Advocates for Historic Masonry Preservation
When we receive a question about a single product, we often take the opportunity to share our overall recommendations for the project. For example, I recently responded to an inquiry from an architecture firm regarding an iconic Pacific Northwest department store built in 1929.
The firm sought advice for choosing the correct Jahn Mortar for patching and making repairs to cast-stone panels installed on the entire building. They were also interested in a Helical Tie Grout.
In my response, I offered advice as well as context, discussing the full range of important considerations and showing why the CSP System is the best option for a repair that looks far better, and lasts much longer, than other products on the market.
The following were my suggestions:
Jahn M90 Mortar and M70 Mortar are recommended for the best substrate compatibility.
Select the correct mortar. For pre-cast stone, use Jahn M90 Concrete Mortar. If the substrate were determined to be limestone, I would recommend our Jahn M70 Limestone Mortar for best substrate compatibility.
Use only certified installers. For either product, contractors should use only certified installers. We offer two-day JAHN Certification in Masonry Restoration Workshops monthly—these are held in Brooklyn, NY, and Hanover, MD.
2-day JAHN Certification in Masonry Restoration Workshops are held monthly.
Repoint the mortar. Any repaired areas will require repointing the mortar joints, and special care must be given to the compatibility of the pointing mortar used. Pointing mortar incompatibility can be a major cause of spalls/failures. The best product for a successful repair would be our M110 Pointing Mortar in the strength of JL (Joint, Limestone). This is an engineered pointing mortar specifically for limestone that can be applied in one lift—regardless of depth.
Use specific cleaners before matching color. To assist with color matching, I typically recommend our Bio Cleaner for dirt, debris, and biological staining. For carbon, rust, and other difficult-to-remove stains, our Oxidation Remover is the best product. Always match the mortar color to a cleaned portion of the existing façade—even in cases where an entire building cleaning is not possible.
Use the proper anchor setting products. Existing pins/helical ties should be removed and replaced with an approved anchor. Should the new detail call for the use of threaded rods/pins, I would advise using our M80 Anchor Setting Mortar for anchoring the pins. If helical ties will be used, it would be best to use our M85 Helical Tie Grout. To address any hollow areas, voids, or other repair requirements found during the restoration process, we offer several injection grouts: M31 (for concrete and hard stone), M32 (for brick and soft stone), and M35 and M40 for larger voids.
R-97 Water Repellent
Use only vapor-permeable waterproofing. Finally, be sure to apply a vapor-permeable waterproofing system to the entire facade. Conditions such as freeze/thaw and moisture entrapment can limit the longevity of any building or cycle of repair. CSP’s R-97 Water Repellent is unique in that it stops liquid water penetration, while allowing vapor transmission to occur. It is also 100% UV stable, which means it will not degrade when exposed to sunlight—a common cause of premature failures in other water repellents.
We believe the CSP System is the best option for better-looking, longer-lasting repairs. To back up our recommendations, we always include data and spec sheets as part of our response—making it easy for specifiers and other preservation professionals to evaluate the CSP System.
After more than 30 years in business, we have consulted with thousands of architects, engineers, preservation specialists, and historic building owners in stone repair solutions. We see ourselves and our products as advocates for the buildings. Preserve and do no harm is our goal—always.
Contact us to discuss your stone repair challenges and learn how the CSP System can help.
