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Outline ACDs Acceptable Construction Details

Air Tightness Strategy


Design Stage

Simplify built form where possible.

Define the line of the air barrier as early as possible. Mark up large scale sections with a bold coloured line.

Consider and rationalise construction sequencing.

Redefine the air barrier route and insulation strategy in critical areas to simplify details and avoid problems.

Decide and specify which materials will form the air barrier. Consider:

  • Material air permeability

  • Buildability

  • Position within the construction

  • Long term durability

Consider junction details between air barrier materials:

  • Practicality of forming the seals on site

  • Durability of the seals, especially where not accessible for future remedial work.

Minimise the number of service penetrations through the external wall.

Consider how service penetrations will be sealed.

Rationalise service routes and penetrations.

Highlight air barrier critical elements and junctions on construction drawings.

Apportion responsibility for sealing critical junctions to specific trades.

Construction Stage

Appoint a site “air barrier manager” to coordinate and inspect the overall formation of the air barrier.

Brief the whole construction team (not just management) on the need for and importance of the air barrier. Inform the team of the air barrier line, the materials which will form the barrier and the critical junctions. Encourage operatives to draw attention to unforeseen difficulties rather than using makeshift solutions. Air barrier management to undertake:

  • Coordination of the formation of the air barrier

  • Site quality assurance

  • Check and sign off all “hidden” air barrier elements before covering up.

Review the construction as work proceeds to identify any weaknesses in the air barrier strategy / areas not previously considered and feed thisinformation back to the design team. Establish solutions to any problems identified. Undertake airtightness testing at the earliest possible opportunity. Use an established pressure testing company capable of giving good diagnostic feedback. All materials and workmanship including air tightness tapes and sealants are to be supplied and completed as per guidelines in Technical Guidance Document D.