Greater London · England
St John's Wood New Build Mastic
New build mastic for St John's Wood and the surrounding area: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Gaps behind new kitchen upstands
- Cracked caulk along new skirting
- Smeared, uneven beads picked up at snagging
Signs you need new build mastic in St John's Wood
On many sites, sealant goes on in the final rush before handover. Dusty, unprimed joints are common, so the bead never bonds properly.
It’s worth asking for a quote if you see:
- Cracks appearing as a new home settles
- Sealant that never bonded to the surface
- Messy sealant that spoils new finishes
- Gaps between new skirting and floors
St John's Wood is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Comparing quotes
- What insurance they hold
- Whether they seal over old material or remove it
- Who does the work, and how experienced they are
- What product goes in the joint
New build mastic in St John's Wood
We work in new homes and on new-build sites across St John's Wood. Whether it’s one en suite or a run of plots, the method is the same: remove, clean, prime where needed, then a neat new bead. If you have worktop and upstand sealant coming away and sealant work across a run of new homes, we can put it right, whatever the surface.
Much of London’s new housing is flats in larger developments. In a new development, snags are often reported through the developer or the managing agent, and shower seals that fail early, skirting joints that open up and gaps at thresholds are all common snags.
We guarantee the work for a year. If something isn’t right with it in that time, tell us and we’ll put it right.
- Place
- St John's Wood (NW8, NW6, NW3)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What happens on the day
Good joint work is mostly preparation, so that’s where we spend the time. Joints are cleaned back and dried before anything new goes in. All told, the work takes anything from a few hours to several days, depending on the number of plots. In a London area like St John's Wood, the main things to plan are parking and access: let us know about parking, the floor we’ll be working on and any lift or shared entrance.
- 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.
Before we arrive
- Keep pets and children clear of the area while we work
- Mention any leaks or damp you’ve noticed
- Tell us about access, such as stairs, a lift or high-level joints
Get a quote
To get a quote, ring 0345 464 0079 or email us and tell us where the job is and what the problem looks like. You’ll have a clear quote before any work starts.
Related advice
Your questions about new build mastic in St John's Wood
Can you help a landlord with a rental near South Hampstead station?
Yes, rental work is part of what we do. You can ring 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before any work starts.
Is parking a problem for a job in St John's Wood?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly.
How long does new build mastic take?
Typically it takes a few hours for most snagging lists, longer for a run of plots. Bigger jobs take longer, and we will tell you how long to expect.
Should I try DIY first?
Some simple jobs can be done by a careful DIYer. Most DIY failures come from sealing over old material, wet joints or too much sealant.
What does new build mastic cost?
There’s no set price, as it depends on the job: how much there is, what’s there now, how we reach it and what it needs. We agree the price before any work begins.
Is it messy?
Very little: the area around the joints is protected first, and we clear up the old sealant and our materials before we leave.
Do you do commercial work?
Yes. Hotels, offices and other businesses use us.
Is there any odour?
Possibly a little. It fades as the sealant cures.
Surface by surface
Kitchens
Worktops in new homes can move slightly as the house dries, opening gaps behind the upstand. A fresh flexible bead closes them.
Skirting and floors
Wet-area floor joints need a flexible seal. They get a flexible, water-resistant sealant.
Keeping the joints in good condition
After the cure time, these simple habits help:
- Check bath and shower seals every few months as the house settles
- Record problems with dated pictures
- Wipe joints with warm soapy water
- Put sealant faults on your snagging list early
Keep the bathroom ventilated, especially in the first year. Run the fan or open a window after bathing so moisture doesn’t sit on the sealant.
Mould takes hold quickly in sealant that has gaps or lifted edges. Dealing with it before it goes black keeps the job straightforward.
Joints and finishes in St John's Wood homes
Many of London’s new homes are flats in bigger developments, where snags may need reporting through the developer or the managing agent. The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
For new homes near South Hampstead station, it’s worth checking the sealant early, while snags are still fresh.
St John's Wood is about 1 mile south of Hampstead, in Greater London. From the centre of St John's Wood to the outskirts, new build mastic is available for homes and businesses alike. St John's Wood is one of 764 towns and villages in Greater London we cover.
We work across NW8, NW6 and NW3 for new build mastic. You’ll find streets such as The Lane, Hall Road and Hill Road, and we cover them all. St John's Wood sits on or near the A5205, so getting to you is simple. Other places close to St John's Wood include South Hampstead (1 mile north), Swiss Cottage (1 mile north), Primrose Hill (1 mile north-east), Lisson Grove (1 mile south) and Haverstock (1 mile north-east). Within a short drive, we also cover London (4 miles south-east), Kensington (3 miles south-west), St Pancras (3 miles east), Shoreditch (4 miles east), Walthamstow (7 miles north-east) and Hoxton (4 miles east).
What’s near St John's Wood
In St John's Wood, that means homes and buildings near Cecil Sharp House, Primrose Hill and Arnold House School, among other places. Other local landmarks include Quintin Kynaston Community Academy (less than half a mile north-west) and Cafe Med pub (less than half a mile north-west). There’s a railway station in St John's Wood itself: South Hampstead station. Other landmarks nearby include Hospital of St John and St Elizabeth (within half a mile south) and Montfichet's Tower (3.5 miles south-east). Not far away are The Long Water and Primrose Hill.
Landlords, agents and businesses in St John's Wood
Housing providers, facilities teams and property managers book us too in St John's Wood and across Greater London. We can quote a run of properties together.
For anyone letting property in or around St John's Wood, several properties can be quoted together. Send us the addresses and the work at each, and pictures by email help.
Also near St John's Wood
Also in St John's Wood
What sealant work cannot fix
We won’t take on work that will not last, so these are the limits:
- Cracked trays, tiles or worktops
- Structural cracks in walls or ceilings
- Deciding who is responsible under a builder’s warranty
Not sure which it is? You can phone 0345 464 0079 or send us an email and we will tell you honestly.
What we seal
- Skirting & floors
- Kitchens
- Plot handovers
- Windows & doors
- Bathrooms & en suites
- Show homes
What happens if it’s left?
A hairline gap at a skirting can wait, but water getting through can’t. If you are unsure which you have, call 0345 464 0079 or email us with pictures. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in St John's Wood, the repair is bigger than a sealant job.
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. Call for a quick quote and we’ll explain what it covers.
Why book with us
- More than 20 years in sealant work
- You choose the colour before work begins
- Any old sealant cut out fully, not covered over
- White, clear, grey or coloured to suit, where the product allows
Read how sealant jobs are priced or our reviews.