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Acceptable Construction Details




The details in this section have been developed for a range of partial and full fill cavity wall construction to support TGD L 2021. The introduction document "Limiting Thermal Bridging and Air Infiltration Acceptable Construction Details" provides practical information with regards to implementation of these details onsite. This guide should be read in conjunction with these details. Details are given for the junctions with a range of roof, ground floor and internal floor types, as well as at external wall opes.

The details are indicative. They focus on the issues of thermal performance and air tightness. Other issues are not considered fully. Insulation thicknesses for the main building elements have not been provided, as these depend on the thermal properties of the material chosen, as well as on the desired U-value.

Masonry materials shown on the drawings are blocks and bricks. Other masonry materials, including precast and in-situ concrete, may be substituted without loss of thermal performance or increased technical risk. The use of thermally resistant materials, beyond that depicted, will naturally increase the thermal performance of the building fabric.

All materials and workmanship are to be installed to Technical Guidance Document D ‘Materials and Workmanship’.

The suitability of full fill construction depends on the site exposure and nature of the outer leaf. Further information is given in the BR 262 “ Thermal Insulation: Avoiding Risks" and relevant Irish Agrément Board certificates.

These diagrams illustrate good practice for design and construction of interfaces only in respect to ensuring thermal performance and air barrier continuity. The guidance must be implemented with due regard to all other requirements imposed by the Building Regulations.

This set of details shows cavity wall insulation used in combination with internal insulation. The cavity wall details can also be used without the addition of internal insulation to achieve the construction described in Table D1. The air barrier detail apply in all cases.

In these details red insulation hatch pattern indicates partial and/or internal insulation and the gray insulation hatch pattern indicates full fill insulation as appropriate.

Insulation hatching is indicative and represents appropriate insulation materials depending on location and application as specified.

Where theses details are used for the Target U-values and construction described in Table D1 of TGD L 2021 the psi values published in Table D1 may be used to calculate the actual Thermal Bridging heat loss for a dwelling for the key thermal bridging junctions in that dwelling.

Technical Guidance Document B and Supplementary Guidance to TGD B provides guidance in relation to the provision of cavity barriers in air cavities, cavity barriers within combustible insulation layers and fire protection of structural elements.

The 2021 edition of the ACDs updates the drawings in the 2011 ACDs to include internal insulation which was previously provided for in the text. The performance requirements of the 2021 ACDs remain the same as for the 2011 edition.