The Role of Control Layers in Building Enclosure Design

Transcription

1 The Role of Control Layers in Building Enclosure Design COLIN SHANE M.ENG., P.ENG., P.E. ASSOCIATE, SENIOR PROJECT MANAGER RDH BUILDING SCIENCE INC. SEPTEMBER 14, 2016 Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board. 1 of 63

2 Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. RDH Building Sciences Inc. 2015

3 The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider #G516. Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This course is registered with 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 materials, methods, and services will be addressed at the conclusion of this presentation.

4 Course Description Building enclosures are responsible for controlling heat flow, air flow, vapor flow and a number of other elements. Through a combination of building science fundamentals and current research, this presentation will explore design considerations associated with wood-frame building enclosures and the role of control layers. Discussion will focus on best practices for designing durable, energy-efficient enclosures using traditional light wood-frame construction.

5 Learning Objectives Review building science fundamentals and building enclosure design considerations for light wood-frame buildings. Explore the role of control layers in building enclosures for elements such as heat flow, bulk water intrusion and air flow. Discuss best practices for light wood-frame building enclosure design, detailing, and construction techniques. Explore the thermal benefits of utilizing wood-frame construction.

6 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 6 of 97

7 Wood-frame Building Enclosure Design Guides 2011 Building Enclosure Design Guide Wood-frame Multi-Unit Residential Buildings Emphasis on best practices, moisture and new energy codes 2013 Guide for Designing Energy- Efficient Building Enclosures Focus on highly insulated woodframe assemblies to meet current and upcoming energy codes CLT Handbook 7 of 63

8 Building Enclosure Design Fundamentals Separate indoors from outdoors, by controlling: Heat flow Air flow Vapor diffusion Water penetration Condensation Light and solar radiation Noise, fire, and smoke While at the same time: Transferring structural loads Being durable and maintainable Being economical & constructible Looking good! 8 of 63

9 Trends in Building Enclosure Design Trend towards more energy efficiently building enclosures Air barriers now required in 2012 IECC and 2013 CEC Continuous insulation becoming more common Seeing more new building materials, enclosure assemblies and construction techniques More insulation = less heat flow to dry out moisture Marginal assemblies that worked in the past may no longer work Amount, type and placement of insulations matters, for vapor, air and moisture control Need to fully understand the science and interaction of design parameters 9 of 63

10 What do we know? Control Air Control Rain Building Enclosure Control Vapor Control heat 10 of 97

11 Building Enclosure Control Layers 11 of 63 11

12 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 12 of 63

13 Rain Penetration Control 3 Conditions for Rain Penetration: 1. A source of water 2. A water entry path 3. A driving force 4 Ways to Control it: 1. Deflection 2. Drainage 3. Drying 4. Durability 13 of 97

14 How do Walls get Wet and Dry? 14 of 63

15 Water Penetration Control Strategies 15 of 63

16 Rainscreen Cladding 16 of 63

17 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 17 of 63

18 Air Penetration Control Why? Code requirement Moisture Air holds moisture that can be transported and deposited within assemblies. Energy Unintentional airflow through the building enclosure can account for as much as 50% of the space heat loss/gain in buildings. 18 of 63

19 Air Barrier Systems Air Barrier Systems Must: Be continuous, airtight, durable Resist structural loads Bridge joints across inter-story and drift joints Not negatively affect drying ability Traditional loose sheet applied house-wrap products are challenging to make air-tight on larger buildings 19 of 63

20 Types of Air Barrier Systems Loose Sheet Applied Membrane Taped Joints & Strapping Sealed Gypsum Sheathing Sealant Filler at Joints Liquid Applied Silicone sealants and silicone membrane at Joints Sealed Plywood Sheathing Sealant & Membrane at Joints Sealed Sheathing Membrane at Joints Self-Adhered vapor permeable membrane Plywood sheathing 20 of 63 with taped joints (good tape)

21 Airtightness Does Not Happen By Accident 21 of 63

22 How to Tell the Membrane is Not the Air Barrier 22 of 63

23 Definitely Not An Air Barrier But What Is? 23 of 63

24 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 25 of 63

25 Conductive Heat Loss Control Insulation between studs is most common heat control strategy Need to consider effective R-values Continuous insulation on exterior becoming more common 26 of 63

26 Wood Framing Factor Impact on Effective R-values 24 o/c 16 o.c. 27 of 63

27 Insulation Placement Consider effective thermal resistance 28 of 97

28 Cladding Attachment Through Exterior Insulation 29 of 97

29 Cladding Attachment through Exterior Insulation Longer cladding Fasteners directly through rigid insulation (up to 2 for light claddings) Long screws through vertical strapping and rigid insulation creates truss (8 +) short cladding fasteners into vertical strapping Rigid shear block type connection through insulation, 30 of 63 cladding to vertical strapping

30 Thermally Improved Performance Continuous metal Z-girts Fiberglass Clips & Hat-Tracks 31 of 63

31 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 32 of 63

32 The Perfect Assembly Rain penetration control: rainscreen cladding over water barrier Air leakage control: robust air barrier system Heat control: continuous insulation layer Locate all barriers exterior of structure Keep structure warm and dry 50+ year old concept! 33 of 97

33 Wood-Frame Assemblies Perfect Wall 34 of 97

34 Wood-Frame Assemblies Perfect Roof 35 of 97

35 Wood-Frame Assemblies Perfect Roof 36 of 97

36 Wall-to-Roof Detail 37 of 63

37 Wall-to-Roof Detail 38 of 97

38 Details Continuity of Control Layers In practice, need to evaluate and design assemblies and details that are not perfect Continuity of control layers within and between assemblies is critical Hygrothermal analysis 39 of 63

39 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 40 of 63

40 Cross Laminated Timber Ronald McDonald House 41 of 63

41 CLT Construction Moisture Keep it dry during construction as best as possible 42 of 97

42 CLT Air Barrier Considerations Structural connections can interfere with air-barrier membrane installation/sequencing and sharp parts can damage materials (applied before or after) 43 of 63

43 CLT Unique Details for Consideration 44 of 63

44 CLT Panel Details Requiring Attention Sealants, tapes, & membranes applied on either side can t address this type of airflow path through the CLT lumber gaps 45 of 63

45 CLT Wall Assemblies 46 of 63

46 Roof Assembly R-40+ Conventional Roof Assembly 2 ply SBS, 4 Stonewool, 4 Polyiso, Protection board, Tapered EPS (0-8 ), Torch applied Air/Vapor Barrier(Temporary Roof), 47 of 63 ¾ Plywood, Ventilated Space (To Indoors), CLT Roof Panel Structure (Intermittent)

47 CLT Considerations Get the architect to take the final photos 48 of 63

48 Roadmap BACKGROUND Basics BEST PRACTICES Walls CASE STUDIES CLT Water Low-slope Roofs Air Steepslope Roofs Deep Energy Retrofit Heat 49 of 63

49 Deep Energy Retrofit Moisture damage at walls and windows Concealed barrier stucco cladding Vented low-slope roof assembly Energy efficient rehabilitation of wall, window, and roof assemblies 50 of 63

50 5-Storey Wood-frame w/ Exterior Insulation 51 of 63

51 New Exterior Wall Assembly 52 of 63

52 New Sloped Roof / Overhang Assembly 53 of 63

53 New Low-Slope Roof Assembly 54 of 63

54 Completed Building Enclosure 55 of 63

55 Summary Control moisture, air, and heat Best practices: Rainscreen cladding Keep structure warm and dry: control layers on exterior Less than perfect practices: Analyze and understand hygothermal behaviour Provide continuity of control layers within and between assemblies and details 56 of 97

56 This concludes The American Institute of Architects Continuing Education Systems Course Colin Shane

57 Discussion + Questions Colin Shane cshane@rdh.com rdh.com 58 of 63