Published 14 October 2026
What counts as a penetration
A penetration is any hole where a service passes through a fire rated wall or floor. That includes pipes, cables, ducts, soil stacks and extract fans. Each one is a weak point where fire and smoke could spread from one compartment to the next, so each one has to be sealed with a tested product that matches the wall or floor it goes through.
In Leeds we see this most often in flat conversions and HMOs around Headingley, Hyde Park and Burley, in loft and garage conversions, and in newer city centre apartment blocks where gaps have been found during fire safety inspections.
Typical costs per penetration
These are realistic ranges for work in and around Leeds. They are a guide, not a fixed price list, because the right product and the time each one takes depend on the job.
- Small cable or pipe holes sealed with intumescent or acoustic mastic: roughly £15 to £40 each
- Plastic pipes up to around 110mm, such as soil pipes, fitted with an intumescent collar: roughly £45 to £120 each
- Bundles of cables or cable trays sealed with coated batt and mastic: roughly £80 to £250 each, depending on size
- Large openings for ductwork, which may need fire dampers or a specialist system: priced individually
- Small jobs often carry a minimum charge, commonly £200 to £400, since setting up and travelling cost the same whether there are three holes or thirty
What pushes the price up or down
Two penetrations that look the same can cost very different amounts. The main factors are:
- Fire rating needed: a 30 minute seal is simpler than a 60 or 120 minute seal between flats or onto a stairwell
- Size and type of service: steel pipe, plastic pipe, insulated pipe and cables each need different products
- Access: holes behind boxing, above ceilings or in tight risers take longer, and boards may need cutting out and making good
- Quantity: a whole block with hundreds of penetrations usually has a lower rate per item than a single flat
- Paperwork: commercial and multi occupancy buildings normally need photos, product labels and a record of every seal, which adds time
- Remedial work: stripping out old foam or unsuitable fillers before sealing properly adds labour
Why the cheapest quote can cost more
Expanding foam from a builders' merchant is not fire stopping unless it is a tested fire rated product used exactly as its test evidence allows. We regularly find general purpose foam, mortar packed loosely around plastic pipes, or collars fitted to the wrong pipe size. If Leeds City Council building control or a fire risk assessor spots this, it has to be removed and done again, so you pay twice.
When comparing quotes, ask which products will be used, what fire rating they achieve in your type of wall or floor, and whether you will get a photo record. A slightly higher rate per penetration with proper evidence is usually better value than a low rate that fails inspection.
Getting an accurate quote
The most reliable way to price fire stopping is a survey. Counting the penetrations, measuring their sizes and checking what the walls and floors are made of lets a contractor give a firm price rather than a rough estimate. If you already have a fire risk assessment or a building control report listing the defects, share it, as it speeds things up.
RWS Plastering & Drylining is based in Rotherham and covers Leeds and the surrounding area, including Wakefield, Morley and Pudsey. Because we also do the drylining and plastering, we can make good any boards we open up, so you are not left needing a second trade to finish the job.
