What's a Board to Do?
It is Inevitable
No matter what type of building you live in, one day, the facade will begin to fail. Whether it is water infiltration, cracking wood, spalling concrete or crumbling brick, it’s only a matter of time before you have failing facade. This article is not about turning your building committee into structural engineers or forensic investigators; however, there are some techniques and terminology you need to be familiar with when it’s time to face an exterior building problem.
Water… the criminal
The villain in most facade failure mysteries is typically water. It causes corrosion, erosion, internal leaking, paint peeling, rot, settlement and a host of other building envelope woes. If your building has concrete elements suffering from spalling or cracking, it might be due to water penetration that has heavily corroded the reinforcing steel in the concrete. Ordinary rust scale expands with incredible force per square inch when confined -- concrete splitting power like Superman.
Many absorptive facade materials, such as concrete, sandstone, mortar, and fired-clay masonry, can be seriously damaged by cyclical freezing and thawing of water that enters the facade material through natural porosity or surface hairline cracks. These pockets of moisture can be trapped in facade walls. When it freezes, it expands and causes further cracking, spalling or displacement of adjacent masonry. This phenomenon is called ice lensing.
Spalling can create dramatic loss of structural integrity to parapet walls, retaining walls and cantilevering decks… not to mention the safety hazards that arise from falling facade. Complicating the diagnosis problems and the repair solutions is the fact that spalling concrete can also be caused by sources other than villainous water like compression, tension or vibration overload.
Along with identifying the source of facade failure, it is equally important to understand what materials make up the facade, as looks can be deceiving. Most old brick buildings in large cities use exterior brick to support the interior floor framing, called bearing wall masonry. These heavy walls were designed to prevent moisture from entering into the building’s interior spaces. The multi-layers of the exterior brick absorb the water, protecting the inner layer, then simply dry out after the storm
What lies beneath?
Over a hundred years ago, steel framing was introduced, which allowed a building designer to hang the exterior facade skin on the perimeter of the frame. This produced a lighter weight and more cost-effective building. Today, brick buildings use a brick veneer as the exterior facade. This brick layer is only the first line of defense against water infiltration. The outer veneer actually shields the true water barrier, a layer of sheathing behind an inner cavity space. This cavity acts as a drainage channel with weep holes at the bottom of the brickwork to allow the water to escape.
Similarly, many older buildings are covered with a stucco facade surface, which is a cement parge coating over a steel lattice -- much like plaster placed onto wood lathe strips. Modern buildings use an Exterior Insulation Finishing System (EIFS) as seen on many condominium and retail building exteriors. An EIFS facade relies on an interior drainage surface and is totally different in repair methods than the old stucco.
Can it wait?
After determining the cause of the facade problem, it is important to decide the level of seriousness. Is immediate repair needed? Or -- if it is not an ‘active’ problem -- can it wait? Waiting would allow for other more pressing issues to utilize capital outlays from the reserve fund.
Seek the pros or DIY
There are a variety of invasive and non-invasive techniques to investigate the problem.
- If the concern is corroding imbedded steel, you can hire a consultant to conduct a chloride ion content test of the concrete or mortar to gather quantitative evidence of potential corrosion.
- Simple stain gages can be placed over cracks to detect active movement.
- Using infrared thermography a consultant can discover unseen facade connection failures, any delaminations or thermal ‘short circuits’ due to wet insulation.
- You can pick up a water moisture content meter (available at building supply stores and woodworker hobby shops) to accurately detect and measure moisture in materials such as wood, drywall and concrete.
Be on the lookout
The good news is there is plenty an observant building committee or property manager can do to prevent a small facade problem from growing into a major expense. Be diligent and watch for any facade problem, even a small one. Seek professional advice from an experienced engineer who can determine the cause, estimate the cost to repair and help you prioritize your (hopefully) short list of needed renovations.
© 2014 Criterium Engineers