There is something magical about taking the rough outline of a building and breathing life into it by crafting how materials and systems "meet and greet". He may not have originated the phrase, but architect Ludwig Mies van der Rohe observed that "God is in the details". The inference being that God, while orchestrator of big events beyond our comprehension, is also master of the delightful subtlety to be found in the smallest detail. Like many great works of architecture, there is an enjoyment of Mies' buildings up close as well as when viewed from afar.
A question I have put to many is whether it is acceptable to poorly deliver a good design. So far everyone has said "no".
A key component of that effort is an understanding of the building's systems and materials along with how they will come together. Many project designs impose unnecessary burdens on contractors and the client's budget due to issues of unneeded complexity and poor constructability that are "baked" into documents and models. A clash free or well-coordinated BIM model does not ensure good constructability. It is wholly possible to model precisely and at the same time reflect poor construction practice.
It's worth noting again this month a word that captures much of what architects do - "Contexture" - the act, process or manner of weaving parts into a whole - Webster's Dictionary
For the purpose of this post, I will represent constructability as the integration of building elements and systems together that can be reasonably fabricated and assembled and that provide reliable performance over time
Three aspects of constructability are:
- Aesthetic - pleasing to the eye; it reinforces or extends the design intent
- Functional - respects the limitations of the budget, materials and systems
- Practical - reasonable to construct
The detailing of visible elements at the exterior should stand the scrutiny of a subjective aesthetic viewpoint while also meeting performance criteria such as preventing or managing moisture intrusion. Designs must accommodate the capabilities and limitations of the materials and systems themselves, being designed with some understanding of how they can be fabricated and installed.
Every project has what I call "critical intersections" - junctures where differing building systems and materials come together. They generally earn our attention for one of the following reasons: they occur at the exterior where we must prevent the infiltration of moisture, where multiple building elements meet or those that require aesthetic consideration. Some details entail each of these.
Many of our problems on projects come from these critical intersections. Identifying and working them out appropriately - and then paying attention to them during construction goes a long way to ensuring they are done right. Some of the criteria to be considered are:
- Reliability over time
- System performance
- Fit & Finish - requires an understanding by the designer
- Quality of Materials
- Quality of installation (especially of what is covered up by other construction)
FORCES AFFECTING CONSTRUCTABILITY
Quite early I was introduced to the realities of construction tolerance. Columns are allowed to be out of plumb a bit and still meet spec and floors may slope slightly in places due to deflection or camber of the supporting elements. One of my first experiences was a 6 inch metal stud partition in line with 6 inch steel tube columns. I don't recall any issue with the column's plumbness, but there was no room to snake the conduit past the face of column and still apply gypsum board onto the metal studs.
It also became apparent that construction drawings that lacked graphic clarity or were poorly coordinated became an obstacle to getting work done correctly in the field. Details that were not thought through or just not buildable led to second-rate results when built. It was in my selfish interest as an architect to not only think through, but to clearly communicate ideas so they would be understood by contractors.
SPENDING MONEY WHERE YOU CAN SEE IT
A constraint we face on almost every project is the construction budget. It is always limited in some respect - and we are generally under obligation to not exceed it. There are many choices to make in the design process - and in order to "pull off" the design intent it is in our interest to make the building less complex to build. What do I mean? Where do we want to spend the construction dollars? Is it on unnecessarily convoluted foundations or difficult to build roof junctures that no one will see? Designing and detailing the building to be less complicated to construct in general and keeping the complexity where it can be seen and appreciated is a practical strategy with financial and aesthetic dividends.
- Regularizing column grid spacings with an arrangement that allows concrete pans to be reused on multiple bays (for pan & joist slabs)
- Simplifying steel edge detailing as discussed in last month's blog
- Coordinating with engineers to most efficiently route HVAC or electrical systems
These can often be done without compromising good design - it just takes some thought and effort from a creative architect or engineer. Yes, there will be situations where we are between the proverbial rock and a hard place - just work to minimize those occurrences.
It was difficult admitting that I wasn't one of those architects who was a "macro" designer with great vision and the Big Ideas. I had instead gravitated towards working with that designer to understand and execute the design in a thoughtful way. And that is one great thing about the architectural profession, there is room for all kinds of people bringing a multitude of aptitudes and abilities.
Next month I'll address issues affecting constructability in today's practice along with practical steps to take to better educate ourselves to excel in this area.