Keene Building Products

Transcription

1 Keene Building Products

2 Keene Building Products is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-aia members are available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific material, methods, and services will be addressed at the conclusion of this presentation.

3 Healthy Walls Rainscreen & Ventilation

4 Learning Objectives Moisture Migration in Wall Systems Moisture Management Methods Research & Codes Components of Rainscreen System Rainscreen Details

5 Moisture Damage

6 Outer Wall Picture from Outside of Structure

7 Inner Wall Picture from Inside of Structure

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11 What are we doing wrong? Buildings are becoming tighter due to energy efficient wall design Energy efficient buildings eliminate thermal leakage Wall assemblies are not ventilating properly

12 Methods of Wall Construction Barrier Wall Stops Water on with One Layer Plane No Control of Water Penetration Usually is Constructed as a Imperfect Barrier

13 Methods of Wall Construction Rainscreen System or Cavity Wall Construction Assumes some Water will Penetrate Cladding Penetrating Water is Collected for Discharge Wall can properly ventilate Types Include Stucco, Manufactured Stone, Lap Siding & Brick

14 Benefits of Rainscreen Drainage Cavity to Allow Water to Drain Down to the Weep Screed & Out of the Wall System Air Flow to Allow Moisture Inside of the Wall to be Able to Dry More Quickly Prevent the Mortar from Coming Through the Lathe & Attaching to the Paper Creating a Mortar Dam Helps the Transition Between Dissimilar Veneers that will be Entryways for Water Cavity Wall Construction

15 Research & Codes Studies on the Need for Rainscreen Hangan, Horia & Surry, David. Wind-Driven Rain Study for the Governor s Road Project. Canada Mortgage & Housing Corporation, Incluet, D. & Surry, D. Simulation of Wind-Driven Rain & Wetting Patterns on Buildings. Canada Mortgage & Housing Corporation, Kerr Associates Technology Transfer. The Rainscreen Wall System. Canada Mortgage & Housing Corporation, Patenaude, Armand. Migration of Water by Capillarity. Canada Mortgage & Housing Corporation, 1993.

16 Research & Codes 2005 National Building Code of Canada, Section , item 1b Products, materials or systems must allow drainage, create a 10 mm gap between the two planes of protection and be not less than 80% open in cross section.

17 Research & Codes IBC Chapter 1 - Administration Exterior wall envelope Construction documents for all building shall describe the exterior wall envelope in sufficient detail to determine compliance with this code. The construction documents shall provide details of the exterior wall envelope as required, including flashing, intersections at roof, eaves or parapets, means of drainage, water-resistive membrane and details around openings.

18 Research & Codes IBC Chapter 14 - Exterior Walls Weather Protection Shall include flashing and WRB WRB not needed over concrete or masonry Drainage layer needed except if tested assemblies show no need Drainage layer needed unless water penetration is not detrimental

19 Cultured Stone s Rainscreen Statement Some building codes require a rainscreen behind cladding materials, including manufactured stone veneer. If you are installing manufactured stone/brick veneer in one of these jurisdictions, or are concerned about extreme weather conditions, it is recommended that you choose a rainscreen system that can achieve the following:

20 Cultured Stone s Rainscreen Statement The system should create a space with a minimum depth of 3/8 (10mm) and maximum depth of 3 4 (19mm). Unless otherwise designed to manage moisture vapor, the system should be vapor open. The materials should be corrosion and rot resistant. If rainscreen space is created with a material other than solid strapping/ furring attached directly to framing, the following must be considered. Lath fasteners must be capable of supporting the weight of the finished wall cladding system considering the unsupported/cantilevered portion of fastener that is equal to the thickness of the rainscreen materials.

21 Research & Codes 2006 IRC Code Exterior Covering Section 703. Exterior Plaster section Section Water Resistant Barriers. Waterresistant barriers shall be installed as required in section R703.2 and where applied over wood based sheathing, shall include a water resistive vapor-permeable barrier with a with a performance at least equivalent to two layers of Grade D paper Exception: Where the water resistive barrier that is applied over wood based sheathing has a water resistance equal to or greater than that of 60 minute Grade D paper and is separated from the stucco by an intervening, substantially non watering-absorbing layer or designed drainage space.

22 Cladding Types for Rainscreen Exterior Covering Stucco Manufactured Stone Thin Stone Brick Lap Siding Etc.

23 What to Look for in a Airspace or Rainscreen Product? Minimum thickness of a 1/4inch Creates an airspace that is a minimum of 80% open air Does not absorb moisture Easy to install Can Transition Between Dissimilar Veneers ASTM E 84 - Standard Test Method for Surface Burning Characteristics of Building Materials Should be made of Recycled Polymers UL Rating

24 Drainage Mats What are Good Characteristics of Drainage Mats?

25 Product comes in a roll

26 Overlap with 3.5 fabric

27 Wrapping Corners

28 Lath over Rainscreen

29 Variety of Veneers

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33 Manufactured Stone

34 Rainscreen

35 Rainscreen

36 Rainscreen

37 Fiber Cement Siding Study Morrison Hershfield, a leading engineering and architecture firm in North America, addressed the concerns about rainscreen installation in siding applications. They conducted a site study on July 9, 2009 at a single-family residence in British Columbia. The wood frame structure was constructed with two layers of building paper, Driwall Rainscreen 10 mm and Hardie Plank cladding. The installation was reviewed, and results were documented in the attached photographs. The capillary break at the fasteners for the Hardie plank was measured to be 10 mm (see Photo 2). Excessive deflection of the Hardie plank was not observed around the fastener penetrations (see Photo 3). The back of a section of Hardie Board plank siding that was nailed directly into the OSB without Driwall Rainscreen was compared to the plank that was installed over Driwall Rainscreen for damage from the fasteners (see Photo 4). Morrison Hershfield consulted Jason Ward, the product development engineer at James Hardie Research USA. Hardie reviewed the photos that were submitted by MH and has indicated that the level of damage to the back of the panels as a result of the unsupported fasteners is acceptable. Hardie will provide its warranty for installation with Driwall Rainscreen as long as proper nail penetration is maintained, minimum code requirements are met and all other James Hardie installation instructions are followed. After looking at the appearance in regard to excessive deflection, Morrison Hershfield concluded that in comparing the installation of most claddings traditionally installed without a drainage material, it is reasonable to assume that performance with Driwall Rainscreen 10 mm would be equivalent or better than performance without.

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39 Brick Architecture Withstands the Test of Time. Sturdy and durable to weather the elements Long lifespan with minimal maintenance Aesthetically pleasing, a timeless look. Independence Hall. Philadelphia, Pennsylvania.

40 Benefits of Cavity Walls DRAINAGE Water drains down the wall and exits through the weep holes. VENTILATION Air flows through the cavity to dry out the sheathing and backside of the brick.

41 Moisture Management Some moisture intrusion is anticipated Water enters the wall system. Reaches the cavity. Unobstructed airspace provides a clear drainage plane. Water reaches the bottom of the wall. Exits through the weep holes.

42 Research and Codes Brick Institute of America BIA Technical Note 21A Recommends a 2 inch airspace Airspaces less than 2 in. (50 mm) cannot practically be kept free from mortar bridging.

43 Two Inch Airspace Room for mortar deflection devices to work properly. The space is large enough to prevent mortar bridging, therefore mortar is allowed to fall down into the cavity and be managed by the mortar deflection device.

44 One Inch or Less Airspace Most mortar is stuck above the through-wall flashing, it is suspended between the brick and the back-up wall, which prevents the mortar collection device from working properly. These mortar bridges prevent drainage and airflow throughout the cavity.

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46 One Inch or Less Airspace Provide Proper Drainage and Ventilation FULL WALL DRAINAGE PRODUCT Keeps cavity free of mortar and debris Ensures an open airspace for maximum drainage and ventilation

47 How to Drain Masonry Cavity Walls Cavity walls of 2 or greater of air space. Use Mortar Deflection product above the through wall flashing Shelf angles Windows Doors Use Weep vents at top and bottom of walls Cavity Wall of 1 or less of air space. Use fluted full wall drainage product Use every where is masonry Use Weep vents at the top and bottom of the walls

48 Thank You for Your Time This concludes the American Institute of Architects Continuing Education Systems Program PLEASE Complete a Course Evaluation Provider Name: Keene Building Products Course Title: Healthy Walls = Drainage & Ventilation Course #: DWRS08 Presenter s Name: Paul Murphy Date of Presentation: Today s Date Location: City, State of Presentation