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SERVE Conference, T.I.SERVE Conference, T.I.SERVE Conference, T.I.SERVE Conference, T.I.

Insulating safely Insulating safely Insulating safely Insulating safely –––– health, health, health, health,

condensation, locationcondensation, locationcondensation, locationcondensation, location

Joseph Little Joseph Little Joseph Little Joseph Little

MRIAI, B Arch, MSc Arch AEES

Doing it well Doing it well Doing it well Doing it well ---- the need for a Code the need for a Code the need for a Code the need for a Code

Preparation of walls for internal Preparation of walls for internal Preparation of walls for internal Preparation of walls for internal

insulationinsulationinsulationinsulation

Understanding moisture, vapour and Understanding moisture, vapour and Understanding moisture, vapour and Understanding moisture, vapour and

temperature movement in wallstemperature movement in wallstemperature movement in wallstemperature movement in walls

Location, location, locationLocation, location, locationLocation, location, locationLocation, location, location

Hygrothermal simulation studyHygrothermal simulation studyHygrothermal simulation studyHygrothermal simulation study

Using the right standardsUsing the right standardsUsing the right standardsUsing the right standards

Insulating walls - performance of different approachesperformance of different approachesperformance of different approachesperformance of different approaches

UK exposure zonesUK exposure zonesUK exposure zonesUK exposure zones

Excerpt from BR 262 ‘Thermal insulation –

Avoiding risks’ showing UK exposure zones

BR 262 sets out the exposure zones for

different forms of cavity wall in the UK

Since publication the BBA has required that

suppliers must carry-out simulations for certain

EWI systems when sites are in the severe (blue)

zones

There is no Irish equivalent.

Performance of insulated walls – impact ofimpact ofimpact ofimpact of location location location location – driving rain

However the driving rain index for the British

Isles could be used in a revised TGD or an Irish

code of practice for refurbishment

Driving rain Driving rain Driving rain Driving rain

index for the index for the index for the index for the

British IslesBritish IslesBritish IslesBritish Isles

Excerpt from

BS 5262

‘External

renderings’


Irish wind zonesIrish wind zonesIrish wind zonesIrish wind zones

Excerpt from TGD A

– wind zones

Exposure zonesExposure zonesExposure zonesExposure zones

for rain penetrationfor rain penetrationfor rain penetrationfor rain penetrationfrom BS 5262 coloured as per BR 262


Driving rain mapDriving rain mapDriving rain mapDriving rain mapExcerpt from NSAI Agréments

for cavity fill. Map originated in ICP

2:2002 ‘Code of Practice for Slating &

Tiling’ & is also in Homebond Manual




Exposure zonesExposure zonesExposure zonesExposure zonescolour code & numbers from BR 262

ModerateModerateModerateModerate

SevereSevereSevereSevere

Very severeVery severeVery severeVery severe

2222

3333

4444

Table 1 from BR 262 sets maximum

recommended zones for different

buildups of insulated masonry walls

222233334444








2222

3333

4444

Table 1 from BR 262 sets maximum



Cavity wall with exposed decorative

concrete blocks in Castlebar: is it suitable

for internal insulation?

Only if 100mm clear cavityOnly if 100mm clear cavityOnly if 100mm clear cavityOnly if 100mm clear cavity

+ tooled flush joints+ tooled flush joints+ tooled flush joints+ tooled flush joints

Example #1Example #1Example #1Example #1

222233334444








2222

3333

4444

222233334444Table 1 from BR 262 sets maximum



Minimum width of cavity 75mmMinimum width of cavity 75mmMinimum width of cavity 75mmMinimum width of cavity 75mm

Which rendered cavity walls are suitable

for full fill with bead in Castlebar?

Example #2Example #2Example #2Example #2




Exposure zones from BS 5262 coded & numbered as per BR 262



Very severeVery severeVery severeVery severe ≥ 150mm≥ 75mm≥ 50mm

≥ 75mm≥ 50mm≥ 50mm

≥ 50mm≥ 50mm≥ 50mm

Facing

masonry

Rendered

finish

Impervious

cladding

Exposure zones from NSAI Agréments for full fill cavity insulation

NormalNormalNormalNormal

SevereSevereSevereSevere NO

NO

Facing

block

NO≥ 90mm≥ 90mm

≥ 90mm≥ 90mm≥ 90mm

Facing

brick

Rendered

finish

Impervious

cladding

Comparing minimum width of cavity suitable for full fill with beComparing minimum width of cavity suitable for full fill with beComparing minimum width of cavity suitable for full fill with beComparing minimum width of cavity suitable for full fill with beadadadad

Note: There is a lack of clarity in these NSAI certs in relation to (a) minimum

cavity widths to be filled (40mm & 50mm are also referenced), (b) structural

& residual cavities, & (c) what guidance relates to existing and new build

Specifying wall insulation under the HES Scheme - standardsstandardsstandardsstandards – issues?

Currently the HES Scheme ‘code of practice’

specifies that work should be done under:

Building Regs L, B, D, F & J etc

Manufacturer guidelines

NSAI agréments certs

UK Energy Saving Trust docs

UK BRE docs

To the best of our knowledge none of these documents:

Puts a limit on the amount of internal insulation that is appropriate

“In particular, the design and installation

of the recommended works must not

compromise the ventilation, air quality,

humidity (and the potential for

condensation) and the quality of the living

environment in the home.”

HES Scheme ‘code of practice’

Differentiates between one type of insulation and another

Highlights that different substrates might result in very different performance

Only NSAI agrément certs for bead insulation & BR 262 refer to driving rain levels & location

Note: NSAI, DoEHLG docs are preferred

SEI documents

Mentions whether or not internal moisture load affects insulation

Gives a value judgment on what to promote to clients: internal or external insulation


To the best of our knowledge none of these documents:

Puts a limit on the amount of internal insulation that is appropriate

Differentiates between one type of insulation and another

Highlights that different substrates might result in very different performance

Building Life Consultancy therefore carried out a series of simuBuilding Life Consultancy therefore carried out a series of simuBuilding Life Consultancy therefore carried out a series of simuBuilding Life Consultancy therefore carried out a series of simulations to seelations to seelations to seelations to see

More can be read on this issue in articles ‘Breaking the Mould IV’ and ‘V’ in Construct

Ireland magazine

We used WUFI Pro hygrothermal simulation softwareWUFI Pro hygrothermal simulation softwareWUFI Pro hygrothermal simulation softwareWUFI Pro hygrothermal simulation software from Fraunhofer Institute in

Germany. A trial version is freely downloadable

ifififif these omissions are of interestthese omissions are of interestthese omissions are of interestthese omissions are of interest and if so and if so and if so and if so to what degreeto what degreeto what degreeto what degree.

It conforms to IS EN 15026IS EN 15026IS EN 15026IS EN 15026 the standard for numerical simulation

Note that almost all assessments of interinterinterinter----stitial condensationstitial condensationstitial condensationstitial condensation in Ireland use the

Glaser MethodGlaser MethodGlaser MethodGlaser Method under IS EN 13788 IS EN 13788 IS EN 13788 IS EN 13788 & BS 5250BS 5250BS 5250BS 5250

Only NSAI agrément certs for bead insulation & BR 262 refer to driving rain levels & location

Mentions whether or not internal moisture load affects insulation

Gives a value judgment on what to promote to clients: internal or external insulation

Internal or external insulation for masonry walls should never be assessed with the Glaser

Method (under IS EN 13788). It’s very important that architects understand this and require

that the assessments carried out use methods that are appropriate to the wall type.


‘Furthermore, since the method only considers steady-state transport under heavily

simplified boundary conditions, it cannot reproduce individual short-term events or

allow for rain and solar radiation.’Künzel H. M. (2000)

Glaser Method (under IS EN 13788) is not suitable because the method does not deal

with these issues:

a) The dependence of thermal conductivity on moisture content;

b) The release and absorption of latent heat;

d) Capillary suction and liquid moisture transfer within materials;

Consequently the method is applicable only to structures where these effects

are negligible.’IS EN 13788, Scope, pg. 4

c) The variation of material properties with moisture content;

f) The hygroscopic moisture capacity of materials.

e) Air movement through cracks or within air spaces;

To do so means using numerical hygrothermal simulation (under IS EN 15026). So far there

are only a handful of people trained to do this in Ireland.

‘Studies have shown that moulds do not require the presence of water, but can germinate and

grow if the relative humidity at a surface rises above 80%. This is a considerably less severe

criterion than the 100% RH [Relative Humidity] required for surface condensation to occur.’BS 5250, 6.3, Mould growth, pg. 8

Graph courtesy of the Fraunhofer

Institute in Germany

Performance of insulated walls – boundaries to mould growth boundaries to mould growth boundaries to mould growth boundaries to mould growth - stay below 80%

Performance of insulated walls – comparative simulation comparative simulation comparative simulation comparative simulation –––– the software

WUFI Pro 4.2 - hygrothermal simulation software from Fraunhofer Institute

We focused on what was happening in the

1mm of original plaster facing the insulation

Performance of insulated walls – comparative simulation comparative simulation comparative simulation comparative simulation –––– the software

Mineral wool

internal insulation

Air space & phenolic

internal insulation

Performance of insulated walls – comparative simulation comparative simulation comparative simulation comparative simulation –––– % RH in plaster

rendered

blockwork

substrate

poor quality

brick substratebetter quality

brick substrate


Mineral wool internal insulation on solid

brick substrate

External brick surface treated against

driving rain ingress (silane or siloxane

impregnation)

Contact Larsen or Stoneco


External wall insulation on solid brick

Left: %RH in inner insulation

Right: %RH in plaster

mineral wool internal insulation on solid

brick substrate

External brick surface treated against

driving rain ingress (silane or siloxane

impregnation)

Performance of insulated walls – ConclusionsConclusionsConclusionsConclusions

Given the emergence of powerful simulation software in the last 10 years and a related

standard IS EN 15026 in 2007 it is no longer defensible that Glaser is used to evaluate

internal and external insulation of masonry walls

Far greater guidance is needed for the Industry. The issues shown here are not trivial:

Damaged walls, collapsed insulation and worse homeowner’s health could be at risk

The comparative simulations were based on materials tested by the Fraunhofer Institute. They

do not therefore exactly represent materials sold in Ireland. The study does raise the question

as to how typical Irish brick, block, plasters and insulations would perform: testing is needed

urgently

Based on our simulations it appears that the HES Scheme grant for internal insulation should

not be for a higher U-value than 0.50 W/m2K. SEAI may unwittingly be subsidising bad practice

Location (i.e. regional changes in humidity, wind speeds and driving rain) needs to be brought

into the guidance and codes. We have created a useful stop gap by combining info from BR

262 & the driving rain map for British Isles (ex BS 5262). We advise that you use this for now

Amongst many other issues discussed today this needs to be encoded in a well-thought out

code of practice for refurbishment. If you agree make your opinion known to DoEHLG & RIAI

The location of insulation within a wall has a large bearing on how moisture and vapour moves

through it, and to what level it can be insulated.

Joseph Little Joseph Little Joseph Little Joseph Little

MRIAI, B Arch, MSc Arch AEES

Thank youThank youThank youThank you

[email protected]

www.josephlittlearchitects.com

www.buildinglifeconsultancy.com

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