L1a and L2a Air Tightness Testing

WM Diagnostics is one of the longest running companies to deliver domestic and commercial air tightness testing within the UK. We offer cost effective bespoke quotes on a per contract basis, we also pride ourselves at being affordable for the Self Build Market.

What is Air Testing?


Air tightness testing is a requirement that was brought into the Part L1a regulations in 2006, we feel it is an important aspect of a development and can save a client thousands in both construction costs and end user heating costs.
It is also an important aspect of Passivhaus design.

Uncontrolled air leakage through the fabric of a building creates heat loss, and significantly affects the performance in standard assessment tools like SAP and SBEM.

For a more in-depth discussion regarding air tightness, please give us a call on 01822 833227 or Contact Us and we will be happy to chat to you about it.

Air Tightness Testing for Non-Domestic Buildings

Air Tightness Testing is also mandatory for new-build commercial units under Part L2A of the Building Regulations – and required for producing final SBEM Calculations.

WM Diagnostics can provide air permeability testing for any type of Commercial unit.

Why Choose Us For Air Tightness Testing?

Pre-Test Inspection (Click here to download the Checklist )
  1. All external doors to be closed.
  2. All internal doors to be wedged open.
  3. Extractors to be sealed, mechanical systems to be switched off and sealed ie kitchen/bathroom extractions fans, cooker hoods etc
  4. Drainage traps to be filled with water.
  5. All boilers and combustion appliances inside the building envelope, to be shut down.
  6. Trickle vents to be closed.
  7. Any fireplaces to be temporarily sealed.
  8. There must be NO temporary seals to doors, letter boxes, manual trickle vents, cat flaps, keyholes, penetrations through walls, tumble drier vents, windows and sills.
  9. There must be NO temporary seals to drains, plugs or overflows
  10. ALL building works must be completed to air seal the building envelope including doors, windows, hatches, sills and services, if not possible best results can be achieved past painting and boxing in If in doubt please contact us ASAP.
After test care

Once the test has been carried out and the dwelling passes the Certificate can be issued. If the dwelling fails to achieve the required results the Engineer will carry out a thorough examination of all of the dwellings aspects and offer advice on what can be done retrospectively, and at best cost to yourself.

The Engineer will communicate the information to our SAP Assessors for them to issue your AsBuilt SAP and EPC (We offer a full package of SAP, EPC, Part O Calculations and Air Test with Water Calculationss and Ventilation Tests at very competitive rates).

For more information feel free to Contact Us or call us on 01822 833227.