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Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
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We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
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 adhesionwith 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. |