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In the design development (DD) stage, all systems are shown on plans and described in specifications. Our big three ideas-gravity, geometry, and technology-must be carried through the building design. It is in this stage that the designers fully develop the systems-level thinking they expressed in the SD phase. By the end of DD, architects will be providing detailed instructions to the builder as to each component that makes up the chosen systems. Drawings will be developed showing builders how they will be joining the systems together-thicknesses, fasteners, pressures, colors, finishes, textures, dimensions, and all pertinent data for full and complete estimation of costs. This, in our opinion, is the purpose of DD drawings. Of course, it's important for the designer to make sure that there is adequate space in the ceiling cavity for all components, that structures don't stick out of the wall, and that power is pro vided where it's needed for coordination purposes, but the main purpose for DDs is pricing. Site design Beginning with site design, cut and fill sections are very useful. You should have soil reports to define the bearing capacity of the ground, and you should look for groundwater issues, drainage patterns, etc. Utility connections and roads, storm water, landscape, and irrigation issues should be addressed. Of them, drainage and groundwater-related issues are most important. This is where you make certain that wherever you place the building, you are not creating water-intrusion problems at grade. Finish floor elevations are established, drainage patterns are designed, volumes for storm water retention and runoff are engineered, etc. Always make certain that finish floor elevations are at least 6 to 8” (15 to 20 centimeters) above finish grade for proper drainage (except for earth-sheltered or basement floors). Site design issues that affect water intrusion start with conveying surface water away from the building footprint. Slope should be away from exterior walls on all sides. Even if the building is located on the downslope of a hill, a swale should be cut into the uphill portion of the site so as to create drainage away from the exterior wall on that side as well. Soil bearing conditions can affect long-term performance of a building exterior wall system. If you are designing a barrier wall out of concrete block, brick, or stucco, you need to minimize differential settling of the foundations. If excessive settling occurs along any portion of the exterior wall system, cracking can result. Use of a perimeter grade beam can reduce the cracking. If the crack exceeds the elongation of the paint, voids will occur in the barrier. The same is true for drainage and rain screen walls. If you know that the site is likely to have excessive differential settling, you can either limit the length of the footprint or use materials such as wood that allow bending. By reducing building length, you reduce cracking forces. By using a more flexible wall system, you can reduce cracking as well. Ill. 1: Elevations at the door. Floor system Building finish floor elevations can't always be that far above finish grade. There are accessibility issues that require many entrances and exits to be located no more than 1/2” (1.25 centimeters) below finish floor. This makes it easier and safer for many people to enter and exit public buildings. This accessibility requirement makes it more challenging for you to meet the building code-required 6” above finish grade. You must work closely with the civil engineers (if involved in your project) to make sure that you meet both of these conflicting sets of requirements. Ill. 2 Section at threshold. Ill. 1 shows in plan view how the area directly outside the door can meet the accessibility code. From there you begin to gently slope down and away at less than 4 percent slope for about 6 feet (1.8 meters) in all three directions. You also have a slight step down at the doorway to minimize wind-driven rain water intrusion opportunities at the door. Ill. 2 shows a section through the threshold. The site must slope away from the building to prevent rain levels from approaching the finish floor elevation, even during a 50- or 100-year storm event. Conveyance devices for surface water drainage need to be reliable. You don't want to rely on a system that's easily blocked or will not work if power is lost. As a last resort, you can rely on closed underground piping, vaults, and /or pumped systems. For these reasons, we tend to prefer gravity as the force to move water in open swales away from the building. For "green" building concepts, we have several swale methods that function to capture rainwater for reuse and purification that work along with gravity draining water away from our building pads. One such scheme uses a series of percolation beds to capture nutrients and pollutants and then relies on select plant materials to reduce the pollution's effects on the downstream discharge off-site. Percolation beds and bioswales are two useful natural processes using free energy to reduce potentially harmful effects of storm water pollution from cars and buildings on the environment. Below-grade floor systems Assume that the program requires one floor or a basement to be built below grade, and just to make it challenging, consider that the site is located near a lake. We will use the example of a groundwater table located about 6 feet (~2 meters) below finish floor elevation. Whether it's a tall building or not, the envelope issues are similar. There will be groundwater considerations. The basement floor slab and a portion of the lowest walls will be below the water line. There are three common solution sets for this example. The first is the most reliable. It relies on over-excavation of the wall area so that workers have access to the outside of the wall. You begin by installing dewatering heads (well points), pipes, and hoses with a pumping system. Then you may begin excavation below the normal water table without digging in water. Excavate to a point below the bottom of finish floor, and begin compaction. You may need to bring in some rock or gravel to attain adequate compaction. We recommend using a 4- to 6-inch mud slab. A mud slab is a concrete subfloor with minimal reinforcing steel placed just beneath the finish floor slab bottom elevation. In this scenario, machines would have carefully excavated an area beyond the exterior walls sufficient for working access space, say, another 3 feet minimum (6 feet ideally) horizontally (1 to 2 meters). Depending on the soil and how much space is available around the perimeter, this may require sheet piles for soil retention (see ill. 3). Many soils won't retain a high angle of repose. Ill. 3 Sheet piles. The designer will have selected an appropriate membrane system to place on top of the mud slab to serve as the water barrier under the finish floor slab. Both sheet membranes and liquid (or fluid) applied membranes can be used. Two of the most commonly relied on sheet membranes are very different in their makeup. The first is similar to plastic or rubber sheet material. This material varies in thickness but is typically in the range of 60 to 80 mils. These sheets are sealed where they lap to prevent water under pressure from coming in contact with the future floor system. The sheets are extended past the edge of the floor so that they can be seamed to the wall membrane later. The other commonly used materials rely on very fine particles, such as volcanic ash or bentonite, woven into a fabric mat. The mat is installed in a similar manner to the rubber-like sheets on top of the mud slab and extended past the edge. These sheets, however, are not sealed at the laps but rather merely laid on top of one another. The idea behind these products is to use the fine particles to seal the void between the mud slab and finish slab to prevent water from penetrating the bottom surface of the finish floor slab. The fine particles will swell up many times their dry size, effectively filling the space tightly and thereby prevent moisture from moving through the slab. For a redundant system in a hard-to-reach location, such as a pedestrian tunnel below a highway system, where you will not be able to reach it in the future and where performance is critical, you might choose to use a combination of both systems. Manufacturers offer a hybridized composite with a combination of bentonite and sheet membranes with sealed lap joints. These have higher initial cost but offer the greatest reliability and resistance to groundwater penetration. An active dewatering system would be another potential solution to reduce or avoid hydrostatic pressure after the building is complete. In some areas, an additional layer of sand or fine stone is placed on top of the membrane and under the finish slab's reinforcing steel. This blotter layer, as it's called, reduces the risk of penetration or damage to the membrane and increases drainage potential. The basement floor slab is then placed on top of the membrane materials or blotter. Care must be taken not to damage or displace the membrane during steel and concrete placement. In this example, the wall forms are placed next, and then exterior walls are poured in place. The weak link in this method is the joint between the floor and wall. Water stop systems need to be installed in the detail between the floor and wall (see ill. 4). Bentonite, rubber, and galvanized or stainless steel are all used commonly. After the exterior wall forms are removed, the sheet materials (or fluid/liquid applied membranes) are applied to the cured concrete, lapped properly, and seamed, if appropriate. Backfill material is applied in lifts and compacted properly. Special care must be taken with the bentonite during backfill because it's not fully adhered to the walls and can't resist damage from careless equipment operation, such as a backhoe. For bentonite to work properly, the backfill must be well compacted against the mat. A less expensive process does not use a mud slab. The membrane is placed on top of the compacted earthen material below the finish floor slab. Reinforcing steel is put on top of the membrane (and possibly the blotter layer) prior to concrete placement. Quality control typically is not as good in this process. Sidewall excavation might not extend past the slab edge. It is more difficult to fully seal the blind side of a wall system. Wall membranes are applied prior to wall concrete placement. Ill. 4 Water stop systems. The least expensive process would be to put the waterproof membrane on the inside of the concrete floor and walls. There are several products made especially for this application, and they are applied like an epoxy paint coating. Depending on the client, the use, and the exact water pressures and volumes, the designer must choose a system that prevents water (liquid and vapor) from entering the building. If you don't have enough experience to make the decision, hire a consultant specialist or get guidance from the contracting firm. As with all things in the envelope, there is a relationship between initial cost and water intrusion. It is not quite as simple as pay more, get more, but generally, this rule holds true. In the non-permeable sheet membrane systems, it's recommended that the wall surface below finish grade (and especially below the water table) uses a drainage board or similar system to promote vertical movement of water. The drainage board gets installed against the membrane after it's applied to the concrete face and extends vertically, where it terminates into a footing drain system. The footing drain is designed to convey groundwater from the foundation system using perforated pipe and filter fabric. The fabric reduces clogging of the perforations and increases the efficiency of the footing drain. It also can lengthen its useful life. Typically, the drain is constructed with coarse gravel surrounding the pipe bed. Depending on site conditions, this drain system may be active or passive. In an underground stream, one might expect an active system with pumps discharging into storm piping or an elevated drain field downstream. For occasional ground water, a passive drainage system may suffice. Building partially below grade Earth-sheltered design and construction have at least a portion of the building located below finish grade elevation (see ill. 5). There are ways to deal with the envelope to prevent problems with water intrusion and condensation. You have to carefully consider temperatures on both sides and within the walls. You must stop water from penetrating the moisture-reduction barrier (MRB) from the outside and permit drying from the MRB in both directions. The way to achieve that's to have increasing perm ratings for each successive material, starting with the MRB and going in both directions (see ill. 6). In order to protect the integrity of the MRB, we frequently place drainage boards outside the barrier as a part of a composite wall system. The best protection boards have drainage cavities built in. The insulation is placed inside the MRB in warm climates. Some exterior walls are made of block, but formed concrete is better. Calculate temperature gradients for all seasons and operating conditions prior to designing the insulation products and R values. Typically, rigid insulation is used on the exterior of the wall, inside the MRB. Closed-cell insulation is preferred to open-cell foams. Refer to Section 4.6.8 for a discussion of insulation. Drainage boards and footing drains are commonly used to protect the rigid insulation and to promote drainage. They combine to provide easy pathways for vertical flow of rainwater and prevent it from staying in contact with the membrane long after rains have stopped. Calculations may show that additional insulation should be added to the interior of the concrete masonry unit (CMU) or concrete wall as a second means of preventing condensation resulting from the dew point having been reached in the wall. Remember, the ground temperature does not vary much. Extreme thermal gradients may take place vertically in exterior walls in earth-sheltered construction, and gradients can cause water and vapor drive. Another important consideration is thermal conductance by materials in the wall. Metal furring and stud framing are excellent thermal conductors. It is always a good idea to interrupt the thermal bridging between exterior masonry and good conductors such as steel. Wood is a good thermal insulator by comparison. If metal framing or furring is to be used, it may be useful to install a thin sheet of insulation material between the concrete or block and the metal. Ill. 5 Section at earth sheltered wall. Ill. 6 Permeability increases from membrane. Permeability of Materials Should Increase from the Vapor Barrier, in Each Direction Moisture Needs to Leave the Walls in Order for the Wall System to Dry Out In cold climates, the thermal insulation should be on the inside face of the wall anyway, so it's in the right place. We recommend using open-cell expanded poly styrene (EPS) boards to isolate the wall from metal framing. Metal framing or furring channels can be fastened right through the insulation with powder-actuated fasteners or screws in such a way that the interior wall sheathing can be installed to the framing. While it can be challenging to keep the framing plumb and true, it can be done with the use of a torque setting on the screw driver. In the cold climate, then add insulation between the framing and install a vapor barrier. We recommend that you always calculate the dew point in the wall for winter and summer conditions before deciding where and how to insulate the walls. If windows are used in the earth-sheltered walls, the window sills must be flashed carefully to convey rainwater out past the MRB below (see ill. 7). We recommend that interior walls below grade be constructed out of permeable wall sheathings containing only inert materials, such as glass fiber reinforced or cementitious building products painted with breathable paints. Placing vinyl wall covering (VWC) on or near an exterior wall in earth-sheltered construction (or any other) is never recommended. VWC has very low permeability and will cause condensation to form. Do not use epoxy paints or ceramic tile, except after careful consideration and certain steps are taken to prevent mold and mildew formation. Floors at or above grade Perhaps the most common floor material is dirt. There are still a lot of people living in humble shelters with dirt floors. Concrete, stone, and woods floor systems are all used widely in developed countries. Concrete floors are often cast in place on grade. These are referred to as slab on grade. A number of products are used to reduce vapor transmission through the soil and the concrete slab and to aid in hydration of the concrete as it cures. Plastic sheet membranes are commonly placed under the concrete after soil treatment has been applied. Recently, this membrane has been increased from the old standard 6-mil sheet to a new standard of 10 mil. Reinforced membranes are also available. These reduce the likelihood of rips and tears that can result from steel and concrete placement, workers walking on the chairs, etc. One should inspect the integrity of the membrane prior to placing the concrete. Any punctures, rips, or penetrations should be sealed against moisture movement prior to concrete placement. This includes sealing pipes or conduits that penetrate the membrane. After the concrete has been placed, it gets leveled, smoothed, and finished. Specifications often recommend different ways to maintain adequate water in the concrete mix for full hydration. Among the most common means are water curing, where water is sprayed on top of the curing slab for a few days, and application of curing agents. Curing agents seal the concrete surface, preventing evaporation. Curing agents trap the water that was in the mix when the concrete was placed. Curing agents also may act like a coat of sealer after curing is complete. This may aid slightly in reducing moisture movement through the top of the slab long after the concrete is fully hydrated. Curing agents may not work well with subsequent finishes, such as ceramic tile, stone, glued down carpet, or vinyl com position tile and therefore must be selected and applied with consideration of future material compatibility. Ill. 7 Sill flashing on ear sheltered wall. Ill. 8 Slab edge recess. If non-compatible products are used, there are mechanical and chemical means for ensuring good bonding. Manufacturers' recommendations often include shot blasting and etching with a mild acid solution. Whenever acids are used, you must consider the possible reactions with exposed materials in the vicinity. Metals such as brass or aluminum may be used in wall tracks or door and window systems, and these items should not be installed or stored in proximity of acid etching. Acid fumes will ruin most metal finishes. Floor sanders, grinders, and sand blasting may be acceptable alternatives to acid. Old fashioned soap and water applied with a nylon brush or pad is another means of final preparation in lieu of acid. Concrete slabs on grade should be placed at an elevation that will prevent wind-driven water from ever reaching their top elevation (finish floor level). Most building codes require 6” (15 centimeters) minimum from finish grade to finish floor. A good rule of thumb is 8” (20 centimeters). Depending on the location and wind and rain issues, you should consider the use of a recessed slab edge detail (see ill. 8). The depth of the recess is normally between 1 1/2 to 2” and must be coordinated with the wall thickness. The purpose of the recessed edge is to aid in the prevention of water intrusion. It goes back to gravity and geometry. The geometry is such that any water that gets past the first line of defense at the exterior face of the wall then must climb up the vertical face of the backside of the recess before it gets into the building. This is another reason why we prefer 8” above grade-we still have 6” below the low point of the recess to finish grade. If subterranean termites are a consideration, we urge you to increase the height above finish grade to 10 or 12”. Entomologists teach us that termites can't survive if exposed to the sun's rays. Sunlight dries them out, and they die. Therefore, subterranean termites construct little tunnels out of dirt to protect themselves. These tunnels can be seen by a quick inspection of the building perimeter and swept away with a broom quite easily. It takes the termites in Florida a little over a year to build these tunnels more than 6 or 8” high, so a once-a-year inspection can prevent the termites from getting into the walls. If their tunnels are not destroyed, the termites will make tunnels in the envelope that water and other insects will follow. Elevated first floors Wood-frame construction typically is built above a crawl space with varying heights above grade. Masonry piers or wood posts are used commonly to support the floor beams and girders. Wood flooring is usually made out of plywood or planks that span over floor joists. Joists are usually installed between 16 and 24” (0.5 meter) apart. The crawl spaces typically are ventilated by allowing openings for natural ventilation by wind currents. The purpose of the vents is to (in theory) prevent moisture buildup from decaying wood structural products (joists and decking). In warm climates, they may in fact introduce warm, humid air because the ambient conditions are such. In cold climates, the vents are kept to a minimum or closed off in the winter. An alternative is to ventilate the space mechanically and seal it off to the outside ambient air. This is the preferred solution for moisture control because it reduces vapor drive. In any scenario, we recommend insulating the area below the floor when possible. The perm rating of the material needs to be considered, much as in a wall or roof system. You want an MRB on the warm side of the insulation and should plan for drying materials both ways from the MRB-inward and outward. In hot, humid climates, we recommend an air and moisture barrier on the outside of the insulation. Introduce enough conditioned air to the cavity to create positive pres sure to the outside (outside the crawl space), yet negative pressure relative to the occupied side of the floor. This may be a good place for variable-permeability insulation, kraft-backed fiberglass insulation, or perhaps extruded polystyrene. You must coordinate permeability of the floor finish with the MRB to prevent trapping moisture in the floor. A good rule of thumb is 4 to 1. This goes for walls and roof systems as well as floors. The lowest perm-rated material in the floor should be 4 times less permeable than any subsequent vapor barrier. Therefore, if you are using stone, terrazzo, vinyl composition tile (VCT), or ceramic tile as a finish material, then the membrane outside the insulation should be 4 times more or less permeable. If you are installing finished wood flooring with a urethane finish, the membrane outside the insulation must be 4 times more permeable because urethane has such a low permeability. If carpet is being applied to plywood subfloor, a low-perm membrane should be used. In cold climates, the low-perm membrane should be below the subfloor and inside the insulation. A foil-backed insulation can be installed (foil up) on top of the floor joists before the subfloor is installed. Floors above grade, for example, second floors and higher in multistory buildings, should be treated much the same as ground-level floors. One difference is that upper-level floors need to stop at the inside face of the exterior walls to prevent rainwater from having an easy pathway to the floor. Water should be conveyed down and away from exterior walls. Exterior walkways should be maintained 6 to 8” (20 centimeters) below finish floor. Try to design the building so that occupied spaces are stacked above occupied spaces. It is more challenging and more expensive (not to mention risky) to have occupied, conditioned spaces below outside walkways and decks. In these situations, the outdoor walks and decks must be treated almost like a roof surface, and rainwater must be dealt with. On concrete slabs above grade, with occupied floors above and below, the concrete does not need to be placed on a sheet membrane (air or moisture barrier). Since the ambient conditions are so similar, except for personal comfort set-point differences, there should be very little vapor drive. Whether formed and poured slabs, filled metal deck, or precast slabs, the concrete should suffice to minimize transmitted moisture through the slabs. Ill. 9 Floor-to-wall section, good. Paint as Barrier; Concrete Wall; Interior Finish; Potential Source of Water Infusion Floor-to-wall intersections The floor-to-wall condition varies depending on the structural and wall systems in use. There are so many that we can't address each of them in the limited number of pages in this guide. We will provide several examples of floor-to-wall conditions that represent the different families of solutions in hopes of explaining the building envelope considerations that affect water intrusion. In the wall sections provided (see ill. 9), you will see several details expressing good, better, and best design conditions for several common wall and floor systems. This example illustrates a concrete barrier wall without a slab edge recess, utilizing a continuous application of paint on the exterior face to reduce water and vapor transmission. This is a very common condition, however many such walls extend far below finish floor to block intrusion above grade. You must first understand the conditions for which you are designing. This goes far beyond understanding the climate. You need to know the client and his or her plans for the building in terms of type of ownership, performance expectations, maintenance, etc. You must consider the available budget for the entire project, the owner's experience, the schedule, available work force, and materials availability. All of this should go into the decision. None of it, however important it might seem at the time, is as important as the weather. If you are designing for West Palm Beach, Florida, where there is high wind coupled with more than 40” (1.15 meters) average annual rainfall, you must design for the likelihood of wind-driven rain being blown up into the corners and wherever the walls meet the ground. These details must prevent the intrusion of liquid and vaporous water with high pressure behind it. Ill. 10 Floor-to-wall section, better. Paint; Texture Coating; Liquid Applied Retarder; Concrete Wall Interior Finish; Applied Closure Strip There are many ways to improve the performance of the earlier example, such as one using an applied closure strip over the joint between floor and wall, (see ill. 10). This example uses an applied vapor retarder behind the applied finish coat of paint. A better design would have the wall sitting in a slab edge recess to reduce the likelihood of wind-driven water reaching the floor elevation, (see ill. 11). As you can see, each successive layer of exterior wall components is lapped over the previous. This has the proven potential to per form better, if well constructed. This detail applies gravity, geometry, and technology all working together. This kind of wall section can not only resist wind-driven rain but also works well if water is sprayed on the wall from irrigation systems or pressure washers. Ill. 11 Floor-to-wall section, best. Paint; Exterior Finish; Sheathing; Furring (Cavity); Sheet Vapor Barrier; Concrete Wall; Interior Finish; Slab Edge Recess; Overlap How on earth can you be expected to design a wall system to withstand all this and be affordable? Well, don't despair; Gravity, geometry, and techno logy are here for your use. The combination of flashings, membranes, finishes, and sealants can prove more than capable to work in concert, over time, to be reliable long-term solutions. You may have to convince the owner not to use the $96 per square foot imported tile on the walls of his or her foyer in order to pay for the membranes and flashings, but real solutions often require compromise and conviction to proven practices and principles. We would like to think that this is why our clients hire professionals, for the benefits of our knowledge and judgment. After we find out the criteria, and hierarchy of needs, we can design an envelope to meet all their needs, aesthetic as well as initial and long-term cost and maintainability. If our buildings are to last centuries, not just a decade or two, we must often choose a system that performs well over the long haul, such as a brick on block cavity wall, (see ill. 12). Depending upon the climate, workforce, image, and other considerations, you may choose to use wood frame exterior walls, with exterior sheathing, in a drainage plane configuration. Ill. 4.13 provides an enlarged section indicating a combination of membranes and flashings that should resist wind-driven and even pressure washing water at the floor to wall joint over time. Ill. 12 Good geometry where slab meets wall. Ill. 13 Enlarged wall section at slab to wall intersection. Membranes on Sheathing Metal Flashing Bend Metal Closure Over on Top to Stop Water from Pressure Washer No Sealant here, to Permit Drainage from Membrane, Above Metal Closure Metal, S.S. Walls Assuming that we have applied the lessons learned from earlier segments, we have the floor higher than the grade or walk. We start off by looking at several regular wall conditions, and then go on to look at a door section or two. It is always a good idea to research the applicable building codes before designing a building, even if you are familiar with the historical codes in the area. Codes are changing. Since many areas of North America have adopted the International Building Code (IBC), we will introduce the 2005 changes from the Florida Building Code (FBC) as an example. Florida incorporated the IBC prior to 2004, supplanting the old Southern Standard Building Code. After Hurricane Charley, the state and local code officials hired a panel of experts to review buildings damaged by the storm and recommend changes to the 2004 code. x. The following are paraphrased changes: FBC Section 1403.3.2: The exterior wall envelope shall have flashing. The exterior wall must have a water resistive barrier behind the exterior veneer and a way to drain water to the outside (unless water that gets behind the veneer doesn't cause problems). Protect against condensation. A weather resistive veneer is not required on concrete or CMU walls. All finishes shall be installed according to the manufacturer's recommendations. You don't have to drain the wall if water in the wall has been proven by a prescribed testing method to not cause problems. FBC Section 1403.9: Must have flashings where drainage wall upper stories are built on top of mass (CMU) walls on lower floors to keep water outside the face of the mass wall. FBC Section 1404.2: Must use water resistive barriers (MRBs) and bond breakers in exterior stucco walls on frame construction. FBC Section 1404.2.2: You can comply with 1404.2 by using two MRBs, or a plastic house wrap and one MRB, or other methods approved by manufacturers. This can be achieved by using paper backed lath and a MRB such as a 15 pound building felt. Building codes will continue to change, trying to provide better minimums for future buildings. Remember that the codes are establishing minimums. Even the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and the U.S. Department of Energy (DOE) are trying to keep up with the trend toward better building design. Our designs are perceived by the observer mostly through visual feedback. Our eyes receive reflected light, our nervous systems transmit signals, and our minds process information. We use stored memories as a means for under standing what is in our visual field. Humans look for meaning, and compare what we know with what we see. What is it like? We look for visual clues such as form, size, texture, color, and other information to form an assessment of the building in front of us. The two dominant components of a building in our visual field are the walls and roof. Since the walls are typically located in the most prominent viewing angles and make up the greatest percentage of the visual information we process, they are the single most determining factor in how we perceive a building (for most buildings). Ill. 14 Staccato or rhythmic façade, Perimeter Institute of Physics, by Saucier Perrotte Architects. At the next level of analysis, perhaps as we move closer, we begin to study the fenestration of the walls. Fenestration includes the windows and doors, line work, and other differentiating characteristics on the facade. The way these elements of design are composed affects our perception of the whole. It may be a chaotic staccato composition intended to jolt our senses, or the facade could be a rhythmic concert of parts (see ill. 14). We may perceive a smooth, seamless obelisk that reflects light at all angles or a massive dark mass of piers and buttresses. The skin of the building typically impacts our senses with the most visual information and forms the lasting impression in our memories. Perhaps that's why many designers look first at shaping the forms and surfaces in their design process. The facade and its fenestration also have significant impact on our senses from the inside of the building. Windows and doors are dominant features in our visual field as we experience a building's interior. Even with electric lighting throughout most buildings, the contrasting light levels during day or night at window glazing capture our visual interest. The size, shape, proximity, clarity, and views through these portals tend to attract our attention. For these reasons and more, many architects design from the inside out. We consider the views and light to be of primary importance in the process of design. Ill. 15 Perimeter Institute Some modern examples from across the globe By skillful manipulation of views, light, shade, and shadow, architects such as the Canadian firm of Saucier Perrotte with offices in Quebec and Montreal, Canada can craft an experiential place (see ill. 15). The company's Perimeter Institute for Research in Theoretical Physics provides us with an exceptional example of design to stir the senses. The window planes are set at a variety of distances from the observer, creating a more nebulous space than would be created by a simple vertical wall (see ill. 16). The designers wanted to create a space where students would ponder everything-from the micro- to macro cosmic. The designers took their conceptual ideas from sketch to reality. Ill. 16 Section at exterior wall.
Ill. 17 Concept sketch. This building is three stories tall, using steel post and beam primary structural systems. Two primary open spaces are the main hall on the ground floor and the garden on the first floor. Offices flank the great spaces to provide visual connection between staff and students. The designers wanted to connect the different levels of the facility through the great garden space (see concept sketch, ill. 17 and image of the finished space, ill. 18), so they crafted three bridge and stair systems that penetrate the north and south facades and all interior planes. The bridges are symbolic and functional connections to people, places, and information. The use of metal wall panels on metal framing was consistent with the desired aesthetic and has the benefit of low maintenance cost. Ill. 18 Interior image of space. Another Canadian project was completed recently, transforming a fairly low density collection of older single-family and small commercial buildings into a thriving new world-class resort. The Mount Tremblant development, located in the mountains north of Montreal, has taken the world by storm. The panoramic image in ill. 19 captures the new look of this modern high-density multi family resort destination. All the modern conveniences are at your fingertips. The developers used today's technologies and program elements in such a way as to multiply the number of room reservations tenfold over previous seasons. Exterior wall designs, roof edge treatments, and waterproofing for winter and summer challenged their designers and builders. The wall section (see ill. 20) indicates the materials and methods used by a local architectural firm in their multifamily projects in the Mt. Tremblant area. Insulation and vapor barriers have to work both ways to prevent condensation in the walls. The 2'' rigid insulation stops at the frost line as a way to conserve cost, yet still prevent condensation in the lower walls. Ill. 19 Mt. Tremblant, Village Panorama Ill. 20 Wall section from Canadian Architects Millette Legare. There are always tradeoffs made between initial and operating costs, particularly as it relates to envelope insulation. We recommend designers permit clients to participate in the decision making process as to how well to insulate the perimeter. This does not mean how little insulation can be installed, but how far in excess of minimal energy or building code compliance the walls will receive in R-value. The location and type of insulations should be determined solely by the designer. Calculate dew points for summer and winter conditions, and use insulation values to prevent condensation resulting from dew point being reached in the walls. We are seeing more and more owners using longer return on investment periods for calculating payback on insulation and other energy related products such as air-conditioning equipment and lighting especially. While it used to be about 7 years, it's not uncommon to find 10 to 30 year planning horizons nowadays. In my travels around the Canadian countryside, my wife and I observed many buildings in the process of construction. We found it very common to observe combinations of batt and spray-applied wall insulation in exterior wall and roof systems, (see ill. 21). Ill. 21 Image of wall insulation, spray applied. Ill. 22 Taipei 101, world's second tallest building. Halfway across the world we find still more examples of buildings creating a dynamic statement. Previously (until July 2007) the world's tallest building, Taipei 101 (see ill. 22), is over 1,670 feet (509 meters) high and was constructed with 101 floors. Completed in 2004, the design was inspired by traditional Chinese pagoda design and incorporates the segmented bamboo form for reinforcing each segment of the tower and as a model of beauty in organic elegance. In contrast, the Guang Zhou Pearl River Tower makes quite a modern silhouette among other tower projects in the area, (see ill. 23). Its grand scale is softened at the street level by the spherical podium, a landscaped terrace above the street level (see ill. 24). These projects are but a few examples of the many buildings being built across the globe as we continue to look for new and exciting ways to design and construct buildings. We will talk about some of them in more detail later in this section, focusing on the glazing. With advances in science and technology, you can expect to see new products; thinner, stronger, and lighter skins; improved coatings; and new insulators. The possibilities are not limited to our imagination anymore. With continued integration of computers into the design process, we have exponentially expanded our realm of possible per mutations and combinations of solution sets. With space exploration, we are not limited to building on earth with our natural forces to respond to; we have a whole new future of designs and building to ponder. However, there will be some commonality to all building on earth, and for the present, we will focus the remaining pages of this guide on ways and means you can use-for the future is now. Ill. 23 Pearl River Tower, Aerial View. |
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