DESIGN REHABILITAT INVESTIGAT E E The Ins and

DESIGN REHABILITAT INVESTIGAT E E The Ins and Outs of Metal Rainscreen Wall Systems 15 October 2012 SMACNA 69 th Annual Convention Las Vegas, Nevada Presented by: Jeff Ceruti www. sgh. com

Outline • • Defining the Rainscreen Wall Metal materials Panel seam types Pressure equalization Water/Air barriers Issues observed in practice – details, etc Fire test requirements

What is a Rain Screen Wall? • Two fundamental approaches to design of exterior walls – Barrier Walls – – Multi-wythe masonry Early EIFS (no drainage) Precast concrete Insulated metal panels – Drainage Walls – – – Brick veneer Rainscreen (metal, phenolic, stone, others) Stucco Vinyl/wood/cement siding Drainable EIFS

What is a Rain Screen Wall? – Multi-wythe Masonry Barrier Wall – Relies on mass of masonry to absorb water and later evaporate; thick walls needed – Occasional leakage to interior during heavy storms

What is a Rain Screen Wall? – Surface Sealed Barrier Wall – Relies solely on the exterior surface of the wall to waterproof the building – Seal failures, breaches, discontinuities = leakage into building – No Redundancy

What is a Rain Screen Wall? • Drainage Walls – Cladding sheds bulk water down the façade – Allows some infiltration – Drainage cavity or media allows infiltration to drain down – Water-resistant barrier behind the cladding – Prevents water from entering building – Flashings at intervals drain any infiltration to the exterior – Openings for drainage also allow venting (drying) of cavity – Two basic types: – No or minimal cavity (clapboards, siding, stucco over water barrier) – Wide cavity (brick veneer, metal panels, dimensional stone, clay tile, phenolic panels, etc. )

What is a Rain Screen Wall? • Drainage Walls – Cladding is not air or water tight – Some test data for water penetration relies on back-up wall – not a true measure of the cladding system Thermal insulation Cladding Waterresistant barrier Drainage space/plane Flashing

What is a Rain Screen Wall? • Back-up Wall – Critical for overall wall performance – Water barrier – Air barrier – Thermal insulation – Vapor retarder • Exterior covering is primarily for aesthetics Thermal insulation Cladding Waterresistant barrier Drainage space/plane Flashing

Metal Panel Rainscreen Materials • Aluminum Composite Material (ACM) – Thin aluminum sheet with core material; total 4 mm (5/32 in. ) – Polyethylene – height limit to 40 ft for non-combustible construction – Fire retardant (proprietary) – Honeyconmb (limited manufacturers) – Various finishes – painted, metallic, anodized, natural

Metal Panel Rainscreen Materials • Aluminum plate – Not widely used – Returns are bent; not as square as ACM • Copper sheet/plate – Durable – Natural weathering – Potential staining issue – Green sidewalks

Metal Panel Rainscreen Materials • Zinc Composite Material – Same construction as aluminum, with zinc both sides – Greater thermal movement – Significant concern of accelerated corrosion on back-side – Must be vented to dry back side of panels

Metal Panel Rainscreen Materials • Zinc Composite Material – Same construction as aluminum, with zinc both sides – Greater thermal movement – Significant concern of accelerated corrosion on back-side • Stainless steel plate – Variety of finishes available, stainless steel types • Titanium – Very expensive – Difficulty in matching finish • Others…

Metal Panel Rainscreen Materials • Aluminum Composite Material (ACM) – Long term track record

Metal Panel Rainscreen Materials • Aluminum Composite Material (ACM) – Flexibility in design

Metal Panel Rainscreens • Aluminum Composite Material – Route back side to form bends

Metal Panel Rainscreen • Aluminum Composite Material – Route back side to form bends

Procurement methods • Pre-manufactured – Purchase formed panels, sub-girts, etc. from manufacturer – Fittings, clips, gaskets, anchors – Testing provided (structural, fire, etc. ) – Structural design calculations (panels, sub-girts, attachments) – Track record for system • Shop manufactured – Purchase panel materials, sub-girts members, fittings, gaskets, etc. – Determine panel design, pieces used, drainage considerations – Testing of “system” – Structural design calculations – Track record?

Panel Joint Types • Wet-sealed Joints – Rout and return, with exposed sealant joint – Sealant is labor intensive – Joint failures inevitable – – Thermal movement Weathering Joint geometry Workmanship – Maintenance issue for owner – Increase reliance on back-up barriers – Replacing sealant without damaging finish – Full seals create vapor retarder

Panel Joint Types • Gasketed Joints – Various designs – Concealed gaskets; some with raised stems – Exposed push-in gaskets – Not a complete seal – Openings at joints, corners – Exposed gaskets prone to loosening, can fall out with thermal movement – Less maintenance than sealed joints – Some sequential installation, some not – Affects panel removal

Panel Joint Types • Gasketed Joints – Various designs – Concealed gaskets; some with raised stems – Exposed push-in gaskets – Not a complete seal – Openings at joints, corners – Exposed gaskets prone to loosening, can fall out with thermal movement – Less maintenance than sealed joints – Some sequential installation, some not – Affects panel removal Gutter

Panel Joint Types • Overlap systems – Panels “shingled” similar to traditional cladding – Sequential installation – Difficult to remove panel in middle of wall – Internal guttering and drainage common – No maintenance involved – Typically good water management

Panel Joint Types • Spline systems – ACM used as backing spline behind joint – Varying design – Some resist water better than others – Depends on internal guttering – Sequential installation – No maintenance involved

Panel Joint Types • Spline systems – ACM used as backing spline behind joint – Varying design – Some resist water better than others – Depends on internal guttering – Sequential installation – No maintenance involved – Double spline systems – Improved performance – Pressure equalized

Pressure-equalized Systems • Function differently than Rainscreens – Positive wind pressure Thermal insulation drives water against Cladding wall – Air fills cavity, equalizing pressure Weather-resistant – Lack of pressure barrier difference reduces infiltration Drainage/ventilation – No driving force – Incidental water drained at intervals space/plane Flashing P+ P+

Pressure-equalized Systems • Intricate design – Cavity must be compartmentalized to control pressure (airtight) – Fine tuning between compartment size and vent size – Sizing different for each building; sometimes for areas of same building (corners) – Testing per AAMA 508 Thermal insulation P+ Cladding P+ Weather-resistant barrier Drainage/ventilation space/plane Flashing

Pressure-equalized Systems • Does it work? – Lab tests can show the pressure equalization – Can be difficult to achieve in the field – Pre-manufactured systems can perform – Field-built systems more difficult – Difficult to measure effectiveness in the field – Variable wind pressures

Pressure-equalized Systems • Is it needed? – Originated when felt paper used on the backup wall – Improved air/water barrier materials – Improved detailing (air barriers; flashing) – More attention to installation of barriers

Air/Water Barriers • Most critical component of wall design

Air/Water Barriers • Most critical component of wall design • Functions – Keeps water out of building – Last line of defense – Keeps building airtight – Condensation, energy – Might be vapor retarder

Air/Water Barriers • Most critical component of wall design • Functions – Keeps water out of building – Last line of defense – Keeps building airtight – Condensation, energy – Might be vapor retarder • Must be integrated with surrounding components – – Wall attachments Windows Penetrations Roof

Air/Water Barriers • Materials: – Rubberized asphalt sheet – Primary material – highly reliable – Provides vapor retarder

Air/Water Barriers • Materials: – Rubberized asphalt sheet – Primary material – highly reliable – Provides vapor retarder – Vapor permeable sheets – Adhered – Short track record – only a few years on market – Some adhesion issues – Primers may not be permeable

Air/Water Barriers • Materials: – Rubberized asphalt sheet – Primary material – highly reliable – Provides vapor retarder – Vapor permeable sheets – Adhered – Short track record – only a few years on market – Some adhesion issues – Primers may not be permeable – Polyolefin sheets – Not adhered; vapor permeable – Successful if properly installed – Often see installation issues

Air/Water Barriers • Materials: – Liquid Applied – Short track record

Air/Water Barriers • Materials: – Liquid Applied – Short track record – Have seen issues with many products

Air/Water Barriers • Materials: – Liquid Applied – Short track record – Have seen issues with many products – – Sheathing Joints Fasteners Cracking/crazing Washing off wall

Air/Water Barriers • Materials: – Liquid Applied – Short track record – Have seen issues with many products – – Sheathing Joints Fasteners Cracking/crazing Washing off wall – SGH testing shows: – Some with high absorption – Some with high filler content – Some are water soluble – No standards for durability – Prefer sheet membranes until these issues are resolved

Back-up Framing • Galvanized steel (G 90) is most common • Open joint systems (terra cotta, Trespa) use stainless or aluminum

Back-up Framing • Galvanized steel (G 90) is most common • Open joint systems (terra cotta, Trespa) use stainless or aluminum • Compatibility issue between aluminum and galvanized – Aluminum will accelerate zinc corrosion • Should consider upgrading for any open joint system • What about sealed systems? – Owner maintenance issue

Window Details • Flashing – Sill flashing critical to prevent against leakage through window – Long-term concern – Break down of window seals – Integrate sill flashing with Air/Water barrier – Water barrier continuity – Air barrier continuity – Install panels without compromising barriers

Window Details • Metal panel detailing can be complicated – Barrier/flashing continuity – Sequencing of installation – Panel attachment

Window Details • Metal panel detailing can be complicated – Barrier/flashing continuity – Sequencing of installation – Panel attachment • Avoid fasteners through sill flashing

Window Details • Metal panel detailing can be complicated – Barrier/flashing continuity – Sequencing of installation – Panel attachment • Avoid fasteners through sill flashing • Intermittent clips for connecting panels – Requires some exposed fasteners

Window Details • Metal panel detailing can be complicated – Barrier/flashing continuity – Sequencing of installation – Panel attachment • Avoid fasteners through sill flashing • Anchor outboard of flashing

Window Details • Head conditions: – Avoid draining water into window head – Barrier continuity – Sequencing of installation – Panel attachment

Window Details • Head conditions: – Avoid draining water into window head – Barrier continuity – Sequencing of installation – Panel attachment • Flanged windows – Integral metal flange on aluminum windows – Connect AWB to flange

Window Details • Jamb conditions: – Barrier continuity – Sequencing of installation – Panel attachment • Flanged windows – Integral metal flange on aluminum windows – Connect AWB to flange

Window Details • Flanged windows – Sill conditions - still provide pan flashing beneath window – Cut flange at sills – flange prevents window leakage from draining into cavity

Curtain Wall Details

Curtain Wall Details • Transition Water/Air Barrier into Glazing Pocket

Other conditions

Other conditions • Horizontal flashing between windows – Drain water out of cavity at intermittent levels

Other conditions • Upward facing surfaces (i. e. , “roofs”) – Panel intended to shed water on vertical surfaces – Not intended for low-sloped surfaces – Expect leakage through joints – Requires membrane roofing below – “Gutter” detail at joints to control leakage through anchors – Better to detail using metal coping with watertight joints

Code Requirements – fire protection • International Building Code (2009) – Permits combustible materials in non-combustible construction – Combustible materials required to be tested, including: • • Exterior Insulation and Finish Systems (EIFS) Metal Composite Materials (MCM) Fiber Reinforced Polymers Foam Plastic Insulation – 2012 IBC includes: • High-Pressure Laminates (HPL) • Water-resistive Barrier Materials – Certain exceptions based on building height, sprinklered building, etc.

The NFPA 285 Fire Testing for Exterior Walls 11 September 2012 68

The NFPA 285 Fire Testing for Exterior Walls 11 September 2012 69

The NFPA 285 Fire Testing for Exterior Walls 11 September 2012 70

The NFPA 285 Fire Test • Most MCM panels can pass test • Typically tested without foam insulation – Test may not be valid depending on wall assembly make-up NFPA 285 Fire Testing for Exterior Walls 11 September 2012 71

The NFPA 285 Fire Test • Limited database of tests available with actual assemblies used – Tests performed by manufacturers • Insulation • Metal Panels • Water-resistive barrier – Not coordinated amongst manufacturers – May limit certain combination of manufacturers – Some now coordinating – which does limit manufacturers • Trespa wall panels and Vaproshield WRB NFPA 285 Fire Testing for Exterior Walls 11 September 2012 72

The NFPA 285 Fire Test • Engineering judgments – Currently being used for WRB products, with small scale fire testing – Could be used for substituting manufacturers within assembly • Most manufacturers aware of requirements • Designers and Code officials becoming increasing aware of the requirements NFPA 285 Fire Testing for Exterior Walls 11 September 2012 73

DESIGN REHABILITAT INVESTIGAT E E Questions? Jeff Ceruti, P. E. jjceruti@sgh. com 781 -907 -9214 www. sgh. com