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Historic Preservation - Technical Procedures

Spectitle:

Guidelines For Evaluating The Condition Of Brck Masonry & Mortar

Procedure code:

0421109S

Source:

Developed For Hspg (Nps - Sero)

Division:

Masonry

Section:

Brick Unit Masonry

Last Modified:

02/24/2012

Details:

Guidelines For Evaluating The Condition Of Brck Masonry & 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.


RATING    DESCRIPTION

0         Bricks are totally disintegrated.

1         Evidence of spalling at least 1/4" to 3" deep.

2         Slight erosion at corners of brick; slight powdering of
         surface when rubbed with hand or scraped with fingernail.

3         Spalling brick in layers when rubbed with hand; fragments
         do not powder.

4         Bricks can be broken by poking and jabbing with
         screwdriver; fragments are semi-hard and resemble
         compacted clay.

5         FIRST CLASS OF STABLE, STRUCTURALLY SOUND BRICK:
         Screwdriver can penetrate the brick by hand roughly 1/4"
         but brick does not crumble.

6         Screwdriver can penetrate the brick roughly 1/4", but
         ONLY with the assistance of a hammer; this may cause
         coarse jagged pieces to become dislodged.

7         Screwdriver 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.

8         Chisel is necessary to crack the brick.

9         Chisel is unable to make an indentation or impression in
         the brick; brick shears cleanly; brick is strong with
         crisp edges and corners.

10        A 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.


RATING    DESCRIPTION

0         No evidence of mortar within at least 1-1/2" of the wall
         face.

1         Mortar crumbles when poked with finger or screwdriver;
         many surface irregularities are evident.

2         Mortar is easily removed with screwdriver, but FEW
         surface irregularities are evident in joint.

3         Mortar collapses and freely and cleanly breaks adhesion
         with brick when scored along centerline with screwdriver.

4         Slight spalling occurs at edges and corners of brick when
         mortar is scored and tapped with screwdriver.

5         Screwdriver is unable to dislodge the mortar; chisel can
         disengage and pop mortar free without damaging the brick.

6         Edges and corners of brick are slightly marred when
         mortar is scored with a chisel.

7         Hammer AND chisel are necessary in order to disengage the
         mortar; there should be little damage to the brick.

8         Several blows with hammer and chisel are required to
         break the mortar into several large pieces; bricks will
         be noticeably marred.

9         MORTAR IS STRONGER THAN THE BRICKS:  Successive blows
         with hammer and chisel crack brick.

10        MORTAR HAS HIGH PORTLAND CEMENT CONTENT:  Successive blows
         with hammer and chisel pulverizes the brickwork.

                         END OF SECTION