How to Maintain Your Masonry Facade
- By Ralph C. Jones
- August 1st, 2000
Observations and Facade Assessments
Every building should be regularly monitored for signs of deterioration or distress. If cracking or dislodging of any components is noticed, an immediate review should be done. If no signs of distress are apparent, a building review, conducted about every five years, is recommended.
The cost to perform a facade study depends on a number of factors.
1. The size of a building affects the time involved. A multistory building can also be more expensive than a single-story building.
2. The type of facade construction and the age of the building can also affect the cost of a study. If a piece of terra cotta must be removed and replaced to observe support conditions, the replacement piece can be relatively expensive.
3. The condition of the facade is a factor in the study cost. A facility with severe deterioration and multiple structural problems will be more time consuming and expensive to analyze than one with few problems.
4. There can be some cost savings in completing multiple buildings at once.
In order to make informed decisions and develop a maintenance plan, qualified professionals must assess facade conditions using a variety of methods.
1. Performing an on-site investigation is a good starting point. The engineering team searches for material deterioration, cracking and other damage.
2. If necessary, some investigations warrant selective demolition, uncovering multiple layers of building materials in order to determine the façade’s condition.
3. While on-site examination is essential, reviewing the facility’s construction documents can also reveal valuable information.
Study findings, repair estimations and ongoing maintenance costs allow administrators to develop a cost-effective maintenance plan that can be integrated into their ongoing maintenance program and budgets.
While each facade is unique, requiring case-specific examination and maintenance planning, routine maintenance solutions prevent common deterioration tendencies, thus extending facade life.
1. To maximize the performance of a masonry facade, clean and seal it approximately every five years. Cleaning costs vary depending on local types of cleaning and building size. Water blasting typically costs between 25 and 30 cents per square foot. Chemical cleaners usually cost 50 to 75 cents per square foot. Application of water repellents runs between 30 to 40 cents per square foot.
There are many different methods of cleaning for masonry facades. Some methods include high-pressure water blast, chemical cleaning agents, hand scrubbing or combinations. The final decision is based upon the type of staining. Application of cleaners and sealers is dependent on weather as colder temperatures can reduce their effectiveness.
2. For facades built in the early 1900s, a stone hardener composite can be applied to the stone surface, enhancing durability and extending its life. Costs vary widely (from $20 to $50 per square foot). The type and condition of the stone will typically dictate the costs. Stone consolidators are typically applied in cycles, three to four applications per cycle. The number of cycles may vary from one to four.
Stone consolidators should be applied by experienced personnel and may require the assistance of the product manufacturer. Sample tests before the actual repair should be done at inconspicuous locations to establish the number of cycles required. Due to its relatively high cost, application of stone consolidators is typically reserved for buildings experiencing deterioration.
3. Cracked or chipped mortar is a signal that tuck-pointing the facade might be necessary. Tuck-pointing involves raking out the mortar joints by hand or cutting out 1/2 in. to 3/8 in. of the mortar and replacing it. The new mortar is replaced in two to three stages by applying a layer of mortar and allowing it to dry to “thumbprint hardness” before applying the next layer. Too often, administrators invest in tuck-pointing that is incorrectly accomplished. This causes newly applied mortar to fail within a few years. Good, solid mortar joints help keep water from entering the building envelope. If there are openings in the mortar joints or the mortar is deteriorated and soft, moisture can enter in and get behind the masonry facade. This can lead to deterioration of the masonry, support members and interior finishes. Costs for tuckpointing vary depending upon condition of existing joints, quantity and access. It is typically performed from spring to fall in order to avoid freezing temperatures.
4. Thermal expansion and other destructive movement cause a facade to break away from the facility’s structure. Given these conditions, the facade needs to be re-anchored with mechanical ties. The type of mechanical tie used depends on the condition of the wall, the facade material, the type of facility structure and other case-specific factors. There are numerous different types of renovation anchors; some of the typical types are epoxy anchors, expansion-type anchors and helical friction anchors.
Selection of the anchor is based on many factors. The back-up structure can consist of concrete, masonry block or brick, wood or other materials. A screw-in anchor or a helical friction anchor would be appropriate for a wood back-up, whereas an expansion anchor, epoxy or helical friction anchor may be appropriate for concrete or masonry.
The condition of the back-up material and the facade material itself may affect the selection of renovation anchor masonry materials. Many times field testing of different anchors may be required to determine the best selection.
The building can still be occupied during installation of the renovation anchors. Installation of renovation anchors can usually take place year-round. Colder temperatures can affect the curing of epoxy systems.
Ralph C. Jones, PE, is senior vice president with Structural Engineering Associates in Kansas City, Mo.