Building Science Forum©
By Brian Burton
The issues facing the commercial and institutional building sector today in maintaining their buildings are becoming increasingly complex. Even a relatively small multi-unit residential building can contain as many components as a jet aircraft and it’s not surprising that these systems need regular inspection, maintenance and repair.
Regular inspection and maintenance can also be an important factor in controlling costs and extending your buildings service life. This is of particular importance when you are able to identify a performance problem in the early stages – before it becomes a full-blown building failure.
Defining the Building Envelope
Building professionals in Canada have long recognized the importance of the building “envelope” which separates the indoor and outdoor environment and provides protection for the occupants and interior systems. The system functions to “enclose space in such a manner that the interior environmental conditions can be regulated and controlled within acceptable limits”
The definition sounds reasonably simple – however because of the hundreds of products, components & systems, the extremity of our climate (as well as the number of trades involved) – the chance of construction deficiencies and premature failure is actually quite high. There is no doubt that it represents a maintenance challenge.
The term “envelope”, when used to describe the wall systems evolved gradually over the years and in many ways the use of the term envelope reflects the ongoing changes in materials employed in its construction.
The technology has evolved to the point where unlike traditional masonry or stone construction employed in the past which could be as much as 3 feet thick, the modern building envelope has no major structural function except to adequately support itself and resist the various physical forces exerted on the assemblies by severe weather, pressure differentials, impact, vibration and other environmental conditions.
In addition to controlling weather factors such as temperature, air movement, humidity, rain, snow and radiation, the system must also be capable resisting the effects expansion & contraction, and the effects of foreign substances.
The building envelope also provides connections to the outdoors, security, controlled access and incorporates fenestration components. The envelope must also be economical, durable, maintainable and attractive.
It is indeed fortunate, considering the rather extensive list performance criteria involved, that the building envelope system is rarely called upon to serve all of its functions at the same time.
Of course we expect the building envelope to be durable, especially in Canadian climate conditions. In most cases it does have a lengthy service life – however it will not last forever.
Maintenance of the Connection Details
Building scientists and engineers are well aware that it is often what we term the “connection details” that represent the true the maintenance challenge. For example weatherstripping, caulking, expansion joints, weep holes and flashings are just a few typical examples.
We also learned that in cold climates the chances of the sealing all the connection joints perfectly is remote or, according to some experts, impossible – as a result of continuous expansion and contraction.
As a result we now design building envelope systems to allow any water that manages to get past the first line of defense to drain out of the wall. This utilizes what is called a “pressure equalized rainscreen wall system”.
Most people understand quite well that roofing systems require periodic maintenance, repair and/or replacement.
However I often have to explain to building owners that in fact it is the building envelope and not the roof that is the source most building performance problems.
We know from experience that the envelope is typically overlooked from a maintenance perspective. Over time this oversight will have expensive consequences.
When inspection and maintenance is overlooked there is a rather long list of problems that can develop:
- Spalling or efflorescence can form on brick & masonry surfaces.
- Rust can damage door/window frames and other appendices.
- Building sealants, weatherstripping, and caulking can be damaged.
- Seams can split on the roof or parking garage.
- Weep holes can become clogged with debris.
- Cracks can form on concrete or masonry and enlarge over time as a result of the effects of freeze thaw cycling.
- Water is able to infiltration and remain in the wall system.
- Condensation can damage fenestration components and interior finishes
When these problems go unnoticed for long periods of time the result is building component deterioration.
By implementing a periodic maintenance program, the service life of the building envelope can be increased and in many cases the cost of future restoration/replacement projects can be decreased because you identified a problem before it mitigated.
This proactive approach serves to minimize repairs that can disruptive to occupants.
Building Envelope Maintenance Program
A comprehensive building envelope maintenance program is a key factor in controlling and reducing building operation costs as well as extending service life.
A building envelope maintenance program should encompass the following elements:
- Preparation of an annual maintenance budget.
- Regular building condition assessments.
- Annual proactive maintenance.
- Routine inspection following severe weather.
Integrating maintenance funding into the yearly budget is essential for the property over the long term, and a regular review of the buildings condition allows a reliable to access the remaining life expectancies of the materials.
Detailed Inspections are a Necessity
Inspection of these numerous components, by necessity, has to be very thorough and detailed. The building envelope inspection should evaluate and report on the condition of:
- Building envelope system &components including connection details.
- Drainage fittings and components (Weep holes/flashings, etc.)
- Exterior sealants, weatherstripping, caulking, flashings and copings to verify integrity.
- Windows, doors, soffits, jambs and sills and other fenestration components, including operable fixtures and hardware
- Interior finishes
Exterior signs to look for:
- Rust marks are present at imbedded steel locations.
- Spalling or efflorescence on brick.
- Cracks in concrete or masonry.
- Rusted door and window frames.
- Condensation on windows or glass.
- Compressed or incomplete building sealants at expansion joints.
- Seam splits on roof or parking garage.
- Weep holes are clogged with debris or caulked shut.
Brian Burton writes a regular column for Glass Canada Magazine entitled Fenestration Forum and was recently appointed to the CSA’s Fenestration Installation Technician Certification Programs Personnel Committee. Brian is a Research and Development Specialist for exp and can be reached at firstname.lastname@example.org or visit http://www.exp.com/.