Greater London · England
Remedial sealant & repairs in St John's Wood, Greater London
Remedial sealant for St John's Wood and the surrounding area: careful preparation, the right product and tidy work. Call for a quick quote.
- Torn expansion joints
- Mould trapped under a layer of silicone
- Smears and lumps from a botched reseal
Different surfaces, different methods
Leaking trays & enclosures
When failed joints are the cause, they’re all cut out and renewed, including the screen profile and tray edges.
Movement & expansion joints
Bonding on three sides is a common reason movement joints tear. Backing stops that, so the sealant grips the two sides only.
About our remedial sealant in St John's Wood
Getting old sealant out properly is slow, careful work. Every layer is cut out, the residue cleaned off and the joint degreased, taking care not to scratch the surfaces around it. Only then can new sealant bond. If you have kitchen joints letting water behind the worktop and a second bead peeling off the first, we can help.
London homes include a lot of flats, conversions and mansion blocks, and many bathrooms sit right above someone else’s ceiling. In St John's Wood, that is a good reason to put tired sealant and grout right early.
Whatever the size of the job, it’s backed by our one-year guarantee.
- Place
- St John's Wood (NW8, NW6, NW3)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
How to look after the new joints
Once the sealant has cured, a few habits help it last:
- Check ceilings under showers for marks
- Air the bathroom so the sealant can dry
- Have loose fittings fixed before resealing
- Keep bleach and abrasives off the bead
Go easy on the new sealant: a mild cleaner and a soft cloth, with no blades or scourers.
Do not keep resealing the same joint. Get the cause found first, otherwise the next attempt will fail too.
Work for landlords, hotels and businesses
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
For anyone letting property in or around St John's Wood, several properties can be quoted together. Just tell us the addresses and what each one needs.
Why it’s worth doing now in St John's Wood
Stripping out botched sealant adds time to a reseal, but not by much: the work takes a few hours for a typical bath or shower, longer where several layers have been applied. Compared with chasing the same leak every few months, it’s time well spent. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Dealing with it early is far simpler.
A failed joint rarely gets cheaper to fix by waiting, as water and mould keep getting in. If you’re not sure whether it needs doing, ring 0345 464 0079 or drop us an email for an honest opinion and a quote.
Why us?
- Sanitary silicone with an anti-fungal additive in wet areas
- Over 20 years’ experience
- Rated 4.9 stars on Google
- ARBOMaster approved applicator
Places near St John's Wood
What else we do in St John's Wood
Your questions about remedial sealant in St John's Wood
Do you work in hotels near St John's Wood?
Yes, we work for hotels as well as homes and businesses. Rooms can be done a few at a time, so the building stays open.
I let a flat near South Hampstead station. Can you help?
Yes, we work for landlords and letting agents. You can call 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before work begins.
Where is Mr Mastic based?
We work from Crawley. We cover St John's Wood and the rest of Greater London, along with the rest of our area.
Do you have insurance?
Yes. We’re fully insured.
Will the old sealant be removed?
Yes. All of the old material is cut out and the joint cleaned before applying anything new.
What sealant do you use?
It depends on the joint: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Can you do several jobs on one visit?
Yes, and it often makes sense. Doing several areas at once is usually more efficient, so mention them when you ask for a quote.
Should I try DIY first?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
What sealant work can’t fix
To be straight with you, there are a few things sealant will not fix:
- A tray or worktop that needs refixing first
- Old mastic in a building from before 2000 that should be checked for asbestos before it’s disturbed
- A cracked shower tray or bath (that needs repair or replacing)
If in doubt, phone 0345 464 0079 or email us and we’ll say what we think.
Where we work in St John's Wood
- Expansion joints
- Leaking tray & enclosure joints
- Mouldy bath & shower sealant
- Shrunken worktop sealant
- Failed movement joints
- Botched or over-sealed joints
DIY versus a professional finish
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
How it works
All our tools and materials come with us in the van. After a quick look at the joints together, we protect the area and start. It normally takes a few hours, depending on how many layers have to come out. In St John's Wood, as in most of London, parking needs a little planning. A visitor permit or a nearby bay makes the visit run more smoothly.
- We protect the surfaces around the joint.
- Every layer of failed sealant is stripped out.
- The joint is degreased and checked for movement and leaks.
- New sealant goes in once the joint is dry, and is tooled smooth.
- We give you the cure time and explain what caused the failure.
Before we arrive
- Mention if the joints have been sealed before
- Keep pets and children clear of the area while we work
- Let us know about parking restrictions
Getting a quote
Every job is quoted individually, so start by telling us what you need. Just phone 0345 464 0079 or send us an email with the details and send pictures if you have them.
Related advice
St John's Wood homes and their sealant
London’s water is hard, so limescale builds up on sealant, grout and fittings. In a London flat, water from a failed bath or shower seal can reach the neighbours below, which is why it’s worth fixing early.
Letting a property close to South Hampstead station? Then botched sealant from a previous quick fix is easier to strip out between tenants. Schools such as George Eliot Primary School are buildings too, and its toilets, changing areas and kitchens need their sealant renewed like any other building’s. St John's Wood is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
St John's Wood is about 1 mile south of Hampstead, in Greater London. We carry out remedial sealant for homes and businesses in St John's Wood. Our area takes in 764 places across Greater London, from the larger towns to small villages.
Our applicators cover all of NW8, NW6 and NW3 for remedial sealant and the streets around it. That includes homes and businesses on The Lane, Hall Road and Hill Road and the roads around them. You’ll find St John's Wood on the A5205, so it’s easy for us to get to with everything needed for remedial sealant. Close by, we work in South Hampstead (1 mile north), Swiss Cottage (1 mile north), Primrose Hill (1 mile north-east), Lisson Grove (1 mile south) and Haverstock (1 mile north-east). Further out, we also cover London (4 miles south-east), Kensington (3 miles south-west), St Pancras (3 miles east), Shoreditch (4 miles east), Walthamstow (7 miles north-east) and Hoxton (4 miles east).
Landmarks near St John's Wood
We work in homes and buildings around Cecil Sharp House, Primrose Hill and Arnold House School and the streets around them. You will also find Quintin Kynaston Community Academy (less than half a mile north-west) and Cafe Med pub (under half a mile north-west). There’s a railway station in St John's Wood itself: South Hampstead station. Well-known places in the area include Hospital of St John and St Elizabeth (under half a mile south) and Montfichet's Tower (3.5 miles south-east). Open spaces near St John's Wood include The Long Water and Primrose Hill.