Rear Ventilated Rain Screen OBEC Mar 2016

Case Studies of RVRS design; Use of Light Weight Panelized Construction in

Multiple Projects OBEC

March 2016 Blair Davies, P.Eng

VP GM Engineered Assemblies

- March 9, 2016 page 1

Engineered Assemblies “Unite the House of Design with The Field of Construction”

–  Thermally Broken RVRS Facades –  Daylighting

–  High performance Metal Roofs Partners

»  Etex - Imetco »  Composites Gurea - SRP Canada »  Formica - AWF »  Gentas - CPI Daylighting

>1000 projects; no warranty claims, no non payment for non performance

Sister company Praxy installation Ontario


Speaker Blair Davies, P.Eng

–  BaSc University of Waterloo – Civil Engineering –  MBA Schulich School of Business –  Building envelope business since 2008 –  Buildings across Canada


Agen

da

•  Introduction – does all this matter? •  What matters •  Definition and history

–  DIN 18516 –  British Standards

•  Pressure Equalization – the debate •  Case Study #1

–  Parliament St Data Centre – ceramic •  Case Study #2

–  McLean Park Towers – fibre cement •  Case Study #3

–  88 Sheppard, Minto – fibre cement •  Case Study #4

–  2 Virtue Street – fibre cement recladding •  Case Study # 5

–  Addington Residence – ceramic recladding •  Unanswered questions •  Conclusion •  Ontario Building Code •  Discussion


Is all this necessary?


What matters •  Ventilation •  Drainage •  Thermal Bridging •  Secure •  Impact •  Weight •  Durable •  Constructible •  Climate and weather •  Acoustics


Light weight matter?

•  Fibre cement 15 kg/m2 •  Ceramic 35 – 50 kg/m2 •  Metal 4.5-7.3 kg/m2

•  Steel stud wall; insulation; thermally broken substructure 20kg/m2 (GUESS)

•  Brick 174 kg/m2

•  Precast (300mm) 718 kg/m2 •  EIFS (100mm) 8 kg/m2 •  Curtain wall 49 kg/m2


Define RVRS

•  Cladding stands off the moisture resistant surface to create a drainage plane and ventilation cavity.

•  Vertical cavity for stack effect and capillary break. •  The wall open top and bottom to allow ventilation, •  Intermediate gaps open or closed; aesthetic decision. •  Insulated or non-insulated.


Source: Wikipedia


•  Framing – stud, concrete, brick, etc

•  Sheathing, AVB •  Insulation •  Weather barrier •  Cavity •  Panels

•  Thermally Broken substructure

- March 9, 2016 page 10

Detail in practice

11

Key Attributes of RVRS Facades?

•  Remove water and vapour in active, natural manner from assembly •  Exterior takes abuse of the weather - full heat, the sun, the wind… •  Ventilation helps the building AND the façade product •  Accommodates any amount of insulation •  Insulation is always drying - better effective R •  Simpler, more easily built and inspected - no caulking •  Lighter thinner systems than concrete and brick •  Unlimited choice in panel selection. •  Better energy efficiency than most curtain wall •  Less expensive than many other systems

History and Standards •  Ventilated façade in Europe

–  DIN 18516 – German Construction Standard •  Specifies all key attributes •  Spacing behind panel minimum 20mm

–  CWCT H92 –  NBS British Construction Standard

•  Canadian Construction Technology Update –  1963 NRC –  1999 CTU –  Cladding leakage area to Ventilation area suggested 10:1

•  USA NIBS

- March 9, 2016 page 12

DIN 18516

•  Covers –  Scope and field of application –  Concepts –  Requirements –  Design loads, thermal effects and structural movements –  Structural analysis –  Protection of materials –  Testing of connectors, fixing and ties –  Documentation –  Inspection

- March 9, 2016 page 13

NBS Section H92

•  Vertical building envelope; Outer skin •  Airtight insulated backing wall, separate by ventilated cavity •  Key distinction is that curtain walling is usually the whole

envelope, while rainscreen cladding is the outer protective layer of the envelope.

- March 9, 2016 page 14

Business Opportunity •  Materials developed to leverage RVRS mostly from Europe

–  High density fibre cement –  Glass reinforced concrete –  Phenolic –  Ceramic –  Porcelain –  Metals –  Stone laminates –  Wood panels –  Hybrids

•  Subsystems •  Design •  Labour

- March 9, 2016 page 15

RVRS suitable for all building types

House Condo Hotel University School Hospital

Alcoa building pittsburgh 1950 1st modern use

Walter Gropius, gropiusstadt, Berlin, b1960-1975

Eternit panels in high rise ventilated facade application

Pressure Equalization •  Ideal

•  Ambiguous

•  Planning ≠ Actual

•  Structural considerations

•  Not part of European standards

- March 9, 2016 page 19

Sources include: National Building Service UK 1-Jan-2010 “Rainscreen cladding; letting air in to keep rain out”

P.E. - compartmentalization •  Horizontal closures so air can get in, but can’t get out •  Seeing specifications with compartmentalization •  Some study that at façade corners and parapets this helps PE.* •  Europeans products do not recognize this practice

- March 9, 2016 page 20

Source: MCA Whitepaper 11/2014 v2 NRC CTU no 17 1998 Graphic by Nichiha

Rain Screen Membrane •  Water resistant, water vapour permeable membrane •  Secondary drainage plane •  Aesthetic black reveal with long term UV resistance

for open joint systems •  Can be the deemed air barrier if sealed •  Installed directly behind cladding

- March 9, 2016 page 21

Weather Membrane § For Closed Joint Systems (with no long term UV)

•  High WVT 150 perms •  120 g/m2 •  Drainage Plane •  CCMC listed •  Air Barrier

Courtesy

Drying Rate MVTR (perms)Comparison

0 20 40 60 80

100 120 140 160

Prod 1 Prod 2 Prod 3 Prod 4

Perms

Perms

Courtesy

Weather membrane UV

§ For Open Joint Wall Systems (long term UV) •  Long Term UV Resistance

l  DIN EN 13859 (5,000 hours exposure <5% loss) •  Drainage Plane •  Air Barrier

courtesy

27

Installation

Ø  Attachment l Over insulation, behind cladding l Clips or system support, screws with plates

Ø  Overlapping

l Shingle style with 6 inch overlap

Ø  Seams l Tape vertical seams and details l Tape all seams in Air Barrier installations

•  Robust •  Breathable •  Water Resistant •  UV Resistant

Why Weather Membrane?

Panels

page 29

Zinc

ACP FRC & GFRC

Phenolic

Porcelain Ceramic

ACP

Stone veneer

Unlimited choice

All conditions have been done

- March 9, 2016 page 30

Case Study 1 Data Centre •  Parliament St Data Centre •  Cladding, cavity, WB, Insulation, Thermally broken substructure,

AVB, framing. •  Effective R Value Goal 21 •  Extruded Ceramic (35kg/m2) + Ceramic Baguettes •  Cavity dimension = 40mm vertical + 63mm. •  Insulation type = Roxul Cavity Rock 4” (100mm) •  WB type = SRP Airoutshield •  AVB type = Soprema •  Special conditions: designed for disaster conditions, so extreme

slab deflections expected •  Why: “Relate local masonry in modern way to reflect use of

building” WZMH •  Architect WZMH, GC Urbacon, Installer Flynn Canada

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Case Study 2 - McLean Park Towers – Tower Renewal •  Social housing, Vancouver •  High Density Fibre Cement, vertical girts, WB, thermally

broken substructure, AVB, Concrete •  HDFC 14.9 kg/m2 faced fastened with colour matched rivets

•  25mm cavity with vertical galvanized steel girts •  Roxul Cavity Rock 4” (100mm) •  Thermally broken facade •  Vaproshield WB •  Soprema AVB •  Special conditions:

•  JRS Engineering; Installer Marine Cladding

- March 9, 2016 page 35

- March 9, 2016 page 36

Case Study 3 88 Sheppard E, Minto

•  HDFC, Vertical girts, cavity, WB, insulation and girts, AVB, Framing or Concrete

•  Effective R value not a goal •  HDFC 14.9 kg/m2 adhered with Dynamic Bond Adhesive •  Cavity dimension 25mm •  Roxul semi-rigid rockboard 40 2” and 3” •  Roxul curtain rock 5”SRP AirOutShield UV •  AVB type TBD

•  Rafael + Bigauskas Architects; GC and Owner Minto; Installer Praxy Cladding

- March 9, 2016 page 37

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Details – need direction

- March 9, 2016 page 39

- March 9, 2016 page 40

AVB

WB

Case Study 4

•  2 Virtue Street •  HDFC, girts, cavity, breather

membrane over brick •  Un-insulated •  HDFC 14.9 kg/m2 •  Cavity dimension 25mm •  SRP AOS UV •  AVB poly inside studs

- March 9, 2016 page 41

- March 9, 2016 page 42

Renovation adds new vigour to a sagging Toronto home Aug 2013

Case Study 5 Addington Residence U Guelph •  Ceramic panels, system rails, weather

membrane, horizontal girts, sprayfoam insulation on top of brick façade

•  Ceramic 35 kg/m2 •  Cavity dimension 20mm •  Spray foam 4” (100mm) •  SRP AOS non UV WB •  Blueskin SA behind girts, Spray foam is AVB •  Unique: Brick fastened back to block, and cavity

filled. Insulated rainscreen fastened to brick façade

- March 9, 2016 page 43

Larkin Architects; GC Harbridge and Cross; Installer AMNA

- March 9, 2016 page 44

What would it take to make a real case study – anyone? •  Instrumentation •  Long term study of RH in insulation •  Measurement during weather incident

- March 9, 2016 page 45

Construction Best Practices

•  5 things need to be done right to have RVRS success with panelized products eg high density fibre cement. 1.  Ventilation top and bottom. 2.  Vertical substructure for ventilation. 3.  Panels allowed to move for thermal and for building

movement, typically with fixed and floating points. 4.  Substructure spacing set by live and dead loads. 5.  Reasonably true wall or adjustable substructure

- March 9, 2016 page 46

Unanswered questions

•  What happens to wet insulation over long term?

•  Why isn’t metal panel / ACP installed as RVRS?

•  Why does OBC not cover topic completely?

•  Why are product choices in Canada limited?

- March 9, 2016 page 47

Conclusion

•  RVRS Façade a significant design choice for aesthetic and envelope performance reasons

•  Engineered extensively, mostly in Europe •  Business opportunity for Canadians •  A few things need to be done right, but reasonable for most

cladding trade companies to learn

•  Thankyou.

- March 9, 2016 page 48

OBC Review

•  Part 4 Structural –  All systems can be designed for all Canadian loads by changing

spacing, gauge and material of substructure. –  Seismic testing available for heavier facades eg ceramic. No

call yet for testing of phenolics, fibre cement, metal panel –  Panels themselves designed to pass live loads back to

substructure, not provide any structural role to the building. •  Part 5

–  5.1.4.2 Resistance to Deterioration –  CSA S478 Durability of Buildings –  5.2.2.1 Determination of Structural loads – comply –  5.3.1 Thermal resistance – not the panels, just the insulation

layer. Expectation is cavity has higher or lower temp than outside, improving energy usage – needs proving.

•  Important to design due point in right place between AVB and Weather membrane

•  Penetration detailing essential – thermal bridging and air transfer to be eliminated

–  5.4.1 Air Barrier – at least two layers of protection, insulation may offer another or replace a barrier.

- March 9, 2016 page 49

OBC •  5.4.1.2 Air Barriers CAN/ULCS741 •  5.5.1.1 (1) assemblies shall be such that they control vapour

diffusion or permit venting to the exterior so as to minimize accumulation of condensation in the building component or assembly.

•  5.6.1 Protection from Precipitation –  Except as provided in Sentence (2), where a building

component or assembly is exposed to precipitation, the component or assembly shall,

•  (a) minimize ingress of precipitation into the component or assembly, and

•  (b) prevent ingress of precipitation into interior space. –  (2) Protection from ingress of precipitation is not required

where it can be shown that such ingress will not adversely affect any of ….

•  5.6.2 Sealing and drainage – reads like sealing is good. May have misguided intentions.

- March 9, 2016 page 50

OBC •  Part 9 is different –  9.20.13. Control of Rain Water Penetration –  9.25.3. Air Barrier Systems –  9.25.4. Vapour Barriers –  9.25.5. Properties and Position of Materials in Building

Envelope –  9.27. Cladding TBD

- March 9, 2016 page 51

Rear Ventilated Rain Screen (Moisture Management)

Drainage and ventilation

Some water gets in, and then

drains out. Condensation

and water vapour vented to

exterior.

Alternatively – Single Skin Construction. Water always gets in causing deterioration

Crack

Drained cavity Rainscreen eg Masonry

•  Masonry uses Rainscreen term – different than RVRS

•  Drainage of water that penetrates the brick is allowed to drain out

•  Limited to no ventilation; closed top and bottom of wall.

•  Less active plenum; reducing benefit of ventilation

•  Constructability issues with ensuring drainage is working

•  Heavier, more steps to build

- March 9, 2016 page 54

RVRS (Insulation)

NATURAL INSULATION – 0.5 R Value from RVRS Energy Efficiency Consumption of AC/Heating Acoustic Insulation

RVRS (Temperature Regulation)

When the outside temperature is HOT, the ventilated rain screen cladding has a cooling effect on the building

•  Most of the sun’s rays are reflected •  Ventilating effect of the air gap

RVRS (Temperature Regulation)

When the temperature is COLD outside the same process occurs: •  Most of the cold air is

reflected by the exterior architectural panel •  The remaining cool air will

partially dissipate by the ventilating effect of the air gap between the architectural panel and the structural wall

•  Insulation is protected, so will remain effective

Rear Ventilated Rain Screen OBEC Mar 2016

Design

Transcript of Rear Ventilated Rain Screen OBEC Mar 2016