestations that could jeopardise the structural integrity of the building.

Do I Need a Damp and Timber Report?

There is a reason that specialist damp and timber reports are recommended, even when a Home Buyers Report has already been completed. This is because damp and timber reports are completed by experts with a great deal more experience within this area than a generalist surveyor. The risks associated with damp and timber problems are severe enough to warrant the services of a C.S.R.T qualified professional that can deliver the information and solutions you really need. That said, here are some of the circumstances where it would be wise to consider a damp and timber report.

You’re Putting your House on the Market

The presence of damp or timber issues can seriously impact the value of a property. In order to maximise the sale price of your home and ensure the sale does not fall through when it comes to buyer’s survey stage; ensure all issues are taken care of from the start.

You’re Buying a new Property

Not only is it wise to get any property you’re considering buying comprehensively surveyed, damp and timber reports are often required by lenders as a condition of the mortgage offer.

You are Concerned about the Presence of Damp or Wood-Rot in your Home

As is the case with many things, it is easier to deal with the problem when it’s detected early. There are many causes of damp, ranging from condensation, damaged pipework or an insufficient Damp Proof Course. The key to resolving the issues is to identify and fix the source of the problem. Early and specialised intervention can help protect your home and family, not only from the structural degradation of the house, but also from the health risks that can arise from the presence of mould in the home.

--[[User:AtlantisDamp|AtlantisDamp]] 16:44, 30 Jan 2019 (BST)

[[Category:Publications_/_reports]] [[Category:Property_law]] [[Category:Property_development]]