how to identify damp proof course

The signs of a failed damp proof course include:

• Damp near ground level. This will often look like tidemarks as the damp soaks up through the wall. Rising damp can travel up to around 1.5 meters, so ...
• Hygroscopic salts. These are salts that are drawn through the pours in the brickwork. They will come through the surface of your wall and form white ...
• Damage to skirting boards. As the water rises from the ground, it will meet decorative features such as your skirting boards. This can lead to ...
• Blistering paint and peeling wallpaper. As the damp soaks through the surface of your walls, this will cause significant damage to decorations. You ...

Full Answer

What is the purpose of damp proof course?

Methods of Damp Proof Course (DPC)

• a. Surface Treatment. Surface treatment includes the method of laying a water repellant layer or water-resistant substance on the surface through which dampness is likely to occur.
• b. Pressure Grouting. ...
• c. Guniting. ...
• d. Integral Treatment. ...
• e. By use of Special Construction Techniques. ...

Why is a damp proofing course so important?

Methods of damp proofing:

1. Damp-Proof Course (DPC):
2. Cavity walls:
3. Shot Concrete (Gunting):
4. Silicone Damp Course:
5. Plastering Work:
6. Sub-floor ventilation:
7. Fixing Skirting Board:
8. Drainage:

What is damp proof course DPC and its properties?

What is Damp Proof Course DPC and Its Properties. Damp proof course (DPC) is generally applied at basement levels which restricts the movement of moisture through walls and floors. Selection of materials for damp proof course and its various methods of applications is as follows. It should be impervious.

How to drill and inject a damp proof course (DPC)?

Injecting a DPC involves drilling a row of small holes about 100mm apart into a mortar course just below ground floor joist level. A silicone-based fluid is then applied under pressure into the masonry where it hardens to form a chemical damp-proof course.

What are the different types of damp proof course?

Different types of damp proof coursesElectro-osmotic damp proof course. ... Chemical damp proof course. ... Pressure grouting. ... Membrane damp proof course. ... Integral damp proof course. ... Cavity wall damp proof course.

How do I know if my damp proof course has failed?

A damp tide mark, typically up to 1.5m high on your inner wall, external wall, or both caused by groundwater gradually rising through the porous surface of your brickwork. Damaged skirting boards. Peeling wallpaper.

Should damp course be visible?

The damp proof course may not be visible because of the external render which if correctly finished should stop at the dpc level and not go below it. If you are unsure that it is there it should be very easy for your builder to show you.

Do internal walls have a DPC?

This is to prevent residual moisture in the concrete affecting the timber. A dpc should be provided below all internal walls where the dpm is applied to the top surface of the slab. The dpcs should be at least the width of the partition.

Can you damp proof without removing plaster?

Damp proof courses can sometimes be replaced or inserted / injected without removing plaster however the contractor must ensure the plaster is tested for the presence of hydrscopic salts which are often present due to being drawn up into the plaster by the rising damp.

Can DPC always show?

It can indeed be hidden between the mortar joint and is not always visible.

Is damp proof course above or below air bricks?

Airbricks can be positioned either above or below the damp proof course (DPC) level, and should ideally be incorporated on all sides of a building, typically at least 75 mm above the ground to prevent water ingress.

Where is DPC placed?

A DPC layer is usually laid below all masonry walls, regardless if the wall is a load bearing wall or a partition wall. A damp-proof membrane (DPM) is a membrane material applied to prevent moisture transmission.

Why does a damp proof course fail?

Some of the most common include: subsidence causing the building to move - creating a break in the original DPC, building renovations that raise the ground level above the current damp proof course, and breakdown due to age and deterioration.

What is a damp proof membrane?

The damp proof membrane is positioned underneath a concrete slab with the intention of protecting the concrete from any moisture and therefore making it damp proof.

What is damp proofing cream?

Sometimes called a ‘remedial’ damp proof course, this process involves the injection of a ‘damp proof cream’ made from a silicone-based liquid that reacts with the silica in the masonry to produce a water-repelling layer within the wall.

Why do we need a damp proof course?

A Damp proof course is an important part of the protection for your property to protect it from rising damp, especially when heavy rainfall is a common problem in the UK. This form of damp proofing provides a long-term solution for moisture breaching the building’s foundation and entering the property. The most common damp problems being moisture ...

How high should a damp proofing course be?

Damp Proofing Course should be least 150 mm above the ground level unless the design of the building is built that will protect the wall. The damp course should be continuous with a damp proof membrane. If there is an external cavity wall then the cavity will need to placed at least 225 mm below the damp-proof course.

What happens if damp proofing fails?

If a damp proofing course has failed then this could potentially lead to rising damp. Rising damp is the movement of moisture through the walls and floors by capillary action. The visual result of rising damp is a “tide mark” left on the walls and plaster peeling off the walls.

What is damp proofing injection?

Damp Proof Course (DPC) Injection- This type of system involves a damp proofing injection being installed into the wall of the building which then acts as barrier ...

How to damp proof a building?

The Building Standards introduced requirements that a damp-proof course must meet when being installed in the Site preparation and resistance to contaminants and moisture: 1 Damp Proofing Course should be least 150 mm above the ground level unless the design of the building is built that will protect the wall. 2 The damp course should be continuous with a damp proof membrane. 3 If there is an external cavity wall then the cavity will need to placed at least 225 mm below the damp-proof course.

Why isn't my house damp proofed?

The most serious implication of not having your property damp proofed is the possibility of timber decaying issues such as wet rot and dry rot. This occurs from not having the damp treated over a sustained period of time. If left untreated the wood rotting issues can lead to varying degrees of structural damage.

How do I know if my walls need damp proofing?

Signs That Your Walls Need Damp Proofing. There are a number of tell-tale signs of damp being present in walls. The most common signs to look out for are: Black spot mould forming on interior walls. This is a common sign also of a condensation problem. Watermarks on walls formed by either rising damp or penetrating damp.

What happens when a damp proof course fails?

When a damp proof course fails, it allows moisture to enter bricks and mortar. The materials in your home act like straws pulling moisture up from the ground. A DPC is installed to prevent this from happening. When a damp proof course fails, moisture can find a way in. When a DPC fails, and moisture begins to enter the brickwork of a building, ...

How long does a damp proof course last?

A damp proof course, even a properly-installed one, may only last for about 20-25 years. An incorrectly installed DPC likely won’t last this long. Also, if your home has a DPC that wasn’t installed correctly, it may have been letting moisture into the brickwork of your home for some time.

What does rising damp mean?

If you have rising damp, it is likely your damp proof course has failed, or wasn’t installed at all. Either way, you need to fix your DPC.

What is it called when a DPC fails?

When a DPC fails, and moisture begins to enter the brickwork of a building, this is called rising damp. A home with rising damp will have a DPC that has failed. Or it may never have had a DPC installed in the first place. A damp proof course, even a properly-installed one, may only last for about 20-25 years. ...

What is an electro osmotic damp proof course?

An Electro Osmotic damp proof course uses wiring to create a small electric charge in the walls of your home. This electric charge reverses the capillary action in bricks and mortar.

What does it mean when you have a damp spot on your house?

Well, the damp gives us clues. If you have a damp ‘tide mark’ on the exterior or internal walls of your home, this is a sign of rising damp spreading up your walls. Penetrating damp leaves isolated patches of damp on the walls of your home. Rising damp, on the other hand, rises up through the brickwork.

How high does damp rise?

Either way, you need to fix your DPC. Rising damp typically only rises to about 1.5m on the walls of your home. After that, gravity takes affects, and the water cannot rise any more. So, if there is evidence of damp up to this height, it has been caused by groundwater. Other tell-tale signs of rising damp include:

What is the choice of material to function as an effective damp proof course?

The choice of material to function as an effective damp proof course requires a judicious selection. It depends upon the climate and atmospheric conditions, nature of the structure, and the situation where DPC is to be provided.

What are the properties of damp proofing material?

Properties of Materials for DPC. An effective damp proofing material should have the following properties; It should be impervious. It should be strong and durable and should be capable of withstanding both dead as well as live loads without damage. It should be dimensionally stable.

What should a DPC cover?

The DPC should cover the full thickness of the walls, excluding rendering. The mortar bed upon which the DPC is to be laid should be made level, even and free from projections. Uneven base is likely to cause damage to DPC.

What is DPC material?

DPC Material for floors, roofs etc. For greater wall thickness or where DPC is to be laid over large areas such as floors, roofs, etc., the choice is limited to flexible materials that provide a lesser number of joints like mastic, asphalt, bitumen felts, plastic sheets, etc.

What is damp proof course?

It is a barrier or obstruction that is primarily designed to prevent the moisture rising by the capillary action. The capillary action through which the moisture rises is known as the rising damp.

What are the desirable properties of damp proofing?

The desirable properties of the materials used for the damp proof course can be listed as follows: a. The material used for the damp proof course must be impervious i.e. it must prevent the passage of moisture through it . b. The material must be strong as well as durable.

What is surface treatment?

Surface treatment includes the method of laying a water repellant layer or water-resistant substance on the surface through which dampness is likely to occur . It is the most common method of damp proofing when the moisture or dampness occurs superficially.

What are the factors to be considered during the construction of a DPC?

Some of the factors that must be considered during the construction of the damp proof course are as follows: a. Before the damp proof course is laid, the mortar upon which it is to be laid must be made level, even and free from any sorts of projections.

What ratio of cement should I use for DPC?

a. For DPC above ground level, it is desirable to use cement concrete of ratio 1:2: 4 (M15). In the case of a damp and humid atmosphere, a richer mix of concrete must be used. Various water-resistant materials such as Pudlo, Impermo, Waterlock may be added to the concrete mix to make it denser.

How deep does mastic asphalt spread?

When the mixture is hot, the consistency is such that it allows the mixture to spread evenly to a depth of about 2.5cm to 5cm. Upon cooling, the mixture sets. However, special care must be taken while laying the mastic asphalt as the damp proof course. b.

What is damp proofing?

In other words, a damp proof course can be defined as the layer of material that is used to prevent the penetration or passage of moisture inside the structure through the floors, walls or roofs. It is commonly applied at the basement level of the structure and thus prevents the passage of moisture through the floors and the walls. 1.1.

What is a Damp Proof Course (DPC)?

Many people would not know what a damp-proof course is. A damp proof course is essential to install, particularly at the basement level or at the building’s foundation upon construction. It prevents rising of moisture through the floors and walls.

Different Types of Damp Proof Courses

Installing a damp-proof course is the best way to protect your property. It works as a protective barrier so that the damp would not rise from the ground. Here are some damp-proof courses you may choose.

Does my Property Need a Damp-proof Course?

When does your property need a damp-proof course? Not all property owners have experience with installing a damp proof course. That is why they don’t know what to do when dampness becomes a major problem in the property. If this happens, know that it’s probably time to consider installing a damp proof course.

Cost Of Having A Damp Proof Course

Hiring a professional to install a damp-proof course would cost a considerable amount of money. The cost of installing a DPC varies depending on the scope of work or the type of damp to fix. The average cost of damp proofing an interior wall is about $90 per square meter.

Should you try to identify a failed damp proof course yourself?

Rising damp can be a major issue and it can cause serious damage if it is not fixed. However, it is also the most misdiagnosed type of damp.

Common treatments when your damp proof course has failed

Fixing a damp proof course can be done in a few different ways. The main techniques for fixing this issue can be seen below:

Conclusion

If you think your damp proof course has failed, you will need to do some investigation to make sure this is the issue. Misdiagnosis is quite common, so you should rule out any other potential issues, such as outside defects causing penetrating damp.

What is a Damp Proof Course?

All modern buildings have what is known as a Damp Proof Course. It is usually abbreviated to 'DPC', and in most buildings less than 30 years old, it consists of a DPM, which is a Damp Proof Membrane, an impermeable layer of material, most often a polyethylene or bitumen-polymer, that is laid in the bedding joint between two courses of bricks.

When did damp proofing become mandatory?

Ground-level damp proof courses have been mandatory in all British buildings since the Public Health Act of 1875 . A typical polymer damp proof course. There are a number of alternatives to the modern dpc-on-a-roll, and these are sometimes found on older properties, particularly those built prior to the Second World War.

How far below the DPC should paving be?

Paving is kept at least 150mm below the dpc and slopes away from the wall at around 1:60. This may need to be increased to 1:40 for some 'difficult to drain' pavings, such as riven flags, or may be decreased for well-draining pavings, such as blocks or plain concrete.

How high can a DPC be?

...and just to confuse matters, there are a couple of traits that can confound the hunt for the dpc.... - The dpc can be considerably more than 150mm above ground or paving level.

How much space between a DPC and the ground?

Bending The Rules. The Building Regulations require at least 150mm between the dpc and the ground or any paving. This is what is known as 'Best Practice'. However, there are situations where it is just not possible, or practical, to maintain this regulation.

How much should paving fall away from walling?

The paving should fall away from the walling quite sharply, at least 1:12. Where a relatively narrow edge course of block pavers is used, the fall can be increased to 1 in 6 or more to reduce the incidence of 'splashback' and ensure any surface water is directed away from the walling as quickly as possible.

What is a land drainage pipe?

A land drainage pipe, usually a perforated plastic type, is laid at the base of the channel, connected to the SW drainage system at a convenient point and covered with a clean gravel to a level no higher than the dpc. The walling may be protected by a drainage composite or tanking.

GarethSE5

I have a ground floor flat in a Victorian (i think) terrace. There's damp in the exterior walls (mould, peeling paint), but not the interior walls. I've done a bit of research and think that the gravel in the back garden and the paving in the front might be 'bridging' the existing damp proof course because they raise the ground level above it.

handyman77

Maybe in manchester they dont have damp courses in london they generally do!

ei8htbuildingservices

Sorry tony! Handyman is right,every house i have worked in has some form of damp course, otherwise they would all be damp.

maltaron

Many Victorian and pre WW2 houses had blue brick or hard red engineering bricks for a damp course. Look for 2 courses of blues or reds that look denser than commons. If so, check that they are not bridged by soil anywhere, air bricks should be below or in the DPC.

GarethSE5

Many Victorian and pre WW2 houses had blue brick or hard red engineering bricks for a damp course. Look for 2 courses of blues or reds that look denser than commons. If so, check that they are not bridged by soil anywhere, air bricks should be below or in the DPC.

tony1851

Manchester builders did build-in some kind of DPC's into some housing stock going back into the mid 19th C. .

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