POINTING/PARGING NEEDED

G.  POINTING/PARGING NEEDED ?:
Many older foundations have had slight moisture problems or even more severe ones for years.  Gradually, the migrating moisture disintegrates the mortar between bricks or blocks.  Often a fuzzy white material seems to grow out of the foundation walls.  This “efflorescence” (Fig. G1, Item A) is actually a lime salt that is deposited on the inside foundation wall by migrating moisture moving through the wall from outside.  It evaporates once it reaches the inside.  The walls gradually weaken with the mortar and blocks disintegrating (Fig. G1, Item B), and tend to become progressively more water porous.  Eventually they must be repaired to keep the foundation strong.   Pointing between the bricks or blocks on the interior can strengthen walls.  A trowel-applied parging with Portland cement on the interior, to fill damaged joints and reinforce damaged materials, will also strengthen walls.  These repairs will do little to keep the interior dry, since transpiration will continue to occur as may seepage.  Work intended to keep the interior dry should be done on the exterior, to deal with the source of the water.

Pointing is accomplished by raking out the existing mortar joints between bricks or blocks and setting a thin bed of mortar in the joint.  The bed is wetted first, and then the mortar is pushed into the raked joint with the point of a trowel.  The mortar joint is then “struck” off with a tool.  Striking compacts the mortar firmly against the adjoining bricks or blocks and is vital in assuming that the mortar bonds well to the masonry units.

Obviously, this work takes considerable hand skill and is slow and tedious.  If the bricks or blocks need not show, parging certainly can be accomplished faster and is almost as suitable a repair.  The raking and wetting of the joints is the same, but the mortar is now troweled over the entire surface of the wall.  The compaction within the joints is not quite the same, but the result is still quite good.  Since this work is more quickly accomplished, the labor cost is reduced.  The skill level necessary is far less as well.

Sometimes bricks in old foundation walls chemically disintegrate.  Red powder falls to the floor around the bricks.  This is usually due to “rising damp” affecting the bricks.  Moisture and chemicals are drawn up into the masonry from the ground.  Usually improving the drainage around the foundation will help.  Different methods need to be employed if the source of the moisture and minerals is from beneath.  There are damp proofing chemical treatments available from specialized commercial companies.  Simple parging over the bricks seems to accelerate the process if the source of the moisture is not terminated.

WHAT TO:  HOW TO:
Amateurs can do pointing but if aesthetics are important, a skilled mason should perform the work.  Parging can usually be done by almost anyone.  Generally, a  three parts sand to one part Portland cement mix is preferred to ensure that it adheres to the wall.  A fresh mix is important to a successful job.  Mix small quantities at first to see how quickly the work progresses.  A special square plate (hawk), with a handle perpendicular to the center of the plate, is used to hold a working quantity of parge mix.  A rectangular trowel is used to apply the parge mix to the masonry wall.