Greater London · England
New-build mastic & snagging in Greenhill, Greater London
Specialist new build mastic for Greenhill: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Worktop and upstand sealant coming away
- Untidy sealant flagged on a snagging list
- Frame joints opening as the plaster dries
Looking after it afterwards
No joint lasts for ever, but care makes a real difference. Our tips:
- Clean sealant with mild detergent, not abrasives
- Avoid running a DIY bead over the old one
- Look at the sealant regularly in the first couple of years
- Report sealant problems to your builder during the snagging period
Ventilation matters in a new home, which is still drying out. Use the extractor fan or open a window after showers so moisture doesn’t sit on the sealant.
A failed seal in a new home lets water into joists, plasterboard and ceilings. Early resealing keeps the job small and the new finishes intact.
New build mastic for homes and businesses in Greenhill
Failed shower seals, gaps along the skirting and messy beads are common items on a new-home snagging list. While the builder’s snagging or warranty period runs, report it to them first and if that stalls, we can do it. If you are dealing with kitchen sealant that has pulled off the wall and sealant that never bonded to the surface, we can put it right.
Much of London’s new housing is flats 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.
A one-year guarantee comes with the work, just as it does everywhere we cover.
- Place
- Greenhill (NW3, NW6)
- Region
- Greater London
- Guarantee
- A year, on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Signs you need new build mastic in Greenhill
Sealant applied onto damp surfaces doesn’t bond well. Site programmes don’t always leave time for joints to dry first.
If you can see any of these, it’s time to have the joints looked at:
- Skirting joints opening in the first winter
- Messy sealant that spoils new finishes
- Shower seals failing in the first year or two
- Sealant work across a run of new homes
If you’ve bought a new home near Hampstead Heath station, the sealant around baths, showers and frames is worth checking in the first year or two.
Comparing quotes
- Whether all the old sealant comes out first
- What happens if they find a problem under the old sealant
- Are they insured?
- When the joint can take water or movement
Nearby places to Greenhill
What else we do in Greenhill
How the job changes by surface
Skirting and floors
Where the floor meets a bath panel or kitchen plinth, the joint keeps mop water out. We seal them with a sealant suited to wet areas.
Plot handovers
Plot mastic is carried out to the developer’s schedule. Each joint is cleaned and primed where needed to keep callbacks down.
Quotes for new build mastic in Greenhill
Every job gets its own quote. These are the things that affect it:
- Any working-time requirements on site
- The old material and how stubborn it is
- The number of rooms or windows
- Mould in or behind the old joints
Commercial jobs are quoted on the same basis as homes: the amount of work, the access and the products needed, along with when we can work on site. Ask us for a quote and we’ll go through it with you.
What we need to know
Before you ask for a quote, have a think about:
- The address or postcode of the job
- The type of property
- How many joints, rooms or windows are involved
- Any access issues, like height or stairs
For new build mastic in Greenhill, call 0345 464 0079 or send us an email. Tell us what the problem is and where, and we’ll agree the price before any work begins.
What sealant work can’t fix
New sealant can’t fix everything, and we’d rather say so up front. It won’t solve:
- A tray or bath that is not properly supported, until it’s fixed
- Damaged fittings that need replacing
- Disputes or warranty claims with your builder
If in doubt, phone 0345 464 0079 or email us and we’ll say what we think before booking.
Surfaces we seal
- Windows & doors
- Kitchens
- Bathrooms & en suites
- Show homes
- Plot handovers
- Skirting & floors
What happens if it’s left?
A hairline gap at a skirting can wait, but water getting through cannot. If you are unsure which you have, phone 0345 464 0079 or send us an email with photos and we will give you a straight answer. 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. Putting it right early is much less trouble for homes in Greenhill.
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. You’ll know the price before we begin.
Why choose Mr Mastic in Greenhill
- Trusted Arbo and Everbuild sealants
- 180+ five-star Google reviews
- You choose the colour before work begins
- We never seal over old sealant
Read our cost guide or what customers say.
Questions from Greenhill
Do you work for landlords with property near Hampstead Heath station?
Yes, landlords and agents are among the people we work for. Just call 0345 464 0079 or drop us an email with the address and what needs doing, and we’ll give you a clear quote.
Do you cover Greenhill for new build mastic?
Yes. Our work covers London and the South East, and Greenhill is part of that. Just ring 0345 464 0079 or email us with a few details of the job.
Why does sealant fail so quickly in new builds?
New homes dry out and move in their first couple of years, and sealant is often rushed onto dusty, unprimed surfaces. Either can make it fail early.
Where are you based?
Our base is Crawley, with over 20 years’ experience. Our area covers South East England, London and Scotland.
Do you do commercial work?
Yes, regularly. We can plan bigger jobs in stages to suit the site.
Can you do several jobs on one visit?
Yes. Just list everything you need and you will get one quote.
My new home is still under warranty. Should I contact you?
While the snagging or warranty period runs, the builder should be your first contact. If it is not sorted, or keeps failing, get in touch with us.
Do the sealants smell?
That depends on the sealant. Some products have a noticeable smell, others very little.
New homes and floors in Greenhill
Many of London’s new homes are flats in bigger developments, where snagging may go through the developer or managing agent. London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Greenhill is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Greenhill is about 1 mile north-east of Hampstead, in Greater London. For new build mastic in and around Greenhill, please phone 0345 464 0079 or email us for a quick quote. We are based in Crawley and cover Greater London. We cover 764 towns and villages across Greater London.
All of NW3 and NW6 is covered for new build mastic, from the main roads to the quietest streets. Streets in the area include Back Lane, Well Road and Ornan Road, and we cover them all. Other places close to Greenhill include Hampstead (1 mile south-west), Vale of Health (1 mile north), West Hampstead (1 mile west), Fortune Green (1 mile west) and Haverstock (1 mile south-east). Further out, we also cover London (5 miles south-east), City of Westminster (3 miles south), Marylebone (3 miles south-east), Kensington (4 miles south), St Pancras (3 miles south-east) and Shoreditch (5 miles south-east).
Near you in Greenhill
Locally, jobs take us to homes and businesses close to Cecil Sharp House, Fitzjohn's Primary School and King William IV Public House. Also close by are South Hampstead High School (0.6 miles south) and Hampstead Heath (0.7 miles north-east). There’s a railway station in Greenhill itself: Hampstead Heath station. Other landmarks nearby include New End Hospital (less than half a mile north-west) and Montfichet's Tower (4.3 miles south-east). The countryside around Greenhill includes Belsize Wood and Parliament Hill.
What we do, step by step
On the day, we start by going over the job with you, so there are no surprises. Surfaces next to the work are protected before work begins. Most jobs take a few hours for most snagging lists, longer for a run of plots. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- First, the list of joints is agreed from your snagging sheet or plot schedule.
- Every bit of the old builder’s sealant is cut out, with no layer left behind.
- Joints are vacuumed and cleaned of building dust.
- We prime where needed and apply a sealant suited to each joint.
- Each bead is tooled and the cure times explained.
How to prepare
- Clear the area around the work
- Plan for the work area to be out of bounds to pets and children
- Tell us about any previous sealing or DIY attempts
How to get a quote
Want a quote for new build mastic? Please ring 0345 464 0079 or send us an email and tell us about the job. We’ll explain what we’d do and send you a clear quote before any work starts.