SYSTEMS/GLASS AND METAL CURTAIN WALLS
Design and Constructions Issues
Good curtain wall performance, thermal and otherwise, requires careful design, fabrication and
installation. Achieving this goal in practice requires good communication and coordination between
all of the parties involved in each of these steps. The AAMA manual on the Installation of
Aluminum Curtain Walls is an excellent reference on these issues. In this document, curtain wall
systems are described as highly-engineered, factory-made elements with close tolerances installed
in a field-built structure with a significantly lower degree of dimensional accuracy. The curtain wall
performance is dependent on how well the curtain wall and structural systems are matched, and
these issues of tolerances and clearances in the building frame alignment are major issues in the
AAMA installation manual.
The AAMA manual discusses these and other installation issues in relation to the responsibilities of
the architect, the general contractor, the curtain wall contractor and the installation contractor. The
architect needs to be aware of field procedures and conditions and then develop clear drawings and
specifications based on this awareness. The architect should work closely with the curtain wall
contractor in developing the details to facilitate fabrication and installation. Inspection during
construction is another key role for the architect to insure that the specifications and shop drawings
are followed. Architects should clearly define maximum permitted tolerances in the alignment of the
building frame, and provide for these tolerances in the curtain wall installation. The general
contractor must develop the construction schedule in consultation with the other players in the
project, allowing sufficient time for the development of the shop drawings, the fabrication of custom
components, and the assembly and testing of a mockup. A realistic schedule must be developed to
enable a quality installation while controlling costs and delays. The curtain wall contractor is
responsible for the fabrication of the wall elements and sometimes also their installation. In either
case, the contractor must work closely with the architect during the design stage to give advice as
the details are being developed.
As mentioned above, a key issue in curtain wall installation is keeping the deviations in the building
frame within the tolerances specified in the design. If this is not done, the curtain wall cannot be
installed without the potential for compromising its performance. The tolerances, or limits on the
dimensional deviations, must be clearly established by the architect and closely followed in the
erection of the frame. Adequate clearances between adjacent elements must also be provided to
accommodate the tolerances and provide the necessary working space.
The AAMA manual also covers other important installation issues of layout and alignment of curtain
wall elements, handling and storage of materials, protection of work during construction and
installation problems during cold weather.
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