Guidelines for Evaluating the Condition of Brick Masonry and Mortar

Guidelines for Evaluating the Condition of Brick Masonry and Mortar

CAUTION: This method of condition assessment is destructive and should only be used to test areas believed to be deteriorated. This test should be performed only by an experienced mason.

This method of evaluation was developed by restoration architect Max Ferro and masonry conservator Tom Russack and appeared in the January/February 1987 issue of the Old House Journal.

Materials

  • Mason’s hammer
  • Cold chisel (1/2 to 1-1/2 inches)
  • Sturdy slotted screwdriver

The deterioration of brick and mortar are evaluated by rating each on a scale from 0 to 10 based on their level hardness or softness. A rating of 0 indicates severe brick and/or mortar deterioration. A brief description of each rating follows.

Assessment of Brick

  • A rating of ‘4’ or below indicates brick in an unsalvageable condition.
  • A rating between ‘5’ and ‘7’ indicates that some remedial measures may need to be taken.
  • A rating of ‘10’ indicates that the brick units are in good, sound condition.
RatingDescription
0Bricks are totally disintegrated.
1Evidence of spalling at least 1/4” to 3” deep.
2Slight erosion at corners of brick; slight powdering of surface when rubbed with hand or scraped with fingernail.
3Spalling brick in layers when rubbed with hand; fragments do not powder.
4Bricks can be broken by poking and jabbing with screwdriver; fragments are semi-hard and resemble compacted clay.
5FIRST CLASS OF STABLE, STRUCTURALLY SOUND BRICK: Screwdriver can penetrate the brick by hand roughly 1/4” but brick does not crumble.
6Screwdriver can penetrate the brick roughly 1/4”, but ONLY with the assistance of a hammer; this may cause coarse jagged pieces to become dislodged.
7Screwdriver is unable to penetrate the brick even with assistance from hammer but may make a slight impression in the surface. There may be a slight ring or bounce as the screwdriver hits the surface.
8Chisel is necessary to crack the brick.
9Chisel is unable to make an indentation or impression in the brick; brick shears cleanly; brick is strong with crisp edges and corners.
10A NEW BRICK: Brick with crisp corners; chisel striking the surface produces a clear ringing sound.

Assessment of Mortar

  • A rating between ‘0’ and ‘4’ indicates that repointing is necessary.
  • A rating between ‘5’ and ‘8’ indicates mortar in satisfactory condition.
  • A rating of ‘9’ or ‘10’, indicates that the mortar is too hard and should be replaced with a softer mortar.
RatingDescription
0No evidence of mortar within at least 1-1/2” of the wall face.
1Mortar crumbles when poked with finger or screwdriver; many surface irregularities are evident.
2Mortar is easily removed with screwdriver, but FEW surface irregularities are evident in joint.
3Mortar collapses and freely and cleanly breaks adhesion with brick when scored along centerline with screwdriver.
4Slight spalling occurs at edges and corners of brick when mortar is scored and tapped with screwdriver..
5Screwdriver is unable to dislodge the mortar; chisel can disengage and pop mortar free without damaging the brick
6Edges and corners of brick are slightly marred when mortar is scored with a chisel.
7Hammer AND chisel are necessary in order to disengage the mortar; there should be little damage to the brick.
8Several blows with hammer and chisel are required to break the mortar into several large pieces; bricks will be noticeably marred.
9MORTAR IS STRONGER THAN THE BRICKS: Successive blows with hammer and chisel crack brick.
10MORTAR HAS HIGH PORTLAND CEMENT CONTENT: Successive blows with hammer and chisel pulverizes the brickwork.