SAP NHER Technical Bulletin

OCDEA Technical Bulletin Issue 31 Version 4.1 | ©National Energy Services 2012

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External wall junctions

E1–Steel lintels perforated base ...................... 4

E2–Other lintels ............................................... 4

E3–Sill ............................................................. 5

E4–Jamb .......................................................... 5

E5–Ground floor .............................................. 6

E6–Intermediate floor within

dwelling.................................................... 7

E7–Intermediate floor between

dwellings (flats) ....................................... 8

E8–Balcony within dwelling ............................. 8

E9–Balcony between dwelling ......................... 9

E10–Eaves (ceiling insulation) ........................ 9

E11–Eaves (rafter insulation) ........................ 10

E12–Gable (ceiling insulation) ....................... 10

E13–Gable (rafter insulation) ........................ 11

E14–Flat roof ................................................. 11

Contents: Table K1 items and their associated ACDs

E15–Flat roof with parapet ............................ 12

E16–Corner (normal) .................................... 12

E17–Corner (inverted) .................................. 13

E18–Party Wall between

dwellings (party corner)...................... 13

Party wall junctions

P1–Ground floor .............................................. 14

P2–Intermediate floor within

dwellings ................................................. 14

P3–Intermediate floor between

dwellings (flats) ...................................... 15

P4–Roof (ceiling insulation) ............................ 15

P5–Roof (rafter insulation) ............................. 16

OCDEAOCDEAOCDEA TechnicalTechnicalTechnical BulletinBulletinBulletin For On Construction Domestic Energy AssessorsFor On Construction Domestic Energy AssessorsFor On Construction Domestic Energy Assessors

Special EditionSpecial EditionSpecial Edition–––Thermal BridgingThermal BridgingThermal Bridging

Issue 31 Version 4.1| October 2012

All content © National Energy Services, Ltd

This is Version 4.1 of the special edition of the NHER OCDEA Technical Bulletin, first published

in July 2011. The special issue was produced to help our OCDEAs, NHER Plan Assessor users

and their customers to better understand how thermal bridging is dealt with in SAP 2009.

It describes the thermal bridging junctions in Table K1 of the SAP 2009 document and the

associated Accredited Construction Details (England and Wales) for each junction. It also

indicates where junction details and associated ѱ values are available from other sources: EST

Enhanced Construction Details, Scottish Accredited Construction Details, Association for

Energy Conscious Buildings and Constructive Details from BBA/RDL.

Web links are provided at the end of this bulletin for each of these sources. Junction details and

ѱ values are also available from some manufacturers.


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Source: The Government’s Standard Assessment; Procedure for Energy Rating of Dwellings; 2009 edition;

incorporating RDSAP 2009; BRE, p. 78

*


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The second diagram above assumes a room in the roof. If no roof room is present and the

ceiling is not insulated, omit E6 and P2 (unless the ceiling is clearly a structural element).


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External wall: Steel lintel (perforated base plate)

—ACD ѱ = 0.5 (default = 1.0) E1

The length of the junction is the length of the

opening in the wall.

In NHER Plan Assessor the lintel length can

be set automatically from the opening width.

Typical example: MCI-WD-01

Masonry:

MCI-WD-01 MII-WD-01

Accredited (Indicative) Detail Number:

MCI-WD-01

External wall: Other lintels—ACD Ѱ = 0.3 (default = 1.0)

E2

The length of the junction is the length of the opening in the wall.

In NHER Plan Assessor the lintel length can be set automatically from the opening width.

Typical example: MCIWD-02

Masonry:

MCI-WD-02

MCI-WD-03

MII-WD-02

MII-WD-03

MEI-WD-01

Steel Framed:

SFW-WD-01

Timber Framed:

TFW-WD-01

Accredited (Indicative) Detail

Number: MCI-WD-02

Scottish Details: 1.08, 2.08, 3.08; Scottish ACDs

also include details for roof lights (5.01, 5.02).

Various EST Enhanced Construction Details are

available with ѱ values of less than 0.1.

The AECB Silver Standard has a junction with a

Ѱ value of 0.06 (calculated with internal

dimensions).

Various Constructive Details are available with

Ѱ values between 0.054 and 0.060.

Various EST Enhanced Construction

Details are available with ѱ values of less

than 0.1.

Various Constructive Details are available

with Ѱ values between 0.28 and 0.38.

EST ECD MV01 lintel

with ѱ = 0.01


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External wall: Sill—ACD Ѱ = 0.04 (default = 0.08)

E3 Masonry:

MCI-WD-04

MII-WD-04

MEI-WD-02

Steel Framed:

SFW-WD-02

Timber

Framed:

TFW-WD-02

Typical example: SFW-WD-02


SFW-WD-02

External wall: Jamb—ACD Ѱ = 0.05 (default = 0.10)

E4

The length of the jamb is the length of the opening in the wall.

In NHER Plan Assessor the jamb can be set automatically from the opening height.

Masonry:

MCI-WD-05 MCI-WD-06 MII-WD-05 MII-WD-06 MEI-WD03

Steel Framed:

SFW-WD-03

Timber Framed:

TFW-WD-03

Typical example: SFW-WD-03

The length of the junction is the length of the

opening in the wall.

In NHER Plan Assessor the sill length can be set

automatically from the opening width.

Scottish Details: 1.09, 2.09, 3.09

The AECB Silver Standard has a junction with

a ѱ value = 0.03.


with Ѱ values between 0.034 and 0.046.

Scottish Details:1.09, 2.09, 3.09

The AECB Silver Standard has a junction with a

ѱ value of 0.03.

Various Constructive Details are available with Ѱ

values between 0.039 and 0.051.


SFW-WD-03


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External wall: Ground floor––ACD Ѱ = 0.16 (default = 0.32)

Masonry:

MCI-GF-01

MCI-GF-02

MCI-GF-03

MII-GF-01

MII-GF-02

MII-GF-03

MEI-GF-01

MEI-GF-02

MEI-GF-03

Steel Framed:

SFW-GF-01 SFW-GF-02

Timber Framed:

TFW-GF-01

TFW-GF-02

TFW-GF-03

E5

Accredited (Indicative) Detail Number: MCI-GF-03

Scottish Details:

1.10, 2.10, 3.10; 1.11, 2.11, 3.11; 1.12, 2.12,

3.12

Various EST Enhanced Construction Details are available, with ѱ values in cases less than 0.04. The AECB Silver Standard has junctions with

ѱ values of between 0.01 and 0.10.


Ѱ value between 0.025 and 0.160.

EST Enhanced Construction Detail MV01 F02 with ѱ = 0.075

Note: for all junctions the ѱ value depends on

the level of insulation in the adjoining elements.

The ѱ value can increase as the level of insula-

tion increases. However, the ACDs (England and

Wales, Scotland) do not prescribe insulation

thicknesses for which the ѱ values apply. The

other options (EST, AECB, CD) are more pre-

scriptive to varying degrees.

Measure the ground floor perimeter of the prop-

erty. Include perturbations (like bay windows)

and any other wall to ground floor lengths.

Floors above unheated space or exposed upper

floors should also be counted as this type.

Example of E5 dimension


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Masonry:

MCI-IF-01

MCI-IF-02

MII-IF-01

MII-IF-02

MEI-IF-01

Steel Framed:

SFW-IF-01

Timber Framed:

TFW-IF-01

External Wall: intermediate floor within a dwelling

—ACD Ѱ = 0.07 (default = 0.14) E6

Typical example:

Scottish Details:

1.14, 2.14, 3.14; 1.15, 2.15, 3.15.

The AECB Silver Standard has junctions with

ѱ values of between 0.00 and 0.03.


a Ѱ value of 0.00. Accredited (Indicative) Detail Number:

MII-IF-02

A floor above a heated basement should be

included in this length.

Enter the perimeter of all external intermediate

floors. These include roof room floors to gables

or to walls where the eaves are above the RIR

floor level.


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External wall: Balcony within dwelling–No ACD (default Ѱ = 0.0 or 1.0)

E8

Typical example: MCI-IF-01 Masonry:

MCI-IF-01 MII-IW-01 MEI-IF-01

This is the external floor perimeter of a flat with another dwelling below. In mid-floor flats this would

also be the ceiling. This should also be used for floors above separate heated spaces such as commercial

premises.

E7 External wall: Intermediate floor between dwellings

—ACD Ѱ = 0.07 (default = 0.14)

No ACDs available.

This DCLG SAP Convention

supersedes and replaces the

*footnote in Table K1.

A default value of 0.00 can be used

if the balcony supports do not

bridge the insulation. Otherwise use

a default value of 1.0 or a

calculated value.


MCI-IF-01

The diagram shows the Scottish ACD 5.11 (for which no ѱ value is quoted).

Various Constructive Details are available with Ѱ values between 0.057 and 0.093.


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Typical example: MII-RE-05* Masonry:

MCI-RE-01

MCI-RE-02

MCI-RE-03*

MCI-RE-05*

MII-RE-01

MII-RE-02

MII-RE-03*

MII-RE-05*

MEI-RE-01

MEI-RE-02

MEI-RE-03*

MEI-RE-05*

Steel Framed:

SFW-RE-01

SFW-RE-02

SFW-RE-03*

SFW-RE-05

Timber Framed:

TFW-RE-01

TFW-RE-02

TFR-RE-03*

TFW-RE-05*

External wall: Eaves (ceiling insulation)

—ACD Ѱ = 0.06 (default = 0.12)

Accredited (Indicative) Detail Number: MII-RE-05

Length of eaves entered.

All wall to eaves bridges should be classified under this junction, this includes bay window walls and

dormer walls.

*Included here as main junction is eaves to roof with insulation over joist at that point.

E10

External wall: balcony between dwellings–

No ACD (default Ѱ = 0.04 or 1.0) E9

No ACDs available.

This DCLG SAP Convention supersedes and replaces the

footnote in Table K1.

A default value of 0.04 can be used if the balcony supports

do not bridge the insulation. Otherwise use a default value of

1.0 or a calculated value.




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Typical example: MEI-RE-04

Masonry:

MCI-RE-04

MCI-RE-06

MCI-RE-07

MCI-RE-08

MII-RE-04

MII-RE-06

MII-RE-07

MII-RE-08

MEI-RE-04

MEI-RE-06

MEI-RE-07

MEI-RE-08

Steel Framed:

SFW-RE-04

SFW-RE-06

SFW-RE-07

SFW-RE-08

Timber Framed:

TFW-RE-04

TFW-RE-06

TFW-RE-07

TFW-RE-08

External wall: Eaves (rafter insulation)—ACD Ѱ = 0.04 (default = 0.08)

Lengths of eaves entered. All wall to eaves bridges should be classified under this junction; this includes

bay windows and dormer walls.

Masonry:

MCI-RG-01

MII-RG-01

MEI-RG-01

Steel Framed:

SFW-RG-01

Timber Framed:

TFW-RG-01

External wall: Gable (ceiling insulation)—ACD Ѱ = 0.24 (default = 0.48)

E11

E12


The AECB Silver Standard has junctions

with ѱ values of between 0.00 and 0.044.


with Ѱ between 0.02 and 0.036.

Various EST Enhanced Construction Details are available, with

ѱ values substantially less than 0.1.

Various Constructive Details are available with Ѱ values between

0.048 and 0.087.

Accredited (Indicative) Detail

Number: MEI-RE-04

Typical example: TFW-RG-01


TFW-RG-01

Scottish Details: 1.02, 2.02, 3.02; 1.03, 2.03, 3.03; 1.05, 2.05, 3.05

All wall to gable bridges should be classified under this junction; this includes bay window walls and

dormer walls.


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Typical example: TFW-RG-04 Masonry:

MCI-RG-02

MCI-RG-03

MCI-RG-04

MII-RG-02

MII-RG-03

MII-RG-04

MEI-RG-02

MEI-RG-03

MEI-RG-04

Steel Framed:

SFW-RG-02 SFW-RG-03 SFW-RG-04

Timber Framed:

TFW-RG-02 TFW-RG-03 TFW-RG-04

External wall: Gable (rafter insulation)—ACD Ѱ = 0.04 (default = 0.08)

E13

Typical example: MCI-RF-01

Masonry:

MCI-RF-01

MII-RF-01

MEI-RF-01

Steel Framed:

SFW-RF-01

External wall: Flat roof—ACD Ѱ = 0.04 (default = 0.08)

E14

Accredited (Indicative) Detail Number: MCI-RF-01


Accredited (Indicative) Detail Number: TFW-RG-04 Various Constructive Details are available with Ѱ values between 0.065 and 0.073.

All wall to gable bridges should be classified under this junction; this includes bay window walls and

dormer walls.

All wall to flat roof bridges should be classified

under this junction; this includes bay window

walls and dormer walls.


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Masonry:

MCI-RF-02

MII-RF-02

MEI-RF-02

Steel Framed:

SFW-RF-02

Timber Framed:

TFW-RF-01

External wall: Flat roof with parapet—ACD Ѱ = 0.28 (default = 0.56)

E15

Further clarification is given in the DCLG SAP Conventions

document: “From the thermal bridging point of view the

principal difference between a parapet and not is whether

the wall passes over the edge of the roof, or the roof

passes over the top of the wall.

These two possibilities form different types of junction. If

the wall passes over the edge of the roof, treat as a roof

with parapet. If the roof passes over the top of the wall,

treat it as a roof without a parapet.”

All wall to flat roof bridges should be classified under this

junction, this includes bay window walls and dormer walls.

Timber Framed:

TFW-EW-01

External wall: Corner (normal)—ACD Ѱ = 0.09 (default = 0.18)

E16

Height of wall to wall corners where internal area is less than external area.

Also describes:

Dormer corners

Corners to unheated garage

There are no England and Wales ACD options available for masonry construction

types; use default ѱ value or a value from another source. If the construction around

the corner is the same as the rest of the dwelling and not interrupted by structural

elements the ACD value of 0.09 can still be used. Ignore corners in bay windows if

the insulation is continuous.

Typical example: TFW-EW-01


TFW-EW-01


TFW-RF-02


The AECB Silver Standard has junctions with ѱ values

of between 0.12 and 0.25.

Scottish Details: 1.23, 2.23,

3.23

The AECB Silver Standard

has a masonry junction with a

ѱ value of 0.066 (ref 2.2.2).


Typical example: TFW-RF-02


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External wall: Corner (inverted)–No ACD (default Ѱ = 0.00)

E17

No ACDs available. A value of ѱ = 0.0 is

normally used. However, there is a Scottish

ACD with ѱ = -0.119.

Typical example

Example of E18 dimensions Masonry:

MCI-IW-01

MII-IW-01

MEI-IW-01

MEI-IW-02

Steel Framed:

SFW-IW-01

SFW-IW-02

Timber

Framed:

TFW-IW-01

TFW-IW-02

External wall: Party wall between dwellings

––ACD Ѱ = 0.06 (default = 0.12)

Front elevation

E18


MCI-IW-01


This is the corner between the external wall

and the party wall.



with ѱ values between -0.08 and -0.052.


ѱ values between 0.035 and 0.046.


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Party wall: Intermediate floor within dwelling–

No ACD (default Ѱ = 0.04) P2 Typical example

Party wall: Ground floor –No ACD (default Ѱ = 0.16)

P1

No ACDs available–use default or calculated

value from another source.

Also use for junction with heated corridor/

stairwells or other heated spaces.

Typical example

Scottish Details: 1.16, 2.16, 3.16; 1.17,

2.17, 3.17; 1.18, 2.18, 3.18

No ACDs available–use default or calculated

value from another source.

The default of 0.04 can also be used for houses

with a split level arrangement.

Disregard intermediate floor junction with walls

adjacent to heated corridor/stairwells or other

heated spaces.


with ѱ values between 0.043 and 0.073.


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Party wall: Intermediate floor between dwellings–

No ACD( default Ѱ = 0.04) P3

Party wall: Roof (ceiling insulation)—ACD Ѱ = 0.12 (default = 0.24)

P4 Typical example: TFW-IW-02

Masonry:

MEI-IW-02

MCI-IW-02

MII-IW-02

Steel Framed:

SFW-IW-02

Timber Framed:

TFW-IW-02


No ACDs available–use default or calculated value from an-

other source.

The default value of 0.04 can also be used for flats with a

split level arrangement. Use this value for each flat.

Disregard intermediate floor junction with walls adjacent to

heated corridor/stairwells or other heated spaces.


TFW-IW-02

Also used for roof adjacent to heated corridor/

stairwells or other heated spaces.

Various Constructive Details are available with ѱ values between 0.041 and 0.087.

Party wall: Roof (rafter insulation)–No ACD (default Ѱ = 0.04)

P5

Further information:

The Accredited Construction Details for England and Wales can be found by visiting the Planning Portal Website.

The EST Enhanced Construction Details can be found by visiting the EST website. These provide alternative details

to ACDs for E1, E2, E5 and E12, with substantially lower ѱ values.

BBA and Robust Details Ltd have junction details under the name Constructive Details. Details of the scheme can be

found here: www.constructivedetails.co.uk/

The Scottish Accredited Construction Details can be found by clicking here. Scottish Details can be used in England

and Wales if the construction matches.

The Association for Energy Conscious Buildings (AECB) also have junction details and associated ѱ values available to

members. Details of membership are available by visiting: www.aecb.net. Their design guidance for the Silver and

Gold standards provides detailed guidance on how to minimise thermal bridging.

All ѱ values from these above sources can be taken as being produced by someone with suitable expertise and

experience for the purposes of Building Regulation submissions.

This technical bulletin is consistent with DCLG SAP Conventions (v4.0), dated 12 September 2012. The DCLG SAP

Conventions are a key reference and provide further detail and background; the DCLG Conventions can be found in

‘NES one useful documents’ and at the BRE website.

No ACDs available–use default or calculated values from another

source. Also used for roof adjacent to heated corridor/stairwells or

other heated spaces.


Dormers

Dormers are not specifically included in Table K1. However, a convention exists for how to enter them

into SAP software. The Scottish ACDs 5.04 and 5.05 include some junctions for dormers.

National Energy Centre, Davy Avenue

Knowlhill, Milton Keynes, MK 5 8NA tel: 01908 672787 fax: 01908 662296

Email: [email protected]; www.nesltd.co.uk

AB O UT O UR B UL L ET IN S We trust you find this edition of the technical bulletin useful. If there are any areas you would like to see covered in future editions drop us a line at [email protected] Back copies of all bulletins are available in the Useful Documents section of NES one.

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National Energy Services ©2012

Typical example

Various Constructive Details are available with ѱ values between 0.069 and 0.071.

http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partl/bcassociateddocuments9/acd

http://www.energysavingtrust.org.uk/business/Business/Housing-professionals/Interactive-tools/Enhanced-Construction-Details/Enhanced-Construction-Details-Matrix

http://www.constructivedetails.co.uk/

http://www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards/profinfo/techguide/acdscot

http://www.aecb.net

http://www.bre.co.uk/sap2009/page.jsp?id=1642

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