Kent · England
New-build mastic & snagging in St Margarets, Kent
Plot mastic for developers and snagging failed sealant in new homes for St Margarets, backed by a one-year guarantee. Call for a quick quote.
- Shower seals failing in the first year or two
- Gaps between new skirting and floors
- Sealant applied over dusty or wet surfaces
About our new build mastic in St Margarets
Some new-home owners let the house settle before resealing. That makes sense for small gaps that are just cosmetic, but a seal that is letting water through needs doing now. We work on windows & doors, bathrooms & en suites and plot handovers, and people most often call us about messy sealant that spoils new finishes and shower seals failing in the first year or two.
Older homes in small places like St Margarets often have timber floors that move with the seasons, so skirting and threshold joints need a flexible sealant rather than a rigid filler.
A one-year guarantee comes as standard.
- Location
- St Margarets (DA4)
- Region
- Kent
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Put sealant faults on your snagging list early
- Photograph failed sealant before it’s redone
- Keep water off fresh sealant until it has cured
- Do not wait for the house to settle if water is getting through
Photograph failed sealant before it’s redone and keep the builder’s replies. It’s useful if you need to raise other issues later.
Don’t let the snagging period run out with sealant problems unreported. After that, putting it right may fall to you so report it promptly.
What affects the cost of new build mastic
You will get a clear quote before any work starts. It takes into account:
- Whether there’s mould to deal with
- Working hours on commercial sites
- The number of rooms or windows
- Access and height
What you pay reflects the work, not guesswork. That is why we ask a few questions first.
Helping us quote
There’s no need for technical detail. It helps if you can tell us:
- The rough size of the job
- The address or postcode of the job
- If it’s domestic, commercial or a hotel
- Whether it has been sealed before
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To arrange one, ring 0345 464 0079 or drop us an email.
Can I do it myself?
Overfilling a joint is a classic DIY mistake. 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 cut it out and start again, so tell us about it when you ask for a quote.
What we do, step by step
When we arrive, we look over the joints with you first, so there are no surprises. We protect the surfaces around the joints before work begins. The work usually takes a few hours in a single home. Somewhere as small as St Margarets, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First, the list of joints is agreed from your snagging sheet or plot schedule.
- The failed sealant is removed completely down to clean surfaces.
- 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.
- Each bead is tooled and the cure times explained.
Before we arrive
- Move anything stored near the joints
- For business premises, tell us about site rules or sign-in
- Let us know about stairs, lifts or work at height
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. We will give you a clear price before any work starts.
Related advice
Questions from St Margarets
Can you help a landlord with a rental near Farningham Road station?
Yes. We work for letting agents and landlords as well as householders, and several properties can go on one quote. You can call 0345 464 0079 or email us with the details for a clear quote.
Is St Margarets in your area for new build mastic?
Yes, St Margarets is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or send us an email and let us know what needs doing.
Why does sealant fail so quickly in new builds?
Cracking in the first couple of years is common, because the house is drying and settling. Poor preparation at handover adds to it.
Where are you based?
Mr Mastic is based in Crawley. Our applicators cover St Margarets.
Should I wait before resealing?
That depends on the joint. A leaking shower or bath seal should be redone straight away, but cosmetic gaps can wait for movement to slow.
Can you do several jobs on one visit?
Yes. More than one area can be quoted together.
Can new sealant go on top of the old bead?
No. Fresh silicone does not stick to the old layer, so it soon lifts and traps water. The old sealant always comes out first.
What sealant do you use?
Products from Arbo and Everbuild, among others, picked for each joint. We explain the product when we quote.
Places near St Margarets
More services for St Margarets
What new build mastic looks like in St Margarets
The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
In and around St Margarets, as anywhere, good new build mastic starts with a clean, dry, properly prepared joint.
St Margarets is about 3 miles south-east of Dartford, in Kent. For new build mastic in and around St Margarets, it’s easy to get a quote: please call 0345 464 0079 or email us. We’re based in Crawley and cover Kent. 922 places in Kent are on our list, large and small. You can also see our page for London, about 16 miles away.
Our applicators cover all of DA4 for new build mastic and the streets around it. Close by, we work in South Darenth (1 mile south-west), Darenth (1 mile north), Green Street Green (1 mile east), Sutton at Hone (1 mile west) and Grubb Street (1 mile east). Larger places within reach include Maidstone (15 miles south-east), Dartford (3 miles north-west), Sevenoaks (9 miles south), Gravesend (5 miles east), Tonbridge (15 miles south) and Northfleet (4 miles north-east).
What’s near St Margarets
Typical jobs here are in homes near Darenth Country Park, Leigh Academy and Fox & Hounds pub. For rail, the closest station is Farningham Road station, about 1.1 miles south-west of the centre. Other landmarks nearby include Stone Museum of Geology (2.5 miles north) and Darent Valley Hospital (1.7 miles north). Open spaces near St Margarets include Sawyers Lake and Wansunt Pit.
Surface by surface
Show homes
Bathrooms, kitchens and frames in show homes are sealed or resealed to a neat finish. Tell us when the home is open so we can plan around it.
Windows and doors
External mastic around new windows and doors is sometimes rushed or missed. It’s resealed with an exterior sealant suited to the frame and wall.
Honest limits
Some problems need a builder, plumber or other trade rather than us:
- Plumbing faults behind the sealant
- Settlement cracks that need a surveyor
- Movement caused by a poorly fitted tray or bath
If you are not sure, just phone 0345 464 0079 or email us and we will give you a straight answer.
Surfaces we seal
- Skirting & floors
- Plot handovers
- Kitchens
- Bathrooms & en suites
- Windows & doors
- Show homes
What we are called out for in St Margarets
The wrong product is sometimes used in the wrong place: decorators’ caulk in a wet area, or a stiff sealant where there’s movement. Neither lasts long.
It’s worth asking for a quote if you see:
- Cracked caulk along new skirting
- Messy sealant that spoils new finishes
- Gaps behind new kitchen upstands
- Beads laid onto grit and dust from the build
If you’ve bought a new home near Farningham Road station, the sealant around baths, showers and frames is worth checking in the first year or two.
Before you book anyone
- How hidden problems are handled
- What product goes in the joint
- How the colour is chosen
- Is the old sealant removed completely?