Greater London · England
New-build mastic & snagging in Lewisham, Greater London
Plot mastic for developers and snagging failed sealant in new homes in Lewisham, with a one-year guarantee on every job. Ask us for a quote.
- Sealant work across a run of new homes
- Kitchen sealant that has pulled off the wall
- Sealant that never bonded to the surface
Honest limits
To be straight with you, there are a few things sealant won’t fix:
- Disputes or warranty claims with your builder
- Movement caused by a poorly fitted tray or bath
- Plumbing faults behind the sealant
If in doubt, call 0345 464 0079 or send us an email and we will say what we think before you book.
What we seal
- Windows & doors
- Bathrooms & en suites
- Skirting & floors
- Kitchens
- Plot handovers
- Show homes
How we handle new build mastic in Lewisham
Dust is the enemy of new-build sealant. We clean every joint thoroughly and prime where the surface and product need it, so the sealant actually sticks. Common call-outs are for beads laid onto grit and dust from the build and second-fix sealing on new plots, across show homes, windows & doors and skirting & floors.
Across London, commercial floors have movement joints that break down under heavy foot traffic, and new homes need their plot mastic finished properly before handover.
All of our work is guaranteed for twelve months.
- Place
- Lewisham (SE13, SE8, SE6)
- Wider area
- Greater London
- Cover
- One year on every job
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Work for landlords, hotels and businesses
We work for landlords and letting agents as well as householders. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Surface by surface
Show homes
Tired or marked sealant in a show home can be renewed. We cut it out and reseal neatly.
Windows and doors
A draught at a new window can be a missed or failed joint. We look at the joints and reseal where needed.
Nearby places to Lewisham
What else we do in Lewisham
Lewisham: your questions answered
Do you cover Lewisham for new build mastic?
Yes, Lewisham is within the area we cover. We work across London and the South East. You can ring 0345 464 0079 or email us and tell us what needs doing, and we’ll give you a clear quote.
Is parking a problem for a job in Lewisham?
Parking in Lewisham, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly.
Are you insured?
Yes. Full insurance covers our work.
Is it worth trying it myself?
That depends on the joint. High-level, external movement and fire-rated joints are professional jobs.
How long will you be here?
Most jobs take a few hours for most snagging lists, longer for a run of plots, including the preparation. We’ll confirm how long when we quote.
How long before the joint can be used?
Different products cure at different speeds, so please follow the time we give you.
Will there be a smell?
Sometimes, a little. Any smell clears as the sealant cures.
Do I need to be at home?
Access is agreed with you when the job is booked. For inside work, that normally means someone being in.
DIY versus a professional finish
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and does not move well, and the joint depth matters as much as the finish.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
Joints and finishes in Lewisham homes
Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Many of London’s new homes are flats in bigger developments, where snagging may go through the developer or managing agent.
Lewisham is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. If you’ve bought a new home near Lewisham station, the sealant around baths, showers and frames is worth checking in the first year or two.
Lewisham is about 3 miles west of Eltham, in Greater London. Every kind of property in Lewisham can book us for new build mastic, old or new, large or small. The work is guaranteed for a year. Across Greater London, we cover 764 places, and Lewisham is one of them.
Jobs for new build mastic in SE13, SE8 and SE6 works the same way as everywhere else we cover. Local streets include Station Road, Lewisham High Street and Lewis Grove, all of which we cover. Lewisham is on the B220, which makes it straightforward to reach. We also cover the places around Lewisham: Ladywell (1 mile south-west), St Johns (1 mile north-west), Hither Green (1 mile south-east), Blackheath (1 mile north-east) and Lee (1 mile south-east). Within a short drive, we also cover London (4 miles north-west), City of Westminster (7 miles north-west), Marylebone (7 miles north-west), Kensington (9 miles west), St Pancras (6 miles north-west) and Shoreditch (5 miles north-west).
Local landmarks in Lewisham
In Lewisham, that means homes and buildings near St Joseph's Academy, Ladywell Fields and The Watch House, among other places. There’s a railway station in Lewisham itself: Lewisham station. Nearby you will also find Greenwich Castle (1.2 miles north) and Fan Museum (1.2 miles north). Green spaces nearby include Knight's Hill and Brookmill Road Local Nature Reserve.
Why act early in Lewisham
The builder is generally the first port of call while the snagging or warranty period runs. If it’s slow, or the same joint keeps failing, a proper reseal from a specialist is the next step. In London conversions, one flat’s bathroom is often above another flat’s ceiling, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble for homes in Lewisham.
Doing several joints on one visit usually makes better use of the time than several visits. You’ll get one clear quote for the whole job.
Why choose Mr Mastic in Lewisham
- Domestic, commercial and hotel work
- Sealant colour chosen to suit
- We are fully insured
- Every job guaranteed for a year
Take a look at what affects the cost and our reviews.
How the visit works
Once we are on site, we compare the joints with what we discussed. If we find something unexpected, we talk it through with you first. After that, the work takes anything from a few hours to several days, depending on the number of plots. In a London area like Lewisham, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- We start by agreeing which joints are on the list, from the snagging sheet or plot schedule.
- We cut out every bit of the failed or messy sealant.
- We clean off dust from the build and prime the surfaces where the product needs it.
- A sealant chosen for each area goes in and is tooled smooth.
- Finally, each room is checked and you are given the cure time.
How to prepare
- Keep pets and children clear of the area while we work
- For indoor joints, keep the area dry beforehand if you can
- Mention any leaks or damp you’ve noticed
How to get a quote
It all starts with a short chat. Describe the problem, the location and the size of the job, and we’ll explain how we’d tackle it. Whenever you’re ready, ring 0345 464 0079 or send us an email.
Advice
Aftercare tips
Joint life depends on how it’s used and looked after. We suggest:
- Avoid running a DIY bead over the old one
- Look at the sealant regularly in the first couple of years
- Photograph failed sealant before it’s redone
- Put sealant faults on your snagging list early
Leave the sealant for the cure time we give you before showering or bathing. Silicone is usually left for about a day to cure enough for use.
Leave a failed new-build seal and water can reach the floor and the ceiling below. Early resealing keeps the job small and the new finishes intact.