Old painted window with a cracked pane beside a curtain

Diagnostic survey

Air-tightness (blower door) test

A blower door test that measures air leakage and finds draughts with a smoke pencil.

Book online

£250–£400

Your fee is set by the size and type of your home, shown before you confirm.

Credited against your installation if you go ahead within 90 days.

Choose a date Or call 020 8914 7824

What you get

What's included

Blower door fan fitted to an external door to depressurise the home
Air leakage measured and reported
Smoke pencil tracing of the main leakage paths

Who it's for

Homes planning MVHR or a deep retrofit
Finding the draughts behind cold, uncomfortable rooms
Checking airtightness work before and after

The visit

Windows and doors stay closed during the test and some vents may be temporarily sealed; we'll explain everything on arrival.

What happens next

From booking to report

Step 1
Pick your survey
Choose the survey that fits — or start with a heat loss survey if you're planning a heat pump.
Step 2
Tell us the size
Property type and size set the fee, within the published range.
Step 3
Choose a date
Pick a two-hour arrival window from the live calendar.
Step 4
Confirm
Your slot is confirmed straight away. Pay on the day or by invoice — no payment taken now.
Step 5
Surveyor visits
Measurements and photos of every room, with reminders the day before and on the day.
Step 6
Report and proposal
Your written report, and a proposal if you'd like one.

Book this survey

Questions

About the air-tightness (blower door) test

Will the test damage anything?

No. The fan creates a small pressure difference and anything temporarily sealed is unsealed afterwards.

Is the fee credited?

If you go ahead with the work through LINX within 90 days, the survey fee is credited against your installation. If you don't, you still keep the report.