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A Masonry Guide For Homeowners

This homeowner resource page covers the most common issues faced by owners of historic and vintage masonry buildings:

When to Call a Professional

Does HFS Provide Contractor Referrals?


How-To Videos: Diagnosing issues with foundations and basements; lintel and stair walls; and chimneys and gutters.

How-To Instructions & Supply Lists: Repointing, Patching, Cleaning, Coating & Staining, & Brick and Terracotta Glaze Repair

How-To Videos: Removing mortar, selecting mortar, and repointing

Chimney Repair Guidelines

A Note on Water Repellents

Supplemental Information

Homeowner FAQs

Recommended Information Resources

Cheat Sheets: Brick Parapets, Concrete Repair, General Masonry, and Pointing with Lime Mortar

If you have additional questions, please visit the Homeowner FAQs page for more information.

While we are happy to answer your questions and help you with your selections as time permits we do ask that homeowners who need special assistance please plan to come to the shop between 11am and 1 pm and call ahead (773-588-0800) to ensure that a restoration team member is available to assist. This time period is between our contractor rush hours so we will be able to more fully meet the needs of all our customers. Thank you for your understanding.

When to Call A Professional

Much of the basic maintenance and repair work is relatively simple and requires time, patience, and practice and is well within the capacity of most homeowners. We have seen some excellent repointing work done by homeowners who have made the effort to learn the skill and taken the time to practice and perform work carefully. Keim Mineral Coating application and spot repointing are common projects that are suitable for many homeowners, as is simple cleaning that doesn’t involve hazardous cleaning chemicals.


Work that requires a permit, involves structural repairs and/or scaffolding and most plastering projects are situations that call for a professional. If you intend on doing a chimney repair we highly recommend hiring a qualified contractor. For more information please visit the Chimney Repair portion of this page. Check with your local building department to find out if a permit is required for your project, and keep in mind that if you’re in a local landmark district special approval may be required before you begin your project even if permits aren’t required for non-landmarked residences.


If you plan on using Cathedral Stone’s JAHN repair mortars you must have a certificate from Cathedral Stone to install these products. HFS offers classes once a year in order to complete this certification. These workshops are open to all including contractors, masons, and homeowners. UPDATE: Due to the ongoing COVID-19 pandemic we do not have any classes scheduled.


Can HFS Refer Me to A Contractor?

We do not post contractor referrals or contact information on our website. However, the Chicago Bungalow Association is a useful resource in finding Trusted Referrals in the Chicago area.


When choosing your contractor there are several factors to consider:


1) Can they provide addresses for jobs they performed 10+ years ago?

2) Can they provide addresses for jobs they performed in the past year? How many were landmarked properties?

3) Can they provide you with a copy of their insurance certificate showing workmen’s compensation coverage?

4) Are they willing to create sample mock-ups on your building (grinding, cleaning, pointing)?

5) Ask what specific materials (mortars, coatings, cleaning chemicals, etc) they plan to use on your project and to provide you with product datasheets.

6) Ask how they plan to prepare your masonry for cleaning, pointing, etc.

7) Ask for proof of licensing and inquire about the training and certifications they have completed. Keep in mind that there is no official certification process to be a “restoration” mason, and experience alone doesn’t mean that a contractor will use the right materials and techniques on your building.


And always check with your local building department to see if you need to apply for any permits before work begins.

Terminology & Common Issues

Every project begins with a condition assessment. You will need to inspect your masonry, identify any damage present, and determine if you are doing repairs, conducting maintenance, or making cosmetic changes. A good resource is available on the National Park Service’s Technical Preservation Services website. A historic masonry consultant or restoration architect may need to perform this survey. The terms below cover the most common problems building owners have to address.

We get lots of calls about this one! Most of these start with “What is this white stuff on basement walls?” Water in masonry causes soluble salts to migrate to the masonry surface as moisture evaporates,…think of it as the footprint of water. The result is a white powdery coating on the affected areas.

The deposit of salt just beneath the masonry surface due to moisture intrusion. Although this substance is not readily seen it can damage masonry units by building up within the unit and damaging the surface. Damaged, exposed surfaces become vulnerable to water penetration and deterioration.

Cracking occurs for many reasons, and settling and freeze thaw cycles are common culprits. However, cracking is often exacerbated by hard mortar that is stronger than the historic masonry units. When the mortar is too hard it doesn’t accommodate the historic brick and stone and it will actually damage it. Mortar should ALWAYS be “softer” (i.e. lower strength) than the masonry. Think of mortar as being like the tires on a car: like tires the mortar should absorb movement and the stress of that movement, and similarly the mortar should be replaced periodically.  When cracking radiates through the masonry units themselves this is an indicator that the mortar is too hard. Stepcracking, or cracking through the mortar joints, is also a sign of movement but it indicates that the mortar is doing its job and protecting the masonry.

The sloughing off of stone in layers due to bedding plane failure. This usually occurs in sedimentary stone, especially sandstone, that has been installed incorrectly so that bedding planes are perpendicular to the orientation of the stone. This allows for accelerated weathering and water penetration.

Superior sandstone (the deep red stone common to Victorian masonry buildings) was particularly vulnerable to the acid rain of the mid 20th century and even properly installed stone may delaminate after years of exposure.

The general deterioration of the masonry due to time and conditions. This can lead to water penetration, cracking, spalling, or delamination of the masonry as well as fading of color and exposure of aggregate.

 The appearance of moss, mold or fungi on the building, usually due to excessive moisture levels. Biological staining is also common on the shaded side of buildings that don’t get dried out by the sun.

The general accumulation of dirt and carbon on the surface of a building that obscures the original appearance of the masonry. Carbon staining commonly occurs in urban and industrial areas but it can also be a remnant of coal heating. The black staining sometimes seen on both the interior and exterior is typically carbon staining.

Matt Wolf, owner of Henry Frerk Sons, recently participated in the Chicago Bungalow Association’s “How-To for Homeowners” series of videos on diagnosing and repairing masonry. If you are having trouble identifying your masonry’s problems these provide useful visual guidance and explanations. They include information on basements & foundations, front steps & lintels, moisture & repointing, and chimney & gutter issues.

Diagnosing Your Vintage Masonry: Basement & Foundation

Diagnosing Your Vintage Masonry: Front Steps & Lintels

Diagnosing Your Vintage Masonry: Moisture & Repointing

Diagnosing Your Vintage Masonry: Chimney & Gutter

How-To Instructions & Supply Lists

Repointing is commonly mislabeled as tuckpointing. Tuckpointing is the ornamental application of new mortar over existing mortar for cosmetic reasons. Repointing describes the removal of old or damaged mortar and its replacement with new mortar. This work can either be done in small spot treatments or across the entire building.

If you need assistance deciding which type of repair mortar is best for your project please visit our Selecting Proper Repointing Mortar page.

How-To Instructions

Shopping List

The use of a matching mortar or concrete to fill areas of loss. Historically masons did “dutchman” patches which were tightly fitted stone patches. Today we generally use cementitious repair products are specifically designed to be compatible with the existing masonry.

How-To Instructions

Shopping List – Most patching projects require the use of Cathedral Stone’s Jahn Repair Mortars. Only Certified Installers may purchase Jahn Repair Mortar. We offer certification to enable contractors, architects, and other professionals to obtain the required product certification. Our classes are two-day sessions and are discounted to $450.00 per person. Check the current schedule for upcoming classes.

If you need to replace bricks, common brick can be purchased from our yard (Note: Availability can be limited.)

The removal of dirt, biological growth, efflorescence, and environmental staining from masonry using water pressure, a detergent, steam, or other method. The gentlest method should ALWAYS be used.


How-To Instructions


Shopping List

Paint and Stain Options

How to Instructions – Procedures vary for different coating product lines. Please visit KEIM’S website and follow the instructions listed on the data sheet for your specific product(s). (Note: KEIM often sometimes recommends multiple products for one system)

Always apply coatings to clean, dry substrates. Should only be applied at temperatures of 40F and rising.

Shopping List – All of our paints and stains are custom order. Please contact HFS directly if you would like to order KEIM or Cathedral Stone coating products.

Recreating the surface of brick or terracotta masonry using a specialized coating. This sometimes requires patching the terracotta itself when loss is present.

How-To Instructions

Shopping list – Coatings must be special ordered, please contact HFS directly if interested. We do stock Cathedral Stone’s Terra Cotta Glaze, which is a clear breathable masonry coating. Please see the patching section for info regarding materials for this portion of your project.


If you need to purchase individual common brick, you can do so in our yard (Note: Availability can be limited).

How-To Video: Removing Mortar, Choosing Replacement Mortar, and Repointing

Chimney Repair Guidelines

Although HFS supplies all of the appropriate materials required to rebuild or repair your chimney, we do not do actual contracting work.


It is not uncommon for chimneys to fall into disrepair.  Chimneys are considered “cold walls” because they are subject to the harsh elements of heat, cold, frost and moisture on all sides.  Do not be surprised if the contractor suggests removing and rebuilding your chimney.  Often chimneys need to be taken down to just below the roof rafters and rebuilt if the mortar between the bricks has rotted away and/or the clay flue liners within have deteriorated.  The extent of the damage can only be determined upon a close up inspection.  Have your contractor take many pictures to show you the issue so you can make an educated decision as to the extent of the repair. If you are uncertain than a masonry consultant may need to assist you.


Proper re-pointing mortars for chimneys are a type “O” cement/lime mortar or a PHL (pozzolain hydraulic lime) mortar.  If rebuilding the chimney is necessary then we recommend re-building with a type “O” cement/lime mortar.  Our historic materials lab can assist you in preparing a custom matching mortar so that your repairs blend in with the rest of the existing masonry.


When you are making your repairs, pay close attention to how the top of the chimney is detailed, as this is the point where water, snow and ice buildup.  If allowed to enter the chimney system it will cause damage again.  We recommend pouring new concrete chimney caps in place.  Have your contractor reinforce the newly poured concrete cap with stainless steel threaded rods.  The concrete cap should have a slight pitch so that water washes away from the flue liner.  The concrete cap should have an overhang on all sides of about 1”.  Ideally, a small ¼” wide channel should be formed into the underside of the overhang about ½” away from the edge of the cap to provide for a drip break.  Your clay flue liner should extend beyond the finished surface of your poured concrete cap by at least 8” and a metal chimney hood should be installed overtop.  All of the items mentioned herein are in stock at our yard.

A Note on Water Repellents

HFS does not recommend applying any type of waterproof “coating” to the interior or exterior of your masonry wall.  This is especially true for masonry walls that are below grade.  Masonry is like a sponge that will absorb moisture readily.  There is nothing you can or should do about this absorption process; however, you want to pay attention to how the moisture evacuates the wall after it is absorbed.  If moisture becomes entrapped in the wall system it will cause deterioration from the inside, out by pulling through to whichever side of the wall is drier and warmer.  In the case of basements, moisture is absorbed from the ground and, through capillary action, migrates through wall to the inside of your basement.


If you apply a waterproof coating to an interior surface it will trap the moisture within the wall and not allow it to dry out.  As a result, the wall will begin to saturate and the mineral salts within the brick and mortar will begin to break down. When the moisture eventually dries out, the water soluble salts will re-crystalize in the form of efflorescence (the white powdery stuff) deposited on the surface of masonry walls.  Because the coating now inhibits that surface drying process, the efflorescence crystals will form just beneath the surface (sub florescence).  When these little microscopic crystals form within the pours or fissures of your mortar and brick they exert outward pressure causing your brick and mortar to spall away from the wall.


If you have already coated the interior of your masonry foundation, it is not quite a hopeless case.  The two sides of a foundation wall are referred to as a positive side and negative side.  The positive side of a wall is where moisture typically enters the wall system.  The negative side of the wall is where the moisture typically evacuates the wall assembly.  In this case, the positive side of the foundation is the exterior side and the interior side that was coated is the negative side.  There are two things you can do to correct this problem.


Option #1

Strip the coating from the interior walls. However, this is a messy process and will not stop the moisture form entering the wall from the positive side.


Option #2

Dig out the foundation and apply a waterproof membrane and drainage mat along the exterior side of your foundation walls.  At the base of the footing dig a trench, fill it with ¾’ stone and install a perforated PVC seepage pipe running to your closest catch basin.  When you backfill against the foundation, the drainage mat will act as a primary waterproof membrane that will also direct water down your wall. The seepage pipe which will then take the water away from your foundation. The waterproof membrane applied directly to the foundation wall will act as a secondary barrier to “waterproofing” your foundation so no moisture can ever penetrate your wall assembly again.  If you follow this option, you should be able to leave the interior foundation coating in place because there will be significantly less moisture passing through your wall now.  This exterior waterproofing method will also cure most of your rising damp issues which are occurring above grade.

Supplemental Information

Homeowner FAQ’s

To explore questions commonly asked by homeowners, please click here.

Recommended Resources

To browse resources that might offer additional help with home repairs and projects, please click here.

Cheat Sheets