Damp-Proof Course Placement and Positioning in Walls for SS 3

Class: SS 3
Term: First Term
Week: 5
Age: 14 years
Duration: 45 minutes
Subject: Block Laying, Brick Laying and Concrete Work
Curriculum Theme: Sub-structure Construction
Previous Lesson: Soil Types, Bearing Capacity and Substructure Construction
Topic: SUB-STRUCTURE CONSTRUCTION at opening (drawing)
Subject Matter: Methods of placing and positioning D.P.C in walls; Need for the provision of weathering structures

Specific Objectives

By the end of the lesson, pupils/students should be able to:

Cognitive Domain

• Define Damp-Proof Course (DPC) and state its purpose.
• Identify various methods of placing and positioning DPC in walls.
• Explain the need for the provision of weathering structures in buildings.

Psychomotor Domain

• Sketch various basement walls showing DPC placement.
• Illustrate DPC placement at window and door openings.

Affective Domain

• Appreciate the importance of DPC and weathering structures in preventing moisture penetration.
• Demonstrate careful consideration for correct DPC placement during practical work.

Reference Materials

The following resources were used in planning this lesson:

• 2025 Revised 9 Years Basic Education Curriculum
• Relevant State Unified Scheme of Work
• Building Construction for Senior Secondary Schools by a suitable author
• The HeadTeacher Scheme of work

Instructional Materials

The teacher will teach this lesson with the aid of:

• Charts showing different types of DPC materials.
• Diagrams illustrating DPC placement in walls, basements, and openings (windows, doors).
• Samples of DPC materials (e.g., polythene sheet, bitumen felt).
• Existing walls or bonding concrete showing DPC (if accessible).
• Drawing materials (sketch pads, pencils).

Rationale for the Lesson

This lesson is essential for students to understand how to protect buildings from moisture damage, which can compromise structural integrity and occupant health. Proper placement of Damp-Proof Courses and the provision of weathering structures are fundamental skills in block and brick laying, ensuring durable and habitable constructions. Mastering these concepts prevents costly repairs and extends the lifespan of buildings.

Prerequisite/Previous Knowledge

Students should have a basic understanding of building components, foundations, and the general principles of wall construction.

Lesson Content/Board Summary

SUB-STRUCTURE CONSTRUCTION at opening (drawing)

Damp-Proof Course (DPC)

A Damp-Proof Course (DPC) is a barrier provided in a building to prevent moisture from rising through walls and floors or penetrating laterally. It is typically a horizontal layer of impermeable material placed at specific levels in a building structure.

The main purpose of a DPC is to:

1. Prevent rising damp from the ground into the walls.
2. Stop lateral moisture penetration in basements or retaining walls.
3. Protect timber elements (like floor joists) from decay caused by moisture.
4. Maintain the dryness and structural integrity of the building.

Methods of Placing and Positioning DPC in Walls

DPC can be placed horizontally or vertically, depending on the type of moisture ingress it is designed to prevent.

Horizontal DPC Placement

Horizontal DPC is the most common type and is typically placed at these locations:

1. Above Ground Level: It is usually placed at least 150mm (6 inches) above the finished ground level to prevent rising damp. This position ensures that rainwater splashing off the ground does not bridge the DPC.
2. Below Timber Floors: The DPC is placed below the lowest timber element, such as floor joists, to protect them from moisture.
3. At Window Sills: A DPC is placed horizontally under window sills to prevent moisture from penetrating downwards into the wall from the sill.
4. At Door Thresholds: A DPC is placed at the base of door openings to prevent moisture from rising into the wall from the ground level at the door.
5. Below Lintels: In some cases, a DPC may be placed above window and door lintels to prevent moisture from penetrating downwards from above the opening.

Vertical DPC Placement

Vertical DPC is used to prevent lateral moisture penetration:

1. In Cavity Walls: Vertical DPC is often incorporated at the ends of cavity walls or around openings to prevent moisture bridging the cavity.
2. In Basements: For basement walls, a vertical DPC (often combined with tanking) is applied to the external face of the wall to prevent moisture from the surrounding soil from penetrating into the basement space.

Need for the Provision of Weathering Structures

Weathering structures are building elements designed to shed rainwater away from the building’s vulnerable parts, preventing water ingress and protecting the building fabric.

The need for weathering structures arises from:

1. Protection from Water Penetration: They direct rainwater away from walls, openings, and foundations, preventing it from seeping into the building.
2. Prevention of Dampness: By shedding water effectively, they help to keep the building dry, reducing the risk of dampness, mould growth, and timber decay.
3. Durability of Materials: They protect exposed building materials from continuous saturation, which can lead to deterioration, erosion, and frost damage.
4. Aesthetic Preservation: Preventing water streaks and staining helps to maintain the visual appeal of the building’s exterior.
5. Structural Integrity: Long-term water penetration can weaken structural elements, so weathering structures are vital for maintaining the building’s stability.

Examples of common weathering structures include:

1. Copings: Protective caps on top of parapet walls or free-standing walls to shed water.
2. Sills: Sloping elements at the base of window openings to direct water outwards.
3. Drips: Small grooves or projections on the underside of ledges, sills, or cornices that cause water to drip clear of the wall below.
4. Flashings: Strips of impermeable material (e.g., lead, zinc, bitumen felt) used at junctions between different building elements (e.g., roof to wall) to prevent water penetration.
5. Projecting Eaves: Overhanging roof edges that protect the walls below from rain.

Teaching Methods/Instructional Techniques

Discussion, Demonstration, Explanation, Question and Answer, Visual Aids, Practical Activity (Sketching)

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Recalling/Engaging

Teacher’s Activity: The teacher greets the students and asks them to recall the importance of a good foundation in building construction. The teacher then introduces the concept of Damp-Proof Course (DPC) as another crucial element in protecting buildings.

Pupils’ Activity: Students respond to questions about foundations and listen attentively to the introduction of DPC.

Learning Point: Building protection importance

Step 2: Definition and Purpose of DPC

Time: 7 minutes

Teaching Skill: Explaining/Defining

Teacher’s Activity: The teacher defines DPC and explains its primary purpose using diagrams or samples of DPC materials. The teacher also states where DPC is generally found in a building, such as at window openings.

Pupils’ Activity: Students listen, ask questions for clarification, and observe the DPC samples and diagrams.

Learning Point: DPC definition, purpose

Step 3: General Placement of DPC

Time: 7 minutes

Teaching Skill: Illustrating/Discussing

Teacher’s Activity: The teacher explains the general principles of DPC placement, such as placing it 150mm above ground level and below timber elements. The teacher uses diagrams of wall sections to illustrate these points.

Pupils’ Activity: Students observe the diagrams and participate in a discussion about why DPC is placed at these levels.

Learning Point: General DPC positioning

Step 4: Methods of Placing DPC in Walls

Time: 8 minutes

Teaching Skill: Explaining/Demonstrating

Teacher’s Activity: The teacher elaborates on the methods of placing DPC, differentiating between horizontal and vertical DPC. Specific examples like DPC in cavity walls and basement walls are discussed, showing how they prevent moisture.

Pupils’ Activity: Students listen to the explanation and identify where DPC are placed in basement walls from the diagrams.

Learning Point: Horizontal, vertical DPC

Step 5: DPC Placement at Openings

Time: 5 minutes

Teaching Skill: Explaining/Visualising

Teacher’s Activity: The teacher specifically explains DPC placement at window sills, door thresholds, and lintels, highlighting their role in preventing moisture ingress around openings. The teacher uses diagrams of window/door details.

Pupils’ Activity: Students observe the diagrams and identify DPC placement at window and door openings.

Learning Point: DPC at openings

Step 6: Need for Weathering Structures

Time: 4 minutes

Teaching Skill: Explaining/Relating

Teacher’s Activity: The teacher explains the concept of weathering structures and their necessity in protecting buildings from rainwater. Examples like copings, sills, and drips are mentioned.

Pupils’ Activity: Students listen and contribute examples of weathering structures they have observed.

Learning Point: Weathering structures’ importance

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. What is a Damp-Proof Course (DPC)?
2. State two purposes of providing a DPC in a building.
3. Mention two common positions for horizontal DPC in a wall.
4. Why are weathering structures important in building construction?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: DPC and weathering understanding

Step 8: Note-Taking

Time: 4 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes on DPC placement and weathering structures into their notebooks.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: DPC notes recording

Step 9: Conclusion

Time: 2 minutes

Teaching Skill: Summarising/Reinforcing

Teacher’s Activity: The teacher summarises the key points of the lesson, reiterating the importance of correct DPC placement and weathering structures for building durability and protection against moisture. The teacher encourages students to observe these features in real buildings.

Pupils’ Activity: Students listen and ask any final questions.

Learning Point: Lesson reinforcement

Continuous Assessment/Further Study

Type: Homework/Practical Exercise

Instruction: Answer the following questions and complete the sketching task:

1. Explain the difference between horizontal and vertical DPC, providing an example for each.
2. List three types of materials commonly used for DPC.
3. Sketch a cross-section of a window opening, clearly indicating the position of the DPC.
4. Sketch a typical basement wall, showing how DPC (or tanking) is applied to prevent moisture penetration.

Lesson Keywords

• Damp-Proof Course (DPC) – A barrier in a building designed to prevent moisture from rising or penetrating laterally.
• Rising Damp – Moisture rising from the ground into a building’s walls by capillary action.
• Weathering Structures – Building elements designed to shed rainwater away from vulnerable parts of a building.
• Coping – A protective cap on top of a wall to shed water.
• Sill – A sloping element at the base of a window opening to direct water outwards.
• Lintel – A horizontal support over an opening in a wall.

Differentiation

For weaker learners: Provide pre-drawn diagrams of wall sections and openings, asking them to label the DPC positions. Focus on identifying the main purpose and placement of horizontal DPC. Provide simplified notes.

For stronger learners: Challenge them to research different DPC materials and their specific applications, or to identify and explain additional types of weathering structures not covered in the lesson. Encourage them to draw more complex details or troubleshoot potential DPC bridging issues.

Suggested Lesson Videos

For further understanding, students can search on YouTube for:

• “Damp proof course installation”
• “Weathering details in construction”
• “Building construction DPC and weathering”

Teacher Guide for Using This Lesson Plan

Before the lesson, ensure you have clear diagrams or charts illustrating DPC placement in various wall sections, basements, and around openings. If possible, bring actual samples of DPC materials (e.g., polythene, bitumen felt) to make the concept tangible. Begin by linking DPC to the previous lesson on foundations, emphasising its role in overall building protection. Guide students through the definition and purpose of DPC, then systematically explain the different methods of placement, both horizontal and vertical, with specific focus on openings like windows and doors. Encourage students to actively participate by identifying DPC in diagrams and making sketches. During the note-taking stage (Step 8), ensure students accurately copy the Board Summary content. Conclude by reinforcing the practical importance of these concepts in real-world construction and encourage observation of DPC and weathering structures in their environment. Pay attention to students’ sketches to correct any misconceptions about placement. Remind them that correct DPC placement is crucial for preventing long-term building damage.