Breathing Construction Walls
1 Definitions

Breathing Construction Walls

• Breathing construction applies to timber framed wall construction where vapour barriers are not used but replaced with an airtightness layer internally, this permits passage of vapour into the construction, this is supplemented by a breathing sheathing board or breather membrane on the outside permitting egress of the vapour from the construction outwards.
• Hygroscopic conductivity thermal insulation needs to be used in breathing wall construction as it will be subject to higher moisture content than with conventional timber frame construction.
• Hygroscopic conductivity thermal insulation will absorb moisture from the air spaces, that normally provide the insulation function, into the material’s fibres without loss of thermal performance and be held until conditions permit evaporation and passage to the exterior air.

However

• Lightweight construction like timber frame panels will not protect the interior from radiant solar heat gain through the opaque fabric walls.
• High decrement delay characteristic is needed in the thermal insulation to delay the passage of solar radiation heat to the interior.
• Hygroscopic radiation and conductivity thermal insulation is therefore needed.
• Materials with these properties include:
  • Dense wood fibre board (used on the face of frames)
  • Medium density wood fibre batt (used in the frame zone)
  • Cellulose fibre flake (blown wet or dry into the frame zone)
  • Cork board (used on the face or between the frames)
  • Cellular glass board (not normally used in timber frame)
• See Also: Diffusion Open, Air tightness layer,
• (NGS BRM ‘09 – GBE BRM ’16)

Breathing Construction Walls

• It is recommended that the construction should be as vapour diffusion open as possible on the outside and as vapour diffusion tight as necessary on the inside to minimise condensation risk and maximise the drying that can occur in the event of moisture entry into the construction.
• (Ecological Building Systems ’09)

Breathing Construction Walls

• In Germany breathing walls can be constructed with untreated timber in the external wall.
• In the UK we would normally expect the sole plate to be treated as it is in touch with the ground floor, albeit with a DPC below.
• (NGS BRM ‘10 – GBE BRM ’16)

© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
18th January 2016 – 7th October 2016

Breathing Construction Walls
2 Images/Icons

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aka BrianSpecMan
18th January 2016

Breathing Construction Walls
3 Relevance to Environmental Construction

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18th January 2016

Jargon
4 Opinion

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18th January 2016

Jargon
5 Examples

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18th January 2016

Jargon
6 Notes

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aka BrianSpecMan
18th January 2016

Jargon
7 Sources

• Ecological Building Systems ’09
• Energy Star ’07
• Enviroform Solutions Ltd. LB ‘12
• GreenSpec AEP ’09
• GBE BRM ’12-’16
• NGS BRM ’09-‘12
• SEDA Airtightness Guide definition

© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
18th January 2016

Breathing Construction Walls
8 Related Jargon

GBE Jargon Buster

• Breathing Construction Walls (JB) (This page) G#9336
• Jargon Buster Navigation G#4178
• Jargon Buster Themes G#1330
  • Overheating
  • Refurbishment/Retrofit
  • Thermal Bridges/Breaks
• Jargon Buster Navigation: Abbreviations + Acronyms G#685 N#707
  • ATL
  • BM
  • BRM
  • ETAG 004
  • VCL
  • WTL
• Jargon Buster Classifications
  • K10 Plasterboard dry linings/partitions/ceilings
  • K11 Rigid sheet flooring/sheathing/decking/sarking/lining/casings
  • K13 Rigid sheet fine linings/paneling
  • K20 Timber board flooring/decking/sarking/lining/casing
  • K21 Timber strip/board fine flooring/linings
  • M21 External Insulation with Rendered Finish
  • P10 Sundry insulation/proofing work/fire stops
• Jargon Buster Numbers N#721
• Jargon Buster Words and Phrases N#705
  • Absorb
  • Air-tightness layers
  • Breathable/Breathing Roofing Membranes (BRM)
  • Breathable Sheathing Board
  • Breather Membrane (BM)
  • Breathing Construction Walls
  • Breathing Sheathing Board
  • Breathing Wall
  • Building Specific Insulation Solutions
  • Capillary Action/Attraction
  • Capilarity Active
  • Convective Air Flow
  • Diffusion Open
  • Diffusion Tight
  • Drylining
  • Hydro-
  • Hydrophobic Material
  • Hygro-
  • Hygroscopic
  • Hygroscopic Material
  • Hygroscopicity
  • Hygroscopicity And Moisture Mass
  • Hygrothermal Performance Testing
  • Interstitial Condensation
  • Moisture Transport
  • Overheating
  • Parge Coat
  • Path Of Least Resistance
  • Refurbishment
  • Retrofit
  • Retrofit For A Future
  • Retrofit Health & Safety
  • Reverse diffusion
  • Risk Assessment
  • Specific Heat Capacity
  • Thermal Breaks
  • Thermal Bridges
  • Thermal Laminates
  • Thermal Looping
  • Vapour Barrier
  • Vapour Check
  • Vapour Closed
  • Vapour Closed V Vapour Open
  • Vapour Control Layer (VCL)
  • Vapour Diffusion Resistance
  • Vapour Diffusion Resistance & Vapour Barrier/Check
  • Vapour Open
  • Vapour Open Breathable
  • Vapour Open V Vapour Closed
  • Vapour Permeable
  • Vapour Tight
  • Vapour Tight With Reverse Membrane
  • Variable Diffusion Membrane
  • Wind tightness layer (WTL)
  • Wicking

© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
18th January 2016 – 7th October 2016

Breathing Construction Walls
10 Q and A

GBE Q&A

• Thermal insulation of existing timber stud external walls G#1803 N#1690
• Rendering system on existing insulated cavity wall G#8288

© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
18th January 2016 – 7th October 2016

Breathing Construction Walls
16 Accessories

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aka BrianSpecMan
18th January 2016

Breathing Construction Walls
11 Defects/Solutions

GBE Defects

GBE Solutions

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18th January 2016

Breathing Construction Walls 
12 CPD/Lectures

GBE CPD

Theme

•  CPD Topics (Navigation) G#472 N#478

Handouts PDF 9 slides/page for printing

• Tech+Env2(21)TimberExtWalls9H12

Seminars PDF for viewing

• (21)TimberExtWalls
• (21)TimberFrame

GBE Lectures

• (21) Timber Frame (P) N#219
• (21) Timber External Walls (P) N#218

GBE Shop

GBE Lecture

• (21) Timber External Walls (Shop) G#11557
• (21) Timber Frame Defects Site Visit (Shop) G#11556

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aka BrianSpecMan
18th January 2016 – 7th October 2016

Jargon
14 Links

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18th January 2016

Jargon
15 Products

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aka BrianSpecMan
18th January 2016

Breathing Construction Walls
9 Checklists

GBE Checklist

G#606 N#627 GBE New Build Checklist Navigation

• G20 Carpentry/Timber framing/First Fixing
• K10 Plasterboard dry linings/partitios/ceilings
• K11 Rigid sheet flooring/sheating/decking/sarking/lining/casings
• K13 Rigid sheet fine linings/paneling
• K20 Timber board flooring/decking/sarking/lining/casing
• K21 Timber strip/board fine flooring/linings
• M21 External Insulation with Rendered Finish
• P10 Sundry insulation/proofing work/fire stops

G#730 N#752: GBE EBC Checklist Refurbishment

• G20 Carpentry/Timber framing/First Fixing
• K10 Plasterboard dry linings/partitios/ceilings
• K11 Rigid sheet flooring/sheating/decking/sarking/lining/casings
• K13 Rigid sheet fine linings/paneling
• K20 Timber board flooring/decking/sarking/lining/casing
• K21 Timber strip/board fine flooring/linings
• M21 External Insulation with Rendered Finish
• P10 Sundry insulation/proofing work/fire stops

G#1253 N#1252: GBE EBC Checklist Refurbishment Decent Homes

G#1438 N#1408 GBE Home Improvement Index

© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
18th January 2016

Breathing Construction Walls
17 Systems/Sub-systems

GBE Sub-systems

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aka BrianSpecMan
18th January 2016

Jargon
18 Issue Papers

• Issue Paper: Overheating G#145

© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
18th January 2016 – 7th October 2016

Breathing Construction Walls
19 See Also:

GBE Jargon Buster

• Air tightness layer
• Breathing sheathing board
• Diffusion closed
• Diffusion open
• Enhanced vapour transfer
• Vapour closed
• Vapour open
• Wind tightness layer

(GBE BRM ’16)

© GBE NGS ASWS BrianSpecMan aka Brian Murphy
7th October 2016