Greater London · England
New-build mastic & snagging in Downe, Greater London
Plot mastic for developers and snagging failed sealant in new homes for homes and businesses in Downe and across Greater London. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Plot mastic for developers ahead of handover
- Smeared, uneven beads picked up at snagging
- Cracks appearing as a new home settles
About our new build mastic in Downe
Building dust is behind a lot of failed new-build sealant. Each joint is cleaned of dust and primed where the product calls for it, so the new bead bonds properly rather than sitting on a layer of grit. If you have beads laid onto grit and dust from the build and second-fix sealing on new plots, we can help.
New flats are going up across London, many of them in larger developments. Snagging there often goes through the developer or managing agent, and shower seals that fail early, skirting joints that open up and gaps at thresholds are all common snags.
All our work is covered by a 12-month guarantee, wherever you are in Greater London.
- Location
- Downe (BR6)
- Wider area
- Greater London
- Guarantee
- One year on every job
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What happens if it’s left?
Running a new bead over the builder’s sealant might look tidy for a few weeks, but it cannot bond to what’s underneath. A lasting seal starts with removing the old one completely. 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 few things move the cost up or down: how much old sealant there is and how stubborn it is, whether mould needs treating, and whether the work is at height. Your quote takes all of that into account.
Why book with us
- A 12-month guarantee on all work
- White, clear, grey or another colour, product permitting
- Rated 4.9 stars on Google
- Full insurance on every job
Take a look at how sealant jobs are priced and customer reviews.
Signs you need new build mastic in Downe
When the heating goes on in the first winter, the house dries fast. Skirting, frames and worktops pull away slightly and cracked sealant shows up.
If you can see any of these, it’s time to have the joints looked at:
- Sealant that never bonded to the surface
- Gaps behind new kitchen upstands
- Sealant work across a run of new homes
- Skirting joints opening in the first winter
If you’ve bought a new home near Chelsfield station, the sealant around baths, showers and frames is worth checking in the first year or two.
Comparing quotes
- What preparation is included
- Whether you can choose the colour
- Are they insured?
- Who does the work, and how experienced they are
New build mastic in Downe: local notes
Rainfall in the South East is lower than in much of the UK, 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 snags may need reporting through the developer or the managing agent.
Downe is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Downe is about 4 miles south-west of Orpington, in Greater London. Homes, rented property, offices and hotels in Downe can book us for new build mastic, old or new, large or small. Every job comes with our 12-month guarantee. Our Greater London coverage runs to 764 places, and Downe is one of them. There’s also a page for London, about 13 miles away.
Here we cover the BR6 postcode area for new build mastic. We cover properties on High Street, North End Lane and Belle Vue Road. If you’re just outside Downe, we cover Farthing Street (1 mile north-west), Hazelwood (1 mile east), Luxted (1 mile south), Leaves Green (1 mile west) and Single Street (2 miles south). Larger places within reach include London (13 miles north-west), City of Westminster (15 miles north-west), Marylebone (15 miles north-west), St Pancras (15 miles north-west), Shoreditch (14 miles north-west) and Hoxton (15 miles north-west).
Near you in Downe
In Downe, that means homes and buildings near The Queens Head pub, Charles Darwin School and South Park. The closest station to Downe is Chelsfield station, about 2.6 miles north-east. A little further out are Crofton Roman Villa (2.7 miles north-east) and Princess Royal University Hospital (1.8 miles north). Open spaces near Downe include Downe Bank Nature Reserve and Betsom's Hill.
What we do, step by step
Good joint work is mostly preparation, and we do not rush it. Every joint is cleaned and dried before new material goes in. In total, it generally takes a few hours for most snagging lists, longer for a run of plots. In a London area like Downe, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- We start by going through the snagging items or plot schedule with you.
- The failed sealant is removed completely down to clean surfaces.
- Joints are vacuumed and cleaned of building dust.
- 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.
Preparing for the visit
- Keep pets and children clear of the area while we work
- Mention any parking rules near the property
- Tell us about any water getting in
Ask for a quote
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we’ll talk you through what we’d do. When it suits you, phone 0345 464 0079 or email us.
Advice
What affects the quote in Downe
Jobs vary more than people expect. The main factors:
- How easy the joints are to reach
- How much there is to do
- Any mould that needs treating
- Working hours on commercial sites
Combining jobs into one visit is usually more efficient than separate visits. You will get one clear quote for the whole job.
What to tell us for a quote
There’s no need for technical detail. It helps if you can tell us:
- Any access issues, like height or stairs
- The type of property
- The rough size of the job
- A few photos by email, if you can
There’s no standard price list. Instead, your job gets its own clear quote. To arrange one, call 0345 464 0079 or send us an email.
Keeping the joints in good condition
No joint lasts for ever, but care makes a real difference. A few tips:
- Follow the cure time we give you
- Avoid running a DIY bead over the old one
- Check bath and shower seals every few months as the house settles
- Use the extractor fan every time you shower
Keep the bathroom ventilated, especially in the first year. Use the extractor fan or open a window after showers so moisture does not sit on the sealant.
Report failed sealant to the builder while you are in the snagging period. After that, putting it right may fall to you, so raise it early.
Also in Downe
Downe: your questions answered
I let a flat near Chelsfield station. Can you help?
Yes. We work for letting agents and landlords as well as householders. Just call 0345 464 0079 or send us an email with the address and what needs doing, and we’ll send you a clear quote.
Is Downe in your area for new build mastic?
Yes. We work across London and the South East, and Downe is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job, and we’ll send you a clear quote.
Do you work for developers?
Yes. Second-fix sealing in bathrooms, kitchens, frames and floors is part of what we do. Good preparation keeps snagging to a minimum.
Can I send you my snagging list?
Yes. Send the list and a few photos of the sealant items, and we will quote. We will flag anything that needs another trade.
Will the old sealant be removed?
Yes. We cut out all the old sealant and clean the joint.
Can you match the sealant colour to my new kitchen or bathroom?
The colour is chosen to suit the tiles, worktop or frame. Let us know your preference when you ask for a quote.
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.
Are you an approved applicator?
Yes. Mr Mastic is an ARBOMaster approved applicator, and we are fully insured.
Can I do it myself?
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.
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly, so just mention it when you contact us.
Landlords, agents and businesses in Downe
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements and we’ll quote.
In hotels, rooms out of use cost money, so the work can be planned room by room. Hotel work is part of what we do, alongside homes and businesses.