RSS
TwitterFacebookGoogle+YouTubeLinkedIn

March 2013: Restoration & Preservation

Facebooktwittergoogle_plusredditpinterestlinkedinmail

By Rhonda MaasRestoration & Preservation

Masonry construction technology has advanced so much over recent decades, that today’s techniques and materials would appear almost magical to a time-traveling mason from 100 years ago. By the same token, when contractors “travel” back in time to restore a building from that era, we confront techniques that may be very different from today’s practices.

Working with an old building requires an understanding of construction technology at the time it was built. After all, the building has survived until now, because it was properly constructed for its time. Modern advances have brought many improvements, but trying to apply these new techniques to an old building often results in failure. So, a contractor charged with restoring a masonry building needs to understand the differences between construction then and now, to avoid applying modern “fixes” that make things worse. Here are a few examples.

Masonry buildings built 100 years ago commonly were constructed with multi-wythe, load-bearing walls, unlike modern, curtain-wall construction based on a structural steel frame. Instead of an air space between the exterior masonry and the interior finish wall, a hundred-year-old building could have interlocking brick, stone or even rubble. The inside and outside walls are inextricably tied together. Understanding how these walls bear loads, flex with thermal movement and transmit moisture is critical to successful restoration.

For example, trying to shore up an old masonry building by tying it to a steel structure is likely to hasten its demise by making it too rigid. Old masonry walls need to be able to flex with vibration or thermal expansion and contraction, or else they will crack.

Another important difference between new and old construction is insulating capacity. Modern insulation is available with very high R-values, so new buildings can be made practically airtight to minimize the expense of heating and cooling. In contrast, thick masonry walls have a low R-value, but high heat-retention capacity. They even out variations in daily temperatures, so masonry buildings don’t need as much insulation as modern, light-weight buildings. Super-insulating a historic masonry building actually can cause damage, because it keeps the outside wall colder and wetter, increasing the chance of freeze-thaw damage.

Moisture transmission is another significant difference between old and new construction. Old bricks and stone actually absorb moisture, but they also allow vapor to transpire. In effect, the building breathes. Introducing a moisture barrier, like a waterproof coating, actually can trap moisture in the masonry, accelerating deterioration.

Even though masonry buildings breathe, they can’t withstand a steady onslaught of liquid water or ice. The biggest threat to old buildings is water damage. Here is where modern advances bring benefits to historic preservation. Adding flashings at parapets or windowsills to direct water away from the masonry will prevent water damage. And a sheet metal cap is one modern (and inexpensive) way to protect the integrity of parapets, cornices and brick rowlocks that keep water off the masonry face.

Note that interior flashings commonly used in modern curtain walls cannot be used in multi-wythe construction.

Proper drainage also is critical. Keep in mind that gutters and downspouts often were much larger 100 years ago than modern standard sizes. An incorrectly sized downspout will not carry the amount of water intended in the original design. It may be necessary to fabricate custom spouts and gutters.

Foundations spotlight another difference between historic and modern buildings. Sandstone, brick or rubble-fill foundations absorb more water than modern concrete, and, because they are below grade, they can’t dry out the way masonry above grade does. It is vitally important to keep water away as much as possible by proper grading, landscaping and drainage. No downspout should empty next to a foundation. If a vapor barrier is desired, it should be applied to the outside of the foundation, leaving the inside open to allow moisture vapor to transpire out of the masonry.

In summary, construction techniques continue to evolve and improve. We wouldn’t build a new building today the same way we built 100 years ago. But we should be equally cautious about applying modern techniques to preserving an old building. Replicating the original construction is the best way to ensure a successful historic renovation.


Rhonda Maas is the co-founder and president of Building Restoration Specialties Inc. (BRS), which specializes in masonry restoration, preservation and conservation of historic buildings. Founded in 1986, BRS has a bonding capacity of about $7 million, and is positioned to handle projects ranging from $2,000 to over $2 million. Learn more at www.brsrestores.com.

Return to Table of Contents

Related Posts

  • 63
    Modern masonry construction can be a high-tech proposition, but building with stone is one of the oldest techniques in the world.
    Tags: building, buildings, masonry, historic, restoration, ago, techniques, construction, modern
  • 61
    While correcting mistakes others make in restoring old masonry structures could become a lucrative side business, it is obviously in the best interest of both the building and its owner to get it right the first time. Here are some avoidable mistakes people make when repairing or, worse, “improving” historic…
    Tags: building, masonry, moisture, historic, buildings, restoration, water
  • 49
    With 150,000 square feet of limestone standing 34 stories high, the Kansas City Power & Light building has prominently adorned the city’s downtown skyline since its construction in 1931. The historic Art Deco-style building at 1330 Baltimore Ave., designed by Hoit, Price and Barnes, held the record of Missouri’s tallest…
    Tags: restoration, building, years, construction, masonry, historic, techniques
  • 47
    The three-part rule of moisture management is to “get moisture off of, out of and away from a construction detail as quickly as possible.” However, we are left with the nagging questions: Off to where? Out to where? Away to where?
    Tags: construction, moisture, water, building
  • 44
    Throughout history, architecture and construction have relied on drawings from which to build. The drawings required multiple views in plan, section and elevation and multiple scales to represent what the building would be. Drawings were made with lines, arcs and text, which could only be interpreted by people.
    Tags: building, masonry, construction

MASONRY MAGAZINE VIDEO NEWS

S26 HEPA Dust Extractor From Pullman Ermator

Ermator HEPA Dust Extractors are equipped with tested and certified HEPA filters that trap the smallest, most dangerous-to-breath dust particles and prevents them from being released in the air. A HEPA Dust Extractor not only exhausts perfectly clean air, it is far more efficient for the fast recovery of bulk dry dust, debris and other building materials found on every Construction, Abatement and Restoration job site.

Drilling and Chiseling Hammer Demonstration | CS Unitec

CS Unitec Drilling and Chiseling Hammer type 2 2414 0010 demonstration. For more information on the tools, drills and other products seen in this video, please visit: http://www.csunitec.com/hammer-drills/

PumpMaster | Masonry Grout Pump for Core Filling | Block Fill | Masonry Wall Grouting

The AIRPLACO PumpMaster PG-30 is shown on a jobsite in Nashville, TN with Masonry Contractor WASCO, Inc. ...