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The Tradition and Science of Window Installations – Where are We Headed with More Highly Insulated Buildings?

EUROLINE TECHNOLOGY FORUM, OCTOBER 20, 2016

GRAHAM FINCH, MASC, P.ENG

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A Brief History of Window Installation Practices in BC

Best Practices for Current BC Window Installations

Trends and Impacts of New Materials & Higher Performance Buildings

Integration of Windows into More Highly Insulated Walls – Do’s and Don'ts

Case Studies

Outline

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The Perpetual Question

+ ?

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We Have Come A Long Way in BC

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Vancouver Early 20th Century

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Early Window Installation “Best Practices”

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Pre 1930’s Architectural Graphic Standards

From Ramsey & Sleeper – Architectural Graphics Standards

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An Appreciation for Slope & Flashings

From Ramsey & Sleeper – Architectural Graphics Standards

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Then Some Things were Forgotten in the 1980s

?

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Building Enclosure Detailing Guidance Mid 1990s?

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No Joke…

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Oh and the Windows Leaked Too…

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And We Had Lots of Condensation Problems

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The Catastrophic Result…

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Early Attempts at Sub-Sill Flashings without Good Water Shedding or Interface Details

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Continually Evolving Best Practices in BC

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Fundamentals: Following & Connecting the Critical Barriers

Water Shedding Surface (WSS) Water Resistive Barrier (WRB) Air barrier (AB)

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Current Best Practices in BC for Rainscreen Window Installation

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Evolving BC Practices

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TOO MUCH Impermeable Peel and Stick

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So What is Changing in BC? Trend towards more efficiently

insulated building enclosures due to higher energy code targets & uptake of passive design strategies

Greater attention to reducing thermal bridging in building enclosures

Many new building materials being introduced and imported into local market

Window installation practices are evolving to incorporate new and/or imported window frames into more highly insulated wall

Ongoing need to balance thermal and durability considerations

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Evolution of Wall Assemblies to Passive Levels

Base 2x6 Framed Wall <R-16 (wood)

Exterior InsulationR-20 to R-60+

Deep Stud, Double Stud, SIPSR-20 – R-80+

Split Insulation R-20 to R-60+

Interior InsulationR-20 to R-30+

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Deep Stud & Double Walls - w/ or w/o Service Wall

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Consideration for Window Installs – Deep Walls

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Exterior and Split Insulated Walls

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Consideration for Window Installs – Exterior Insulation

Lots of Options including buck-outs with Varying Levels of Complexity!

Key detail – drain outboard of the insulation

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City of Vancouver – R-22 Wall & Window Details

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Industry Trends Impacting Walls & Windows Shift away from mechanically attached sheathing

membranes/WRBs like building paper & even synthetic membranes for more air-tight and taller buildings

Building Paper

RIP 2016

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Trend Towards Combined Exterior Air Barrier (AB) Water Resistive Barrier (WRB) Approaches

Mechanically attached AB/WRB

Self-adhered vapour permeable sheet AB/WRB

Fluid applied vapour permeable sheet AB/WRB

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Trend Towards Combined Exterior Air Barrier (AB) Water Resistive Barrier (WRB) Approaches

Sealed sheathing AB (adhesive tapes or sealants) with additional overlay WRB

Sealed coated sheathing AB/WRB

Sealed rigid foam insulation AB/WRB (special tapes)

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Desire for More Vapour Permeable Materials?

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New Good and Some Not-So-Good Vapour Permeable AB/WRB Membranes

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Ongoing Research – Use of Vapour Permeable Liquid Flashings on Wood-frame Window Sills?

Can or should horizontal flashing membranes be vapour permeable like the jambs & head?

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Assessing the Risk of Vapour Permeable Flashings on Window Rough Opening Devised a test which looks at the uptake of moisture ponding on a

horizontal window sill flashing into the framing lumber & sheathing over time

Compare results with control membranes that are known to fail or work well

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Plywood Edge - At Center

Are Vapour Permeable Liquids Safe for Use on Wood-frame Window Sills?

Safe MC <20%

not safe with these liquids or permeable SAM

safe with this liquid & impermeable SAM

maybe okay with these liquids?

Moisture Content of Edge of Plywood at Window Sill

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Impact of the Wrong Liquid Applied Vapour Permeable Flashing on a Wood Window Sill

Mould after 30 days due to absorption into OSB sheathing below a relatively absorptive & permeable liquid applied window sill flashing

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Definitely Not the Right Product for This Application

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Oops! Someone Missed the Memo

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Tapes as “Flashing” on a Horizontal Window Sill?

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High Performance Buildings & Passive House Voluntary ultra-low energy construction standard Rapidly gaining interest & acceptance in North America Some codes targeting PH levels in next decade

>R-38

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Some of BC’s First Passive Houses

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Passive House Window Considerations Every single Watt (Btu/hr)

of heat loss matters within a Passive House It is a fine balance of a

building’s passive solar & internal gains compared to all of the conductive & convective losses

Heat loss through windows and installation details around perimeter becomes very important and often becomes a focal point for improvement (especially during construction!)

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Standard Window Installation Details Aren’t Often Good Enough for PH Projects

Key considerations:• Avoid metal flashings that bypass

framing or insulation• Reduce wood framing around

window• Over-insulate the window frames

where feasible • Air tight (and properly water

managed)

Too much insulation displaced & too large of metal flashing

Too much wood

Too much wood

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PH Details May Look more Like This!

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PH Details May Look more Like This!

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Some Frames Are Made to Hide With Insulation

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Perimeter Heat Loss from Window Installations aka Linear Transmittance, psi-value - Window placement within the rough opening and the

detailing around the frame directly impacts the window perimeter heat loss & installed U-value/R-value

This factor is referred to as a linear transmittance, psi-value Bad psi-values = >0.040 W/m∙K Better psi-values = <0.020 W/m∙K Excellent psi-values = <0.010 W/m∙K

The psi-value is multiplied by the perimeter length of the window and energy added to the uninstalled window U-value to get an installed window U-value (i.e. it always worsens it) Impact on whole house with lots of windows can be significant,

especially when trying to meet stringent PH targets Typically modeled/calculated for specific details with some

baseline values provided by PH window suppliers

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Certified Passive House Window Report Information

Window U-values

Frame U-values

Psi-values & Installed U-values

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Window Installation Linear Transmittance Thermal Modeling

Window installation heat loss is the additional heat flow through the interface/gap/framing/flashings between the wall and window

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Psi-Value Case Study: What Matters & How Much? Window:

Euroline 4700 ThermoPlus inswing tilt & turn with high performance triple glazing (U-0.75 W/m2∙K, R-7.6 IP)

Walls: Split insulated 2x6 wood frame filled

with fiberglass batt and 6” exterior mineral wool with long screws through insulation to support cladding (R-40 effective)

Windows installed at inner, middle and exterior of wall with and without additional insulation over the frames

Additional data for deep stud 2x10 w/ interior 2x4 service wall (R-40) also provided in handouts (no time today!)

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Split Insulated Wall – Standard Install, No Insulation Over Frames

This means that the window U-value gets 16% worse just by installing it Seems small but it does matter when talking about the performance of Windows

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Split Insulated Wall – Impact of Over Insulating Frames

16% loss in window U-value for no over insulation vs 8% with

No impact to worst case modeled window surface temperature, <1°C at jamb/head

Watch temperatures if insulating on inside!

If over-insulatingat sill watch drainage!

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Split Insulated Wall – Impact of Placement in R.O.

Based on window size of 1.2 x 1.5 m. Cladding not modeled for conservative estimate

Window towards the exterior is better thermally, small impact on interior surface temperatures

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Split Insulated Wall – Impact of Placement in R.O. with Over Insulating Frames

Based on window size of 1.2 x 1.5 m. Cladding not modeled for conservative estimate

Over insulation drops psi-value by about half

Placement impact is similar, middle is slightly better

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Window Size Matters!

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Length and Width of Frame (ft)

Thermal Performance of Euroline 4700 Frame - Center of Glass vs Window vs Final Installed By Size of Frame

Center of Glass Window InstalledWhat really matters

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Rigid Foam Below & Supporting Window Frames? Thought by some PH designers or

modelers that it may be worth replacing one of the wood sill plates (200 to 900 psi compressive strength) with XPS insulation (30 psi compressive strength @ 10% compression)

Weight on setting block shims for a typical triple glazed passive house window (several hundred pounds) will be in the order of 100 to 200 pounds well over 30psi unless large distributed

shims or over more wood? Most shims are only a few square

inches in area – therefore foam compresses initially or over time damaging installation, seals and potentially window

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Possible Benefit of XPS Below Window Sill – If Bearing Capacity Can Be Addressed

Can see why it might be suggested but for a 2% difference I would look for other improvements unless bearing issues are addressed

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Bella Bella Passive House Case Study Design Build project for Vancouver

Coastal Health for a 6-plex staff housing to replace housing that had burned down

Target of passive house certification and delivery in 6 months

First modular Passive House in Canada

First Passive House in a First Nations Community

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The Window Details!

2x6 wood frame wall with 6” exterior insulation

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Split Insulated Passive House Window Installation

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Split Insulated Passive House Window Installation

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Split Insulated Passive House Window Installation

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Split Insulated Passive House Window Installation

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Split Insulated Passive House Window Installation

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Modular Passive House Construction

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Modular Shipping

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Site Assembly & Completion

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Key Conclusions Long history of iterative progress in

the installation of windows in British Columbia – many past failures and successes

Evolution is continuing with higher performance windows (imported and locally made in more highly insulated wall assemblies

Be careful with the selection of new membranes, flashings, tapes, sealants and foams – ensure durability and moisture control while balancing thermal needs

Always look at continually improving the thermal performance of your window installation details!

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Discussion + Questions

CONTACT ME AT:gfinch@rdh.com604-873-1181