Greater London · England
Fire Rated Sealant in St Johns
Fire rated sealant across St Johns and nearby, with old sealant always removed completely and a one-year guarantee.
- Damaged fire sealant left by other trades
- Gaps left after a refit or conversion
- Gaps around pipes and cables through fire-resisting walls
Why it’s worth doing now in St Johns
Items left open on a fire risk assessment tend to come back at the next review. Getting them done and written up gives you evidence that the item was dealt with. In a flat in St Johns, failed sealant seldom stays inside your own four walls: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
Doing several joints on one visit is usually more efficient than separate visits, so tell us about everything that needs sealing. You’ll get one clear quote for the whole job.
Why choose Mr Mastic in St Johns
- A 12-month guarantee on all work
- 180+ five-star Google reviews
- Fully insured
- 20+ years of sealant experience
Read what affects the cost and what customers say.
About our fire rated sealant in St Johns
Fire stopping only performs as intended if it’s done to the detail: correct depth, correct backing and a product suited to the surfaces. That detail is what we take care over. If you’re dealing with linear gaps at the head of walls and door frames with gaps between frame and wall, we can help.
London’s offices, shops, hotels, student accommodation and blocks of flats all have joints to look after, whether that’s washroom resealing or fire-rated sealant around service openings. Out-of-hours working can be arranged where a building in St Johns can’t close.
All our work comes with our 12-month guarantee.
- Place
- St Johns (SE13, SE10, SE8)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Price
- A clear quote up front
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Landlords, agents and businesses in St Johns
Housing providers, facilities teams and property managers book us too. Several sites can go on one quote, and we’re fully insured for the work.
If you manage several properties in or around St Johns, jobs at different addresses can go on one quote. Just tell us the addresses and what each one needs.
What fire rated sealant looks like in St Johns
Many London buildings have tight access and loading restrictions, so out-of-hours working can be arranged where needed. Workplaces and the common parts of blocks of flats in England need a fire risk assessment under the Regulatory Reform (Fire Safety) Order 2005, which is often where open fire-stopping gaps are first noticed. We apply fire-rated sealant to the assessor’s or designer’s specification and the product’s tested details.
Letting a property close to St Johns station? Then fire-rated sealant around pipes and cables through walls and floors needs making good whenever new services go through. If you look after a church, hall or community building such as Church of St John, service openings in its walls need the right fire-rated sealant, as in any building.
St Johns is about 4 miles south-east of London, in Greater London. Across the SE13 area, we can carry out fire rated sealant at your property. St Johns is one of 764 towns and villages in Greater London we cover for fire rated sealant.
Work in SE13, SE10 and SE8 works the same way as everywhere else we cover. Streets in the area include Avon Road, Mill Lane and Clare Road, all of which we cover. St Johns sits on or near the A2210 and A2211, which makes travel easy. Other places close to St Johns include New Cross (1 mile west), Deptford (1 mile north), Lewisham (1 mile south-east), Telegraph Hill (1 mile west) and Ladywell (1 mile south). Within a short drive, we also cover London (4 miles north-west), City of Westminster (6 miles north-west), Marylebone (6 miles north-west), Kensington (8 miles west), St Pancras (6 miles north-west) and Shoreditch (5 miles north-west).
Near you in St Johns
We work in homes and buildings around Wickham Arms, Brookmill Park and Addey and Stanhope School. Nearby too are St. Paul's (0.7 miles north) and Laban Centre (0.8 miles north). There’s a railway station in St Johns itself: St Johns station. Well-known places in the area include Fan Museum (0.9 miles north-east) and Lewisham Shopping Centre (0.7 miles south-east). For a walk, there’s Brookmill Road Local Nature Reserve and Tower Hill.
Honest limits
To be straight with you, some problems need a different trade:
- Doors that are not fire doors in the first place
- Big openings where sealant alone isn’t the tested solution
- Sign-off of the building, which sits with building control or your assessor
If in doubt, ring 0345 464 0079 or email us and we will say what we think.
What we seal
- Plasterboard & masonry
- Pipe & cable gaps
- Service penetrations
- Flats & HMOs
- Linear gaps
- Door frames
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions.
The biggest DIY mistake is sealing over old sealant. Silicone doesn’t stick to old silicone, so it peels away and traps moisture behind it. Everything old must be removed first.
When to call us in St Johns
A lot of fire stopping is out of sight: in ceiling voids, service risers and behind boxing. Out of view, damage sits unnoticed until someone inspects.
Common reasons people contact us include:
- Open joints along the top of partitions
- Ordinary sealant used where a fire-rated product was needed
- Open holes round services passing through fire walls
- Unsealed gaps around fire door frames
As a London address, St Johns can be tricky for parking: let us know about parking bays, permits or a driveway.
Before booking anyone
- Are they insured?
- How hidden problems are handled
- Which sealant they’ll use, and why
- The length of the guarantee
Other services in St Johns
How to look after the new joints
After the cure time, these simple habits help:
- Don’t fill fire-stopping gaps with ordinary foam or silicone
- Flag any open gap you spot round a pipe or cable
- Take pictures of fire stopping before ceilings or boxing go back
- Keep the record of products and locations with your fire safety documents
Include fire stopping in your regular building checks. Watch for cracking, gaps or seals that have been disturbed and have them put right.
Any job that breaks through a wall or ceiling should include resealing. Catching it then saves a separate visit later.
What we do, step by step
All our tools and materials come with us in the van, so you do not need to buy or prepare anything. After a quick look at the joints together, we protect the area and start. Most jobs take anything from a few hours to several days, depending on how many gaps there are. In St Johns, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- We plan the order of work and access, floor by floor or flat by flat.
- We take out any damaged or unsuitable sealant.
- Gaps are cleaned of dust and loose material.
- The fire-rated or intumescent sealant is applied and tooled to the tested detail.
- We record what was done and flag anything that needs a different system.
How to prepare
- Tell us about any previous sealing or DIY attempts
- Keep children and pets away from the work area
- Let us know if you’ve seen damp or leaks
Get a quote
Getting a quote is simple: let us know what needs doing and where and its rough size. Photos by email help us understand the job, and we’ll come back to you with a quote.
Related advice
St Johns: your questions answered
Can you help a landlord with a rental near St Johns station?
Yes. We work for landlords and agents as well as homeowners. You can phone 0345 464 0079 or send us an email with the details for a clear quote.
Can parking be tricky for a visit in St Johns?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot.
What does fire rated sealant cost?
We do not publish prices, because the cost depends on the job: its size, the old material, access and the product needed. We agree the price before any work begins.
Which products do you use?
We choose the sealant for the joint, not the other way round. Movement, water and weather all affect the choice, and we’ll tell you what we’re using.
Can you tell me which gaps need fire stopping?
No, assessment is not something we do. When your assessor or designer has set out what’s needed, we will quote for the sealant work on it.
How long does fire rated sealant take?
Typically it takes a few hours for a handful of gaps, and longer for a whole building. Bigger jobs take longer.
Can you do several jobs on one visit?
Yes, we can. More than one area can go on one quote.
What’s the difference between intumescent and fire-rated sealant?
An intumescent sealant expands when it gets hot to help seal the gap. It’s one type of fire-rated sealant; which product suits depends on the gap, the substrate and the service.