Greater London · England
New-build mastic & snagging in Northumberland Heath, Greater London
Plot mastic for developers and snagging failed sealant in new homes for Northumberland Heath, backed by a 12-month guarantee. Ask us for a quote.
- Kitchen sealant that has pulled off the wall
- Plot mastic for developers ahead of handover
- Internal frame sealant that has split
New build mastic in Northumberland Heath
Snagging sealant properly means taking the failed bead out completely. New silicone won’t bond to old silicone, so the joint is cut out, cleaned, dried and resealed. If you are dealing with gaps behind new kitchen upstands and leaking shower tray seals in a new home, we can put it right, on windows & doors, plot handovers and kitchens alike.
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.
Our work is backed for twelve months.
- Where
- Northumberland Heath (DA8, DA7)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Ventilate bathrooms well, especially in the first year
- Check bath and shower seals every few months as the house settles
- Avoid scourers and strong chemicals on sealant
- Report sealant problems to your builder during the snagging period
Photograph failed sealant before it’s redone and keep the builder’s replies. It’s useful if you need to raise other issues later.
If a shower tray or bath seal splits in the first year, look for movement. Have it resealed, and the tray or bath checked, before it gets worse.
The process
There is not much for you to do on the day. Show us the job and we’ll take it from there. The work itself takes a few hours for most snagging lists, longer for a run of plots, including the tidy-up. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Northumberland Heath. It helps if you can point us to a visitor permit or a bay close to the door.
- We start by going through the snagging items or plot schedule with you.
- The failed sealant is removed completely.
- We clean out the dust and grit left from the build.
- Primer goes on where the surface and product need it, then the new sealant.
- We tool every joint neatly and tell you when each area can be used.
How to prepare
- Mention any sign-in or site rules at work premises
- Where the joints are inside, avoid wetting them before we arrive
- Tell us about any water getting in
Ask for a quote
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To get started, phone 0345 464 0079 or email us.
Advice
Why act early in Northumberland Heath
Small cosmetic gaps can wait for the house to settle, but water getting through can’t. If you’re unsure which you have, call 0345 464 0079 or email us with photos and we’ll give you a straight answer. In London conversions, one flat’s bathroom is often above another flat’s ceiling, and a slow leak from a failed seal can end up in the flat below. Dealing with it early is far simpler for homes in Northumberland Heath.
No two jobs are quite the same, so each one gets its own quote. Size, access and the product the joint needs all play a part, and we’ll explain the quote if you ask.
Why book with us
- We agree the colour with you first
- Sealant colour chosen to suit
- 180+ five-star Google reviews
- We never seal over old sealant
Take a look at our cost guide or what customers say.
Your questions about new build mastic in Northumberland Heath
Is parking an issue for new build mastic in Northumberland Heath?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
I let a flat near Barnehurst station. Can you help?
Yes, we work for landlords and agents. You can call 0345 464 0079 or send us an email with the address and a few details, and we will give you a fixed price before we start.
Do you work for hotels and businesses?
Yes. Commercial and hotel work is a large part of what we do. We can talk about working times when we quote.
Can I send you my snagging list?
Yes. Snagging lists are a common starting point for us. We will go through the sealant items and agree what we will do.
Where is Mr Mastic based?
Mr Mastic is based in Crawley. Our applicators cover Northumberland Heath.
Can you quote for more than one area?
Yes. Several rooms, windows or areas can go on one quote.
Can you do plot mastic on a new development?
Yes. We carry out plot mastic and second-fix sealing for builders and developers. Send the schedule and any specification and we will give you a quote.
Are you ARBOMaster approved?
Yes. We’re approved under the ARBOMaster scheme.
Common problems we fix in Northumberland Heath
Baths and trays settle under load once the home is lived in. If a bath wasn’t filled when it was sealed, the bead is stretched the first time it’s used and the sealant may split.
Look out for any of the following:
- Skirting joints opening in the first winter
- Plot mastic for developers ahead of handover
- Cracks appearing as a new home settles
- Smeared, uneven beads picked up at snagging
Northumberland Heath is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Before booking anyone
- What the quote includes, VAT included or not
- What insurance they hold
- How long the guarantee is
- Whether you can choose the colour
Places near Northumberland Heath
Also in Northumberland Heath
Can I do it myself?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, then guaranteed for a year.
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.
Different surfaces, different methods
Show homes
Tired or marked sealant in a show home can be renewed. The old bead comes out and a clean new one goes in.
Skirting and floors
Floors and skirting move as the house dries and the heating runs. Caulk cracks; a flexible sealant moves with it.
When something else is needed
Sealant isn’t the answer to every problem, and we’d rather say so up front. It won’t solve:
- Settlement cracks that need a surveyor
- Leaks from pipes, valves or wastes, which need a plumber
- A tray or bath that isn’t properly supported, until it’s fixed
If in doubt, phone 0345 464 0079 or drop us an email and we will say what we think before booking.
Where we work in Northumberland Heath
- Show homes
- Skirting & floors
- Windows & doors
- Bathrooms & en suites
- Plot handovers
- Kitchens
New build mastic in Northumberland Heath: local notes
Much of London’s new housing is flats in larger developments, where snags may need reporting through the developer or the managing agent. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you’ve bought a new home near Barnehurst station, the sealant around baths, showers and frames is worth checking in the first year or two.
Northumberland Heath is about 3 miles north-west of Dartford, in Greater London. Homes, rented property, offices and hotels in Northumberland Heath can book us for new build mastic, old or new, large or small. The work is guaranteed for a year. Northumberland Heath is one of 764 places in Greater London where we work for new build mastic. We also work in London, around 11 miles away.
Postcode districts we cover here for new build mastic: DA8 and DA7. Whether your property is on Mill Road, Penda Road and Chalk Road or a nearby road, our applicators can take on the job. Neighbouring places we cover for new build mastic include Bexley Riverside (1 mile south-east), Erith (1 mile north), Barnehurst (1 mile south), Belvedere (1 mile north-west) and Lessness Heath (1 mile north-west). We also work in nearby towns such as London (11 miles west), City of Westminster (14 miles west), Marylebone (14 miles west), St Pancras (13 miles west), Shoreditch (11 miles west) and Walthamstow (11 miles north-west).
Near you in Northumberland Heath
In Northumberland Heath, that means homes and buildings near Trinity School, The Royal Oak pub and Braeburn Park, among other places. The nearest railway station is Barnehurst station, roughly 0.6 miles south-west of the centre. Well-known places in the area include Erith Museum (0.7 miles north-east) and Erith and District Hospital (under half a mile north). For a walk, there’s Crossness Nature Reserve.