Cavity wall   flashing/weep holes

t.  Cavity wall   flashing/weep holes:
Cavity masonry walls (Fig. t1, Item A) and brick veneer walls over framing (Fig. t1, Item B) have air spaces between the individual walls. These can collect condensation.  Weep holes should be installed to allow condensation to exit the wall (Fig. t1, Item C).  Flashing is set within the wall to encourage the draining of condensation through weep holes (Fig. t1, Item D). 

Fig. t1

It is common to find walls without weep holes.  Such walls can experience freezing, or rusting and expanding lintels.  Many walls that are located in temperate climates suffer few visible symptoms.  Efflorescence, spalling brickwork, rusting lintels, etc. may be symptomatic of weep hole or flashing difficulties in walls (Fig. t1, Item E).  The incidence of finding correctly installed flashing and weep hole combinations in new construction is very rare.
 
What to:    How to:
Do not mortar those butt joints of bricks that seemingly were missed and have small holes. “Notice that they are all in a horizontal row.”  They are weep holes that are there for a purpose.

Repairs to masonry walls usually require a careful professional analysis and repairs by a qualified professional mason.