Cavity walls — start/termination of cavity and damp-proofing practice Choose the correct combined statement about where a cavity in a cavity wall should start and terminate, and how damp-proof courses (DPC) are laid in the two leaves.

Introduction / Context:
Cavity walls consist of two leaves separated by an air gap to reduce rain penetration and improve thermal performance. Correct detailing of where the cavity begins and ends, as well as damp-proof course (DPC) placement, is critical to prevent moisture bridging and to ensure durability of the building envelope.

Given Data / Assumptions:

• Cavity ties, weep holes, and DPCs are correctly detailed.
• Both sloping and flat roof terminations may occur.
• Local climatic exposure is typical of building practice.

Concept / Approach:
The cavity generally starts near ground level above the base DPC so that rising damp and splash water do not bridge through. It terminates near the eaves for sloped roofs or near the coping/parapet for flat roofs, with closures to prevent debris and water ingress. DPCs are laid separately in both leaves at the same level to maintain continuity while preserving the cavity function. These coordinated measures prevent moisture transfer and preserve the thermal and weather-resisting benefits of the cavity.

Step-by-Step Solution:

Verification / Alternative check:
Standard details illustrate weep holes and cavity trays above openings and at roof abutments, consistent with these statements.

Why Other Options Are Wrong:

• Any single statement alone is incomplete; all together form good practice.

Common Pitfalls:
Bridging the cavity with mortar droppings; misaligned DPCs; missing weep holes causing water accumulation in the cavity.

Final Answer:
All the above