High Performance Silane / Siloxane Water Repellents

One month ago, I walked into a national chain discount store. Coming out of the exit door was a woman with a 5 gallon can of a highly advertised masonry sealer in her shopping cart. My gut instinct told me that she was probably buying it to spray on her brick walls or concrete driveway. I just didn't get the feeling that she worked at a testing laboratory. Anyway, what a shame. The product she purchased was stearate-based. That means the main component of the product is very likely animal fat. These products and silicone based sealers are actually film forming sealants. They are just about the worst thing you could ever put on your brick or masonry surfaces - especially if you live in a climate that experiences freezing temperatures.

Film forming sealants do just that - they form a film on the surface of your masonry. It is a clear film that can sometimes turn cloudy. The film can also block water vapor from escaping to the atmosphere. If water vapor works its way to the surface of masonry, collects and then freezes, you can suffer spalling, flaking and other surface deterioration.

The better way to treat masonry is to apply penetrating water repellents. These products contain special chemicals called silanes and siloxanes and/or a blend of the two chemicals. These nifty chemicals partially block the capillaries in brick, concrete and mortar. The partially blocked spaces then actually repel water instead of allowing it to enter the masonry. Since the passageways are not entirely blocked, they allow water vapor to readily escape to the atmosphere.

I have listed a few companies that make high performance silane and/or siloxane water repellents. There are undoubtedly twice as many as I have listed ... maybe more. Many if not all of these products are sold exclusively at brickyards or specialty building supply stores that sell to bricklayers or concrete contractors. You can find these stores by looking in your Yellow Pages. Look under "Building Supplies" or "Brick." One of the companies below not only sells to these specialty stores but also sells directly to homeowners. They ship the product directly to your front door via UPS. Call Saver Systems listed below and see real customer service in action! Ask for Masonry Saver.

Act Quickly

Many of the brick and masonry sealers have to be applied in favorable weather conditions. Most are temperature sensitive. That means the air and surface temperature must not be below a certain minimum temperature. Read the instructions carefully!

Further Reading

• Measuring Water Penetration
  by Kim Basham & John Meredith
  Masonry Construction November 1995
  (This article is available in PDF format for free downloading from the Masonry Construction web site!)

• Reducing Water Permeance in Masonry Walls and Chimneys
  John Meredith
  Sweeping April / May 1994

Flashings

We already know that brick walls are not waterproof. Once the water is behind the brick veneer, we need to capture it and redirect it to the exterior of the wall so it can't cause damage. This is the job of flashing material. Flashings are not easy to install correctly. This is especially true at inside and outside corners. The flashings need to be overlapped and cut in such a way so that water will not enter through the seams.

What's more, the water resistant membranes such as tar paper or the new, fancy water barriers need to overlap the flashings. This practice requires work above doors and windows. The flashings need to be "laced" behind the water membranes.

Flashings also need to be placed at door sills, window sills and any other place where the brick has a horizontal break or interruption.

Quite possibly the best brick flashing I have seen is one made by the Grace Construction Products. It is called Perma-Barrier.

The Water Pathway

Mortar droppings can easily clog the narrow space behind brick. The droppings accumulate as the brick wall gets taller and taller. If this space becomes clogged, then the water can't easily escape through the weep holes below. There is only one product I have seen that permits water to easily find its way to the weep holes. This product is called Mortar Net. It is a plastic mesh product that looks like a saw-toothed shingle. This product can be found at companies that sell brick.

Weep Holes

These are the simple drain holes at the base of walls or on the first course of brick above a door or window. Without weep holes, there is no easy way for water to escape from behind brick walls. The Brick Industry Association recommends weep holes be placed on 2 foot centers. Most model building codes permit a spacing of 4 feet on center. In my opinion, you can't have too many weep holes.

I have seen unknowing homeowners caulk these holes closed. Don't do it! They are important and must be left open at all times.

Masonry Wall Ties

Non-professional bricklayers often create hazards by not installing a sufficient number of masonry wall ties in brick veneer work. A wall tie is a connector. These simple metal devices attach the brickwork to the wood frame structure. Without wall ties, a brick wall can simply fall down and away from the house. The model building codes are very specific in the spacing of wall ties. They tell you how often they should be spaced vertically and horizontally. Sometimes they will specify a minimum amount of wall ties per square foot of brick work. The building codes also tell you how far each nail should penetrate into the wood sheathing or wood studs. Pay attention to this specification!

Mortar

This is going to be your biggest challenge. I would like to see you have your bricklayers make their mortar like the old timers. The premixed mortars used today are simply too strong. That is fine for today's higher strength brick, but it is unnecessary in brick veneer work. A low strength mortar with a high lime content is what you want. The extra lime in the mortar actually will help prevent water from getting between the brick and mortar contact zone. A great low strength mortar that you might try can be mixed using the following proportions: 5 measures of sand, 3 measures of lime and 1 measure of Portland cement. This mortar mixture is an absolute necessity if you decide to use used brick on your house or chimney.

The Future

If you want to set up your son or daughter in a future business that is going to do quite well, I suggest you teach them how to remove the bottom eight courses of brick from a house without causing the brick above to collapse. They will also need some carpentry skills as they will be replacing the rim joist or band board that sits on top of the foundation. You see, these wood framing members and quite possibly joist ends and wall studs are going to be rotted. Years of penetrating moisture will have caused this damage. The sad thing is that all of this expensive work could have been avoided. If only the bricklayers and builders had done their homework and taken the necessary steps to collect and divert the incoming water.

Preventing Brick Leaks

Bricklaying is a true craft and art form. Like so many things in residential construction today, it is a dying craft. There are just a handful of masons who still strive to do quality work and want to do it right. You will find that the largest majority of these masons actually do commercial and institutional work.

Many residential masons - hundreds of whom work in southwest Ohio - do not have adequate training. They are young people who start to work for bricklayers who have not had any training themselves, or who do not stay abreast of new products or technology. The same thing may be true in your city or town. You may have bricklayers who are simply doing things wrong because they don't have a clue how to do them right!

You stop leaks in brick masonry by understanding that water does penetrate brick and mortar. You solve leaks by capturing the water and doing whatever is necessary to redirect it outside the brick wall. These methods are covered in greater detail later in this Bulletin.

Brick Sealers - What For?

I am amazed at how people think you have to seal masonry to preserve it. Fifty years ago there were no brick sealers! How have all those old brick buildings lasted? How did they survive before sealers? The point is that many of today's brick are much stronger than those that are 70 to 100 years old. Old brick sometimes didn't get fired as hot or as long as today's brick. There were inconsistencies in materials and quality standards. A good brick made today can easily last hundreds of years without a sealer.

The mortar many bricklayers use today is also different than that used 100 years ago. Today we use high strength mortars. They have considerably more cement in them than those from 100 years ago. The added cement helps to protect the mortar from weathering. As such, sealers aren't needed to protect the mortar.

The use of sealers has blossomed, I believe, because of the problems with leaks. The growth of the industry is also fueled by massive amounts of advertising. If a company can convince you that you have a problem and they have a solution, then a sale is a possibility.

A Finger in the Dike

So your bricks leak now. What do you do? A sealer - really, you want a water repellent - is maybe going to solve your problem. There is a possibility that the brickwork is so poor and the water entry paths so large that a water repellent just can't stop all of the water migration.

Remember that wind driven rain is your biggest culprit. The weight of the water driving against brick and mortar actually squeezes water through the brick like toothpaste through a tube. You have probably noticed this fact.

Some heavily advertised national brand products are film forming sealants. These are also rans as far as the Brick Industry Association is concerned. The best technology available involves special chemicals called silanes and siloxanes. These are cousins of the old standby silicone. Silicone is also a film forming sealant. It is not recommended for any masonry that can be subjected to freezing temperatures.

Many of the silane and siloxane sealers are environmentally friendly. They are water based and clear. They apply easily with a hand pump sprayer. I recommend that you follow the installation instructions to the letter. Some instructions are detailed and some water repellents may require two coats. Spend the time to read the label!

The above product links are affiliate links. I get a tiny commission if you purchase these from Amazon.

There is a common thread in all of the following articles about instructions for tuckpointing. Tuckpointing that looks good is not an easy task. Patience, skill and hand-eye coordination are necessary if you want your tuckpointing to match the existing mortar. Some of the articles have older publication dates. Don't let that scare you. Much of the information concerning tuckpointing masonry is timeless. It has been known for quite some time how to do it. The trouble is that craftsmen and others simply forget or fail to pass along the information correctly.

Avoid mismatching mortar! Find a good contractor and learn the secrets to repairing masonry with my Masonry Repair (Chimneys, Stucco & Brickwork) Checklist. I offer a 100% Money Back Guarantee.

Mortar Mixtures for Tuckpointing - Hydrated Lime is Best

Original Copyright 1998 - Tim Carter ALL RIGHTS RESERVED - Revised 2023

A Blending Experiment

The mortar mix you see used by brick layers today contains two ingredients: hydrated lime and Portland cement. In fact, the Portland cement ratio is quite high. Old brick layers used to mix their own mortar on the site by blending lime with Portland cement. Old houses, say over 100 years, rarely had any Portland cement in the mortar. The bricklayers just used hydrated lime and sand. This is what the Romans used to make their concrete. They also discovered early on to blend volcanic sand that had a very high silica content. They mined this from local volcanos in Italy. It's called pozzolanic deposits if you want to get technical. 

How do I know this? My college degree is in geology. Why is it so important to have a high silica content in your mortar or concrete? Silica has a hardness of 7 on the Mohs scale and is a major component of granite. Surely you know how long-lasting granite is, right?

Hydrated lime and Portland cement are available at building supply houses that supply bricklayers. If you look in the Yellow Pages under "Brick - Supplies" you will eventually find a company that sells bags of lime. It is inexpensive and it is white - pure white! Author's Note: The previous sentence shows you how old this article is. What young person even knows what the Yellow Pages are?

Mortar Strength / Self-Healing Properties

Brick walls are constantly on the move. The heat of the sun causes them to expand and contract. If the mortar between the brick is too hard, the brick will crack. Portland cement makes mortar hard. Older brick tend to be softer than today's brick. Thus, old mortar had much less Portland cement than today's mortar. The lime content of the old mortar was very high.

Why is hydrated lime so important? You need to understand how it's made. You also need to recall a bit of your high school chemistry. Hydrated lime is a powder. It's made by taking the extremely durable rock limestone and heating it to a very high temperature. The heat of the fire creates a chemical reaction in the rock. The Romans discovered quite by accident this as they probably had roaring fires that were surrounded by pieces of limestone to contain the fire. Once the fire was out and a rock was crushed, they discovered if you took the powder and mixed it with water, the slurry would get HOT and once it cured it was ROCK again! They simply reversed the chemical reaction.

Lime adds another benefit, one we could use in today's mortars and even concrete. Hydrated lime is somewhat water soluble and reacts with carbon dioxide and water. Small amounts of the hydrated lime remain in the mortar you make. As time goes on, the lime in the brick will can wake up if a small crack develops. The crack allows water and carbon dioxide to enter deep into the mortar. The lime reacts with the water and gas and heals the crack.

This is a fantastic small book sharing exactly how you should use hydrated lime. CLICK THE IMAGE or HERE to have it delivered to your home in days.

Avoid mismatching mortar! Find a good contractor and learn the secrets to repairing masonry with my Masonry Repair (Chimneys, Stucco & Brickwork) Checklist. I offer a 100% Money Back Guarantee.

Proportions

The first step in mixing new mortar is to blend Portland cement and lime together. If the mortar is very soft and old, you may choose to blend six parts lime to one part Portland cement. If your mortar is very light in color, be sure to purchase white Portland cement. If the mortar is darker, you may get by with gray Portland cement. Mix a very small batch to begin. I would mix no more than 7 to 8 ounces (by volume) to begin. You then mix two parts sand to one part of the blended lime and cement. Be sure to write down your proportions.

You blend the sand, lime and cement together dry. Then add just enough water to make it wet enough to form into a ball. The color of this mixture should match very closely the color of the existing mortar when it is wet. If not, you need to start over with your lime and cement proportions. Pay attention to the sand proportions too. If the existing mortar has not too much sand visible, you may have to mix 1.5 parts sand to 1 part of the blended lime and cement.

To get a perfect match, you should let the mortar dry for several weeks. Hold the sample next to the existing mortar to see how close you came.

Read about an aid for tuck point mortar joints in my September 1, 2009 Newsletter and September 15, 2009 issue.

In a Rush? - Don't Apply!

Buildings sometimes settle and cracks develop in the mortar joints. Older mortar will succumb to the elements and simply erode away. This is often the case if water leaks from a gutter or downspout and is allowed to stream over the face of a brick or stone wall.

I have chiseled out many a mortar joint. It is tedious work, plain and simple. If you want excellent results, be prepared to take your time. The brick must not be chipped in the process. You can easily chip brick or stone if you aggressively attack the mortar joint. Hard blows from a hammer will transfer concentrated blasts of energy to the mortar. This energy is often absorbed by the brick. Chips and cracks are common if you hammer too hard. The chiseling action must be directed sideways in the joint, not towards a brick.

Mortar Removal Tips and Techniques

The removal of the old, loose mortar is the most important part of a tuckpointing job. If you cut corners here, you might as well forget about doing the job at all.

There are three ways to tackle the job: hand work with a hammer and chisel; the use of power equipment, or a combination of the two. If you have just a little repointing to do, a hammer and chisel may be the trick. However, if there is a significant amount of work you may combine a grinder or a hammer drill to assist you.

IMPORTANT TIP: Power equipment will permanently damage brick surfaces. You will become fatigued and a drill, power chisel, or a grinder will slip and scar or chip a brick. I only advocate the use of power equipment for small periods of time when you are fresh and alert.

Need to repair your masonry? Find a good contractor and learn the secrets of the trade with my Masonry Repair (Chimneys, Stucco & Brickwork) Checklist. I offer a 100% Money Back Guarantee.

Pointing Chisels

The task of removing mortar by hand is made easier if you choose the correct chisel. Purchase a special brick pointing chisel. It is a small, flat chisel that resembles a miniature, thickened carving knife. The chisel comes to a point and the shaft of the chisel is approximately 1/8 to 3/16 inch thick. This way it can easily fit between two brick.

You need to chisel approximately 3/4 inch deep into the old mortar to enable you to get a good bond with the new mortar. The new mortar needs to be able to have adequate brick surface to adhere to.

If the mortar is old lime mortar, chiseling will be easy. If the mortar is a rich Portland cement mortar you may have to use a roto-hammer with a 1/4 inch bit. Drill straight into the mortar keeping the holes about 1/4 inch apart. This method will allow you to finish the job with the pointing chisel.

Always remove the loose mortar and dust before proceeding. I always squirt out the joints as well with water. The surface of the old joint must be dust and grit free for a good bond.

Matching Mortar Color

Once you have removed all the loose mortar, you still must invest a lot of time for a perfect match. Mortar texture and color must be matched. Color tinting may be involved. It was not uncommon for masons of old to add natural pigments to the fresh mortar mix. Dirt and weathering forces can cause the mortar to have a different appearance than when first installed. This is especially true of horizontal mortar joints, as you will find in brick walkways. My front sidewalk mortar is very dirty, even though it is only eight years old. When I go to repair a joint, I will be forced to scrub the joints clean with my Stain Solver Oxygen Bleach to make sure the repairs will match.

Sand Colors

Look closely at your existing mortar joints. If your house is older you will undoubtedly see lots of sand particles. Notice the different sizes and colors of the individual grains of sand. These small dots of color are responsible for a vast majority of the overall color you see. It is no different than the color photographs you see in the newspaper each day. Those photographs are made up of tiny color dots.

If you want your tuckpointing to match the existing mortar, you must start first with the correct sand. It might not be as hard as you think to locate the sand. The key will be to think about when the house was built and where sand pits were located at that time, not the present locations. Freight, or hauling, is the largest cost when buying sand. That is true today and it was true 100 years ago. For this reason, brick masons try to purchase sand from a convenient source.

Ask the experienced employees at the local brick supply houses and gravel pits where the sandpits of old used to be located. Try to see if there is still sand available from these old pits.

Mortar Analysis

To get a sample of sand from your existing mortar to compare with new sand, you need a little bit of muriatic acid. The acid will dissolve the old lime and cement from the mortar. The net result will be sand in the bottom of the glass or other vessel you choose to use for this simple process.

If you live in a coastal area, where sand often contains sea shells and other calcium carbonate pieces, the acid treatment will not work. The acid will dissolve the sand!

Mix 1 part of acid to 5 parts water in a clear glass if possible. Drop in some of the old crumbling mortar. If the mortar begins to bubble vigorously, that is usually an indication that the mortar contains a high percentage of lime. If there is minimal bubbling, Portland cement may be a majority binder.

In either case, allow the mortar to sit in the acid solution for up to several hours or days. You can redo the experiment after the bubbling stops to make sure the acid has done all its work. When completed, there should just be sand particles in the bottom of the glass. Pour off the acid and get the sand into a paper towel to dry. Once dry, put the sand into a small clear glass or plastic bottle that you can get from your local pharmacist. It's time to go find the new sand. Be sure you look at dry sand samples at the gravel pits and building supply stores. Pay attention to particle size and color.

Installing New Mortar

Once you have found the correct sand, and followed my instructions on how to blend the right amount of lime and cement with the sand, you are ready to point the brick joints. You need two or three simple tools to make this an easy task. Purchase or borrow a regular brick trowel, a small pointing trowel and a tooling jointer. The pointing trowel is simply a thin, rectangular piece of metal that is attached to a wooden handle. They come in different sizes to match the width of the mortar joint. Always use one slightly smaller than the width of the joint. The tooling jointer is simply a tool that creates a profile to match that of your existing joint. Some are concave, others create a V-groove and still others create a line.

You need to dampen the old mortar joint before installing the new mortar. Place mortar on the full sized brick trowel and hold this level with the joint to be filled. Use the small jointing trowel to bulldoze mortar into the joint. Take your time and do not get any mortar on the face of the brick. Strike off any excess mortar and allow the mortar to stiffen before tooling it.

To really match color and texture, you may have to distress the new joint in a month. Acid washing will often create a weathered appearance. Coffee, tea or other colored liquids can add colors to recreate dirt or other stains. Stand back at the street to judge the results of your work.