Best Practices

5 Common Mistakes Found in Construction Documents

Repeated flaws and oversights that we can all learn from.
Brian Novello
August 5, 2021

The development of Construction Documents can be a long and complicated process, often riddled with errors and omissions given the technical nature of the work. However, these gaps in the documentation will often lead to costly overruns in schedule and budget during construction. Below are five mistakes that commonly occur within drawing sets.

Roof Plans: Out Of Sight, Out of Mind

Despite their considerable size, roof plans are commonly under-developed or overlooked within Construction Documents. As architects, we tend to focus our time and energy on what's contained within the structure using building plans, and defining the exterior aesthetic through elevations and sections. . As a result, the roof plan is often an afterthought that is forced to fit the pre-established design. Roof plans are frequently poorly thought through with minimal coordination with the consultants. Details are minimal, often generic, and key areas prone to water infiltration are overlooked. The roof is arguably the most important part of the building envelope, essentially doing the "heavy lifting" in protecting the building from wind, rain, and snow and should be given its fair share of consideration in the Construction documents.

Building Envelope

Another common area of deficiency with the drawing set is the required air, water resistive, and thermal barriers which make-up the building envelope.  These layers are frequently shown in the wall and roof assemblies but are misplaced or discontinuous in the details.  For example, at a parapet condition the roof membrane may be applied to the back of a parapet and the air/water resistive barrier to the front, but they both stop short of wrapping over the top to create a continuous seal.  Alternatively, a balcony may be structurally framed as part of the floor assembly, but vented without an adequate air and thermal barrier between the conditioned and unconditioned space.  Incomplete detailing can lead to omissions during construction resulting in problems during commissioning, and long-term comfort and maintenance issues throughout occupancy. Clarifying the continuity of the barriers through all parts of the envelope is essential in creating an efficient and durable building.

Generic Manufacturer Detail Blocks

Manufacturers provide an ever growing pool of details for their products and these can be invaluable in developing the drawing set. Unfortunately, these are frequently incorporated without being integrated within the unique design intent of the project. A wall panel detail could be provided from the manufacturer and shown with a dashed line for the structural wall, but it is essential that the detail be developed to demonstrate the actual relationship between the wall panel and structure, and how those attachments are sealed when they penetrate the air and water resistive barriers. Metal roof and gutter details are commonly provided without showing the project specific structural framing, the sheathing, and the ice and water shield that are essential to the assembly. The details provided for specific products are helpful, but must be developed to provide all information for construction and to be project specific.

Coordinate Early & Often

Discipline coordination across the drawing set is a constant pain point for Architects.  Consultant drawings contain critical information, which if not properly integrated, will result in construction conflicts that trigger costly change orders and sacrifice design intent as a result.  While it is the Architect-of-Records responsibility to orchestrate the integration of these siloed consultants, architects frequently don’t receive engineer drawings until the last minute before a deadline submission, leaving little to no time for this scope to be integrated. This pervasive shortcoming results in countless conflicts, such as missing slab openings for mechanical shafts, air-handling units which don’t fit within plenum spaces, or lighting fixture and mechanical diffuser configurations that conflict with soffit designs to name a few common issues. Utilizing consultant information early to understand the systems being specified will reduce time and coordination effort later in the process.

BIM Dependency

Another issue that is common in Construction Documents is relying on the modelling software to convey the design intent without further refinement.  This is most often seen in wall sections, and sometimes details, which are cut directly from the model without development.  In these drawings, the intersections between walls, roofs, and floor assemblies are purely graphic and lack any tectonic logic.  Finishes and framing members frequently overlap, and critical linework is missing or misplaced.  These drawings provide information that can be both helpful and detrimental to the coordination and construction efforts.  BIM software is an incredibly powerful tool for architecture but it must be carefully edited and reviewed to ensure that the information provided is accurate and coordinated.

The building industry is rapidly evolving with an ever expanding array of construction methodologies, building technologies, and material advancements.  It is the architect’s mandate to continuously educate themselves and expand their knowledge base, leveraging the latest production tools while communicating with all project stakeholders to ensure the highest level of care is provided within the contract documents.

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