Government

Updating Traditional Building Systems Are Not Enough for Today’s Schools

Modifying existing building systems is a difficult, costly compromise

School districts are asking much more from new school buildings than ever before. Building codes are also requiring better per­for­mance with respect to energy effi­cien­cy and life safety. The natural response to these new criteria has been to modify the tra­di­tion­al building system in order to provide the addi­tion­al per­for­mance required. The archi­tec­ture-engi­neer­ing-con­struc­tion industry has found it easier to simply stick with what they have always done and attempt to make mod­i­fi­ca­tions to meet the new, highly evolved per­for­mance goals.

For wall systems in par­tic­u­lar, this has meant adding multiple layers of materials to meet each of the indi­vid­ual objec­tives. The two most common wall systems used in the con­struc­tion of school buildings have been concrete masonry and struc­tur­al steel with light-gauge framing. The challenge for these systems has been address­ing the insu­la­tion and air tightness required to meet the new energy effi­cien­cy goals, while also avoiding fire and life-safety concerns intro­duced by the addi­tion­al insu­lat­ing and air barrier materials.

Adding layers to either of these tra­di­tion­al systems has intro­duced more com­plex­i­ty in designing the details of a wall system, espe­cial­ly at window and door openings, con­nec­tions to other building elements, and inte­gra­tion with exterior finishes. These more complex designs have also increased the amount of time and money it takes to construct a school building.

More layers of material means more trades on a job site, more coor­di­na­tion issues as each trade attempts to accom­plish their scope of work, and more labor required overall to get the job done. Adding layers of materials to increase energy effi­cien­cy results in chal­leng­ing many con­trac­tors’ budgets and schedules.

The hierarchy of needs has focused the attention of design and con­struc­tion pro­fes­sion­als on meeting changing building codes first. Wall component man­u­fac­tur­ers have responded by providing code-compliant accessory materials that can be added to masonry and steel frame wall con­struc­tion. However, many of the options stop at minimum code com­pli­ance with respect to energy effi­cien­cy and air tightness, and do not sig­nif­i­cant­ly improve the per­for­mance of the building from the per­spec­tive of fire safety, storm safety and long-term sustainability.

Archi­tects, engineers and con­struc­tion companies need to consider the following when eval­u­at­ing mod­i­fi­ca­tions to existing wall systems like concrete masonry and steel con­struc­tion for school building projects.

First Costs

Both concrete masonry and struc­tur­al steel with light-gauge framing require addi­tion­al insu­la­tion and air barrier layers, and in some cases, multiple insu­lat­ing materials in an assembly. While these tra­di­tion­al systems have been rel­a­tive­ly cost effective to date, the increased number of materials and trades involved in providing a complete wall system today has made con­struc­tion slower, more complex and more costly. Speed of con­struc­tion and increased labor costs are sig­nif­i­cant chal­lenges for these wall systems.

Operating Costs

Both systems can be designed to meet the current energy codes, but are expensive in regard to achieving higher per­for­mance than code requires. Cost of main­te­nance and repair for concrete masonry is good, however light­weight steel framing and cavity wall designs are still chal­lenged in the long term with mold, rot and overall dura­bil­i­ty issues.

Health and Safety

Again, with proper air barrier and sealant design and con­struc­tion, either system can provide a rea­son­able level of air tightness to reduce the infil­tra­tion of allergens and pol­lu­tants into class­rooms. However, cavity wall con­struc­tion is much more sus­cep­ti­ble to mold and rot which can be com­pound­ed by more airtight buildings. For both systems, fire ignition barriers must be installed over the insu­la­tion if it’s com­bustible. Concrete masonry can only provide major storm pro­tec­tion when fully grouted. Steel con­struc­tion is not normally rated for windstorm protection.

Sustainability

For both systems, it can be costly to achieve more than code-compliant levels of energy effi­cien­cy, but sig­nif­i­cant­ly harder for steel con­struc­tion than masonry. Masonry walls also con­tribute sig­nif­i­cant weight of material to a project, while steel con­struc­tion requires many different materials to complete an assembly. Neither system provides any sig­nif­i­cant amount of recycled materials. Building life­cy­cles are usually good with masonry con­struc­tion, yet only modest with struc­tur­al steel.

Improved Learning Environment

With proper insu­la­tion and air barrier design, both systems can provide a rea­son­able level of air tightness and energy effi­cien­cy. However, it may be more difficult to achieve optimal per­for­mance from the steel cavity wall con­struc­tion. Concrete masonry can provide better potential thermal comfort and noise reduction than steel con­struc­tion, thanks to the insu­la­tion and thermal mass of the wall.

Continue reading in our white paper, Lead­er­ship in School Con­struc­tion.

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