You can send your own masonry questions to Morte at [email protected] or use our Contact Us page.
Q: Dear Morte:
I want to get ugly paint off the bricks of a house I just bought. Should I sandblast?
Signed,
Brick Lover in Florissant
A: Dear Brick Lover:
Only if you really hate the house. It’s almost impossible to avoid using excessive pressure when sandblasting. Too much pressure exposes the softer, inner portion of the brick to the ravages of weathering. Cracking between brick and mortar appears, and wind-driven rain can get in. A kinder, gentler cleaner is needed, even if it costs a few bucks more. That is, unless you want to get rid of the house. Then either sandblasting or dynamite will do the trick.
Morte
I want to get ugly paint off the bricks of a house I just bought. Should I sandblast?
Signed,
Brick Lover in Florissant
A: Dear Brick Lover:
Only if you really hate the house. It’s almost impossible to avoid using excessive pressure when sandblasting. Too much pressure exposes the softer, inner portion of the brick to the ravages of weathering. Cracking between brick and mortar appears, and wind-driven rain can get in. A kinder, gentler cleaner is needed, even if it costs a few bucks more. That is, unless you want to get rid of the house. Then either sandblasting or dynamite will do the trick.
Morte
Q: Dear Morte:
Is there a difference between the terms “tuckpointing” and “repointing”?
Signed,
A St. Louis Architect
A: Dear St. Louis Architect:
According to the Brick Industry Associations (BIA), there is a slight difference. Tuckpointing refers to the act of placing new mortar in defective joints. Repointing is the act of cutting out defective joints and replacing them with new mortar.
Morte
Is there a difference between the terms “tuckpointing” and “repointing”?
Signed,
A St. Louis Architect
A: Dear St. Louis Architect:
According to the Brick Industry Associations (BIA), there is a slight difference. Tuckpointing refers to the act of placing new mortar in defective joints. Repointing is the act of cutting out defective joints and replacing them with new mortar.
Morte
Q: Dear Morte:
I’ve got ivy growing on the brick walls of my house. My wife wants me to pull it off because she thinks the ivy is destroying the brick. I disagree. We even have a bet on it. So who’s right?
Signed,
Ivy Lover in Afton
A: Dear Ivy Lover:
Have fun doing the laundry, waxing the car or whatever, because you lose! The Brick Industry Association (BIA) estimates that deterioration by ivy can reduce the life of a well-constructed wall of quality materials by up to 10 percent. More if the wall isn’t well made. Putting it simply: ivy eats brick, you eat crow.
Morte
I’ve got ivy growing on the brick walls of my house. My wife wants me to pull it off because she thinks the ivy is destroying the brick. I disagree. We even have a bet on it. So who’s right?
Signed,
Ivy Lover in Afton
A: Dear Ivy Lover:
Have fun doing the laundry, waxing the car or whatever, because you lose! The Brick Industry Association (BIA) estimates that deterioration by ivy can reduce the life of a well-constructed wall of quality materials by up to 10 percent. More if the wall isn’t well made. Putting it simply: ivy eats brick, you eat crow.
Morte
Q: Dear Morte:
The specifications on my rehab project call for reusing old brick since it looks like the original material. Is this a good idea?
Signed,
Contractor in Festus
A: Dear Festus:
Well, if the building owner is into gambling big time, it’s a great idea because used brick is a definite crapshoot. First, the surfaces of used brick are often filled with mortar particles or dirt, preventing a good mortar bond. As a result, the joints may be inferior and there’s a good chance of water getting in. Second, when old buildings are torn down, the surface and back up brick tend to get mixed up together. If the old back up brick is put on the surface of the new project, the owners could be facing problems down the road. The smart bet is to avoid problems by avoiding used brick or at the very least, use it very, very carefully.
Morte
The specifications on my rehab project call for reusing old brick since it looks like the original material. Is this a good idea?
Signed,
Contractor in Festus
A: Dear Festus:
Well, if the building owner is into gambling big time, it’s a great idea because used brick is a definite crapshoot. First, the surfaces of used brick are often filled with mortar particles or dirt, preventing a good mortar bond. As a result, the joints may be inferior and there’s a good chance of water getting in. Second, when old buildings are torn down, the surface and back up brick tend to get mixed up together. If the old back up brick is put on the surface of the new project, the owners could be facing problems down the road. The smart bet is to avoid problems by avoiding used brick or at the very least, use it very, very carefully.
Morte
Q: Dear Morte:
What is the difference between control joints and expansion joints and how do I know where to use each? Shouldn’t the mason contractor know where to place them?
Signed,
Architectural Intern
A: Dear Architectural Intern:
This is a good question and the answer should be learned early. Space here is limited but here goes. You would think that since clay expands in the wall during its curing process that it would make sense that control joints (CJ) would be used for clay. But that’s not the case: an expansion joint (EJ) used. An EJ on the on the drawing should be free of mortar or other obstructions to allow the wall to expand without cracking, chipping or spalling. Often compressive filler is called for to assure the joint is free of mortar. Using this designation allows the writer of the specification to know to spec mortar free joint. Concrete, on the other hand, will shrink as it cures. This would lead you to believe the abbreviation should be SJ for shrinkage joint, but no it is CJ for control joint, which will control the location of the cracking like a joint in a sidewalk. These joints are usually mortar joints, raked back and filled with caulking. By the way, both clay and concrete will expand with thermal change, so do we need TJ for that? No, EJ works just fine. As to location, unless you don’t care about the appearance of your design you should take the time to show where the joints should go. Besides, the code (MSJC) says joints should be shown on the construction documents by the design professional. You’ll want to memorize the terms and their abbreviations since the proper terminology is important in the bidding and execution of the project. By the way, NCMA and BIA both offer technical notes giving calculations for joint location as well as rule of thumb location. Thanks for your question and good luck with your career.
Morte
What is the difference between control joints and expansion joints and how do I know where to use each? Shouldn’t the mason contractor know where to place them?
Signed,
Architectural Intern
A: Dear Architectural Intern:
This is a good question and the answer should be learned early. Space here is limited but here goes. You would think that since clay expands in the wall during its curing process that it would make sense that control joints (CJ) would be used for clay. But that’s not the case: an expansion joint (EJ) used. An EJ on the on the drawing should be free of mortar or other obstructions to allow the wall to expand without cracking, chipping or spalling. Often compressive filler is called for to assure the joint is free of mortar. Using this designation allows the writer of the specification to know to spec mortar free joint. Concrete, on the other hand, will shrink as it cures. This would lead you to believe the abbreviation should be SJ for shrinkage joint, but no it is CJ for control joint, which will control the location of the cracking like a joint in a sidewalk. These joints are usually mortar joints, raked back and filled with caulking. By the way, both clay and concrete will expand with thermal change, so do we need TJ for that? No, EJ works just fine. As to location, unless you don’t care about the appearance of your design you should take the time to show where the joints should go. Besides, the code (MSJC) says joints should be shown on the construction documents by the design professional. You’ll want to memorize the terms and their abbreviations since the proper terminology is important in the bidding and execution of the project. By the way, NCMA and BIA both offer technical notes giving calculations for joint location as well as rule of thumb location. Thanks for your question and good luck with your career.
Morte
Q: Dear Morte:
I have had several code officials ask me about U.L. labels on block for firewalls. I’m kind of hazy on what they mean. What can you tell me about labeling?
Signed,
A Mason Contractor
A: Dear Mason Contractor:
Since there are several hundred block (CMU) manufacturers in the country, it’s not realistic to believe that they all could go through the process of testing all their units to establish fire ratings. Services such as Underwriters Laboratories (U.L.) are happy to test various types, aggregates and sizes; however, there are alternative methods available. The most common procedure is the equivalent thickness method, which has been developed through research and calculations to show the fire rating for masonry units. Both NCMA and BIA have published technical documents on this method, which has been acceptable to Codes for years. After several years of deliberation, a joint committee of the American Concrete Institute (ACI) and The Masonry Society (TMS) published a consensus document Standard Method for Determining Fire Resistance of Concrete and Masonry Construction Assemblies ANSI/ACI 216.1-97, TMS 216-97. Copies of these documents are available from MISL.
Morte
I have had several code officials ask me about U.L. labels on block for firewalls. I’m kind of hazy on what they mean. What can you tell me about labeling?
Signed,
A Mason Contractor
A: Dear Mason Contractor:
Since there are several hundred block (CMU) manufacturers in the country, it’s not realistic to believe that they all could go through the process of testing all their units to establish fire ratings. Services such as Underwriters Laboratories (U.L.) are happy to test various types, aggregates and sizes; however, there are alternative methods available. The most common procedure is the equivalent thickness method, which has been developed through research and calculations to show the fire rating for masonry units. Both NCMA and BIA have published technical documents on this method, which has been acceptable to Codes for years. After several years of deliberation, a joint committee of the American Concrete Institute (ACI) and The Masonry Society (TMS) published a consensus document Standard Method for Determining Fire Resistance of Concrete and Masonry Construction Assemblies ANSI/ACI 216.1-97, TMS 216-97. Copies of these documents are available from MISL.
Morte