If reading building codes does not get you excited, you’re reading them wrong.  This is a brief blog post on brick and mortar within the literal confines of building codes, state laws, and colonial law language for the city and state of New York.    The commonly misunderstood oldest existing building code for New York City is the considerably modified Building Code of 1938.   This is historically incorrect, moreover the 1938 building code that one is allowed in practice today to reference when dealing with building code issues in New York City is the 1968 version.  What is mainly stricken from the original 1938 building code are means and methods and technical data.  The codes you are allowed to reference today based on the various possible scenarios when working in New York City are 1938, 1968, 2008, and 2014.  All four mainly address fire, life safety, and basic health issues at a conceptual level.  These codes very much reflect the codes of today and do not delve into means, methods, or technical data as these are referenced items determined by testing and standard agencies.   Imagine being able to sue the city for a bad detail! 

The American Section of the International Association for Testing Materials - ASTM was founded in 1898.  This is around the same time the series of books A Treatise on Architecture and Building Construction - Prepared for Students of the International Correspondence schools (1899) were issued, all volumes linked below.  Some modified images used here are taken from these books.  The original New York City Building Code of 1938, now a removed section -  7.1.1.2.1 defines a brick as “All brick when delivered for use shall comply with the standard specifications of the A.S.T.M., D., C 62039 for “B” brick.”  Prior to this how was a brick defined and how was it required to be laid? 

In 1703, in the colony of New York, mixed in with a law covering casks, weights, and measures the brick was defined to be throughly burnt and sized at 9” inches in length, 4” inches in breadth, and 2 ½” inches.   It appears that by 1773 an Act was established to regulate the quality of the sale of bricks in the colony of New York as the former 1703 law apparently did not prevent the “mischiefs” of brick makers and sellers.  The law indeed includes the word “mischiefs” and the additional language added defines more oversight by government officials to address complaints with regard to proper sizing and quality of brick. 

[1899 – New York and New Jersey Brick about 8”x4”x 2 ½”, image above is from Audels 1929] 

This response to mischiefs is in a nutshell the history of building codes or laws in general.  A couple knuckleheads cheat or are just dumb humans, someone gets hurt and then the laws have to be rewritten.  Your job as a professional is to explain these laws to knuckleheads and sometimes dumb humans who do not read: anyway. 

“I’ve been doing it this way for 20 years.” – Mason contractor

 “You’ve doing it wrong for 20 years.” – Architect

Typically, the most concise history on codes is always best illustrated by a city’s response to massive destructive fires.  For New York City see this link - How Fire Disaster Shaped the Evolution of the New York City Building Code By Charles Shelhamer, Code Analyst, NYC Department of Buildings. 

In the 1800’s the laws of New York state designated which districts (fire districts) of its various cities were required to be built of brick or stone construction and occasionally included specific means and method on how to lay the brick.  In 1830 a law for the Prevention of Fire in the City of New York required that all openings at the rear and front of buildings in fire districts be constructed of brick arches and limited the use of bond timber* in masonry walls.  The language though is limited with regard to means and methods for building these brick arches; after all these are lawmakers and not builders.    An act to address Unsafe Buildings in New York city in 1856 was passed that clarifies in much more detail how brick and mortar walls were to be constructed.  This act is further elaborated and consolidated into various acts into the late 1880’s before being transferred from New York State laws directly into New York City building codes.  Below is a list of key technical parts of a brick wall and how bricks are to be laid.  What is not covered here are overall wall tie-backs or lateral support or wall thickness requirements, which deal more with the building envelope structural performance than the actual laying of brick.  Also excluded are brick laying for chimneys, fireplaces, hollow and veneer walls.  Hollow walls of 1899 are now called Cavity Walls.  Metal ties are not discussed either and only the American Bond (Garden or Running Bond) is covered here as it relates directly to the New York codes and laws.  Flemish and English bonds are the other historically popular brick bond patterns.

First a few “How to Lay Brick” Definitions from Audel's Masons and Builders Guide #1 (1929): 

Brick – A standard unit of building material, made by fashioning clay into rectangular solid blocks, and subjecting them to burning in a kiln.

Course – A horizontal row of brick in a wall. 

Wythe** – is a continuous vertical section of masonry one unit in thickness.

[Audel's – 1929] 

Lap – The distance one brick extends over another.

Bond – The overlapping of brick in various ways so as to give both longitudinal and transverse strength to the wall, and at the same time produce a pleasing appearance.[Audel's – 1929]

Stretcher – A brick laid on its flat side so as to show its face on the surface of the wall. 

Header – A brick laid on its flat side across the thickness of the wall, so as to show the end of the brick on the surface of the wall. 

Mortar – A mixture of lime and sand, or cement and sand, or of lime, cement and sand, used for laying bricks and filling in the joints between them. 

Cement – A burned mixture of clay and limestone pulverized for making mortar or concrete. 

Lime – The base of mortar, and the result of limestone burned in a kiln until the carbon dioxide has been driven off. 

Sand – Small grain of mineral, largely quartz, which is the result of disintegration of rock.

Itemized List of Key Technical parts of a brick wall as it relates to one particular section of the Laws and Code (1856-1915+/-): 

(1) - Brick walls and Header Requirements 

It appears the first mention of a header brick utilized for bonding
purposes within the law was introduced into New York State Laws of 1856
addressing Unsafe Buildings, first noting every fifth course and not
sixth course and by the time it lands in the New York City Consolidation
Act of 1882, An Act to Consolidate into One Act and To Declare the
Special and Locals Laws Affecting Public Interest in the City of New
York, Being Chapter 410 of the Laws of 1882 – Title Construction of Buildings Section 480 – reads as follows:

“In every brick wall every sixth course of shall be a heading course, except where walls are faced with brick, in which case every fifth course shall be bonded into the backing by cutting the course of the faced brick and putting in diagonal headers behind the same, or by splitting face brick in half and backing the same by a continuous row of headers… All heading courses shall be good, hard, perfect brick. The backing in all walls, of whatever material it may be composed, shall be of such thickness as to make the walls, independent of the facing, conform as to thickness with the. requirements of sections four hundred and seventy-six and four hundred and seventy-seven of this act.”

[Audels 1929]

This language appears more or less the same before eventually being removed from code and law.  The first part describes the American Bond, while the second is of more interest.   Perhaps you want a wall that is continuous in the running bond pattern full height without the header interruption and it is not a veneer wall. How is this built? 

The diagonal headers have also been referred to as the herringbone pattern.  Brunelleschi’s Dome in Florence Italy (1420-1436) utilizes the herringbone brick install pattern for portions of its dome for structural purposes.  Imagine, the dome defined as multiple arches that are self-supporting and utilizing the herringbone pattern to avoid scaffolding for temporary support until the built arches/dome collapses on itself and self-supports.

[more on the construction of the dome]

How did this pattern end-up as a method for bonding bricks in a wall?  Did a mason know a lawmaker or did a lawmaker have a copy of Alberti’s “On Architecture”? Maybe some lawmaker was into architecture? 

or did Cousin Vinny tell the Mason – “In Firenze we had bricks of 5”x10” because an Italian man’s hands are larger than an English or Dutch mans, and we built the dome better because we used a herringbone pattern, so let’s build our entire wall that way...and you know what larger hands mean, right?” [the law was 5”x10” for the Brick in Florence, Italy in Brunelleschi’s time][Herringbone Bond - 1899 – Treatise on Architecture – Volume II] [Herringbone/Diagonal Bond #1 – Audels 1929][Herringbone/DiagonaLBond #2 – Audels 1929] 

Regardless of how this all came about, this blog is a literal interpretation of code and laws for bonding bricks and we will investigate further with simple math this code in the illustrations below in the thesis portion of this blog.

(2) – Brick Arches

In 1830 the New York Law addressing prevention of fire in New York City notes that all openings in a building at the front and rear of buildings should have a secure brick arch over it.  That is all the law states – secure.  Later, the brick arch is better defined in the law of 1856 addressing Unsafe Buildings, the rise of at least 1” inch per 1’ foot between beams and laid on the centres (British spelling in 1856). For those who believe in proportions of divine intervention, the brick arch’s rise as defined by New York Law in 1856 is the same as the Americans Disability Act with regard to requirements for a ramp to be 1” inch per 1’ foot of ramp.  Maybe that is the solution for comfort against gravity for both the brick and the wheelchair? But, what if there were 13” inches in a foot?   Not possible.  There are 24 hours in a day, and therefore there are 12” inches in a foot and therefore the Imperial measure is much more divine than that meter metric – surely.[Segmental Arch - 1899 – Treatise on Architecture – Volume II] [Segmental Arch - 1899 – Treatise on Architecture – Volume II]

(3) – Mortar Mixes            

As you might suspect by now, the first mention of more descriptive measures for proper mixture of mortar appears first in the laws passed in 1856 to address Unsafe Buildings.  Defined as follows:

“Mortar used for brick work, one part of lime to three parts sand; and mortar used for stone work, one part lime and four parts sand.  No inferior lime shall be used, and all sand shall be clear, sharp grit, free from loam.  Nothing shall be construed in this law as to prevent the use of cement.” 

This law is revised and tweaked until around 1887 where the laws note the following:

“The sand used for mortar in all buildings shall be clean sharp sand and shall not be finer than the standard samples kept in the office of superintendent of buildings which samples be approved by the of examiners named in this title and be kept in suitable glass for the guidance of the officers ..."

Prior to ASTM, the building department was to keep the control sand sample in a glass jar for inspection comparison.  By 1901 the building code (ordinances) of New York City begin to better define the mortar mix and by the original issuance of the New York City 1938 building code the means and methods and technical data are clearly and numerically defined, see sections 7 and 8, now stricken from the current 1938 code. 

(4) – Wetting Brick and Freezing Weather  

Section 8.4.2.3 in the original 1938 New York City Building code states “All brick having appreciable absorption shall be thoroughly wet before laying.”  A Treatise on Architecture and Building Construction - Prepared for Students of the International Correspondence schools (1899) addresses the purposes of wetting brick, to mainly avoid the brick absorbing too much moisture from the mortar and therefore weakening the effective strength of the mortar.  In 1915, in which many technical means and method codes for New York City were made effective and adapted into the first version of the 1938 building code, the code addresses wetting and freezing weather.  Section #251 of Article 13 – Masonry Construction (As amended by ordinance effective October 6, 1915) states: 

“(2) Protection against freezing.  No masonry shall be built when the temperature is below 28 degrees F. on a rising temperature or 32 on a falling temperature at the point where the work is in progress.  No frozen materials shall be built upon.

(3) Wetting brick.  All brick shall be thoroughly wet just previous to being laid, except in freezing weather, when they shall be thoroughly dry.”

This essentially means, a couple knuckleheads tried to wet brick in the winter or install brick over frozen mortar below freezing and something went wrong, and code had to be written.

Thesis:   Case Study on bonding mortar area based on literal CAD drawing interpretations of Chapter 410 of the Laws of 1882 – Title Construction of Buildings Section 480 

This math problem is formulated as follows: mortar area inches bond / brick wall cubic inches = a percentage%.  The greater the ratio the better the bond, in theory.  This consideration for better bonding excludes possible geometric and overlapping differences between the brick bonding patterns.  We're strictly looking at the area of mortar per quantity of brick laid and are proposing more mortar as glue is better, in theory.

Scenario #1 – Header Turned Every Sixth Course  (based on drawings this is actually a 7 course problem): 345.78 sq.inf/5343.68 cu.in = 0.0647 = 6.47%

Scenario #2 – Diagonal Headers Every Fifth Course Herring Bone/Diagonal #1 (nothing researched indicated this bonding course happens more than every fifth course):75.70 sq.in/3816.91 cu.in = 0.0198 = 1.98% 

Scenario #3 – Diagonal Headers Every Fifth Course Herring Bone/Diagonal #2 (nothing researched indicated this bonding course happens more than every fifth course):  90.00 sq.in/3816.91 cu.in. = 0.0236 = 2.36% 

Scenario #4 - Splitting face brick in half and backing the same by a continuous row of headers (nothing researched indicated this bonding course happens more than every fifth course):  180.00 sq.in./3816.91 cu.in/180.00 sq.in. = 0.0472 =4.72%

Conclusion: The diagonal and herringbone brick laying pattern has far less bonding area ratio to cubic brick wall than the basic detail outlined in the code.  If the amount of bonding mortar is what holds a wall together and after 100 years one of the above scenarios is failing, what then is the threshold for minimum bonding mortar before failure?

Footnotes:  

*Bond Timber – This is a bad idea.  A wood timber to bond your bricks.  Common sense would tell you wood decomposes far faster than baked clay – brick.  Why would you place this between hundreds to thousands of pounds of brick?

**Wythe is not defined in Audels (1929), rather “withe” is defined as – a partition between two flues in the same chimney.  

References:

[1] Link to all New York laws from 1638-1922 - all laws were reviewed for references to the Brick

[2] Brunelleschi's Dome: How A Renaissance Genius Reinvented Architecture by Ross King

[3] Audels Masons and Builders Guide #1 (1929)

[4] 1899 – Treatise on Architecture: I, II, III, IV, V, VI , VII, VIII