Why do brick spall?

(Michael Bryan) #1

Brick spall when they are too soft and porous. This permits the brick to absorb and retain too much water which then can freeze and expand breaking away the brick surface.

While this is merely a general rule and not an absolute, there are two typical times when brick spalling occurs. The first is when brick have been reclaimed and re-layed as "used brick". The second is a manufactured brick that was simply substandard.

The interesting thing about the first reason is that early American masons actually did understand brick density and vulnerability issues. They culled and set aside the soft brick for the interior withes of solid masonry construction. Unfortunately, masons in the 60's and 70's weren't as thoughtful and installed them as exterior brick. It didn't take long for them to fail.

Occasionally an inspector may notice spalled brick on the side of an old row house and assume this is an exception. But, typically, upon closer examination it will become obvious that even these exposed soft brick were not originally exterior brick. Another building which has been torn down once adjoined this building. The silhouette of the previous building will be apparent (outlined) through a change in brick appearance and quality of workmanship.

The second common circumstance under which an inspector will see spalled brick is in houses built in the 60's and 70's. Some brick manufacturers during that period of time were using inferior materials. When that fact became apparent, the ASTM devised absorption standards that some pits and manufacturers could not meet. They were forced to close down.

For these reasons, an inspector should not expect to see much brick spalling in homes built in the recent past or future.

As a side note, on occasion we may see brick that have come apart near the top of a chimney, but this is not typically spalling. When the crown of top joints fail on a chimney and permit water to enter and freeze in the cores bricks can literally spit apart.

(Jae Williams) #2

Thanks, Michael--most informative.

I've never really wondered why bricks would spall, though I have seen
it on many occasions, but now that you have explained it so well, I
think I will start wondering--and now I know why.

Thanks again. I can pass on this info to others and, boy!! will they
think I'm smart!!!

(Rick D. Jarrett) #3

Another part worth mentioning is the fact that manufactures in the brick making process were and still are using sawdust added to the clay before firing. What this did was allow the the sawdust to burn off in the firing process and make a lighter, softer brick. This was great for the brick layer and the freight charges but made a porous brick that would absorb water and freeze and pop the faces off of brick. Most of these bricks were designed for the southern staes that did not have freezing temperatures. The problem came when the northern states started selling them.

(Jae Williams) #4

Hey, now I'm even smarter--thanks, Rick.

(William J. Decker) #5

Bryan, Jae, et al.

In this area, at least, we have a lot of 3 and 4 flats that were built in the 20s. They use double wall brick construction with the inner wall being structural. They usually have flat roofs and brick parapet walls with clay coping tiles.

A common defect is for the coping tiles to crack or the mortar between them to go bad. This lead to water falling down between the two brick walls. Having no weep holes the water starst to pass through the brick and efflorece. This is usually accompanied by spalling.

Most people will just parge the brick, but they hardly every fix the cause, the cracked coping tiles. Or, if they do, rather than replacing the tiles, they just use plastic roof cement and patch. This only lasts about 1 or 2 years, then it is back to square one.

Just my little contribution.

(Michael Bryan) #6

And, interestingly enough, parging the brick without stopping the moisture intrusion actually accelerates the deterioration of the brick. The cement in the mortar holds the moisture in to freeze and expand.

(Marcel R. Cyr, CMI) #7

My two cents to the subject; this might help explain why bricks spall.
I would also try to help Jae in more learning. He is getting smarter by the minute. Here is more information for you Jae.

Durability. The durability of brick results from incipient fusion and partial vitrification during firing. Since compressive strength and absorption are also related to the firing temperatures, these properties, together with saturation coefficients, are taken as predictors of durability. However, because of differences in raw materials, a single value of compressive strength or absorption will not reliably indicate the degree of firing.

The classification of brick is determined by the usage of brick in specific applications. Brick used in the wrong application can lead to failure or an unpleasing appearance. Standard specifications have been developed to produce uniform requirements for brick. The standard specifications include strength, durability and aesthetic requirements.

The classification of brick is determined by the usage of brick in specific applications. Brick used in the wrong application can lead to failure or an unpleasing appearance. Standard specifications have been developed to produce uniform requirements for brick. The standard specifications include strength, durability and aesthetic requirements.

The classification of brick is determined by the usage of brick in specific applications. Brick used in the wrong application can lead to failure or an unpleasing appearance. Standard specifications have been developed to produce uniform requirements for brick. The standard specifications include strength, durability and aesthetic requirements.
The classification of brick is determined by the usage of brick in specific applications. Brick used in the wrong application can lead to failure or an unpleasing appearance. Standard specifications have been developed to produce uniform requirements for brick. The standard specifications include strength, durability and aesthetic requirements.

BRICK CLASSIFICATION
[size=2]Depending on its use, brick can be classified by one of several specifications.

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http://www.upchurchkimbrough.com/technotes/images/9aspecification.jpg

**Efflorescence
**Efflorescence is a crystalline deposit of water-soluble salts which forms on the surface of masonry. The principal objection is an unsightly appearance, though it typically is not harmful to brick. The test for efflorescence is described in ASTM C 67. The brick is given a rating of "effloresced" or "not effloresced". ASTM standards (C 216, C 652, C 902, C 1088) require the rating for brick to be "not effloresced".

Marcel :) :) ;) :mrgreen:

(Raymond E. Wand) #8

In many old farmhouses which were double "clay" brick" due to age and construction methods they did not use vapour barrier. Of course the warm moist laden air was often drawn out through the outer walls carrying with it moisture. During freeze thaw cycles the soft bricks face would pop. Over the years the cycle repeats, causing more spalling. Another cause is the lack of gutters, and water spilling/splashing against the brick causing spalling.

(Michael Bryan) #9

However, keep in mind, guys, that a properly fired brick of the correct materials composition should not spall under any circumstances. That is the larger part of the original message. Brick spalling is a materials problem which is exasparated by poor conditions.

(Raymond E. Wand) #10

Michael,

I guess it depends alot on where the red clay comes from. In my area there are pristine red clay bricks over a hundred years of age, and other old brick that has considerable spalling. Of course in the old days they did not have modern computerized kilns or quality control like today.

(Jae Williams) #11

From Marcel...
"The durability of brick results from incipient fusion and partial vitrification during firing. Since compressive strength and absorption are also related to the firing temperatures, these properties, together with saturation coefficients, are taken as predictors of durability. However, because of differences in raw materials, a single value of compressive strength or absorption will not reliably indicate the degree of firing."

Now I have a headache.

(Michael Bryan) #12

Hmm.... why did we have to take something so basic and simple and make it into something no one can comprehend? :-D

What I wrote as the beginning of the thread is easy to understand and it's the gospel.

Brick spalling should be and as far as I can tell is a thing of the past. Bricks made since about 1980 aren't experiencing that problem anymore.

(Michael Bryan) #13

Raymond,

Are you experiencing spalling on materials produced within the last 20 years? I kinda doublt it, but let me know if you are.

In the late 70's or early 80's the ASTM came up with pretty tough absorption standards which put a few pits and manufacturers out of business. That should have been the end of spalling.

I haven't seen anymore spalling.

(Marcel R. Cyr, CMI) #14

Hi. Michael;

Since I have given Jae a headache, :) :) ;) I guess it would be proper to apologize for this rampant information.

I have tried to give advice off the cuff before, but was always brought down by some Manufactures literature that someone found, and when I use the same information I get the same reluctance in information forwarded, I guess I can't win for losing.

I know the reason bricks spall, and the information supplied in the earlier post describe some of it.
I worked in a block and brick Manufacturing Plant back in 1969, (the golden years) and learned quite a bit about brick, which included visiting Citatel Brick in Canada. Very educational for those years. Would like to actually visit it today to see the technology change in brick Manufacturing.

Working with Manufactured Products everday, because the HI business is part-time, you get to learn what works and what does not. Not all Manufactures Products prove fruitfull to the Common Public. Some Products don't make it after the first year. They call it business.

Again, I would like to apologize for any statements that could have been construed over and beyond people's or this boards intent.

I would like to point out at this moment, that I am here to help anyone that belongs to NACHI, and hope that my experience can and will help at least one person. That would make my day.

Many things said, if anything helps, I hope I have accomplished something to benefit the growing public.

Thank you for your patience.

Sincerely, Marcel
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(Michael Bryan) #15

Hmmm... maybe I owe you an apology! :-D (we're Chip and Dale, the chipmonks!) I certainly didn't think an apology was in order. And, we're all trying to merely instruct based upon our experience.

I bet you know or remember Seymour Barr out of Winchester? He was a plant owner/manager until he retired to simply sales.

I was a journeyman mason for about 12 years and a gen mgr and estimator after that.

At any rate, please feel free to contribute or even correct at any time! I don't claim infallibility. Most of what I dare to write about I've investigated during my career with expert friends like Seymour or Riverton Lab Techs etc. simply because I care to understand. And, being a member of the BIA and NCMA helped a lot.

But, again don't ever apologize for teaching. It's the ultimate gift. I just try to keep things simple mostly because what we must ultimately do is explain the complex and complicated to clients with little understanding.

(Jay Moge) #16

:( I'm not yet a member Marcel, so does this mean that all the "help" you've given me is crap??:( :mrgreen: ;-)

(ekartal5) #17

Hey Will,

How about some of those 2-flats in Rogers Park north of Devon. Decayed brick and mortar practically on the sidewalks.

Erol Kartal

(Michael Bryan) #18

No, Jay, just that the "help" you've given us was crap. :-P Have a good and safe day all! Off to another day of inspections...

(Marcel R. Cyr, CMI) #19

Jay;
ABSOLUTELY not.

You are a great potential Member and still trying to invoke you in joining the Team at NACHI.
I believe you have the material and expertise to meet these qualifications.

Keep up the good work. Come and join us.

I will support the NACHI members, but also hope that since the NACHI board is free to all, that some knowledge from the Board will trickle down to Others.

Marcel
:) :) ;-)

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(Marcel R. Cyr, CMI) #20

Thank you Michael;

Marcel