Greater London · England
Remedial sealant & repairs in Coldharbour, Greater London
Professional remedial sealant in and around Coldharbour, with every bit of old sealant taken out first and a 12-month guarantee.
- Dark patches showing through the sealant
- Gaps opening along the back of the worktop
- Wide, uneven beads that look worse than the old ones
Common questions in Coldharbour
I let a flat near Mottingham station. Can you help?
Yes, we work for landlords and agents. Just ring 0345 464 0079 or drop us an email and tell us about the property, and we will give you a clear quote.
I live in a flat in Coldharbour. Can a failed seal leak into the flat below?
Yes. In a flat, water from a failed bath or shower seal has only one way to go, and that’s down. Cutting out the old sealant and laying a new bead early stops it getting that far.
Is it worth trying it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
What should I tell you?
Just the basics: the address or postcode, what’s wrong and any access issues. After that, simply phone 0345 464 0079 or email us.
What sealant do you use?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. We use products from Arbo and Everbuild.
Can old silicone be taken off without scratching the tiles?
Yes, with care. We cut and lift the old sealant with tools suited to the surface, then clean off the residue. Any existing damage is pointed out before we start.
Where are you based?
Our base is Crawley, with over 20 years’ experience. We work across South East England, London and Scotland.
Can you reseal a split movement joint?
Yes. Where mortar or filler has been used instead of sealant, it’s removed where it can be, and reseal with a flexible product.
Remedial sealant in Coldharbour, done properly
Remedial jobs in Coldharbour generally fall into a few patterns: sealant over sealant, mould under the bead, leaks that come back and movement joints that have split. Each is stripped back and done again properly. We work on botched or over-sealed joints, failed movement joints and mouldy bath & shower sealant, and common reasons people get in touch are leaks that keep coming back after resealing and wide, uneven beads that look worse than the old ones.
London homes include a lot of flats, conversions and mansion blocks, and many bathrooms sit right above someone else’s ceiling. That makes worn sealant and cracked grout in Coldharbour more than a cosmetic job.
The work is guaranteed for twelve months. If something is not right with it in that time, tell us and we’ll put it right.
- Where
- Coldharbour (SE9, BR7)
- Region
- Greater London
- Cover
- A year, on every job
- Quotes
- A clear quote up front
- Call
- 0345 464 0079
- Updated
- 26 October 2026
What the job involves on each surface
Over-sealed & botched joints
A thick bead smeared across tiles often hides mould or gaps. We strip it back so we can see the joint, and then we reseal it neatly.
Windows & doors
Smeared or badly matched mastic can be cut out and redone neatly, in a colour that suits the frame.
When it is not the sealant
We’d rather tell you now than do work that will not last, so these are the limits:
- A leaking trap, valve or supply pipe
- Sealant in an older building that needs testing for asbestos first
- Movement from fittings that aren’t supported
If in doubt, ring 0345 464 0079 or send us an email and we will say what we think.
Where we work in Coldharbour
- Expansion joints
- Mouldy bath & shower sealant
- Shrunken worktop sealant
- Botched or over-sealed joints
- Leaking tray & enclosure joints
- Failed movement joints
Aftercare tips
Aftercare is simple, and it makes a real difference:
- Air the bathroom so the sealant can dry
- Use a soft cloth, not a scourer, on silicone
- Ask why a joint failed before redoing it
- Never seal over old silicone
Ventilation keeps mould away from the new bead: run the fan during and after showers, or open a window.
Do not keep resealing the same joint. Get the cause found first, otherwise the next attempt will fail too.
Why deal with it now?
Adding more sealant is the usual quick fix, and it rarely works. It cannot bond to what’s underneath, leaving the leak in place and one more layer to cut out later. In a flat in Coldharbour, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Every job is a little different, so we quote each one individually. Size, access and the product the joint needs all play a part.
Why choose Mr Mastic in Coldharbour
- Tidy, careful work
- Full insurance on every job
- A 12-month guarantee on all work
- ARBOMaster approved applicator
How we quote for remedial sealant
Every job gets its own quote. This is what makes a difference:
- Whether the work is at height
- The number and length of the joints
- Which sealant suits the joint
- The number of rooms or windows
Leaving a failed joint generally makes the job bigger, not smaller. If you are unsure, call 0345 464 0079 or drop us an email and we will give you an honest view and a quote.
Helping us quote
When you contact us, it’s useful to know:
- Whether it has been sealed before
- If it’s domestic, commercial or a hotel
- The problem you’ve noticed
- Roughly how big the job is
For a quick quote, get us on the phone, or send an email if you’d rather. Tell us about the joints that need doing and we will talk you through the work.
What remedial sealant looks like in Coldharbour
London has hard water, so limescale builds up on sealant, grout and fittings, and it has to be cleaned off before new sealant goes in. 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.
Coldharbour is in London, so parking needs planning: let us know about parking bays, permits or a driveway. Rented homes near Mottingham station change hands often, and a joint that keeps failing is best fixed properly while the property is empty. If you look after a building such as Mottingham Primary School, we reseal washrooms and kitchens in schools and businesses as well as homes.
Coldharbour is about 4 miles north-west of Orpington, in Greater London. Every kind of property in Coldharbour is covered for remedial sealant, old or new, large or small. Every job comes with our one-year guarantee. Our Greater London coverage runs to 764 places, Coldharbour among them. For nearby work, see our London page.
We cover every part of the SE9 and BR7 postcode area for remedial sealant. That includes homes and businesses on Green Lane, Horley Road and Dorset Road and the roads around them. We also cover Mottingham (1 mile west), Chinbrook (1 mile west), New Eltham (1 mile north-east), Eltham (1 mile north) and Middle Park (1 mile north-west). We also work in nearby towns such as London (8 miles north-west), City of Westminster (11 miles north-west), Marylebone (10 miles north-west), Kensington (12 miles north-west), St Pancras (10 miles north-west) and Shoreditch (9 miles north-west).
Near you in Coldharbour
Locally, jobs take us to homes and businesses close to Elmstead Wood and St Thomas More Catholic Comprehensive School and the streets around them. For rail, the closest station is Mottingham station, about 0.6 miles north of the centre. Other landmarks nearby include The Glades (2.4 miles south-west) and Metropolitan Police Museum (2.2 miles east). The countryside around Coldharbour includes The Tarn and Summer Hill.
What we do, step by step
On the day, we start by going over the job with you. We protect the surfaces around the joints before any work begins. Most jobs take a few hours, depending on how many layers have to come out. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Coldharbour. A visitor permit or a nearby bay makes the visit run more smoothly.
- Surrounding tiles, trays and frames are protected first.
- Every layer of failed sealant is stripped out.
- We clean and degrease the joint and look for signs of movement or water.
- Once dry, a suitable sealant is applied and tooled.
- You get the cure time and our view on why the joint failed.
How to prepare
- Let us know if you’ve seen damp or leaks
- Clear items away from the joints we are working on
- For business premises, tell us about site rules or sign-in
Ask for a quote
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To arrange one, ring 0345 464 0079 or drop us an email.
Read more
Landlords, agents and businesses in Coldharbour
We work for letting agents and landlords as well as householders. Sealant work between tenants keeps a property looking cared for.
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance.