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What is DPC?

The damp proof course (DPC) is generally applied at basement levels, which restricts the movement of moisture through walls and floors. The selection of materials for the damp proof course and its various methods of applications in buildings is discussed.

Materials for Damp Proof Course (DPC)

Properties of Materials for DPC

An effective damp proofing material should have the following properties;

  1. It should be impervious.
  2. It should be strong and durable and should be capable of withstanding both dead as well as live loads without damage.
  3. It should be dimensionally stable.
  4. It should be free from deliquescent salts like sulfates, chlorides, and nitrates.

Types of Materials for Damp Proof Course

The materials commonly used to check dampness can be divided into the following three categories:

  1. Flexible Materials: Materials like bitumen felts (which may be hessian based or fiber/glass fiber-based), plastic sheeting (polythene sheets), etc.
  2. Semi-rigid Materials: Materials like mastic, asphalt, or a combination of materials or layers.
  3. Rigid Materials: Materials like first-class bricks, stones, slate, cement concrete, etc.

Selection of Materials for Damp Proof Course in Buildings

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.

Dam Proof Course (DPC)
Fig 1: Cross section of Damp Proof Course.

The points to be kept in view while making selection of DPC materials are briefly discussed below:

1. DPC above ground level

For DPC above ground level with wall thickness generally not exceeding 40 cm, any one of the types of materials mentioned above may be used. Cement concrete is however, commonly adopted material for DPC at plinth level, 38 to 50mm thick layer of cement concrete M15 (1:2:4 mix) serves the purpose under normal conditions.

In the case of a damp and humid atmosphere, a richer mix of concrete should be used. The concrete is further made dense by adding waterproofing materials like Pudlo, Impermo, Waterlock, etc. in its ingredients during the process of mixing. It is used to apply two coats of hot bitumen over the third surface of the concrete DPC.

2. 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.

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The felts, when used, should be adequately bonded to the surface with bitumen and laid with joints properly lapped and sealed.

3. DPC Material for situations where differential thermal movements occur

In parapet walls and other such situations, materials like mastic, asphalt, bitumen felts, and metal (copper or lead) are recommended.

It is vital to ensure that the DPC material is flexible to avoid any damage or puncture of the material due to differential thermal movement between the material of the roof and the parapet.

4. DPC material for Cavity Walls

In cavity wall construction, like cavity over the door or window should be bridged by flexible material like bitumen felt, strips or lead, etc.

Methods of  Damp Proof Course Installation in Construction

The general principles to be observed while laying a damp proof course are:

  1. The DPC should cover the full thickness of the walls, excluding rendering.
  2. 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.
  3. When a horizontal DPC is to be continued up a vertical face, a cement concrete fillet 75mm in radius should be provided at the junction before the treatment.
  4. Each DPC should be placed in correct relation to other DPC to ensure a complete and continuous barrier to the passage of water from floors, walls, or roof.

Figures 1 to 7 explain the provision of damp proof course under different conditions

Methods of Applications of Damp Proof Course in Buildings
Figure 2: Air Drain
Damp Proof Course Treatment for basement on undrained soils

Fig 3: Damp Proof Course Treatment for basement on undrained soils
Damp Proof Course Details for Buildings
Fig 4: Plan of building showing DPC
Damp Proof Course Treatment for Basement in Damp Soil
Fig 5: Damp Proof Course Treatment for Basement in Damp Soil
Damp Proof Course using Asphalt for Basement
Fig 6: Asphalt tanking for basement
Damp Proof Course for Flooring
Fig 7: Damp Proof Course for Flooring
damp-proof-course-for-internal-walls
Fig 8: Damp Proof Course for Internal Walls
1. What is Damp Proof Course?

The damp proof course (DPC) is generally applied at basement levels, which restricts the movement of moisture through walls and floors.

2. What is the abbreviation of DPC in Construction?

The abbreviation of DPC is the Damp Proof Course.

3. What are the desirable properties of DPC Material?

The desirable properties of DPC material are-
A. It should be impervious.
B. It should be strong and durable and should be capable of withstanding both dead as well as live loads without damage.
C. It should be dimensionally stable.
D. It should be free from deliquescent salts like sulfates, chlorides, and nitrates.

4. What are the types of DPC Materials?

A. Flexible Materials: Materials like bitumen felts (which may be hessian based or fiber/glass fiber-based), plastic sheeting (polythene sheets), etc.
B. Semi-rigid Materials: Materials like mastic, asphalt, or a combination of materials or layers.
C. Rigid Materials: Materials like first-class bricks, stones, slate, cement concrete, etc.

Read More: Materials for Damp Proof Course in Construction Works

Gopal Mishra

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19 Comments

  1. i'm from Department of Quantity Surveying…and thanks alot for those information…i really need it for my exhibition….

  2. I need aparter to join and promote my finished dpc products across africa, and u are free to buy ashare in or company.

  3. Thanks for the hardwork;am amanufercturer of dpc in uganda,ineed your help to start my company on the knowledge on how set up my product.thanks patrick, sokolosure chemicals ug ltd.

  4. can i get the data ,analysis and a result of the DPC.. im student of civil engineering to review of the DPC. in my country doesnt have a place to doing labbotory of this DPC.. anyone help me please.

  5. all is clearly indicated here as I wanted, good site.

  6. Thanks dear sir! I got a clearer picture. Am a Public Health Major! God Bless you abundantly!

  7. In A horizontal D.P.C. thickness of cement concrete (1:2:4) is generally.

  8. hi sir i want know about structure of R.C.C. FOR BASEMENT ,if building ht 50′ and building 50’X90′ in rectangular shape ,and live load on building of 1500 hundered peoples then what suggest for structure, like thickness of bars in mm.

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