Summer 2002

Form Meets Function
Contract Documents Can Make or Break a Project
by Glenn Heitmann

As an independent building enclosure consulting firm, this office of professionals has had the opportunity to work with many architects throughout the years. We operate with a few fundamental beliefs:

    • The building skin, regardless of materials/components/systems must function as a single entity;
    • The building skin, at some point in time, will take on water so it must have a way to divert it back to the outside;
    • Being conservative and realistic are good traits;
    • Every project should have submittals (product data, test reports, shop drawings and structural support  calculations) submitted and reviewed for technical compliance with the contract documents;
    • Taking the high road always pays off in the end;
    • Our allegiance is always to the project itself.

For conversation’s sake, let’s agree on a few things. First, each project has its own challenges/obstacles to overcome, with schedule, budget, risk and clients wanting more for less seeming quite common. Second, a building is judged initially by its cover, and that envelope is somewhere in the top-10 overall project costs. That envelope provides the main protection and comfort to the people and its contents inside against Mother Nature, and after recent historical events, sick and saddened minds. Lastly, whatever the building may be, it will likely have a glazing application, be it a curtainwall, window wall, window unit or a storefront.

In the Details
Without question, it is the architect’s job to determine the aesthetic characteristic of the wall, its overall pattern and texture, the materials to be used, the proportions of its elements and the profiles of its members. This can only be accomplished and optimized after careful attention to the owner’s wants, needs and priorities through soul-searching questions. Communication throughout the entire process with all the members of the team will add higher probability of total project success. 

The extent of the contract documents (architectural drawings and specifications) for a design/bid/build project is to include all items necessary for the proper understanding, execution and completion of the work by the contractor and/or his glazing subcontractor. Simply stated, the drawings should show design intent, and the specification should identify minimum performance levels for the applicable system(s). Yes indeed, each architectural firm has its own varying strengths, style and preference as to what should be represented in these documents. However the more complete and coordinated the documents the fewer questions and assumptions others will have to make in bidding or completing this work.

The amount and level of detailing by the architect depends on factors like whether the wall will be custom, standard or modified standard as well as environmental conditions and the size and value of the project. How the contract might be structured (i.e., competitively bid, negotiated or design build) and what appropriate team players are available and qualified should be considered early on.

Keep in mind that whomever is successful in securing the award of the curtainwall is ultimately responsible for designing, engineering, manufacturing, fabricating and installing it to meet or exceed the architectural plans and specifications. With this in mind, there is a fine line as to how far you go with your details and their extent, because telling a contractor specifically how to design or build might become your problem. How difficult is this dilemma of “not too little, but not too much?”

What Works?
The architectural details and the applicable specification section(s) should take into account the basic design considerations such as structural integrity, provisions for movement, weather tightness, moisture control, thermal insulation, fire safety, smoke prevention, sound transmission and security.

Curtainwall detailing and specification is project-specific. However, the architect, at a minimum, should consider the following to achieve a complete and coordinated set of documents:

    • Define specific levels of acceptance for the above referenced basic design considerations;
    • Establish design wind pressures that comply with code and/or wind tunnel study;
    • Establish the wall pattern;
    • Locate all principal members;
    • Designate materials and finishes;
    • Allow for weep system and gutters;
    • Indicate the type, size and locations of operable window units (if applicable);
    • Show the cross-sectional dimensions of framing members;
    • Specify the type, thickness and size of glass and give specific glazing performance criteria;
    • Identify preferred tolerance between exterior wall and building structure;
    • Provide for floor sag;
    • Consider the building’s structural frame;
    • Identify the preferred anchorage method;
    • Establish test requirements (on-site and off-site);
    • Sizing of sealant joints;
    • Vapor barrier continuity;
    • Presence of fire and smoke resistance/containment systems;
    • How to physically maintain the building;
    • Consider the interior wall, window treatments and ceiling details;
    • Material compatibility;
    • Thermal and seismic performance.

With proper attention the entire team and project can benefit by avoiding or minimizing these often heard voices of frustration saying:

    • “I thought the other trade was going to handle the interface conditions;”
    • “I want a no-maintenance building;”
    • “Our wall costs are all over the place;”
    • “Why does my building leak?”
    • “We just got selected; let’s prepare our list of RFI’s and RFC’s;”
    • “Lowest price wins;”
    • “I built exactly what you drew;”
    • “Why am I experiencing glass breakage?”
    • “This list of bidders is not an apples-to-apples comparison;”
    • “I did the best with the information that was provided at the time of bid;”
    • “This schedule is aggressive, actually darn-right unrealistic;”
    • “The documents (specification, architectural drawings and structural drawings) have conflicting                 information;”
    • “I am not a mind reader;”
    • “The team’s (owner, architect, engineer, consultant, construction manager, contractor and subcontractor) goals are conflicting;”
    • “The wall is over budget now that it has been formally bid. Therefore we must do value engineering and/or re-design the skin;”
    • “The code and performance criteria wasn’t identified clearly, so I used what I thought was appropriate;”
    • “Why didn’t you bring up your concerns and exceptions at the 
time of bid?”
    • “Curtainwall and storefront are really one in the same;”
    • “The system you detailed and specified won’t work;” and
    • “You need a big working joint to handle that kind of movement.”

Team Work
With the on-going changes our industry is facing, it is imperative, now more than ever, that we work in harmony. Communicate as a team and invest the necessary time, effort and resources in order to accomplish our common goal of doing (being involved with) a successful project. We must meet or exceed the multiple challenges, be proud of what we have accomplished and walk away (after seeing the project through to completion) without reservation.

Let’s recommit to raising the standard in all phases of design and construction by making each and every project that we are part of the best it can be while knowing full well that each will have its unique obstacles that have to be overcome. Follow your heart while listening to your gut, be passionate in all you do and put your best foot forward. 

• Heitmann & Associates Inc.:;

• Glass Association of North America, building envelope contractors 

• See related article in the September 2000 issue of USGlass, page 40.

Glenn Heitmann is president and chief executive officer of Heitmann & Associates Inc. of Chesterfield, Mo.

Architect's Guide to Glass & Metal

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