South Africa has now legislated, in terms of SANS 0400 XA, that cavity wall construction is mandatory for the the following reasons:

Poor construction methods have compounded these factors and an insert of polystyrene sheeting has become an option to enhance the thermal properties of the cavity wall construction. However, recent factors have come to light that need to be addressed in this construction method:

Weep holes may seem a small part of masonry wall construction, but they are critical to the durability and performance of cavity walls. Cavity walls and veneers are designed to drain the wall of moisture. Without weep holes or with clogged weep holes, walls collect moisture and hold it like a dam.

Weep holes should be installed in the masonry head joints above all stepped DPC courses. This includes the base of the wall, above all window and door lintels. Anywhere the cavity is interrupted, you must install a stepped DPC course and weeps. Be sure to keep the cavity clean of mortar droppings so the weep holes don’t get blocked and the DPC is not compromised.

STEP 1
The internal brickwork is to proceed the outer skin to allow for the DPC to be laid one course above the external course of bricks. The stepped DPC is then dropped down on the outer skin of brickwork to form a natural drainage away from the internal brick-work and assist in self-drain.

STEP 2
Construction of the inner skin of brickwork may proceed making sure that no mortar droppings fall onto the DPC and contaminate the integrity of the DPC. During the process brick ties are installed into the inner skin to receive the insulation and tie the outer skin brick once this is laid. (It is recommended that a lift of no more than 1.5m is laid in a single shift)

STEP 3
EcoWeep™ is installed in the mortar bed along brick header on the outer skin to allow natural ventilation and drainage at approximately 700mm centres, or 3 brick stretcher courses. The Eco Weep represents the width of a brick perp and will allow a consistent aesthetic appeal to the brick wall.

STEP 1
Identify the positions of the existing weep vents in the existing walling structure. If the are no weep vents, then mark of where these are to be installed.

STEP 2
Use a masonry drill bit to open the perp in the mortar of the brick to receive the EcoWeep™. This should be just larger than the EcoWeep™ which is 73mm high, so a height of 75mm should suffice. All loose mortar and dust are to be removed. Extreme care should be given that the DPC is not compromised in this process!

STEP 3
Make sure that the EcoWeep™ will fit in neatly and that it is slightly dropping to the outer side of the wall so that drainage will be not compromised. Apply a small bead of silicone on the outer face of the EcoWeep™ which will assist in positioning and setting.

EcoWeep™ is a patented weep hole, specially designed to enhance the durability and performance of cavity walls. The unique features encompass the louvered system on the inner side to prevent rain, and the penetration of vermin into the cavity wall. The external opening is designed to suit building and cleaning conditions during construction which allows a builder/painter the ability to clean the EcoWeep™ without compromising the DPC (Damp Proof Course), both during and post brick laying or plastering of the wall.