Question

Q3. Draw a sketch of a cavity masonry wall and explain the role of the cavity space, drainage, flashing, weep holes. What aspects of cavity wall construction are most critical to its success in preventing water leakage? (30 pt.) Answer

Answer 1

Please find the answer from below pictures
OUTER WALL -INNER WALL AIR SPACE (2")- METAL TIE FLASHING TO FORM CAVITY GUTTER -BRICK -MORTAR JOINT WEEP HOLE (MORTAR OMITTED) FOUNDATION WALL

A cavity wall is a type of wall that has a hollow center. They can be described as consisting of two "skins" separated by a hollow space (cavity). The skins typically are masonry or cinder block. Masonry is such brick as an absorbent material and therefore slowly draws rainwater or even humidity into the wall Cavity space One function of the cavity is to drain water through weep holes at the base of the wall system or above windows. The weep holes allow wind to create an air stream through the cavity that exports evaporated water from the cavity to the outside. Usually, weep holes are created by separating several vertical joints approximately two meters apart at the base of each story. Weep holes are also placed above windows to prevent dry rot of wooden window frames. A cavity wall with masonry as both inner and outer skins is more commonly referred to as a double wythe masonry wall. |

Flashing The flashing component is important. Its main purpose is to direct water out of the cavity. Metal flashing usually extends from the interior wall through the outer wall and a weep hole with a downward curve allows the water to drain. Flashing systems in cavity walls are typically located close to the base of the wall, so that it will collect the water that goes down the wall Weep holes Weep holes are drainage holes left in the exterior wall of the cavity wall, to provide an exit way for water in the cavity Weep devices play an equally important role, as do flashings, because, of course, if the moisture is unable to find its way to the face of the wall, what's the point? While it's the actual void in the head joint that provides the means by which moisture finds its way to the exterior, the weep device provides uniformity across the surface of the wall. They offer a structure by which moisture and air may move freely, though some may do a better job than others

The most critical aspects of cavity wall construction to its success in preventing water leakage are given below 1. Keeping a clean cavity that is free of mortar droppings 2. Providing weep holes at frequent intervals 3. Providing proper flashings