AIA PRESENTATION. Retrofit Roof Systems NURF-1 (1 credit hour)

Transcription

1 AIA PRESENTATION Retrofit Roof Systems NURF-1 (1 credit hour)

2 Best Practice Slide MBCI is a Registered Proider 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 aailable 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 approal 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 serices will be addressed at the conclusion of this presentation. 2

3 Learning Objecties Define and better understand Market Demands Benefits Various Applications for Retrofit Roof Systems Framing Fundamentals Project Considerations Assessing the Existing Roof Design Considerations 3

4 Oerall Roofing Market New Construction Market size : 102 Million New Roofing Metal Modified Shingle EPDM Plastic Other 21.5 Million 6.5 Million 4.9 Million 2.6 Million 3.6 Million 2.5 Million 1.4 Million NOTE: All data is in squares. Source: 2010 Freedonia Roofing Report 4

5 Oerall Roofing Market Reroofing Market size : 102 Million Reroofing Modified Shingle EPDM Metal Plastic Other 80.5 Million 27.1 Million 16.4 Million 13.5 Million 12.8 Million 8.5 Million 2.2 Million NOTE: All data is in squares. Source: 2010 Freedonia Roofing Report 5

6 Retrofit Defined For the purpose of this presentation retrofit is defined as: Relatie to the metal construction industry, the term means complete fully-engineered structural roof systems used for adding slope to existing buildings with flat or nearly flat roofs for correcting problematic roof geometry for reroofing oer existing sloped roofs for extending the life expectancy of a roofing system The systems include light-gauge support framing with metal roof/wall cladding 6

7 WHY RETROFIT WITH METAL? Benefits of Retrofitting

8 When to Retrofit Framing Systems Replace leaking roof Regulation/code requirements Structural changes Aesthetics Correcting roof geometry Improe entilation Proide thermal upgrades New building construction 8

9 Metal Roofing Benefits Attributes Durable Sustainable Aesthetics Benefits Reduces maintenance; longer life Contributes to LEED points Increases property alue 9

10 Metal Roofing Benefits Attributes Aailable in Cool Colors Virtually 100% Recyclable Long Serice Life Benefits Reduces heat-island effect Reduces land fill waste Life cycle performance 10

11 Metal Roofing Benefits Each year, an estimated 9 to 10 million tons of asphalt roofing waste goes to U.S. landfills, costing more than $400 million on disposal fees* A metal roofing retrofit eliminates the need to tear off the existing roof in most cases *Source: Corps of Engineers

12 Metal Roofing Benefits Oer Single Ply Features Life Expectancy Maintenance Benefits 41.6 s years $0.10 s. $0.26/ft 2 /yr Source: Metal s. Single-Ply Ducker Worldwide Report 12

13 Improing Our Energy Efficiency Tax incenties now extended through 2013 on commercial buildings For up-to-date listing of adopted areas, go to or 13

14 Initial Cost s. Energy & Maintenance Saings *Source: 2007 Ducker Worldwide Report High School Winchester, Ind. 108,000 Square Feet 6 Insulated Attic Ventilated Existing Roof = BUR (asphalt) Retrofit Benefits BUR (asphalt) Tear Off & Replace Retrofit Roof Replacement Estimated Energy Saings ($0.10 / sq ft x 108,000 sq ft)* Estimated Reduction of Maintenance Cost ($0.10 / sq ft s. $0.17 x 108,000 sq ft)* Estimated Saings based on not haing to Reroof BUR (Asphalt) (Ag. BUR Reroof cost of $3.75 / sq ft* annualized based on 23 yr serice life* and 3.12% inflation rate) Cost s. Saings $1.5M $1.6M <$100K> $10,800 $7,560 $35,695 Estimated Annual Saings $54,055 Estimated Maintenance & Energy Payback of $100K Initial Retrofit Cost Difference Estimated Maintenance, Energy and Future Replacement Cost Payback of $100K Initial Retrofit Cost Difference 5 ½ Years 2 Years 14

15 RETROFIT APPLICATIONS Low-Slope, High-Slope, Geometry Issues and Metal Roofoers 15

16 Low-Slope Typically drien by economy, these utilitarian applications are designed to simply discharge rainwater from the roof without improing the curb appeal of the existing building Roof slopes from ¼ to 2:12 Common metal roof systems are: Trapezoidal Standing Seam Exposed Fastened Rib Panel 16

17 High-Slope These architectural applications are employed when the roof will be a design element in the beautification of an existing school or during additions where the existing buildings are upgraded to match new construction Roof slopes typically aboe 2:12 Embraced by Schools and Federal, State and Municipal Goernment for oer two decades Ideal for Cool Roof rated metal roof Recommended metal roof system is: Vertical Rib Standing Seam 17

18 Problematic Roof Conditions Retrofit systems can be employed on building facilities that hae undesirable issues with discharging rainwater Correcting Roof Geometry Issues Fill-ins and Crickets Multi-Gable or Stepped Increase Slope Reerse Slope Remoe Barrel Reerse Slope Remoe Barrel Cured oer Flat Stepped Increase Slope Sawtooth 18

19 Reroofing Oer Sloped Roofs When the existing roof is being replaced with a new long-term performance (typically lasting 40 years or more) standing seam metal roof system Metal oer metal Metal oer composition and other conentional membranes Correctie alternatie to failed roof systems Wind Load and FM upgrades 19

20 FRAMING FUNDAMENTALS Components, Design and Layout 20

21 Base Members Angle Clip Base Shoe Continuous Base 21

22 Columns Typically cee-shaped Sizes ary from 4 to 8 Usually field cut from standard lengths Also referred to as post or stanchion Column 22

23 Purlins Spaced to support roof membrane Typically zee-shaped Sizes ary from 3½ to 10 Field cut or detailed to required lengths Purlin 23

24 Bracing Common members include: Struts Transerse and Horizontal Vertical Bracing Diagonal Transerse and Longitudinal Transerse Bracing Longitudinal Bracing 24

25 Common Existing Roof Assemblies Wood framed Dimensional lumber Glue-laminated Heay timber Steel framed Beam and metal deck Open-web joist and metal deck Structural concrete Steel Beam and Deck Concrete Beam supported Concrete tee Bulb tee oer joist with Tectum Metal building systems Purlin Open-web joist 25

26 Framing System Adaptability Systems can be designed to adapt to arious existing roof assemblies and support systems Steel 26

27 Framing System Adaptability Systems can be designed to adapt to arious existing roof assemblies and support systems Concrete 27

28 Framing System Adaptability Systems can be designed to adapt to arious existing roof assemblies and support systems Wood 28

29 Understanding Roof Grids Nearly all existing building roofs are constructed using a primary and secondary structural grid layout regardless of the support method or type of system employed Retrofit framing systems employ a structural grid that imposes a series of concentrated point loads into the existing roof system These two grid systems must be compatible to ensure the existing roof s structural integrity is maintained 29

30 Framing Design Existing Joists 30

31 Parallel Framing The type of base member is dictated by the existing roof s secondary structural span and orientation. Parallel Framing Base shoe or channel Usually field drilled for anchor installation Width aries based on column width 31

32 Parallel Framing Example New Ridges New Valley New Zee Purlin Intermittent Base New Column Point Load 32

33 Perpendicular Framing The type of base member is dictated by the existing roof s secondary structural span and orientation. Perpendicular Framing Continuous Zee Usually field drilled for anchor installation Continuous base member spacing dictated by purlin spacing of new roof 33

34 Perpendicular Framing Example New High Eae New Pitch break New Column Continuous Base Point Load New Zee Purlin 34

35 Load Distribution: Base Members Example shows both continuous zee and base shoe framing systems Continuous Zee Spacing is per design Base Shoe Retrofit Purlin Spacing on flat Continuous Zee Base Shoe 35

36 Load Distribution: Vertical Framing Spacing is dictated by the existing roofs secondary spacing and span orientation New Retrofit Columns Retrofit Purlin Spacing on flat Continuous Zee Base Shoe 36

37 Load Distribution: Bracing and Purlins Bracing resists lateral forces Purlins withstand lie and dead loads Valley Support Framing Bracing Retrofit Purlins Continuous Zee Base Shoe 37

38 Remember The existing roof s physical footprint and other rooftop conditions will more than likely control the new roof s geometry. 38

39 ASSESSING THE EXISTING ROOF

40 Project Scope Considerations Define and Proide Existing Roof Plan Perimeter Conditions Rooftop Obstructions Roof Support System Substrate Assembly Define and Proide New Roof Plan Ventilation System Insulation New Roof System Perform pre-bid design analysis and testing Partner with a Manufacturer for expertise 40

41 Testing and Inspection Responsibility The Owner or Design Professional is accountable for the inspection and testing of the existing structure and for proiding this information to the manufacturer. 41

42 Existing Roof Information Detail Existing roof footprint Expansion 42

43 Existing Roof Information Detail Existing roof footprint Expansion joints Roof perimeter construction such as grael stops and parapets Interior firewalls Existing drainage systems 43

44 Inspect the Existing Roof System For existing joists and their support identify: Type Size Spacing Span orientation 44

45 Inspect the Existing Roof System Determine all collateral loads on the exterior and interior of the existing building: HVAC Electrical Plumbing Ceilings Sprinkler, etc. 45

46 Inspect the Existing Roof System Locate Rooftop Equipment Electrical HVAC locations Plumbing Document 12? C? HVAC B A 46

47 Inspect the Existing Roof System Ealuate existing substrate for: Trapped moisture Deterioration Presence of harmful material (i.e. asbestos) 47

48 Inspect the Existing Roof System Conduct pull-out testing so anchorage requirements can be determined. 48

49 Compressie Resistance Test 49

50 Compressie Strength When retrofitting a roof, compression strength is defined as the ability of the existing roof substrate to resist the forces created by the attachment of the retrofit roof framing so that the underlying material is not crushed and excess deflection is not introduced in the new roof. 50

51 Compressie Resistance Imposed Load Existing Substrate Determine if the base member s bearing surface area is adequate (min. 25 psi). 51

52 Insufficient Compressie Resistance Insulation/Deck Deterioration Remoe membrane and insulation Inspect decking for possible damage (rust, rot, etc.) 52

53 Bid Document Summary Proide: Comprehensie roof plan Information on joists and their support Internal and external collateral loads Existing substrate assessment Pull-out test Compression resistance ealuation 53

54 DESIGN CONSIDERATIONS

55 Adding Insulation Include the insulating alues of the existing material in any R-Value requirement * Typically, older roof assemblies and materials do not offer adequate thermal protection 55

56 Ventilation A properly designed entilation system is crucial Consult a Mechanical Engineer to ensure proper entilation 56

57 External Loads Assess external loads including: Lie Loads Wind Uplift Snow Loads Dead Loads Seismic Loads 57

58 Additional Weight Beware of unplanned snow drift loads on: Ridges (unbalanced) Valleys Adjoining roof and wall Penetrations caused by existing roof conditions Adjacent buildings Wind The design professional should ealuate these added loads for required remediation of the existing structural system. 58

59 Anchorage Requirements Characteristic Determined by: Wood or steel frame Structural concrete Anchor Length Joist type Strength and deck thickness Thickness of existing roof assembly Due to probable moisture content in the existing substrate, anchors should hae a corrosion resistant coating Anchor installation into steel and wood joists should be closely monitored 59

60 Framing System Anchorage Most retrofit failures are caused by improper anchorage 60

61 Framing System Anchorage Make sure you enlist experienced registered professional engineers, manufacturers and installers to ensure the best results. 61

62 Anchorage Installation Tip To reduce moisture penetration caused by anchors: Specify shims to eleate continuous base members so not to obstruct the existing drainage system Require all anchorage penetrations to be sealed with compatible sealant 62

63 SELECTING THE RIGHT PARTNERS

64 Qualifying a Manufacturer Retrofit Design Manual in Place Certify Contractors Reliable Weathertightness Warranties 64

65 Retrofit Manufacturer What should the retrofit system manufacturer proide you? Framing layout drawings Sealed design calculations including: Positie (graity) and negatie (wind uplift) imposed loads at each framing attachment location Lateral wind forces at gable ends and other ertical surfaces Shear requirements from bracing 65

66 Qualifying a Contractor History of retrofit projects Certified by a manufacturer Insured and bondable 66

67 Performance with a Payback Retrofit metal roofing is the only roof replacement system that proides long-term reliable performance with a payback 67

68 Please Note Contents on your CD: Performance Specifications CSI Format and MasterFormat 2004 Frequently Asked Questions Roofing Components Reference Information Required information needed for a contractor to obtain an Estimate RFI Form Standard Details ACAD PDF MBCI s other CES Program Opportunities: * Retrofit Roof System Design and Application (3-hour) * Insulated Metal Panels (1-hour) * Standing Seam Roof Systems (1 and 3-hour) * The Deil is in the Details (1-hour) * Weathertightness Warranties (1-hour) 68

69 The AIA/CES education portion of the course has ended. Are there any questions? Thank you. Retrofit Roof Systems NURF-1 (1 credit hour)

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