A failed ventilation test doesn't have to blow your deadline.
Get it validated early — before sign-off day becomes a scramble.
On-site airtightness and ventilation validation — certified results, fast turnaround, no surprises on sign-off day.
Why Forsah is the right fit for your retrofit.
A personal introduction from Sean Collins or John, Forsah Director
Ventilation validation is the most common failure point on retrofit projects.
Airtightness and ventilation get treated as two separate boxes to tick — but they're not. Improve one and you change what the other needs to do. Get either wrong and it undermines the whole job.
Airtightness
Seal a retrofit up tighter and you cut the uncontrolled draughts — but you also remove the natural ventilation the building was quietly relying on.
Ventilation
Once airtightness improves, the ventilation system has to work harder — designed for the building as it now performs, not as originally built.
This is usually a design-stage issue, not a test-day one. Which is exactly why it pays to talk to us before the work starts, not after it's tested.
A partner through the project — not just a test on the day.
As your partner in getting the retrofit compliant, we offer this range of support detailed below to suit different stages of your project.
Design Review
Share your retrofit spec and we flag airtightness and ventilation risks early — before anything's built.
Get in touch →Project Call
Talk it through directly — book a 15-minute slot that suits you, no obligation.
Book a call ↓Ventilation Compliance Tool
Check your design against Part F requirements yourself, whenever you need to.
Try the tool ↓On-Site Support
WhatsApp us the moment something comes up — we're on hand, not just at test day.
Chat on WhatsApp ↓Support through the whole project — not just before it starts.
Something come up on site? Message us directly. Retrofit Support is there for the length of the job, not only the pre-project chat.
Retrofit Support, on WhatsApp
Ask a question, get a straight answer — no ticket system, no waiting on hold.
Chat With Us on WhatsAppGet a reply within minutes on queries about your project.
Talk it through before you're on site.
15 minutes, no obligation — talk through your project's ventilation and airtightness requirements before you're on site. Or send us a message and we'll get back to you.
See exactly what Part F requires for this job.
Enter the rooms and extract points and get the airflow rates and system sizing your retrofit needs to meet Part F — the same tool our own team uses on site.