#7 (rev. 2001) Water Resistance of Brick Masonry - Design and Detailing Part I
#7A (rev. 2001) Water Resistance of Brick Masonry - Materials, Part II
#7B (rev. 2002) Water Resistance of Brick Masonry - Construction and Workmanship, PArt III
#7C (1965) Moisture Control in Brick and Tile Walls - Condensation
#7F (1986) Moisture Resistance of Brick Masonry - Maintenance
#8 Mortars for Brick Masonry
Brick Veneer Wall Flashings and Mortar Netting
There are numerous products that will work as good flashing materials. Where do you find them? Well, it may not be easy. I doubt that you will find them at a large home center. Generally, you must find a large brick supplier in your town that has a full line of brick supplies. If they don't stock the materials they almost always can order them. You can check the manufacturers listed below and ask who distributes their products as well. What ever you do, do not purchase PVC or low density polyethylene garbage bag type plastic.
RKL Building Specialties, Inc. This is a thin copper flashing coated with asphalt.
Carlisle Coatings & Waterproofing They make rubber flashings.
Firestone Building Products Co. As you would expect, rubber flashings - just like their tires!
Grace Construction Products Perm-A-Barrier - a modified asphaltic compound bonded to high density cross laminated polyethylene. Self adhering. This product looks like a winner to me.
Wirebond Fiberweb polyester film and Aqua-Flash® flashing
Cassady Pierce Company Copper and rubberized asphalt flashings
Sandell Manufacturing Co. Copper and rubberized asphalt flashings
York Manufacturing These are copper flashings available in different weights and with different fabrics and compounds. Flexible, just about any flashing for any purpose.
Mortar Net USA A wonderful invention that keeps water flowing!
Masonry Construction - This is a trade publication magazine that appears monthly. It is loaded with excellent articles on masonry. If you go back through past issues you will find numerous articles that speak about brick veneer leakage, flashings, and special mortars. The publishers even sell a book of past articles titled "Flashing in Masonry Construction: Selection, Detailing and Installation."
This is what the back of your brick veneer looks like. Note how it often touches up against the wood wall sheathing! This column was SO GOOD that I shared with the 31,000 subscribers who read my November 18, 2018 AsktheBuilder Newsletter. Copyright 2018 Tim Carter
"Water enters brick walls where the mortar contacts the brick. Yes, I know that looks like a solid joint, but we're talking tiny cracks."
Brick Veneer Leaks Checklist
brick veneer has a long history of leaking
hydrated lime mortar is the best one to use
high-quality flashings in the brick capture the water
unclogged weep holes are a must
Brick Veneer Leaks Are A Surprise To Many
The reason I felt that brick construction was waterproof was based on my observations. I had worked in hundreds of older brick homes. None of them had any apparent water damage. I never recall getting a complaint from a homeowner in one of these older homes about water streaming down an interior foundation wall after a moderate rainfall.
There is a big difference between the solid brick houses of 100 years ago and the brick veneer houses of today.
This is a solid brick house. Behind the brick you see on the outside is a layer of 4-inch-thick concrete block or another interlocking row of brick. All you have to do to determine this is to look for the stretcher brick that is laid on end in the different rows. Copyright 2018 Tim Carter
When Were Solid Brick Houses Built?
Brick houses from the turn of the century and even those built during the 1950's where almost always solid masonry construction. That is, the exterior walls were constructed of several layers or wythes of brick. Some older houses that I worked on had brick walls that were 3 rows thick! These walls often measured 14 inches thick.
These older brick walls were massive. They were structural in nature. That is, they were designed to support the floor loads and roof loads of the structure.
New brick construction doesn't even compare. The brick on your new home or the one you might be getting ready to build is simply a facing, a veneer. Rarely are these bricks supporting anything but themselves. The walls are only one brick wide.
Where Does Water Leak Into Brick?
Water enters brick walls where the mortar contacts the brick. Yes, I know that looks like a solid joint, but we're talking tiny cracks. What's more, when you add wind to the rainfall, you can have real problems. Driving rain happens all over the U.S., but some places get driving rainstorms more than others.
Why Don't Solid Brick Houses Leak?
The older solid brick houses didn't experience leakage for two primary reasons. The water had a long way to go and the bond between the brick and mortar didn't have as many tiny cracks. Older brick construction provided an often solid barrier. The water may have to penetrate 12 to 14 inches before it got inside. By this time, the rainstorm may have long since passed.
Was the Brick Mortar Different?
Furthermore, the mortar that was used to hold together the brick years ago is very different than the mortar used today. Years ago the bricklayers blended their own mortars. They would mix sand and hydrated lime to make their mortar.
Some masons might have added Portland cement. A typical mix of this tri-blend might be five parts sand, three parts lime and one part cement.
Does Modern Mortar Contain Lime?
Most modern-day premixed bagged mortars do not have as high a lime content. They tend to have a higher proportion of cement.
This gives the mortar higher strength, but strength is rarely a factor when dealing with a brick veneer. Remember, the brick on a brick veneer home has no structural value. Strength is not a factor.
The lime in a mortar plays a special part. Its presence allows for better bonding qualities, plasticity or workability, moisture content stability and elasticity. These may sound confusing so let me explain.
Lime is a unique compound. In the dry form, it's simply a powdered form of calcium hydroxide. When this dry compound reacts with water and carbon dioxide it begins to crystallize.
This is a fantastic small book sharing exactly how you should use hydrated lime. CLICK THE IMAGE to have it delivered to your home in days.
If enough lime is present in a mortar mix, believe it or not, not all of it gets totally wet when initially mixed. Some of the lime sits around for years deep inside a mortar joint. Then, if a small crack develops, water and air might start to penetrate the brick. The lime gets wet and crystals start to grow. Soon the crack has closed up. This magical property is called autogenous healing. It can stop water leakage big time.
Did Bricklayers Know Brick Leaks?
Commercial builders and bricklayers have known for many years that brick walls are not waterproof. They have developed extensive building practices and products to capture this water and redirect it back to the exterior face of the brick. They use continuous flashings. These flashings work very much like the flashings on the roof of your house. A flashing is simply a barrier material that is unaffected by water.
How Was Brick Knowledge Taught Years Ago?
Years ago, workers who entered the construction trades did so as apprentices. The knowledge of each craft was passed down slowly and methodically. For whatever reason, this practice ended at the end of the 1950s for the most part.
Construction workers today simply don't receive the training like they used to. Knowledge about a trade is either missing or not transmitted. The result is poor performance of products or construction techniques.
A perfect example of this is bricklaying. The connection of knowledge transfer between the commercial bricklayers and the residential bricklayers is broken. Many residential bricklayers (and builders) don't have the foggiest idea why a wall flashing is an integral part of a brick wall.
What is the Worst Brick Flashing?
This is why you see builders and bricklayers use the inexpensive black garbage bag type plastic. This is why the joints where this plastic overlaps are not sealed. This is why there is no flashing above window or door headers and below window and door sills. It is a nightmare. Just ask any homeowner who has a leaking brick house.
You now know that the garbage bag plastic is worthless. It tears easily. It becomes brittle. Some builders (very few) switched to a thicker PVC flashing five to 10 years ago thinking that this would solve the problem. Heck, I used this stuff. Recent studies have shown that this material is not much better than the worthless garbage bag type plastic. The PVC looses its plasticity within five to 10 years and becomes brittle. Brick movement can cause tears.
Are There Great Brick Flashing Materials?
There are good flashing materials available. They cost a little more than the bad flashing materials. They take a little more time to install. But, if done properly, you will have a leak free brick home.
What are the Best Brick Flashings?
Some of the best brick flashings incorporate a very thin piece of copper embedded in an asphalt impregnated mat. Other flashings are high-density cross laminated polyethylene membranes. Some of the materials are modified asphalts with rubber. They all are made so that overlapping joints, inside and outside corner details can be easily sealed.
How Does a Brick Flashing Work?
A brick flashing is designed to intercept, capture, and divert the water flowing down the back of the brick. It redirects the water back out to the front of the wall.
Let's assume that you've put in your perfect flashing. That is only part of the job. Now we need to get the water back from behind the wall. We need to create little tunnels and make sure that the pathways to the tunnels are not blocked.
What Happens to Excess Mortar?
When laying brick, if too much mortar is used, excess mortar can fall behind the wall as the brick is pushed into place. These mortar droppings can't be removed.
This is what the back of your brick veneer looks like. Note how the excess mortar often touches up against the wood wall sheathing! Copyright 2018 Tim Carter
Can A Hidden Mortar Dam Form Behind the Wall?
If enough mortar falls behind the wall, a solid barrier can form. The trapped water then looks for a place to go.
I've seen where this water has built up, entered the frame wall and traveled under a hardwood floor some 10 to 12 inches. The water finds a seam in the subfloor and then drips into the basement. Imagine what will happen to this house in a short period of time!
What are Brick Weep Holes?
Weep holes allow water to escape to the outside of a brick wall. They should be placed as low as possible where a course of brick sits on top of a horizontal barrier (foundation, or a window or door lintel.) These weep holes should be placed every 24 inches.
I would also give serious consideration to a specialty product as well. This product is a plastic netting that fits behind the first several courses of brick immediately behind the weep holes. The netting is cut in such a fashion that it has different horizontal levels. Mortar droppings fall onto these levels and build up. However, the water can move sideways and then fall through the mesh. It hits the flashing and flows uninterrupted through the weep holes.
If you want a leak-free brick home, you must obtain some of the literature I have listed. Also, obtain some of the product literature brochures for clear, crisp illustrations of how these specialized flashings work. A little homework on your part will pay huge dividends.
Many of the following manufacturers will not be familiar to you. Their products are not commonly sold at most local hardware stores or 'giant' home centers. To find quality products, you may have to drive just a little farther and visit the stores that professionals buy from. In many instances, you will find the products below at building supply stores where sand, cement and plaster are sold. Brick companies often sell these high quality clear coatings. Once again, beware of products that say 'water repellent'. You may be purchasing a film forming sealant! If you have questions about a specific product, email me. I have a super detailed list of just about every clear coating made and its chemical makeup. I can tell you if it is a film forming sealant or a penetrant. Don't hesitate to contact me.
Author's Notes:
In August 2001, Joan Kaufenberg of ChemRex Technical Services sent me the following letter.
The EPA regulations that went into effect September 1999 lowered acceptable VOCs for all architectural coatings. There is a wide range of what is acceptable, depending on how the product is classified.
Most companies have reformulated their more popular products to be higher in active ingredient with a lower solvent content, or they have developed a waterbase or waterborne version. In some cases they have kept the same name, which is confusing, or they have added "VOC" after the old name to denote VOC compliance. In other cases, products have simply been dropped.
Descriptions of "water repellent" vs "sealant" vs "sealer" seem to be used interchangeably in the industry. One name more than the other does not necessarily denote a film former or a penetrant. However, we usually use the word "Sealant" to refer to a compound used for caulking--sealants are the higher quality elastomeric urethane, silicone, epoxy or polyurethane products used in expansion and control joints. The term "Sealer" usually refers to a coating or a penetrating product. It can be silane, siloxane, acrylic, urethane, or epoxy (or an inorganic silicate material which is used for hardening and dustproofing a concrete surface).
If customers want to contact us, they can call Customer Service at 800-433-9517 to find out the nearest dealer. Or they can call Technical Service at 800-243-6739 with product/application questions.
Dow Corning Corporation PO Box 994 MIDLAND MI 48686-0994 989-496-7881
BASF Building Systems 889 Valley Park Dr. Shakopee, MN 55379 952-496-6000
Hydrozo Silane Sealers
SaverSystems 800 S. 7th St. Richmond, IN 47374 800-860-6327
Masonry Saver Silane/Siloxane Blend penetrant
Thompsons Company 101 Prospect Ave. NW Cleveland, OH 44115 800-367-6297
Thoro Systems Products 7800 N.W. 38th Street Miami, FL 33166 800-327-1570
Thorosilane Siloxane Penetrant
Are you one of the manufacturers listed above? Do you want your company name to be a link to your website? Click here.
Properties of Various Clear Coatings
Data compiled by the Brick Institute of America 1995
Breathability - Water Vapor Transmission
Ability to Repel Water
Service Life
Film Forming Sealants
Acrylics
Poor
Very Good
5-7 Years
Stearates
Poor
Varies
1 Year
Mineral Gum Waxes
Poor
Good
Varies
Urethanes
Poor
Very Good
1-3 Years
Silicone
Fair
Varies
1 Year
Penetrants
Silanes
Very Good
Very Good
10+ Years
Siloxanes
Very Good
Very Good
10+ Years
Blends
Varies
Varies
Varies
Clear Coatings Literature
Colorless Coatings for Brick Masonry 6A (www.gobrick.com/BIA/technotes/TN6A.pdf) Moisture Resistance of Brick Masonry Maintenance 7F (http://www.brickinfo.org/pdfs/7F.pdf)
Available from:
Brick Institute of America 11490 Commerce Park Drive Reston, VA 22091 http://www.gobrick.com/
Reducing Water Permeance in Masonry Walls & Chimneys (http://www.chimneysaver.com/reducing_water_permeance_in_masonry_walls_and_chimneys.html) by: John Meredith Sweeping April - May 1994 Issue
Sweeping is a trade publication for chimney sweeps. It is possibly available in your library.
Brick, concrete block, stucco and mortar can absorb massive quantities of water. In fact, bricklayers often cover brick and block piles on the jobsite to protect them from rain. The reason is simple. Brick and block have a property referred to as 'suction'. This suction draws water from wet mortar into a brick or a block when it is laid. This, in turn, rapidly stiffens the wet mortar. This stiffening allows the bricklayer to continue to lay row after row of block and brick. If bricks absorb too much water, they can't suck water from the mortar. When this happens, the brick or block 'swims' in the wall.
Like a Sponge (Hum....)
Those of us who live in areas that experience freezing weather can testify to the power of freezing water. Allow water to soak into a brick, let that water freeze, and BINGO, major problems soon develop.
Efflorescence growing in the mortar of a brick fireplace. PHOTO CREDIT: Michael Hannum
Many people have experienced efflorescence (white salt deposits) on brick or block. Efflorescence is made possible by the tiny passageways in brick, block and mortar. Water travels right through a brick and dissolves the salts. These salts deposit on the surface of a brick after the water evaporates.
100 Years Ago
Many people have houses built from reclaimed or 'used' brick. These brick were often fired in low temperature kilns. The outer face each brick would vitrify (get hard), but often the core would remain relatively soft. Some bricks were harder than others depending upon their location within the kiln. It was an inexact science.
New brick are not all the same. Some new brick can be very soft. The clay used to make the brick can be of poor quality. The manufacturer may cut costs by reducing the amount of time the brick spend in the kiln. Quality control may be non-existent.
The point is this, in order to protect your brick structure, you may have to consider using some of the new clear masonry coatings. However, as in all things, there is a big difference between products you may be considering.
Sealers vs. Repellents
During the past 25 years, there has been an explosion of products that can be used to 'seal' masonry surfaces. The problem is, some things should be sealed and others should not.
My Webster's Dictionary defines seal as "a tight and perfect closure (as against the passage of gas or water)". Hmmmmmmmm, do you see the problem? A true sealer will totally block the passage of water. In fact, it will most likely block it no matter which direction it is headed (into or out of the item being sealed).
There are two primary categories of colorless coatings that you might apply to brick or masonry surfaces: film forming sealants and penetrants.
A film forming sealant produces a thin, solid film on the surface. A penetrant, on the other hand, is absorbed into the brick or masonry.
Sealants
Sealants work great if you are trying to coat brick or masonry to prevent absorption of oil, paint (graffiti), chemicals, etc. They also do a fantastic job of keeping water from entering brick or masonry. However, they have serious drawbacks.
Sealants can inhibit, or stop, the ability of a brick or masonry surface to breathe. Because they form a film at the surface of the brick or surface, they stop trapped water or water vapor from escaping into the atmosphere. In colder climates, this can cause brick spalling (flaking) when water, trapped behind the sealant, freezes, expands and fractures the brick or masonry.
Film forming sealants can also trap dirt, discolor, change the color of the masonry or brick, and produce a sheen or gloss when applied.
Sealant Ingredients
Film forming sealants often contain one or more of the following principal ingredients: acrylics, stearates, mineral gum waxes (paraffin), urethanes, and silicone resins. All of these ingredients act like paint when they come into contact with brick or masonry. They simply 'stick' to the surface and form a film. Some sealants are so heavy bodied that they can bridge small hairline cracks.
On a microscopic level, sealants are 'big'. Their large molecular structure does not allow them to penetrate into the small passageways in brick, block, stucco and mortar.
Often the principal ingredients of a sealant are listed on the product label. If you see any of the above things mentioned, you very likely are dealing with a sealant. Don't be fooled by labeling that says 'Sealant - Water Repellent'. Yes, sealers repel water, but you may want a product that breathes.
Penetrants
Penetrating clear coatings are, in almost all instances, the top performer. These products are excellent water repellents. They have a great ability to penetrate deeply, sometimes up to 3/8 inch into a brick or masonry surface.
Penetrants do not form a film on the surface of brick or masonry. Rarely do they change the appearance or color of the surface. They are able to penetrate because of their tiny molecular structure. These products coat the insides of the tiny passageways of the brick and mortar.
The primary ingredients of penetrants are silanes, siloxanes, or a blend of these ingredients. Note that these two ingredients look very similar to silicone. Do not confuse them!
Silanes have a very small molecular structure. They can penetrate deeply into masonry surfaces. Siloxanes have a slightly larger molecular size, but they also penetrate quite well. The interesting thing is that both of these compounds can chemically bond to the silica and alumina minerals often contained in brick, block, stucco and mortar. This bonding property and their ability to penetrate make for long service lives. Often these penetrating compounds can last in excess of ten years!
Be sure to read product labels. If the label doesn't say what it contains, call the manufacturer and ask. Always ask for the technical department when calling.
Over the years, I've seen many different spellings of efflorescence. Here's my growing list: effervesce, effervescence, effervescent, effleresants, effloreflance, efflorescence, efflorressance, effluorescence, eflorescence, eflorescents, ellforesce and ifflorescence.
Jennifer emailed me about a problem with mold in her shower drain pipe. Let her tell you what's going on:
"Help Me Tim!
In my newly constructed bathroom, I can already see mold (black and red mold) growing down inside the white PVC drain pipe of the new shower. Since it's only a couple of months old, I am wondering what happens after years go by.
Did the plumber use the right material when he installed a white PVC pipe for our shower drain? How is someone supposed to get rid of that mold without taking apart the shower drain every month? Thanks!"
Here's my answer to Jennifer:
That mold is normal. It can and should be cleaned. The sides of the pipe leading from the drain strainer down to the trap get covered in a bio-film. This gooey film is made up of soap, shampoo, body oils, bacteria, etc. It is a perfect environment for mold to grow in and on.
Simply take off the chrome ring of the drain strainer and use a bottle brush to clean the sides of the pipe as you run water in the shower. The mold and bio-film will wash off very easily. As for preventative measures, there isn't much you can do. Once you see how easy the mold and bio-film disappears, you will not be concerned.
These website links worked for me when this bulletin was published. Sometimes web pages disappear so if you get an error message make sure the link is exactly as it appears below before you give up.
http://www.aiha.org/ This website is the home of the American Industrial Hygiene Association - 1-703-849-8888. You can find environmental consultants/contractors here.
http://www.cdc.gov/health/mold.html This website is the home for Centers for Disease Control and Prevention (CDC), National Center for Environmental Health Questions and Answers on Stachybotrys chartarum and other molds.
http://www.cal-iaq.org//iaqsheet.htm This fact sheet from the California Department of Health Services provides information to people who have experienced water damage to their home and presents the health concerns related to mold exposure. It also provides general guidelines on mold detection, cleanup & removal of mold contaminated materials.
http://www.ehib.org/html_entity.jsp?bcc=papers&paper_key=FUNGI_INDOOR_1996 This web page from: Health & Environment Digest Vol 10, No. 2, pages 9-12, May/June 1996 titled Fungi & Indoor Air Quality written by Sandra V. McNeel, DVM and Richard A. Kreutzer, MD describes types of molds commonly found indoors in home and offices. Health effects and the physical conditions that encourage their growth are discussed. This article contains a table containing selected important molds found in damp buildings and how to prevent and control mold contamination.
http://www.epa.gov/mold/moldresources.html This website is provided by the EPA on identifying mold, clean-up and prevention. This site also contains links to other sites including the American Red Cross, New York City Department of Health and Occupational Disease Prevention, University of Minnesota, Department of Environmental Health and Safety and the Carpet and Rug Institute.
http://www.epa.gov/iaq/schools/tfs/guideh.html This is another website provided by the EPA and addresses mold and moisture in schools. This site goes into identifying and correcting common mold and moisture problems.
http://aappolicy.aappublications.org/cgi/content/full/pediatrics%3b101/4/712 This webpage is from the AMERICAN ACADEMY OF PEDIATRICS Committee on Environmental Health tells about the toxic effects of indoor molds. This page describes mold, their toxic properties, and the potential for causing toxic respiratory problems in infants. Also gives recommendations for pediatricians to reduce exposure to molds in infants and children.
http://iaq.custhelp.com/cgi-bin/iaq.cfg/php/enduser/std_adp.php?p_faqid=3018 This web page provided by the EPA is about Biological Pollutants in Your Home. This page provides you with information to identify what indoor biological pollution is, whether your home or lifestyle promotes its development and how to control its growth and buildup. Gives a list of questions to ask your doctor to help determine the effects on your health that may be related to biological pollutants in your home. This is a really helpful webpage.
If you want to remove mold in a hurry, it is best to use a solution of chlorine bleach and water. Chlorine bleach is an awesome sanitizer. But chlorine bleach is so harsh it can take the color out of fabrics and actually ruin fabrics. Chlorine fumes are also unpleasant, and can cause distress in people who suffer from asthma. If you make a mistake and mix chlorine bleach with other cleaning products, you can make poisonous chlorine gas!
The alternative is oxygen bleach. Oxygen bleach does a fantastic job of cleaning mold from surfaces and fabrics. My Stain Solver oxygen bleach is blended with soda ash to produce a powder that has maximum cleaning action. Call us at 513-407-8727 to order or visit: www.stainsolver.com
Manufacturers of Colored Mortar and Mortar Pigments
flamingo-BRIXMENT
Solomon Colors
Lambert Corporation
Lehigh Cement Company
Ebonex
Dynamic Color Solutions
Study the information on their web sites with respect to the proper techniques to employ when mixing and working with the colored mortars. They can be tricky!
Are you one of the manufacturers listed above? Do you want your company name to be a link to your website? Click here.
Several of the followings things can cause the color in your brick job to be inconsistent:
Using premixed mortar from different runs from the plant - all bags must be from the same run or batch.
Using different types of sand throughout the job.
Using too much water in the mortar.
Acid washing the brick.
Using too much or too little pigment in each batch of mortar if adding your own colorant.
You can find a list of over 100 brick manufacturers at the Brick Industry Association web site. Click the Resources tab; BIA Members tab; and Manufacturers tab. Choose ALL in the drop down lists to display a complete list. You can also search by state.
Most of these manufacturers have web sites with great product information and locations of local distributors.
Literature Sources and Installation Tips
Literature Sources
Some of the best literature, concerning brick and masonry construction, can be found in three different places: the Brick Industry Association; the Masonry Institute of America; and the Portland Cement Association. The Brick Industry Association (http://www.bia.org) publishes periodic pamphlets called Technical Notes on Brick Construction. These deal with just about any aspect of brick that you can think about. They also publish an incredible book called Principles of Brick Masonry.
Installation Tips
I could write pages and pages concerning installation of brick. The Brick Industry Association listed above has numerous books and pamphlets on this subject, as does the Portland Cement Association (http://www.cement.org). The key points are understanding that mortar is just like concrete. It requires special attention and techniques to achieve maximum strength. This is vitally important, as the mortar holds the bricks together!!! Brick veneer construction needs to be adequately attached to the walls behind the bricks, or else it might simply tip over and fall down. Flashing details and weep holes are important so water does not collect behind bricks. Start reading!
Bricks are basically a form of artificial rock or stone. They do not occur naturally. The raw material from which they are made, however is a raw material which is very abundant. Clay, which is a major portion of many soils, is used to manufacture brick. Shale, a soft sedimentary rock, is used as well. These two materials are found just about everywhere in the world.
The process of turning clay and shale into bricks is a somewhat simple process. The clay and/or shale is refined and then mixed with a small amount of water until it can be shaped into bricks. The bricks are then dried and put into a kiln, sometimes for days. The kiln is nothing more than a very hot oven. Temperatures can reach in excess of 2,000 degrees F. This heating or firing process is what transforms the soft clay into hard bricks. In this manner, the clay and shale become an artificial stone.
Surface Textures
Prior to placing the soft bricks into the kiln, manufacturers can do any number of things to the soft bricks to give them a texture. Some bricks are either rolled, brushed, scratched, or dimpled after they come out of the forming die.
Some manufacturers offer the capability to produce custom textures for a certain brick, however it is very expensive to have this done. But, if you have the money and want a very unusual texture, it can be produced. Patterns, letters, even sculptures can be produced on the face of individual bricks.
Coatings
If you visit a brick showroom, you will undoubtedly come across bricks which have coatings applied to them. These coatings, once again, are applied prior to the bricks entering the kilns.
Some of the coatings commonly seen are sand coatings, colored slurries of fine clay, pigments and water called "engobes", and Portland cement mixed with pigments. The colored Portland cement is mixed with water and applied to the bricks.
All of the coatings are semi-permanent. They do not produce color throughout the body of the brick. If the coating wears off or is chipped, you will see the inside color of the brick. Thus, it is important for you to choose a brick with a high quality coating if you like the appearance of these products. This is especially true of the Portland cement-based slurries. I have seen these coatings wash off of bricks after 15 or 20 years. This can be a severe problem if all the bricks on your house do not receive the same amount of weathering.
Strength
Not all bricks have the same strength. Their strength is a function of the type of clay and/or shale used as a raw material, and the temperature and length of time the bricks spend in the firing kiln. The higher the temperature and the longer you leave a brick in the kiln, generally speaking, the stronger it will be at the end of the process.
This is very important to know when shopping for bricks, as the last two points are directly related to the cost of a brick. Think of it, if you use more fuel to achieve a higher kiln temperature and you leave the bricks in for a longer period of time, your costs per brick are going to be higher.
Bricks which have been fired longer and hotter generally are a deeper color. Deep red, purple, and brown bricks are usually very hard.
A good example of bricks which are not hard and durable are those orange colored bricks you often see from old buildings in our inner cities. These bricks were usually produced in lower temperature crude kilns.
The hardest portion of some bricks is just the outer 1/4 inch. This is why it is dangerous to sandblast bricks. Sandblasting can expose the soft inner portion of the brick and cause it to weather at an accelerated rate.
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