Section 4: Architectural Design
4.1 Design Flexibility and Compatibility 设计灵活性和兼容性
4.2 Moisture Protection 防潮
4.3 Surface Treatments 表面处理
4.4 Exterior Surface Treatments外立面
4.5 Interior Surface Treatments 内墙面
4.6 Coating Manufacturers涂料制造商
4.1 Design Flexibility and Compatibility
Depending on the structure, there are fundamentally different considerations to a well designed building. The three most critical design objectives are: aesthetics, functionality and sustainability. Each of these design objectives is significant, yet a truly successful project is one where project goals are identified early on and where the interdependencies of all building systems are coordinated concurrently.
When an Architect uses Hebel Autoclaved Aerated Concrete (AAC), a choice is made to use one of the most versatile, user friendly and environmentally responsible materials.
Design flexibility and compatibility with other building systems is easily achieved with Hebel AAC. The introduction of Hebel AAC should ideally occur during the early phases of a project to capitalize on the many product benefits. This early introduction also proves to be more economical for the Owner and Architect.
设计的灵活性和与其他建筑系统的兼容性很容易实现与Hebel AAC。Hebel AAC的引入应该理想地出现在项目的早期阶段，以利用许多产品的优点。这种早期的引入也被证明对业主和建筑师更经济。
Hebel AAC provides a multitude of design options and flexibility. While Hebel AAC can be a major component of the superstructure, it is also compatible with other building systems and materials such as brick, concrete, fiberglass, glass, light gage metal and wood. Creative designs can be achieved with Hebel AAC alone, or by combining these materials without loss of functionality.
Hebel AAC提供了大量的设计选项和灵活性。虽然Hebel AAC可以作为上层建筑的主要组成部分，但它也可以与其他建筑系统和材料兼容，如砖、混凝土、玻璃纤维、玻璃、轻量金属和木材。创意设计可以单独使用Hebel AAC实现，或者通过结合这些材料而不丧失功能。
Figure 4.1: Condominiums built of AAC图4.1:AAC建造的公寓
Figure 4.2: AAC building
Figure 4.3: Window trimmed
4.2 Moisture Protection防潮
Moisture protection is a primary consideration in building design and construction. The objective is to eliminate water from causing damage to the building or causing an unhealthy environment. While water does not harm the structure of Hebel AAC, it can result in short-term disadvantages such as increased thermal conductivity, which causes lower thermal insulation performance.
When addressing moisture protection, the properties of the building materials are the first consideration. Hebel AAC’s material properties together with protection of the material by a suitable finish do not allow moisture to absorb deep into the material. This is due to the closed pore structure of Hebel AAC. The capillary action breaks down quickly and moisture cannot continue “pulling” very deep into the material.
在解决防潮问题时，建筑材料的性能是首要考虑的因素。Hebel AAC的材料特性以及适当的表面处理对材料的保护不允许水分深入到材料中。这是由于Hebel AAC的封闭孔隙结构。毛细作用迅速分解，水分不能继续“拉”入材料的深处。
Figure 4.5: A closer look at AAC
Only the surface directly in contact with AAC with the water is affected, allowing installation and finishing to be applied to Hebel AAC walls at various phases of construction. Interior walls and components of the building may be completed at a convenient schedule without concern of water damage.
Figure 4.4: Autoclaves where AAC is pressurized and cured
During the manufacturing process, Hebel AAC is cured in an autoclave. At this time, AAC is under significant pressure and saturated with steam and moisture. By the end of the autoclaving process, the AAC contains approximately 30% (by weight) water, which dissipates naturally over time to stabilize at a moisture content of 4% to 8%.The initial drying-out process includes two different rates of water dissipation.
First, as the internal moisture content of AAC exceeds 18%, it experiences rapid diffusion. Vapor permeable coatings on wall surfaces and interior roof panels do not hinder this diffusion process in most situations. Although, depending on the time of construction, moisture levels can be at or below 18% by the time the building is “dried-in”. With expedited construction schedules, dehumidifiers may aid in the initial phase of drying. Vapor barriers should not cover AAC at this stage due to this natural process of water diffusion. After the internal moisture content of the AAC material falls below 18%, the rate of diffusion is reduced. Generally, the rate of drying is low enough that additional moisture and humidity entering the building can be effectively removed by the HVAC system. The moisture from the AAC is minor and unnoticeable to occupants.
High moisture levels are common in building materials during the first few months after construction. Moisture protection is achieved by proper design, detailing and construction practices. To expedite equilibrium of moisture content in AAC, follow these design and construction measures:
1) Coatings: Specify and use coatings which repel water, yet allow the AAC to breathe on both interior and exterior walls. These coatings should allow vapor penetration, but not moisture penetration.
If a waterproof coating which restricts vapor flow through the exterior surface of a wall is applied to AAC, such as a basement wall, moisture within the AAC can only be diffused toward the interior of the building, increasing the time necessary to achieve equilibrium moisture content in the wall. Do not to seal both the interior and exterior surfaces of walls with any type of vapor barrier such as damp proofing on the exterior surface and vinyl wallpaper on the interior surface.
If two impermeable systems are used, internal moisture becomes trapped.
2) HVAC System: Design of proper air handling systems is critical to building efficiency and occupant health. Air handling equipment should be designed at the proper size for the building needs, using maximum building loads.
Figure 4.6: Thermal efficiency
3) Building Envelope: When a structure incorporates both Hebel AAC Wall and Floor/Roof panels together, (with special attention focused on common thermal leaks, such as doors, windows, and other openings) the result can be the highest performance attainable for an air tight building envelope. This adds to the overall thermal efficiency and can positively influence a buildings energy rating. While the moisture content of Hebel AAC decreases during construction, if construction schedules require quick occupancy, dehumidifiers may be desirable during the first year of occupancy. These temporary dehumidifiers would take care of the excess moisture being emitted from the walls and roof systems. In instances where the humidity levels inside a building are high and the temperatures drop below the dew point, condensation will form – regardless of the building materials. As long as the humidity and temperature are properly controlled, the dew point temperature should never be realized. Normal building operating conditions are 75o F and 60% relative humidity. 75o F is well above the dew point temperature of 60o F for 60% relative humidity and condensation formation should not occur. All buildings must be protected from the influence of external moisture sources.
建筑围护结构:当一种结构将Hebel AAC墙体和地板/屋顶板结合在一起时(特别注意常见的热泄漏，如门、窗和其他开口)，其结果可以达到气密建筑围护结构的最高性能。这增加了总热效率，可以积极地影响建筑物的能源评级。虽然在施工过程中Hebel AAC的水分含量会降低，但如果施工进度要求快速占用，则在第一年占用期间可能需要使用除湿器。这些临时除湿器将处理从墙壁和屋顶系统排出的多余水分。当建筑物内的湿度很高，而温度又低于露点时，不论使用什么建筑材料，都会发生冷凝现象。只要湿度和温度控制得当，就永远不可能实现露点温度。正常的建筑运行条件是75o F和60%的相对湿度。对于60%的相对湿度，75o F远高于60o F的露点温度，不应发生凝露。所有的建筑物都必须受到保护，以免受到外部潮湿源的影响。
Moisture protection with Hebel AAC is obtained without additional treatments, allowing construction details to focus on simplicity and aesthetics. AAC exterior walls can be finished with water-protecting brick façades or stucco,paints or bituminous coatings and with proper flashing and architectural details. Depending on the desired aesthetics of the building, an exterior wall coating can be chosen from a wide selection of options and will provide the desired moisture protection.
4.3 Surface Treatments
Due to Hebel AAC compatibility, various surface treatments are available for exterior and interior applications. Colors and textures can be applied to enhance aesthetic or match existing buildings. Exterior surface treatments include coatings of textured surfaces or smooth, in various colors and designs, paint and a variety of façade options. Interior wall treatments are much the same yet include; gypsum board, wallpaper,tile or paneling.
With consideration, limitless design variations can be incorporated, including exposed joint or unique coating techniques. Coatings manufactured for AAC are designed to be physically compatible with Hebel AAC products.
Select coating manufactures are referenced in Section 4.6. Patching mortars, made specifically for AAC, are available to repair damaged areas preceding the application of surface treatments. Reference the Hebel AAC Installation Guides or specifications and more information.
4.4 Exterior Surface Treatments
Coatings such as lightweight Portland cement stuccos must be manufactured specifically for AAC. These stuccos are designed with comparable strength and density properties of AAC to withstand high thermal tension and have permanently high elasticity. To enhance bonding and workability, AAC lightweight stuccos are polymer modified, vapor permeable as well as hydrophobic, preventing water infiltration.
Hebel AAC block applications are generally coated with a single coat of exterior lightweight stucco at a minimum thickness of 5/16 inch. After the surface has hardened, a texture coat at 1/8 inch follows.
Coatings should always be applied in accordance with manufacturer’s specification. After the stucco has set, two coats of vapor permeable masonry paint can be applied.
Hebel AAC Panels with mortared joints must be treated prior to the application of coatings. The panel joints should be coated with a thin layer of a cement-based compound.
Figure 4.7: Exterior surface treatment over AAC
Figure 4.8: Details of exterior coating
Figure 4.9: AAC’s design versatility
Along the panel joints, an alkaline resistant fiberglass mesh should be embedded into the cement-based compound. The basecoat of cement-based compound is applied over the entire surface at a minimum thickness of 1/8 to 3/16 inch. Within one hour, when the basecoat is dry, skip trowel a light texture over the basecoat. Once the textured coat has set, apply two coats of vapor permeable masonry paint.
In exterior applications, paint can be applied directly to horizontal tongue and groove panels without mortar. In this application, the paint must seal any surface irregularities of the panels, requiring an acrylic coating with a higher fill capacity.
The polymeric coatings are typically applied in two coats to achieve a total thickness of at least 1 mm.
Paint can also be applied directly to walls with mortared joints constructed of Hebel AAC blocks and panels. This application requires precision to achieve an acceptable appearance. Extreme care must be taken in joint preparation.
The joints in a Hebel AAC mortared wall are much thinner than in conventional masonry construction and therefore are more likely to reveal minor imperfections.
Even with the acrylic coatings noted above, joints may be visible. For applications where appearance is not a dominant consideration, such as industrial buildings or garages, applying paint directly to a Hebel AAC wall can be an inexpensive and time-saving alternative. Any paint that is used must be vapor permeable to allow moisture inside the block to escape.
Ventilated façades as an exterior surface treatment is beneficial from a humidity and thermal point of view. Façade treatments such as wood shakes, brick, stone, metal siding, vinyl siding and cementitious panels can be utilized. A furring strip substructure is advantageous since it allows back ventilation. The furring strips are best attached to Hebel using fasteners compatible with AAC. Install all external materials per the specific manufacturer’s recommendations. Typical waterproofing details including weep holes,flashing, lapping, connections and membranes should be incorporated in order to achieve the desired weather tight construction.
Figure 4.10: Painting over exterior AAC walls
Figure 4.11: Applying coating to exterior AAC panels
Figure 4.12: AAC with brick façade
Follow coating manufacturer recommendations for joint treatment of exterior and interior joints. In any case, the horizontal and vertical joints in Hebel AAC walls must be weather tight. Consult with your design professional for suitable options depending on the project requirements. All materials must be compatible with AAC.
Ceramic tiles are not recommended for direct application to AAC. They do not provide suitable weather protection because of the varied thermal conductivity of ceramics as compared to AAC. This difference can cause considerable tension, leading to loose or cracked surface of the ceramic tiles.
4.5 Interior Surface Treatments
AAC Interior coatings are designed for use with Hebel AAC products. Skim coat plasters and lightweight interior plasters must have material properties that are compatible with AAC. To provide maximum adhesion and resiliency,bonding agents are often incorporated into these products.
Wall panels should be coated with a skim coat plaster to achieve a smooth, consistent surface. With block applications, lightweight interior plasters provide a thicker coating to level and straighten walls. This also provides a base for interior paints and finishes.Interior plaster is usually applied in a single coat to a thickness of 3/32 to 1/8 inch, following the manufacturer’s recommendations.
The surface is then finished to a smooth and even quality.
Depending on the size and complexity of a project, plaster can be applied by either a sprayer or trowel.
Gypsum board may be applied to Hebel AAC exterior and interior walls.
Pressure treated furring strips can be used to fasten gypsum boards.
Wall Tile Tile can be applied directly to Hebel AAC walls using either a cement thin set mortar or an adhesive. Surface preparation is only necessary when the AAC wall surface requires leveling. If the AAC wall requires leveling, a Portland cement or gypsum-based parge coat can be applied prior to setting the ceramic tile. In moist applications, such as shower areas, use only Portland cement parge coatings. The ceramic tile can then be adhered to the prepared wall with a cement thin set mortar or an adhesive.
Figure 4.13: Filling AAC wall panels for a smooth surface
Figure 4.14: Tile applied over AAC
Paneling systems can be installed using furring strips. Wood, plastic, masonite and composite paneling can all be installed using furring strips in the same manner as suggested for gypsum board. The furring strips are best attached to Hebel AAC using fasteners compatible with AAC. An alternative is to fasten the gypsum board directly to the wall using a commercial adhesive and screws only if moisture resistant gypsum board is used. Consistent with standard construction practice, moisture resistant gypsum board is recommended in high humidity regions such as bathrooms and saunas.
Hebel AAC walls can be directly painted, yet joint preparation is critical and requires skillful detail to achieve a smooth surface. The joints in Hebel AAC mortared wall systems are thinner than conventional masonry construction and can expose slight imperfections. In applications such as industrial building or garages, where appearance is not a high priority,applying paint directly to an Hebel wall can be an inexpensive and timesaving alternative.
Hebel AAC墙可以直接粉刷，但是接缝的准备是关键，需要熟练的细节来达到光滑的表面。Hebel AAC砂浆墙系统的接缝比传统的砌体结构更薄，可以暴露轻微的缺陷。在工业建筑或车库等外观不是很重要的应用中，直接在Hebel墙壁上涂漆是一种既便宜又省时的选择。
Paint used with AAC must be vapor permeable to allow moisture to escape.
Wallpaper which is vapor permeable can be directly applied to an Hebel AAC wall. Vinyl wallpaper is not recommended. To level or smooth the AAC surface prior to wallpaper installation, use a Portland cement or gypsum-based parge coating.
Ceilings may be finished with AAC coatings as referenced in this section. Suspended ceilings and grids can be installed and fastened directly into an Hebel floor/roof panel or into pressure treated furring strips fastened to the Hebel floor/roof system.
Hebel floor panels are cut to specified dimensions during production. Toppings are usually not required since all Hebel panels are produced with zero camber. If necessary, a leveling topping can be used to create a smoother surface. Hebel floor panels allow toppings such as carpet, vinyl sheet, vinyl composition tile, ceramic tile, rubber tile, terrazzo, wood and linoleum.
Figure 4.15: Interior AAC walls
4.6 Coating Manufacturers
The following pages feature a few AAC coating manufacturers.
Elite Building Products markets a broad range of decorative specialty finishes, patching materials, and thinbed mortars for Hebel AAC. Like any good structural material, AAC must be protected against the elements so that its extraordinarily good characteristics are maintained. To accomplish this, Elite Building Products systems and materials were developed which are now a fundamental component of AAC construction.
For more than 30 years Litewall SL has been the chosen exterior stucco finish for autoclaved aerated concrete.
Through years of true pioneering research, Litewall SL, Gypspray, Acryl M and other related materials were developed to provide a product family of the highest quality and compatibility with AAC.
Long term durability and decorative appeal is not all that counts. Equally important is having a quality product which is easy to use and highly cost effective. Elite provides this, and as specialists in the materials that compliment AAC,we offer invaluable application and consulting knowledge catered to your project. Please feel free to contact us.
Since 1962, Sider-Oxydro’s commitment to innovation through technology continues to expand our product line for AAC including:
• Exterior cement and acrylic finishes外部水泥和丙烯酸饰面
• Interior gypsum plasters室内石膏抹面
• Thin and coarse bed mortars抹灰层
• Repair mortars修补粉
• Floor coatings地坪
Our products for AAC are blended under strict regulations and followed by a precise quality control. You can be assured of a perfect blend in every bag. Furthermore, our proven blending technology, use of advanced additives and fiber reinforcement are crucial to assure longevity and durability of our products.
Shown by an exemplary tract record, the quality and performance of our products equate our dedicated customer service.
About Sto Corp.
Sto Corp., based in Atlanta, Georgia, is an innovative world leader and producer of a broad range of versatile cladding and coating systems for building construction, maintenance and restoration. Sto Corp. is ISO 9001 certified and operates production plants strategically located to serve more than 200 distributor shipping locations across North America. At research and development laboratories in the U.S. and Europe, Sto continues to revolutionize the industry with the highest quality products and application technology.
Sto AAC Base Coat SC
Sto AAC Base Coat SC is a one-component, polymer modified, cement base coat for use on AAC substrates.
Sto AAC Base Coat TC
Sto AAC Base Coat SC is an acrylic-based material used as a base coat over AAC substrates. It is a two component product to be combined with Portland Cement.
Sto AAC Finishes
Sto AAC Finish is a ready-mixed, flexible textured wall finish used as a decorative and protective wall finish over prepared vertical, above grade, exterior AAC substrates.
Sto AAC Mesh
Sto AAC Mesh is a specially designed, coated glass fiber fabric used for reinforcement of AAC substrates with Sto AAC base coat.
Sto AAC Mesh是一种特殊设计的涂层玻璃纤维织物，用于加固带有Sto AAC基底涂层的AAC基底。
DISCLAIMER. This document is not intended to replace the knowledge, experience and judgment of design professionals. Xella Aircrete North America, Inc. is not responsible for ensuring weather-tightness, overall functionality or fitness for use of the panels, nor compliance with federal, state, or local laws, ordinances or regulations, including building, environmental and other codes.
WARNING. Property damage, personal injury or death may result from improper design, use, or installation.
Licensed design and construction professionals, who maintain good standing with the governing authority and have the necessary knowledge, experience and judgment of the specific building system and its components, should be retained to ensure a proper design, use, and installation.
MODIFICATIONS. Xella Aircrete North America, Inc. reserves the right to change its Technical Manual, Design Guide, safe working loads, panel dimensions or installation techniques at any time without prior notice. Last modified: 1/7/2010.
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