Technical Advice Note - Coventry€¦ · external insulation to their properties. 1 EWI comprises an insulation layer fixed to the outside of an external wall using a combination

Technical Advice Note Version 1.0 (August 2013) Page 1 of 17

Technical Advice Note:

Retrofit External Wall Insulation (EWI)

Applied to Dwellings

August 2013


Technical Advice Note –

Retrofit External Wall Insulation (EWI) Applied to Dwellings

1. Introduction

Background

In a typical house, between 33% and 45% of the building's heat is lost through the walls. The

addition of external wall insulation (EWI)1 is therefore an effective means of both increasing

thermal efficiency and reducing fuel bills, with expected annual savings of between £250 and

£550 for a three-bedroom semi-detached house2. EWI is a particularly useful measure for

those dwellings classed as 'hard-to-treat', typically older dwellings of solid wall construction,

meaning that they are unsuitable for cavity wall insulation. Coventry has a large number of such

properties, including over 45,000 in the city's private housing sector alone2.

Until recently, the uptake of EWI had been very limited in Coventry, primarily due to the

relatively high costs involved. However, mainly as a result of its inclusion in the utility company-

funded Community Energy Saving Programme (CESP), which finished at the end of 2012, and

its replacement, the Energy Company Obligation (ECO), EWI is becoming increasingly common.

CESP and ECO set legally-binding targets requiring utility companies to invest in insulation and

heating improvements, particularly in deprived areas. By December 2012, some 2,900 housing

association dwellings and 300 private dwellings in the city had been treated with EWI, and it is

predicted that this number will increase dramatically over the coming years.

Given the above, a need has emerged for clear guidance on requirements - covering planning,

building control and highways - relating to the application of external wall insulation to domestic

properties in the city, which this document has been produced to fulfil. It is directed at any

individual or organisation seeking information on requirements for EWI, including Green Deal

providers, housing associations, and private householders and landlords considering adding

external insulation to their properties.

1 EWI comprises an insulation layer fixed to the outside of an external wall using a combination of mechanical fixings

and adhesive, and a protective render or cladding finish. It is suitable for solid wall, non-traditional and cavity wall properties and offers several advantages, in addition to the energy efficiency improvements referred to above, as follows:

Work is done externally so there is very little disruption and no internal redecoration is required afterwards;

No living space is lost as a result of the insulation being applied;

The system will provide additional protection to the property and, in some cases, the appearance of the building is improved;

Condensation risk is managed to the outside of the home and, if the insulation is continuous, thermal bridging is minimised; and,

Little maintenance is required.

2 Opinion Research Services (2012). Private Sector Stock Condition Survey: Coventry City Council. Report of

Findings. Draft 22nd

March 2013. Swansea: Opinion Research Services


Guidance scope, aims and overview of content

This guidance covers the application of external wall insulation (EWI) to existing dwellings in

Coventry. It aims to:

a) explain the current Planning, Building Control and Highways requirements and provide

guidance on how they are applied in the Coventry context; and,

b) give examples of how these are applied in practice.

The remainder of this document is divided into six sections, as follows:

Section 2 covers the current planning requirements applicable to external wall insulation

Section 3 gives an overview of relevant building control requirements

Section 4 describes requirements relating to highways

Section 5 gives some examples of how this guidance would be applied in the case of some

typical house types in Coventry

Section 6 covers some of the questions frequently asked about EWI

Section 7 shows the contact details of relevant departments within the Council to whom any

relevant questions should be addressed.


2. Planning requirements

Is planning permission required for external wall insulation?

External wall insulation is classed as permitted development, which means that planning

permission is not required, but this applies only if the materials used are of a similar

appearance to those used in the existing building. In any case, permission is generally only

needed where the EWI is to be applied to the front facades of a building. Full details are given

in The Town and Country Planning (General Permitted Development) (Amendment) (No.2)

(England) Order 2008 and associated technical guidance3, which states

"Development is not permitted [i.e. planning permission is required] if:

(d) the enlarged part of the dwellinghouse would extend beyond a wall which –

(i) fronts a highway, and

(ii) forms either the principal elevation1 or a side elevation of the original

dwellinghouse."

Clarification specifically of the status of EWI with respect to the above is provided in the

technical guidance, as follows:

"The installation of solid wall insulation constitutes an improvement rather than an

enlargement or extension to the dwellinghouse and is not caught by the provisions of d(i)

and d(ii)."

However, a number of conditions are stipulated which must be complied with in order for this to

apply, including that:

"The materials used in any exterior work…shall be of a similar appearance to those used

in the construction of the exterior of the existing dwellinghouse.

The condition above is intended to ensure that any works to enlarge, alter or improve a house result in an appearance that minimises visual impact and is sympathetic to existing development. This means that the materials used should be of similar visual appearance to those in the existing house, but does not mean that they need to be the same materials. For example, the external walls of an extension should be constructed of materials that provide a similar visual appearance – for example in terms of colour and style of brick used – to the materials used in existing house walls."

3 Town and Country Planning (General Permitted Development) (Amendment) (No.2) (England) Order 2008. SI

2008/2362, London: TSO / Department for Communities and Local Government (2013). Permitted development for

householders. Technical guidance. London: DCLG.


In practice this means that, where EWI with a standard smooth or lightly textured render

finish is being proposed:

for a redbrick building with no existing render, planning permission is required;

a redbrick building which is partially rendered, on the other hand, is classed as

permitted development, i.e. planning permission is not required;

in the case of a fully rendered building, planning permission is not required; and,

for a pebbledashed or wet dashed building, permission is likely to be required, as the

addition of EWI render would be expected to result in a change of texture and appearance.

However, in any given case whether planning permission is needed will depend on the

particular circumstances, so if you are uncertain please check with Planning (contact details

given in Section 7).

Where a dry dash (pebbledash) or wet dash finish is proposed:

a property which is already pebbledashed or wet dashed, either fully or partially, would

not usually be expected to need planning permission, on the basis that the appearance

of the building would not be fundamentally changed; whereas

in all other cases, planning permission would normally be required. Again, if you are

unsure how to apply this guidance in your particular circumstances, please contact Planning

(see Section 7 for contact details).

Notes:

A. For some locations within the city, planning conditions have been applied in order to remove

some or all permitted development rights. Depending on which particular rights have been

removed at a given location, this may or may not affect whether planning permission is

required for EWI. The following link will take you to an interactive map showing all areas of

the city where some or all permitted development rights have been removed:

http://www.coventry.gov.uk/info/1023/planning_advice_and_guidance/1333/online_planning

_map

To see only the layer relating to permitted development rights, untick all items on the Map

Legend (left hand side of page) except the one entitled 'NPD Area'. Affected areas are

hatched in blue on the map. By single-clicking on a particular hatched area you can see

details of which permitted development rights have been removed at that location. If the

statement ‘All permitted development rights removed’ appears in the pop-up box, this means

that planning permission will always be required be required for EWI. If a different message

appears, on the other hand, you are advised to clarify with Planning whether permission is

needed before commissioning or commencing any work.

http://www.coventry.gov.uk/info/1023/planning_advice_and_guidance/1333/online_planning_map

http://www.coventry.gov.uk/info/1023/planning_advice_and_guidance/1333/online_planning_map


B. For buildings located within designated Conservation Areas (known as Article 1(5) land), the

following requirements apply:

"In the case of a dwellinghouse on Article 1(5) land, development is not permitted [that is,

planning permission is required]…if:

a) it would consist of or include the cladding of any part of the exterior of the

dwellinghouse with stone, artificial stone, pebble dash, render, timber,

plastic or tiles;

b) the enlarged part of the dwellinghouse would extend beyond a wall forming

a side elevation of the original dwellinghouse; or

c) the enlarged part of the dwellinghouse would have more than one storey

and extend beyond the rear wall of the original dwellinghouse."

This means that in practice planning permission will always be needed for houses located

within Conservation Areas.

C. In the case of Listed or Locally Listed Buildings, any proposals should always be discussed

with the Council prior to an application for planning permission being submitted. In addition

to planning permission Listed Building consent will be also be required. (This latter

requirement applies to Listed Buildings only. It does not apply to Locally Listed Buildings.)

What factors are taken into account by Planning when deciding whether to give planning

permission (where needed) for EWI?

In determining planning applications for external wall insulation, each case will always be judged

on its own individual merits, and a balance struck between good design and improving energy

efficiency of properties. The main national and planning policies to which reference will be

made are as follows:

National Planning Policy Framework4

"Local planning authorities should not refuse planning permission for buildings or

infrastructure which promote high levels of sustainability because of concerns about

incompatibility with an existing townscape, if those concerns have been mitigated by

good design (unless the concern relates to a heritage asset and the impact would cause

material harm to the asset or its setting which is not outweighed by the proposal's

economic, social and environmental benefits".

[Section 7 ('Requiring good design'), Clause 65]

"To support the move to a low carbon future, local planning authorities should…

actively support energy efficiency improvements to existing buildings".

[Section 10 ('Meeting the challenge of climate change, flooding and coastal change'),

Clause 95]

4 Communities and Local Government, 2012. National Planning Policy Framework. London: DCLG


The Coventry Development Plan 20015,

o Policy OS4 (Creating a More Sustainable City):

"The developing concepts and techniques of sustainability will be applied through

policies in this Plan to:

ensure the efficient use and re-use of land and buildings;

……. and

promote the good stewardship of the natural and built environment."

o Policy H4 (Residential Extensions):

"Extensions or other alterations to residential properties should respect the local

character and street-scene of the area".

o Policy BE2 (Principles of Urban Design):

"High quality urban design will be promoted by ensuring that all new development

takes into account the following design principles:

enhancing townscape and landscape character by reflecting locally distinct

patterns of development;

strengthening the continuity of street frontages and the enclosure of space by

development which clearly defines the boundaries between private and public

space; and,

…….

ensuring that developments are sustainable in terms of their design, layout and

density."

In general terms, this means:

for traditionally-built brick terraces, semi-detached and detached houses consideration

will be given to the impact on the overall character of the area and street-scene, together

with the architectural merit of the property / properties concerned. It may be deemed

necessary for traditional, characteristic or decorative design features of the property, such

as lintels, cills, dentil courses, corbelling and bay windows, to be retained or replicated as

part of the external cladding. Where such features cannot adequately be retained or

replicated it is likely that planning permission would not be granted

for properties in Conservation Areas planning permission will only be granted if it can be

clearly demonstrated that the historic character of the area will not be adversely affected.

The addition of EWI will not be permitted in cases where it is deemed to have a negative

impact on either the building itself or the conservation area as a whole

for Listed and Locally Listed Buildings planning permission is unlikely to be given for

external wall insulation applied to any elevation, owing to the significant impact it would have

on the appearance and historic fabric of the building.

5 Coventry City Council, 2001. The Coventry Development Plan 2001. The City of Coventry Unitary Development

Plan 1996-2011. Coventry: Coventry City Council


What information needs to be provided in support of a planning application for EWI?

When applying for planning permission for EWI, the following information needs to be

submitted:

Set of completed standard application forms

Stipulated application fee

Location plan of the application site at a scale of 1:1250, with the site outlined in red

Photograph(s), taken prior to any works commencing, of all elevations of the building

to which the application refers

Elevation drawing(s) or (a) photo image(s) clearly showing the extent of the

proposed cladding. Again, these should cover all elevations of the building to which

the application refers

Cross-section drawings to show thickness of cladding and any detailing where

specialist treatment may be required, as described in Section 2.

Applications should be made online via the Planning portal, at:

www.planningportal.gov.uk?PpApplications/genpub/en/Ecabinet .

Details of fees payable can also be found at the same location.

Note:

At the discretion of Planning, where there are a significant number of properties within the same

locality to receive EWI treatment, it may be possible to make a block application, covering a

number of different addresses. Contact Development Management (details given in Section 7)

for further details.

http://www.planningportal.gov.uk/?PpApplications/genpub/en/Ecabinet


3. Building control requirements

The application of external wall insulation to an existing dwelling is covered by the requirements

of The Building Regulations 20106, on the basis that one or more thermal elements7 are being

renovated. The requirements relating to building work are given in Schedule 1 to the

regulations. For EWI, as long as the work does not constitute a material alteration8, the only

applicable section of the Schedule is L1(a)(i), which requires:

"reasonable provision for the conservation of fuel and power in buildings by:

(a) limiting heat gains and losses -

(i) through thermal elements and other parts of the building fabric"

Details of how this can be achieved in practice are given in Approved Document L1B:

Conservation of fuel and power in existing dwellings9. The main requirement is that where a

thermal element is being renovated an area-weighted U-value of 0.3W/m2K for the whole

element needs to be achieved10. However, if it can be demonstrated that this requirement

would result in a simple payback of more than 15 years, a higher, less stringent U-value may

apply. This would need to be agreed with Building Control in advance of the any works being

carried out.

External wall insulation is now covered by a number of competent persons schemes. This

means that an installer who is registered with such a scheme is permitted to self-certify their

work as being compliant with Building Regulations. Details of current competent persons

schemes and how they are authorised can be found on the GOV.uk website11. An installer who

is not a member of a scheme may still carry out external wall insulation works but must have

them certified by a building control body (either the local authority or an approved inspector). As

part of this, prior to works commencing the installer is required either give notice to the local

authority of the intention to carry out the work or deposit a full set of plans with the local

authority, as described in the Building Regulations.

Listed Buildings and dwellings in a Conservation Area need not comply with energy efficiency

requirements of Part L if to do so would unacceptably alter the character of appearance of such

buildings. (However, as explained in Section 2, in most cases planning permission would be

refused anyway for the retrofitting of EWI to these types of buildings.)

Further information about Building Control can be found at: www.coventry.gov.uk/buildingcontrol

6 Building and Buildings, England and Wales. The Building Regulations 2010. SI 2010/2214, London: TSO

7 'Thermal element' means a wall, floor or roof (but does not include windows, doors, roof windows or roof-lights)

which separates a thermally conditioned part of the building from either outside, or a part of the building which is not thermally conditioned or is conditioned to a different temperature. 8 An alteration is considered to be 'material' where the work being carried out would at any stage result in a building

or controlled service or fitting (for instance a window, drain or electrical work) either not complying where it did prior to the works being carried out or being made less compliant 9 HM Government, 2010. The Building Regulations 2010. Conservation of fuel and power. Approved Document L1B:

Conservation of fuel and power in existing dwellings. In effect from 1 October 2010. London: NBS 10

This requirement applies where the area being renovated covers at least 50% of the individual element or 25% of the whole building envelope 11

Located at: https://www.gov.uk/competent-person-scheme-current-schemes-and-how-schemes-are-authorised#current-schemes

http://www.coventry.gov.uk/buildingcontrol

https://www.gov.uk/competent-person-scheme-current-schemes-and-how-schemes-are-authorised#current-schemes

https://www.gov.uk/competent-person-scheme-current-schemes-and-how-schemes-are-authorised#current-schemes


Table 1 gives an overview of the Planning and Building Control requirements that are likely to

apply for external wall insulation for particular property types and locations.

Table 1: Summary of Planning and Building Regulations requirements

Dwelling type

1. No designation (i.e. columns 2, 3 and 4

do not apply)

2. Dwelling located

in Article 4

Direction area

3. Dwelling located

in Conservation

Area

4. Listed or Locally

Listed Building

Planning

permission

required?

No – but only if

materials used are

of a similar

appearance to

those used in the

existing building

Yes – all other

cases

May or may not be

required depending

on what is included

in Article 4

Direction covering

location

Yes Yes

Conditions likely

to be applied to

permission

(where relevant)

Significant

architectural

features to be

retained or

replicated as

specified

Significant

architectural

features to be

retained or

replicated as

specified

Appearance of

building to remain

unchanged

Planning

permission not

expected to be

granted due to

impact on

appearance and

historic fabric of

building

Listed Building

consent

required?

Not applicable Not applicable Not applicable Yes (for Listed

Buildings only)

Building

Regulations

apply?

Yes – Part L only Yes – Part L only Yes – Part L only Yes, if character &

appearance of

building can be

retained to an

acceptable degree

(refer to Building

Control for advice)

Building

Regulations Part

L requirements

Area-weighted U-

value of 0.3W/m2K

to be achieved on

all thermal

elements to which

EWI applied*

Area-weighted U-

value of 0.3W/m2K

to be achieved on

all thermal

elements to which

EWI applied*

Area-weighted U-

value of 0.3W/m2K

to be achieved on

all thermal

elements to which

EWI applied*

Area-weighted U-

value of 0.3W/m2K

to be achieved on

all thermal

elements to which

EWI applied*

* Note: if simple payback to achieve U-value of 0.3W/m2K would exceed 15 years, then a higher, less stringent U-

value may be agreed. Please refer to Building Control for advice.


4. Highways requirements

Highway encroachment

Where EWI is added to a dwelling immediately adjoining a public highway (i.e. where there is no

fore garden), Section 177 of the Highways Act 1980 applies, on the basis that the construction

will project beyond the boundary of the property into the highway or associated footway. This

means that, in theory at least, a licence to carry out the works is required. However, the Council

takes a pragmatic approach and, for standard 60mm phenolic board and 90mm expanded

polystyrene EWI systems, a licence would not usually be required, except in cases where the

width of the existing footway is less than 150mm, when the Highways department should always

be consulted (see Section 7 for contact details).

Scaffolding licences

If the work requires the erection of scaffolding and this scaffolding will extend onto a public

highway or associated footway, a scaffolding licence will be required from the Council’s

Highways department. In order to apply for a licence, the following information needs to be

provided:

Completed application form. (Blank forms are available from Highways – see Section 7

for contact details)

A copy of the scaffolding company’s public liability insurance certificate (minimum

required coverage of £5 million)

Plan(s) clearly showing where the proposed scaffolding is to be located in relation to the

building(s) to which it is applied

Stipulated licence fee.


5. Examples: typical Coventry house types

A. No-fines property

Description Wimpey no-fines property, constructed c.1950

Typical features None

Proposed EWI system

Wetherby Building Systems Epsicon 3 Wall insulation system –

60mm phenolic foam, glass fibre mesh embedded in scrim adhesive

and aggregate dash (pebbledash) finish on dash receiver render

Overall thickness approx 70 - 80mm.

Planning permission

required

Yes

Specific conditions

applied to permission

None

Property prior to

addition of EWI

(smooth render finish)

Property following

addition of EWI

(aggregate dash finish)


B. Traditionally-built terraced house – few architectural features of note

Description Mid-terraced house, constructed pre-1919

Typical features Corbelling / dentil course, plain stone lintels / cills, bay windows

Proposed EWI system

Wetherby Building Systems - 60mm phenolic foam plus WBS silicone

render system (scrim adhesive coat reinforced with glass fibre

reinforcing mesh, scrim adhesive levelling coat, silicone primer and

silicone finish)

Overall thickness approx 70mm

Planning permission

required

Yes

Specific conditions


Any lintel, cill and corbelling detail on the existing dwelling shall be

retained or replicated on the external elevation of the cladding hereby

permitted in accordance with the indicative details shown on the

approved elevation or sectional drawings

Typical property

without EWI

Typical property

following addition of

EWI


Note:

In the example above the cill had already been removed during previous works carried out at

the property and therefore replication was unnecessary in this instance. The illustration below

shows a property where the original cill detailing has been replicated using a WBS proprietary

system.

Property with EWI

applied, showing cill

and lintel replication

Cill detail drawing

(image reproduced with

permission from Wetherby

Building Systems Ltd)


C. Traditionally-built detached house – significant architectural features

Description Detached house constructed pre-1919

Notable features Corbelling, decorative lintels / canopy over door, checkerboard

brickwork pattern, name plaque

Proposed EWI system

Wetherby Building Systems - 60mm phenolic foam plus WBS silicone

render system (scrim adhesive coat reinforced with glass fibre

reinforcing mesh, scrim adhesive levelling coat, silicone primer and

silicone finish).

Overall thickness approx 70mm.

Planning permission

required

Yes, although unlikely to be given

Specific conditions


Application not made following preliminary discussions with Planning.

Proposals did not adequately maintain or replicate architectural

features – suitable solution not deemed to exist currently.

Property prior to

addition of EWI


6. Frequently Asked Questions

Why do I need planning permission for external wall insulation when what I'm doing will benefit

the environment by helping to combat climate change and reduce energy use?

Planning permission is required in some instances because, as explained in Section 2, not all

properties are covered by permitted development rights. However, where permission is required,

in determining the application due consideration will be given to the wider benefits of the

proposals, and a balance will be struck between the need to preserve the character of a building

and its neighbourhood, and the energy efficiency improvements / carbon dioxide emissions

reductions that will result from the work being carried out.

If my home is in a Conservation Area will I automatically be refused planning permission?

No, your application will be assessed on its individual merits. However, the need to retain

Conservation Area status is paramount, and will usually mean that planning permission will not

be granted for the addition of EWI unless it can be clearly demonstrated that the appearance of

the building will not be changed. It is therefore recommended that in these instances you seek

advice prior to submitting a planning application.

Are there any restrictions to the type of EWI finish that may be applied?

There are a number of different EWI finishes available on the market, including render (the most

commonly used type), brick slips, tiles and decorative boards. Whilst there are no particular

restrictions on the type of finish that may be applied, Planning will, when determining planning

applications for EWI, take into account the overall appearance of the building, which should be

preserved as far as possible, as described in Section 2 above.

If the proposals do not meet the requirements of Part L of the Building Regulations due to the

payback period exceeding 15 years, will Building Control approval still be granted?

If you consider that a U-value of 0.3W/m2K cannot be achieved without the simple payback

exceeding 15 years, it may be possible to agree a higher U-value target with Building Control.

However, it is important that you seek advice from Building Control prior to the commencement

of works.


7. Contacts

For enquiries about planning permission / planning applications:

Development Management (Planning)

Civic Centre 4 – Floor 3

Much Park Street

Coventry CV1 2PY

Telephone: 024 7683 1212

Email: [email protected]

For enquiries about Building Regulations:

Building Control


Much Park Street

Coventry CV1 2PY

Telephone: 024 7683 2057


For enquiries about Conservation Areas and Listed Buildings:

Conservation and Archaeology Officer


Much Park Street

Coventry CV1 2PY

Telephone: 024 7683 1271


For enquiries about Green Deal & ECO:

Domestic Energy Efficiency Manager


Much Park Street

Coventry CV1 2PY

Telephone: 024 7683 1356


For enquiries about highways:

Assistant Engineer – Traffic Management


Much Park Street

Coventry CV1 2PY

Telephone: 024 7683 2035


mailto:[email protected]





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Technical Advice Note - Coventry€¦ · external insulation to their properties. 1 EWI comprises an insulation layer fixed to the outside of an external wall using a combination