Bidding and Pre-construction for Waterproof Design

WELL-DEFINED SCOPE

One good way to make certain to continue with the execution of the building envelope the way it was intended is to have defined it well from the early stages of design. If the project was well defined, there should be less scope creep that can result from bidders learning about things that were not represented in the earlier cost estimates.

Scope creep can result from two root causes, and either can be problematic.

Owner scope creep results from the owner continuing adding elements or, worse, square footage and perhaps even upgrading finishes. The longer the design stage stretches out, and the less control there is in the owner's organization, the more scope keeps getting added to the project. "We wanted to have retractable glass walls around the pool area; didn't we tell you?" Or worse, "You're going to be putting in that state-of-the-art audio visual system, like we saw in Las Vegas, aren't you?" This kind of continuing change can add up in a hurry, taxes a budget, and can strain a relationship.

AVOIDING SCOPE CREEP

Bid scope creep may be worse. There are many ways to estimate a project from early-bid documents; one of the most common is the area-takeoff method, also known as the old square-foot-cost method. This is usually done based on gross takeoffs of plan and elevation views of the building using systems cost data. It can be done quite accurately. One of the good things about this method is that not everything has to be shown in order to be included in the number. By this, we mean the fasteners, membranes, and paint don’t all have to be called out in the details.

The estimator doesn't have to measure the linear feet of flashing. Those kinds of things are included in the gross systems cost information. As long as the design doesn't increase the floor-to-floor heights or stretch the building length or some thing, the estimate should prove quite close.

If, on the other hand, the early pricing checks are not including things that may not yet be shown on the details or specifically called out in notes on plans and elevations, the early estimates may not include them. This can be the result of poor assumptions on the part of the estimator or using material and labor component pricing or subcontractor bids at the early stages before the drawings are complete. Another thing that can result in later cost exceeding early estimates is if the architect and/or engineer keeps adding improvements as the plans are developed. This can be as innocent as showing accessories or trim tiles in rest rooms as the large-scale interior elevations are developed. Or it could be the addition of roof drains, walls, doors, and sealants that were changed because the designer thought they might work better or look better.

There are hundreds of potential issues that may arise as the process of completing drawings is carried out. Scope creep can result in rising costs, and that can be problematic. If there is insufficient communication among the designers, owners, estimators, and contractors throughout this process, the problems can cause bigger problems. The best way to prevent this from happening is continuous and full communication among all parties involved. If the client has experience at building, he or she typically will know how much contingency to have in reserve for completion of bid documents. Some owners call this design contingency. This should be in addition to the contingency budget for escalation and for owner-requested changes.

Scope creep should be managed so that it does not cause a reduction in project quality. Some of the reactions that project management teams have had in the past have led to reductions in the quality of the roof (change from three ply modified bitumen to single-ply EPDM), lower-cost (and lower-quality) windows and doors, less capacity in the HVAC system, reduced-performance paints and sealants, omission of the air barrier, cancel commissioning, cut back on the roofing inspections, reduction of roof overhangs, reduction of insulation thicknesses, and so on. We would hope that notice the resulting reduction in building envelope performance likely coming from these changes. This is what we call cost cutting, and it’s certainly not value engineering and won’t result in an equally performing building.

BID ENVIRONMENT

Another dynamic variable is the bidding environment. Throughout the late 1990s, we saw some very good bidding environments and steady and low inflation rates. In the period from 2003 to 2007, it was difficult to get anybody to hold his or her price on anything. Price escalation hit historic highs. Prices in copper, concrete, cement, drywall, and several building products skyrocketed.

Labor prices went up because the work force was unable to keep up with demand. Bidders were able to build great profits into their bids because their competition also was doing so. Nobody was hungry in our region. We had to get bids on roofing from thousands of miles away. Hurricanes, terrorism, and social pressures can make prices jump up one month and seldom do prices go down. Changes in the bid environment are hard to predict very far into the future because they can be dramatically affected by current events. For these reasons, experienced project leaders budget for just such occasions. Two common terms for this are owner's contingency funds and project reserve. In many scenarios, the early estimates from contractors carry escalation figures based on how far in the future the project is scheduled, other work on the books, and advance prognostication from experts. While these practices can result in higher initial cost estimates, they also can be very useful in planning worst-case project cost estimates for marketing plans and to prevent projects from coming in over budget later.

VALUE ENGINEERING

You may hear this term used in a multitude of ways. Decades ago, we never heard this term at all. If a project bid came in too high, we would reduce scope (such as make the building smaller) or hammer on the subcontractors to lower their number for the designed scope (such as promise them that they can make a good profit on the next job). In certain bid environments and with certain relationships, this still can be observed in many regions today, although per haps to a lesser extent. This is not value engineering but scope reduction or cost-cutting. True, value engineering could be described as coming up with a better way to get the same (or an acceptable and nearly equal) thing. This is the best for all concerned. The bidders don’t have to reduce their unit costs or profit, the designer doesn't have to accept a poor substitute, and the owner is able to afford the resulting solution.

All too often, "value engineering" does not result in all three parties coming out with this kind of win-win-win position. For value engineering to work properly, the persons making the decisions need to have all the information pertinent to the choices. Overly simplified assessments of cost comparisons can leave out important considerations in an attempt to make the numbers work out. An example of this would be to take credits for a stick-built frame wall with stucco and insulation, cavity airspace, fiberglass sheathing, air barrier, waterproof membrane, R _ 19 insulation, and paint and replacing it with a tilt concrete wall system. In the first place, this is not an equivalently performing system from a water intrusion and condensation point of view. To make things worse, the cost comparison didn't take into account the textured coating for the outside surface and other cost considerations, such as casting beds, crane mobilization, etc. We could list hundreds of decisions made in the heat of a cost-cutting meeting that did not weigh all the cost increases compared with taking all the savings.

There are many examples of good value engineering, some wherein the results performed better than the original design and cost less. This can result from a system or systems that were initially either over designed or perhaps not the best fit for the needs. What we are trying to prevent is ending up with a solution that can not perform well, requires too much maintenance, and can lead to water intrusion in the building for any reason. In the building envelope, there are few lower-cost systems that perform as well as higher-cost systems- you generally get what you pay for. But there are opportunities in every component of the building to look for good performance at lower cost. Rather than start off by eliminating the paint or waterproof membrane, let's look at a few other areas first.

We like to look first at the foundation system because this is where we have had great success in the past. There are typically many decisions made in designing a foundation system without feedback and directions from the owner or contractor. There are always ways to look at the implications of an alternate way of doing the same thing. As an example, the schematic design is often done prior to receipt of a soils report. We don't know why, but most owners don't know the subsoil conditions or water table until after the design is well underway. They should consider paying for site soil and water table tests before the offer to purchase is tendered. But most do not. So the foundation may be designed based on a false assumption; it happens all the time. Then, months later, the report comes in, and designers now learn what is beneath the soil surface. The bearing capacity could be far worse than the assumptions and is almost never better.

Let us assume that the soils report reveals seven borings in a line that have no bearing capacity for more than 67 feet in depth (21 meters). The conclusion is drawn that there are voids or subsurface caverns such as exist in the Floridan aquifer. The civil engineer (CE) may respond by recommending driven piles throughout the building footprint. For a medium-sized building footprint, say, 100,000 square feet (33 meters), the resulting pile and cap costs can exceed $2.5 million depending on loads and depths. This indeed did happen on a 17 story mixed-use project, and would have eaten up the owner's contingency fund before we completed the design. This was not good. To make a long story short, we redesigned the slab on grade to use a hybrid anger-cast pile mat with adequate reinforcing steel to span a calculated sinkhole diameter with a factor of 2. The resulting increased cost was only around $450,000, or one-third the contingency budget. This is value-engineering thinking applied during the design process. The hybrid mat was as good as the piles for a lot less money.

We could list numerous examples of value-engineering successes and failures from past projects. Among them, it’s more important to learn from the mistakes.

Mistakes in value-engineering include changes that result in lesser-performing systems than the original, or cost-cutting. When that lesser performance results in future problems such as moisture intrusion, condensation, and mold, the resulting corrective measures cost far more than the savings that were returned for the change in systems.

Let us share a success story from a recent project going through value engineering. We were in the role of design/build architects after a design criteria firm had completed the design development (DD) documents. We had to shave about 16 percent from the DD estimated cost of $17.1 million without reducing square footage or changing the look. We looked in every division of the specifications for requirements that did not yield equivalent returns for the initial cost. We looked at the details and the bids for areas where we could reduce costs.

We found several areas for savings. One was in the glass. The Design Criteria Architect had specified a very expensive glass in the project, and the facade was to be half glass. By increasing the emittance slightly, we opened up the bidding to include several competitors, thereby lowering material and labor costs. By reducing the size of the board chambers slightly (about 4 percent), we reduced occupant load to below the threshold level and were able to reduce the importance factor from 1.15 to 1.0. This resulted in the structural beam sizes, light gauge framing spacing, and curtain wall system thickness all being reduced. We refused to look at reducing air or moisture barrier components. We reduced the size of the emergency generator to a lower-cost size after confirming that it was more than adequate for the planned loads.

We found some savings in the roof insulation as well. As a result of the geometry of the roof area, one portion of the roof had extensive cricket length to build up slope to drain at ¼”/ft. The cricket was nearly 59 feet in length, which would have resulted in about 1 6.9 inches of tapered insulation at the ridge. Roof insulation has become expensive. We were able to build the bar joists with most of the taper in them, requiring little additional steel cost, and were able to save thousands in roof insulation.

The last thing we did was to modify the HVAC equipment to omit CO2 monitoring and fan-powered boxes. Our mechanical designer used variable-air volume (VAV) mixing boxes instead of fan-powered boxes. This resulted in lower duct and equipment costs, as well as lower operation and maintenance costs. Our mechanical designer prefers the reliability of VAV boxes regard less of the comparative cost. He believes that the VAV boxes provide better dehumidification and creature comfort. The CO2 monitoring issue can be debated in terms of the resulting indoor air quality, but we believed that omission of CO2 monitoring results in dryer supply air in the spaces, as well as healthier air with more outside air and less CO2 in the rooms. These kinds of cost saving measures were seen as reducing cost substantially without a negligible reduction in building envelope performance or occupant health.

These changes resulted in significant electrical bill reduction too.

BIDDING

There are many ways to approach the transition period between design and construction because each project delivery system, permitting and review authority, and designer/contractor relationship can be different. Once the plans and specifications hit the street, the process of bidding begins. Typical bidding periods can range from 2 weeks to 2 months. Bidders may ask questions before the contract documents are complete, as well as after. Changes in the documents during bidding usually are referred to as addenda (plural of addendum). Often the bid questions come in the form of pre-bid requests for information (RFIs) and may have an impact on the resulting bid values. Therefore, pre-bid RFIs should be distributed to all bidders.

At some point in this process, plans and specifications are signed and sealed by registered professionals, and multiple copies are submitted to the permit ting review agency or agencies. Several agencies may be involved, and the process may be linear, where one agency must approve them before they move to the next agency. If the project is not linear, you may be able to submit to multiple agencies at the same time. Frequently, each agency will issue a list of questions for the designers to answer. These are usually code-compliance issues and may contain administrative questions or requests for additional information. Under the best conditions, permitting can be quick and easy. The longer and better the relationship between permitting agencies and submitting firms, the better the process can go for all concerned. This process can take more than 6 months. Any changes to the drawings for permitting need to be signed and sealed, usually clouded (encircled with segmented arcs that resemble clouds) and accompanied by a written narrative of changes, and resubmit ted. Additional permit fees can be charged for reviewing the modified permit drawings and specifications.