Greater London · England
New-build mastic & snagging in Kensington, Greater London
Problem with your new-build sealant joints in Kensington? We cut out the old, prepare the joints and apply the right sealant.
- Messy sealant that spoils new finishes
- Kitchen sealant that has pulled off the wall
- Gaps between new skirting and floors
New build mastic in Kensington
Some owners wait for the first year’s movement before having joints redone. That makes sense for small gaps that are just cosmetic, but a failed shower or bath seal shouldn’t wait. We work on bathrooms & en suites, skirting & floors and kitchens, and common reasons people get in touch are worktop and upstand sealant coming away and smeared, uneven beads picked up at snagging.
From brand-new flats to converted terraces with new flooring, London has every kind of floor. Every joint between floor, skirting and threshold has to cope with some movement.
We guarantee the work for a year. If something is not right with it in that time, tell us and we’ll put it right.
- Location
- Kensington (W11, W8, W14, SW7)
- Region
- Greater London
- Cover
- A year, on every job
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
The process
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. Typically it takes a few hours for most snagging lists, longer for a run of plots. In Kensington, as in most of London, parking needs a little planning. 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, with no layer left behind.
- Joints are vacuumed and cleaned of building dust.
- Primer goes on where the surface and product need it, then the new sealant.
- Each bead is tooled and the cure times explained.
Preparing for the visit
- Tell us about any previous sealing or DIY attempts
- Keep children and pets away from the work area
- For indoor joints, keep the area dry beforehand if you can
Get a quote
We do not publish a price list, because every job is different. Instead, we send you a clear quote for your job. To get started, phone 0345 464 0079 or send us an email.
Related advice
Do you need new build mastic in Kensington?
Sealant is often one of the last jobs before handover. Dusty, unprimed joints are common, so the bead never bonds properly.
Keep an eye out for any of the following:
- Worktop and upstand sealant coming away
- Cracks appearing as a new home settles
- Sealant work across a run of new homes
- Gaps between new skirting and floors
If you’ve bought a new home near Kensington Olympia station, the sealant around baths, showers and frames is worth checking in the first year or two.
Before booking anyone
- Whether they seal over old material or remove it
- How the joint is cleaned and prepared
- What insurance they hold
- Is VAT in the price?
Keeping the joints in good condition
Simple care keeps the joints in good condition. Our advice:
- Photograph failed sealant before it’s redone
- Look at the sealant regularly in the first couple of years
- Put sealant faults on your snagging list early
- Wait for the cure time before using a resealed shower
Keep the bathroom ventilated, especially in the first year. Run the fan or open a window after bathing so moisture does not sit on the sealant.
Mould takes hold quickly in sealant that has gaps or lifted edges. Dealing with it before it goes black saves a harder job later.
What new build mastic looks like in Kensington
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. Much of London’s new housing is flats in larger developments, where snags may need reporting through the developer or the managing agent.
Kensington is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Kensington is about 5 miles west of London, in Greater London. Jobs in Kensington get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. 764 places in Greater London are on our list, large and small.
Here we cover the W11, W8, W14 and SW7 postcode area for new build mastic. That includes homes and businesses on Kensington High Street, Edwardes Square and Somerset Square and the roads around them. Kensington is on the A402 and B316, which makes it straightforward to reach with everything needed for new build mastic. We also cover the places around Kensington: Holland Park (1 mile north), Notting Hill (1 mile north), Shepherd's Bush (1 mile west), Notting Dale (1 mile north) and White City (1 mile north-west). Further out, we also cover London (5 miles east), Marylebone (3 miles north-east), St Pancras (4 miles north-east), Shoreditch (6 miles east), Walthamstow (10 miles north-east) and Hoxton (6 miles north-east). Kensington is one of the larger places we cover in Greater London.
Local landmarks in Kensington
We work in homes and buildings around Holland Park, Scarsdale Tavern and Holland Park School, among other places. Nearby too are Kensington School (0.5 miles east) and Abdus Salam Library (1 mile east). Kensington has its own railway station: Kensington Olympia station. A little further out are Kensington Arcade (within half a mile east) and London Museum (0.7 miles north-east). Green spaces nearby include WWT London Wetland Centre and The Long Water.
Should I try it myself first?
The biggest DIY mistake is sealing over old sealant. Silicone doesn’t stick to old silicone, so it peels away and traps moisture behind it. All the old material has to come out first.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it doesn’t work out, we can still put it right.
FAQs for Kensington
Can you help a landlord with a rental near Kensington Olympia station?
Yes, we work for letting agents and landlords. You can phone 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before work begins.
Is Kensington in your area for new build mastic?
Yes. Our work covers London and the South East, and Kensington is part of that. Just phone 0345 464 0079 or email us with a few details of the job, and we’ll give you a clear quote.
How long before the joint can be used?
It depends on the product and the temperature. We tell you how long to leave it before we go.
Where is Mr Mastic based?
We are based in Crawley, and we cover South East England, London and all of Scotland.
Is the work guaranteed?
Yes, always. There’s a 12-month guarantee on every job.
Do you work for developers?
Yes. Plot mastic and second-fix sealing for developers is part of our work. Send the schedule and any specification and we will give you a quote.
Do I need to be at home?
It depends on the job. Inside work needs someone to give us access, while outside work can sometimes be arranged differently.
What do you put in the joint?
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.
Places near Kensington
Also in Kensington
What affects the cost of new build mastic
Some jobs are bigger than they look, and some smaller. The main factors:
- How much old sealant there is and how hard it is to remove
- Whether the work is at height
- The size of the job
- Whether there’s mould to deal with
Leaving a failed joint usually makes the job bigger, not smaller, because water and mould keep working on it. If you’re not sure whether it needs doing, phone 0345 464 0079 or send us an email for an honest opinion and a quote.
Asking for a quote
To help us quote quickly, let us know:
- Any access issues, like height or stairs
- Whether it has been sealed before
- The problem you’ve noticed
- The type of property
Need a quote? Please phone 0345 464 0079 or send us an email and tell us about the job. You’ll know what we plan to do, and what it will cost, before any work begins.
How the job changes by surface
Bathrooms and en suites
Shower trays in new homes often move slightly in the first year. The joint is stripped back before the new bead goes in.
Show homes
Show homes need sealant that looks right from day one. Every bead is neat and coloured to suit the room.
What we can’t put right
Before you book, it’s worth knowing the limits too:
- Cracking that points to a structural problem
- Baths and trays that move too much for sealant to cope with
- Cracked trays, tiles or worktops
Not sure which it is? You can call 0345 464 0079 or drop us an email and we will tell you honestly.
What we seal
- Bathrooms & en suites
- Kitchens
- Windows & doors
- Show homes
- Plot handovers
- Skirting & floors