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Accredited Construction Details

Accredited Construction Details (ACDs) have been developed to help the construction industry achieve the performance standards required to comply with the energy efficiency requirements (Part L) of the Building Regulations.

The details and introductory section of this document focus on the issues of insulation continuity (minimising cold bridging) and airtightness. They are not intended to provide any detailed guidance on other performance aspects such as vapour control and ventilation, which must also be considered by the design and construction team.

The details contain checklists which should be used by the designer, constructor and building control body to demonstrate compliance. The details have been grouped by generic construction type. It is strongly recommended that the introductory section ‘Accredited Construction Details’ is read in conjunction with the particular set of ACDs, in order to better understand the principles underpinning the details themselves.

Above information is from the Planning Portal website.

However since the 2010 & 2014 Part L changes have been in force the methods of achieving compliance have changed.

 

Please click our maps for SAP Calculations/SAP Ratings in your area.

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Accredited Construction Details 

Before the 2010 changes, it was commonly assumed that new dwellings followed the guidance for Accredited Construction Details which can be found on the Planning Portal website. In addition for a higher specification dwelling, designers would use guidance on the Energy Saving Trust website. These are known as Enhanced Construction Details.

Since the 2010 changes and more so the 2014 changes, Thermal modelling has been introduced as a way of achieving compliance along with the Planning Portal, Enhanced and manufacturers details.

The details that need to be justified under the new changes are as follows.

Came into force 6th April 2014 – Applicable to new dwellings application on or after that date.

External Wall JunctionsRefJunction DetailAccredited
Ψ (W/m·K)
Default
Ψ (W/m·K)
External Wall JunctionsE1Steel lintel with perforated steel base plate0.501.00
External Wall JunctionsE2Other lintels (including other steel lintels)0.301.00
External Wall JunctionsE3Sill0.040.08
External Wall JunctionsE4Jamb0.050.10
External Wall JunctionsE5Ground floor (normal)0.160.32
External Wall JunctionsE19Ground floor (inverted)0.07
External Wall JunctionsE20Exposed floor (normal)0.32
External Wall JunctionsE21Exposed floor (inverted)0.32
External Wall JunctionsE22Basement floor0.07
External Wall JunctionsE6Intermediate floor within a dwelling0.070.14
External Wall JunctionsE7Party floor between dwellings (in blocks of flats) a)0.070.14
External Wall JunctionsE8Balcony within a dwelling, wall insulation continuous b)0.000.00
External Wall JunctionsE9Balcony between dwellings, wall insulation continuous b) c)0.020.04
External Wall JunctionsE23Balcony within or between dwellings, balcony support
penetrates wall insulation
1.00
External Wall JunctionsE10Eaves (insulation at ceiling level)0.060.12
External Wall JunctionsE24Eaves (insulation at ceiling level - inverted)0.24
External Wall JunctionsE11Eaves (insulation at rafter level)0.040.08
External Wall JunctionsE12Gable (insulation at ceiling level)0.240.48
External Wall JunctionsE13Gable (insulation at rafter level)0.040.08
External Wall JunctionsE14Flat roof0.08
External Wall JunctionsE15Flat roof with parapet0.56
External Wall JunctionsE16Corner (normal)0.090.18
External Wall JunctionsE17Corner (inverted – internal area greater than external area)-0.090.00
External Wall JunctionsE18Party wall between dwellings c)..0.060.12
External Wall JunctionsE25Staggered party wall between dwellings c)0.12
Junctions with party wallRefJunction DetailAccredited
Ψ (W/m·K)
Default
Ψ (W/m·K)
Junctions with party wallP1Ground floor0.16
Junctions with party wallP6Ground floor (inverted)0.07
Junctions with party wallP6Intermediate floor within a dwelling0.00
Junctions with party wallP3Intermediate floor between dwellings (in blocks of flats)0.00
Junctions with party wallP7Exposed floor (normal)0.16
Junctions with party wallP8Exposed floor (inverted)0.24
Junctions with party wallP4Roof (insulation at ceiling level)0.24
Junctions with party wallP5Roof (insulation at rafter level)0.08
Junctions within a roof or with a room in roofRefJunction DetailAccredited
Ψ (W/m·K)
Default
Ψ (W/m·K)
Junctions within a roof or with a room in roofR1Head of roof window0.08
Junctions within a roof or with a room in roofR2Sill of roof window0.06
Junctions within a roof or with a room in roofR3Jamb of roof window0.08
Junctions within a roof or with a room in roofR4Ridge (vaulted ceiling)0.08
Junctions within a roof or with a room in roofR5Ridge (inverted)0.04
Junctions within a roof or with a room in roofR6Flat ceiling0.06
Junctions within a roof or with a room in roofR7Flat ceiling (inverted)0.04
Junctions within a roof or with a room in roofR8Roof to wall (rafter)0.06
Junctions within a roof or with a room in roofR9Roof to wall (flat ceiling)0.04

Came into force 1st October –  Applicable to new dwellings application on or after that date.

External Wall JunctionsRefJunction DetailAccredited
Ψ (W/m·K)
Default
Ψ (W/m·K)
External Wall JunctionsE1Steel lintel with perforated steel base plate0.501.00
External Wall JunctionsE2Other lintels (including other steel lintels)0.301.00
External Wall JunctionsE3Sill0.040.08
External Wall JunctionsE4Jamb0.050.10
External Wall JunctionsE5Ground floor0.160.32
External Wall JunctionsE6Intermediate floor within a dwelling0.070.14
External Wall JunctionsE7Intermediate floor between dwellings (in blocks of flats) a)0.070.14
External Wall JunctionsE8Balcony within a dwelling b)0.000.00*
External Wall JunctionsE9Balcony between dwellings a) b)0.020.04*
External Wall JunctionsE10Eaves (insulation at ceiling level)0.060.12
External Wall JunctionsE11Eaves (insulation at rafter level)0.040.08
External Wall JunctionsE12Gable (insulation at ceiling level)0.240.48
External Wall JunctionsE13Gable (insulation at rafter level)0.040.08
External Wall JunctionsE14Flat roof0.040.08
External Wall JunctionsE15Flat roof with parapet0.280.56
External Wall JunctionsE16Corner (normal)0.090.18
External Wall JunctionsE17Corner (inverted – internal area greater than external area)-0.090.00
External Wall JunctionsE18Party wall between dwellings a)0.060.12
Junctions with a Party Wall a)P1Ground floor0.080.16
Junctions with a Party Wall a)P2Intermediate floor within a dwelling0.000.04
Junctions with a Party Wall a)P3Intermediate floor between dwellings (in blocks of flats)0.000.04
Junctions with a Party Wall a)P4Roof (insulation at ceiling level)0.120.24
Junctions with a Party Wall a)P5Roof (insulation at rafter level)0.020.04

Click the links to the below to see typical junction details. The Accredited Ψ values in the above table are from the Planning Portal website. These are standard details that apply to a lot of typical construction. The Enhanced details link will take take you to the Energy Saving Trust website and are a higher spec of details but help the DER/TER calculations a great deal.

Planning Portal Details

Enhanced Construction details

 

a) Value of Ψ is applied to each dwelling
b) This is an externally supported balcony (the balcony slab is not a continuation of the floor
slab) where the wall insulation is continuous and not bridged by the balcony slab
* Value valid only if balcony support does not penetrate the wall insulation. If it does so
penetrate, either a Y-value must be calculated for the junction, or the SAP calculation uses
the default overall thermal bridging of y = 0.15

 

 

Please Contact us for information on Accredited Construction Details
.


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