Greater London · England
New Build Mastic in Belgravia
Plot mastic for developers and snagging failed sealant in new homes in Belgravia, with a 12-month guarantee on every job. Call for a quick quote.
- Internal frame sealant that has split
- Gaps behind new kitchen upstands
- Joints pulling apart as timber shrinks
New build mastic in Belgravia
Some owners wait for the first year’s movement before having joints redone. For small cosmetic gaps, that’s reasonable, but a failed shower or bath seal shouldn’t wait. If you are dealing with gaps between new skirting and floors and sealant work across a run of new homes, we can help, whatever the surface.
London homes range from new-build flats to period conversions with new floors laid over old boards. Wherever a floor meets a wall, a skirting or a threshold, the joint has to allow for movement, in Belgravia as anywhere.
All of our work is guaranteed for twelve months.
- Location
- Belgravia (SW3, SW1X, SW1W)
- Wider area
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Belgravia questions
Is Belgravia in your area for new build mastic?
Yes, Belgravia is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or email us with a few details of the job.
Is parking an issue for new build mastic in Belgravia?
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.
Will the old sealant be removed?
Always. Sealing over the old bead is the commonest cause of early failure, and it’s something we never do.
Can you reseal over the builder’s sealant?
No. Fresh silicone doesn’t stick to the old layer, so it soon lifts and traps water. We cut the old bead out completely.
Are you insured?
Yes. Mr Mastic is fully insured.
Is it worth resealing while the house is still settling?
Where water is getting through, do not wait. Small gaps that are just cosmetic can be resealed once movement has slowed.
Can I add another job to the visit?
Of course. Doing several areas at once is generally more efficient, so mention them when you ask for a quote.
Can tenants book the work?
Yes. Check with your landlord; we can send the quote to them too.
Common problems we fix in Belgravia
New homes are full of moisture from plaster, screed and concrete, which takes a year or two to dry out. Drying timber shrinks and pulls joints apart, and sealant that cannot keep up splits.
These are the problems we are asked about most:
- New-build shower sealant that has already split
- Kitchen sealant that has pulled off the wall
- Smeared, uneven beads picked up at snagging
- Internal frame sealant that has split
For new homes near London Victoria station, it’s worth checking the sealant early, while snags are still fresh.
Questions to ask before booking
- How much experience the applicator has
- How the colour is chosen
- Which sealant they’ll use, and why
- When the joint can take water or movement
Joints and finishes in Belgravia homes
Much of London’s new housing is flats in larger developments, where snags may need reporting through the developer or the managing agent. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
As a London address, Belgravia can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
Belgravia is about 1 mile south of City of Westminster, in Greater London. Homes, rented property, offices and hotels in Belgravia can book us for new build mastic, old or new, large or small. The work is guaranteed for a year. Our Greater London coverage runs to 764 places, Belgravia among them.
Every address in SW3, SW1X and SW1W is within our area for new build mastic. If you need new build mastic at a property on Hans Road, Eaton Lane and Gerald Road or a nearby road, our applicators can take on the job. You’ll find Belgravia on the A3214 and A3217, so it’s easy for us to get to with everything needed for new build mastic. If you are just outside Belgravia, we cover Brompton (1 mile south-west), Victoria (1 mile south-east), Chelsea (1 mile south-west), Pimlico (1 mile south-east) and Westminster (1 mile east). Larger places within reach include London (3 miles east), St Pancras (3 miles north-east), Shoreditch (4 miles north-east), Walthamstow (8 miles north-east), Hoxton (4 miles north-east) and Whitechapel (4 miles east).
Near you in Belgravia
In Belgravia, that means homes and buildings near Saint Thomas More Language College, Green Park and Natural History Museum Library and Archives and the streets around them. You will also find Star Tavern (within half a mile north-west) and Inchbald School of Design (under half a mile south). The nearest railway station is London Victoria station, about 0.5 miles south-east. Other landmarks nearby include Health Exhibition Centre (within half a mile south-east) and Harrods (less than half a mile west). Not far away are Campden Hill and Serpentine.
Quotes for new build mastic in Belgravia
The price is agreed before any work begins. It’s based on:
- How many areas need sealing
- Working hours on commercial sites
- Access and height
- The number and length of the joints
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. You will know the price before we begin.
Asking for a quote
There’s no need for technical detail. Just tell us:
- The type of property
- If someone has resealed it before
- A few pictures by email, if you can
- Where the property is
Asking for a quote is easy: let us know the job and the location, and roughly how big it is. Photos by email help us understand the job, and we’ll come back to you with a quote.
Should I try it myself first?
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
The process
There’s no need to move everything out, just the space around the work. We protect the rest, and the job takes anything from a few hours to several days, depending on the number of plots in most cases. In a London area like Belgravia, the main things to plan are parking and access: let us know about parking, the floor we will be working on and any lift or shared entrance.
- We start by agreeing which joints are on the list, from the snagging sheet or plot schedule.
- The old bead comes out in full, with no layer left behind.
- We clean off dust from the build and prime the surfaces where the product needs it.
- New sealant suited to each joint is applied and tooled neatly.
- We check every joint and tell you how long each needs to cure.
Getting ready for the visit
- Keep children and pets away from the work area
- For business premises, tell us about site rules or sign-in
- For indoor joints, keep the area dry beforehand if you can
How to get a quote
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is, and we’ll talk you through what we’d do. Whenever you’re ready, call 0345 464 0079 or send us an email.
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When something else is needed
New sealant can’t fix everything, and we’d rather say so up front. Sealant will not put right:
- Damaged fittings that need replacing
- Baths and trays that move too much for sealant to cope with
- Cracking that points to a structural problem
If you’re not sure, just ring 0345 464 0079 or send us an email and we’ll give you a straight answer before you book.
Joints and surfaces we work on
- Plot handovers
- Windows & doors
- Bathrooms & en suites
- Show homes
- Kitchens
- Skirting & floors
Landlord and commercial work in Belgravia
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Resealing at the right time is simple maintenance.
Housing providers, facilities teams and property managers book us too. Several sites can go on one quote, and we’re fully insured.
Why it’s worth doing now in Belgravia
Sealant done properly at handover means fewer callbacks. Snagging visits for failed sealant cost time on every plot, and they’re avoidable with good preparation. 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. Putting it right early is much less trouble.
The cost reflects the work involved, not a rough estimate. That is why we ask about the job first and agree the price before starting.
What you get with us
- 12-month guarantee on every job
- Quality sealants from Arbo and Everbuild
- Any old sealant cut out fully, not covered over
- Experience in homes, commercial sites and hotels
Read our cost guide and customer reviews.