Wall chases

Limit on the depth of chases:

• Vertical chases indicated B on the above diagram should not be deeper than ⅓ of the wall thickness, or in a cavity wall ⅓ of the relevant leaf.
• Horizontal chases indicated C on the above diagram should not be deeper than ⅙ of the wall thickness, or in a cavity wall ⅙ of the relevant leaf.
• Chases should not position so as to impair the stability of the wall; back to back chases are not permitted.
• For hollow or cellular blocks maintain a residual thickness of 15mm between the chase and the void unless otherwise recommended by the manufacturer.