Why it belongs with fire stopping
A service penetration through a compartment wall is a fire stopping problem. The same penetration through a separating wall between two flats is an acoustic problem under Part E. The same penetration through the thermal envelope is an air leakage problem under Part L. It is one hole.
When those three duties are split between three contractors, two things reliably happen. The second trade disturbs the first trade's seal to fit their own. And nobody ends up holding a complete record for the aperture, so when the building fails an air test or a sound test, or an auditor asks about the fire seal, the answer is a shrug.
We treat the aperture as one asset with a defined performance, and seal it once, correctly, with the products that achieve all of the requirements that apply to it — recording each performance separately.
Air-tightness sealing
Air permeability is tested on completion, and the result is a whole-building number that a main contractor cannot fix on the last day. It is made and lost at hundreds of small junctions: service penetrations through the envelope, the joint between the floor slab and the external wall, window and door perimeters, loft hatches, riser tops, and the gaps around soil stacks and extract terminals.
We seal those junctions as the building goes up, using flexible sealants, membranes, tapes and expanding seals appropriate to the substrate and the movement expected at that joint — and we photograph them, because once the finishes go on nobody can see whether it was done.
Where a building has already failed its air test, we work from the smoke test or thermographic survey results to find and close the leakage paths rather than sealing everything and hoping.
Acoustic sealing
Separating walls and floors between dwellings, and partitions around meeting rooms, consulting rooms and teaching spaces, are specified for a sound reduction they only achieve if they are sealed. A 5mm continuous gap at a wall head will undo the performance of the entire wall.
We seal perimeters, head and base junctions, service penetrations, socket boxes and floor voids with acoustic-grade sealants, mineral wool packing and acoustic sleeves, to the detail the tested construction requires — and, where the wall is also a compartment wall, using products compatible with the fire-stopping detail rather than in conflict with it.
Getting that compatibility right is the actual expertise. An acoustic mastic that has no fire classification is not an acceptable seal in a compartment wall, however well it performs on sound.
Typical scope
- Service penetrations through separating and compartment walls and floors, sealed for fire and sound in one detail.
- Head-of-wall and perimeter joints to partitions and separating walls.
- Floor-to-external-wall junctions and slab edges.
- Riser tops and bottoms, and the voids around soil stacks and extract ducts.
- Window and door perimeter sealing within the air barrier line.
- Socket box, back box and switch drop treatment in acoustic partitions.
- Remedial sealing following a failed air permeability or pre-completion sound test.
What is certified, and what is not
Air and acoustic sealing is not third-party certified work and we do not present it as such. It is installed to the tested construction detail and the manufacturer's requirements, and evidenced in the same way as our certified work. Where the same aperture also requires fire stopping, that element is delivered under our Q-Mark scheme 05B certification.
The deliverable, every time
One aperture, one record — Each penetration recorded once with every performance it delivers set out separately — fire, acoustic, air.
Photographic evidence — Images of every junction before it was covered, because after the finishes go on the evidence is gone.
Product and detail references — The sealant, backing and detail used at each junction, with datasheets.
No hand-off gaps — One contractor responsible for the hole, so there is no argument about whose seal failed.
From enquiry to certification
Enquiry
Tell us about the building and the works you need.
Site survey
Every asset inspected, photographed and QR-tagged.
Specification
Clear scope and pricing against tested systems.
Certified works
Competency-assessed operatives under scheme control.
Evidence pack
Photos, registers and product data for every asset.
Certification
Q-Mark labelled, registered and traceable for life.
Answered by the people who do the work
More on the full FAQ page.
Is acoustic and air sealing certified work?
No. Our BM TRADA Q-Mark 05B certification covers fire stopping installation. Acoustic and air sealing is installed to the tested construction detail and the product manufacturer's requirements and is fully evidenced, but it is not third-party certified work and we do not describe it as such.
Can you do it at the same time as the fire stopping?
That is the point of offering it. One visit, one set of access arrangements, one aperture opened once, and one record covering every performance the seal has to deliver. It is almost always cheaper and always cleaner than sequencing three trades.
Our building has failed its air test. Can you help?
Yes. We work from the leakage evidence — smoke testing or thermography — rather than blanket-sealing. That finds the paths that are actually costing you the result, and it is far less disruptive.
Will acoustic sealant compromise the fire seal?
It will if the wrong product is used, which is exactly why these should not be separate trades. In a compartment wall we use products that carry the fire classification required for that detail and meet the acoustic requirement, rather than adding a non-classified mastic over a certified seal.
Do you test the result?
We do not carry out air permeability or pre-completion sound testing ourselves — that needs to be done by an independent tester, and it should be. We seal to the detail, evidence it, and work alongside whoever is testing.
Related pages
Tell us about the building.
Send over what you have — a drawing, an old report, or just a description — and we will come back with a scope and a fixed price. Call 020 8769 8869.
Ask about air and acoustic sealing
Send us the details and anything you already have — drawings, an old survey or photos. We will be in touch within one working day.
- BM TRADA Q-Mark certified, certificate 4515
- Named Approved Persons accountable for the work
- Every asset photographed and recorded
Prefer to talk? Call 020 8769 8869 (Mon–Fri 07:30–17:30) or email fire@arcticltd.com.