The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Care And Repair Of The House

Leakage Through Joints.

Sometimes the quality or condition of the mortar in the joints, or the condition of the bond, may allow moisture to seep through the joints. When the bricks do not make a good bond with the mortar, shrinkage cracks may appear between the bricks and mortar as the materials dry out. If the mortar is not of good quality, it may disintegrate and fall out, causing leakage.

Occasionally there is leakage around a closure, or short piece of brick, inserted to fill out a course. This leak occurs when the closure is not cut small enough to allow plenty of mortar to be placed around it on all sides.

For best results bricks should be laid in a full bed of mortar, and all vertical joints should be well filled and packed with mortar. Vertical joints which are merely " buttered with mortar, cause more leaky walls than almost any other single factor. All exterior joints should be carefully struck smooth with the trowel to compress the mortar in order to make it dense and impervious. Joints raked out, or rough cut for artistic effect, are common causes for leaking walls, since ice, snow, and rain water have an opportunity to lodge in the recesses thus formed, and gradually work through the wall.

Some prefer, when it is found that a particular spot or area of a wall requires frequent repointing to use an integral waterproofing compound in the mortar, thoroughly mixing it with the other ingredients.

Repointing and Waterproofing.

Carefully examine the exterior surface of the wall where damp spots appear, to see whether the mortar is in place and otherwise in good condition.

If it is found that the mortar is cracked and has fallen out in places, these joints should be repointed. For this purpose, a mixture consisting of 1 part Portland cement, 3 parts well-graded but not too coarse sand, and 10 to 15 per cent of the volume of cement in a finely divided material, such as hydrated lime, is recommended. When the right quantity of water is added, this makes a workable mortar, which, if thoroughly mixed and troweled in well, should be practically impervious to moisture.

Before beginning to point, remove all loose mortar and brush small particles and dust out of the joints. Dampen the joints and adjoining surfaces before applying the new mortar, so that the moisture in the latter will not be absorbed.

After this preliminary work, pack the mortar tightly into the joints to fill all voids and form a good bond with the old mortar and bricks. The surface of the joint should then be troweled firmly to make a smooth finish, preferably sloped downward to shed water readily.