Interior Insulation of Masonry Walls Assessment and Design
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Dr. ir. Paul Steskens & ir. Xavier Loncour, Belgian Building Research Institute
Prof. dr. ir. Staf Roels & ir. E. Vereecken, KU Leuven
September 11 2013
Contents
Introduction
Problem Definition
Research Objective
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Methodology
Results
Conclusions
IntroductionInterior Insulation of masonry facades
Historical buildings
Urban environment
Hygrothermal risks
• Moisture load and frost damage risk
• Interstitial and summer condensation
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• Interstitial and summer condensation
• Thermal bridges
• Infiltration, exfiltration and circulation of airflow
Uncertainty
• Type of interior insulation
• Quality of materials and realization
• Indoor climatic conditions
• …
IntroductionInterior Insulation of masonry facades
Historical buildings
Urban environment
Hygrothermal risks
• Moisture load and frost damage risk
• Interstitial and summer condensation
Previously:Building professionals have been
kept from the application of
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• Interstitial and summer condensation
• Thermal bridges
• Infiltration, exfiltration and circulation of airflow
Uncertainty
• Type of interior insulation
• Quality of materials and realization
• Indoor climatic conditions
• …
kept from the application of
interior insulation
Nowadays:Risks are manageable and
controllable
But, proper diagnosis
and design is required!
Problem DefinitionDiagnosis and design of interior insulation
Hygrothermal modeling and simulation
• Influence of a specific interior insulation system on masonry
facade is analyzed
• Requires specific knowledge of material properties
• Time-consuming
• Relatively complex
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Guidelines
• WTA guidelines (Germany), Videncenter for energibesparelser i
bygninger (Denmark)
• No concise assessment tool
• Strongly dependent of building engineer’s expertise and
experience
Strong desire for an assessment tool in order to analyze the
applicability of interior insulation
Development of Assessment Tool• helps the building designer determine whether interior insulation is possible
• serves as a basis for selection and design of the insulation system
• is independent of building engineer’s, architect’s expertise and experience
Research Objective
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State-of-the-Art
Methodology
Practical Experience
Tool Development
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Tool Development
Validation
ImprovementCase Studies
Assessment Framework (Tool)
Interior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Visible Damage
Moisture load and frost
damage risk
Structure
• 4 Key Performance Indicators (KPIs)
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Material properties of
the existing masonry
wall
Indoor Climate
State of the facade:
• complies with the requirements in the green column
• corresponds to the description in the red column (for one or more KPIs)
• meets the description in the orange column
Assessment FrameworkCase Study - Example• Traditional row-house in city-center of Louvain (Belgium)
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Assessment Framework (Tool)
Interior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Visible Damage
Moisture load and frost
damage risk
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Material properties of
the existing masonry
wall
Indoor Climate
Assessment FrameworkVisible damages• Cracks
• Moisture problems (stains, efflorescence of salts, …) or sources
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Assessment FrameworkVisible damages• Cracks
• Moisture problems (stains, efflorescence of salts, …)
Stains caused by dripping water
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Protection against water
Stains caused by dripping water
Assessment FrameworkInterior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Vis
ible
Da
ma
ge
No visible damage (traces of
moisture in the
interior/exterior finish, such
as irregularities, stains) or
moisture sources
No visible damage, however,
presence of moisture sources
(for example rising damp)
which may lead to moisture
problems and damage after
installing the insulation
Presence of moisture (stains,
moisture ingress, efflorescence of
salts, algae, cracks, irregularities)
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Vis
ible
Da
ma
ge
Improvement:• Eaves (reduced moisture load)
Assessment Framework (Tool)
Interior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Visible Damage
Moisture load and frost
damage risk
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Material properties of
the existing masonry
wall
Indoor Climate
Assessment FrameworkWind-driven rain load• Thickness of the facade
• Orientation, geographical area
• Height
Wooden beams and floors
Technical Installations
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Technical Installations• Water conducting pipes/ducts
Assessment FrameworkWind-driven rain load• Thickness of the facade
• Orientation, geographical area
• Height
Wooden beams and floors
Technical Installations
1½-stone thick
Urban environment
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Technical Installations• Water conducting pipes/ducts
Wooden beams are
removed/replaced
Interior insulation is applicable Applicability is unknown Interior insulation is not
recommended
Mo
istu
re l
oa
d a
nd
fro
st d
am
ag
e r
isk
Typology of the existing façade and exposure to rain
Solid masonry facade having a width
of two stones or thicker, or (≤ 1½
stone) exposed to a relatively small
(wind-driven) rain load
Solid concrete wall
1½ stone (exposed to a
moderate/high rain load)
≤ 1 stone (exposed to a
moderate/high rain load)
Non-insulated cavity wall
Insulated cavity wall
Internal wall
Assessment Framework - Example
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Mo
istu
re l
oa
d a
nd
fro
st d
am
ag
e r
isk
Internal wall
Floor Construction
Concrete floor or wooden floor,
which is not connected to the facade
Undamaged wooden construction
which is connected to the facade
Wooden construction, connected to
the façade, containing moisture
damages
Technical Installations
• Water pipes or ducts, which are
susceptible to frost or frost damage
are not present
• Technical installations which do not
require the penetration of the
interior insulation are not present
Water pipes or ducts, which are
susceptible to frost are frost
damage are present
Assessment Framework (Tool)
Interior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Visible Damage
Moisture load and frost
damage risk
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Material properties of
the existing masonry
wall
Indoor Climate
Assessment FrameworkMaterial properties of the existing facade• Exterior finish (plaster, tiles, varnished bricks, water-repellent coating, …)
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Bricks and Mortar joints• Frost resistance of bricks and mortar
Interior finish• Degradation, loose parts, …
• No vapor retarding layers (wall-paper)
• Remove contaminations
• Provide supportive subsoil with sufficient carrying capacity
Assessment FrameworkMaterial properties of the existing facade• No exterior finish
Bricks and Mortar joints• No visible frost damage
Interior finish• Removal of wall-paper
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• Removal of wall-paper
Interior insulation is applicable Applicability is unknown Interior insulation is not
recommended
Ma
teri
al
pro
pe
rtie
s o
f th
e e
xis
tin
g m
aso
nry
wa
ll
Exterior finish
No exterior finish or an exterior finish
which has a good condition, has a
good quality, and is vapour-open
Exterior finish which has not a good
condition, and/or contains damages
Vapour retarding exterior finish such
as varnished bricks, tiles, mosaic,
vapour-retarding paint
Bricks
In accordance with NBN 771, Very No visible frost damage Visible frost damage, brick susceptible
Assessment Framework - Example
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Ma
teri
al
pro
pe
rtie
s o
f th
e e
xis
tin
g m
aso
nry
wa
ll
In accordance with NBN 771, Very
resistant to frost damage (NBN B27-
009/A2 or DIN 52252-1)
No visible frost damage Visible frost damage, brick susceptible
to frost damage
Mortar joints
In accordance with NBN 771, Very
resistant to frost damage
No visible frost damage Visible frost damage, mortar
susceptible to frost damage
(NBN B27-009/A2 or DIN 52252-1) Lime mortar (for ex. mortar containing sandy clay)
Interior finish
No visible damage
No irregularities or loose parts
Smooth, non-structured surface
Irregularities and/or loose parts
Very structured/irregular surface
Interior finish which is susceptible to
moisture (damage)
Vapour retarding interior finish
Visible damage (for example cracks,
paint which is flaking off, degraded
plaster)
Assessment Framework (Tool)
Interior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Visible Damage
Moisture load and frost
damage risk
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Material properties of
the existing masonry
wall
Indoor Climate
Assessment FrameworkIndoor climate• Humidity class (≤3) according to EN ISO 13788
• Well-controlled and efficient ventilation and heating system
Humidity class Building
1 Unoccupied buildings, storage of dry goods
2 Offices, dwellings with normal occupancy and ventilation
3 Building with unknown occupancy
4 Sport halls, kitchens, canteens
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4 Sport halls, kitchens, canteens
5 Special buildings, e.g. laundry, brewery, …
Interior insulation is applicable Applicability is unknown Interior insulation is not
recommended
Ind
oo
r C
lim
ate
Indoor climate
Indoor Climate Class 3 according to
ISO EN 13788
Indoor Climate Class 4 according to
ISO EN 13788
Indoor Climate Class 5 according to
ISO EN 13788
HVAC System
Well-controlled and efficient
ventilation, climate control and
Insufficient ventilation
Assessment Framework
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heating system
Assessment Framework
Interior insulation is
applicable
Applicability is unknown Interior insulation is not
recommended
Visible Damage
Moisture load and frost
damage risk
Case Study - Example
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Material properties of
the existing masonry
wall
Indoor Climate
State of the façade complies with the requirements in the green column:
Interior insulation is applicable
Additional ResultsCase Study - Example
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Conclusion and DiscussionAssessment Framework (Tool) for the Assessment of the
Applicability of Interior Insulation has been developed• helps the building designer determine whether interior insulation is possible
• critical hygrothermal risks are taken into account
• serves as a basis for selection and design of the insulation system
• is independent of building engineer’s, architect’s expertise and experience
Further Development
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Further Development• Framework is applicable for vapor-retarding interior insulation systems
• Tool is extended for capillary-active systems
• Additional validation/verification
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