Kent · England
External Mastic in Thong
Sealing brickwork movement joints, render, cladding and façade joints for Thong, backed by a one-year guarantee. Ask us for a quote.
- Plants rooting in failed movement joints
- Joints with sealant missing in places
- Panel joints letting water in
External mastic in Thong
We cut out failed sealant, set the joint depth with closed-cell backing rod and reseal with a low-modulus exterior sealant. We pick a colour that sits well with the wall so the line blends in. We work on joints between brick and frames, render & cladding joints and copings & trims, and the jobs we see most are movement joints filled with mortar instead of sealant and joints where the bead has come unstuck.
Somewhere as small as Thong, homes and farm buildings often face open ground, so walls and rooflines take the full force of wind and rain. Joints on those walls need a sealant that moves with the building and stays in place.
Whatever the size of the job, it’s backed by our one-year guarantee in Thong and across Kent.
- Location
- Thong (DA12)
- Region
- Kent
- Guarantee
- 12 months on all our work
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
DIY sealant or a professional job?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is, then guaranteed for a year.
If you do try it yourself, take your time over the preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
What we’re called out for in Thong
Poor preparation causes many early failures: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The new sealant then lets go long before it should.
If you can see any of these, it’s time to have the joints looked at:
- Sealant pulling away from one side of the joint
- Water getting into walls through failed joints
- Joints pointed up with cement by mistake
- Plants rooting in failed movement joints
For an older house near a landmark such as Church of St Peter and St Paul, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Questions to ask before booking
- Whether all the old sealant comes out first
- Whether the sealant suits the joint
- The length of the guarantee
- Is VAT in the price?
Outside joints around Thong
Thong is within about 3 miles of the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. Both are hard on movement joints and outside wall joints, which can dry out and crack sooner where a building faces the weather. Historic houses like Cobham College (about 1.5 miles south) are a reminder that the area around Thong has older buildings as well as new. Where a home is older, older brick and stone need a sealant that suits them, at the right joint depth.
Managing a site like Riverview Infant School? Then larger buildings have long runs of movement joint that eventually need resealing. Rented homes near Sole Street station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Thong is about 2 miles south-east of Gravesend, in Kent. Every kind of property in Thong can book us for external mastic, old or new, large or small. The work is guaranteed for a year. Thong is one of 922 places in Kent we cover for external mastic. For nearby work, see our London page, about 22 miles away.
Jobs for external mastic in DA12 works the same way as everywhere else we cover. Close by, we work in Upper Ifield (1 mile east), Shorne Ridgeway (1 mile east), Shorne (1 mile east), Chalk (1 mile north) and Higham (2 miles east). Further out, we also cover Maidstone (11 miles south-east), Sittingbourne (15 miles east), Dartford (8 miles west), Sevenoaks (13 miles south-west), Northfleet (3 miles north-west) and Swanley (10 miles west).
What’s near Thong
Locally, jobs take us to homes and businesses close to Shorne Woods Country Park and Thamesview School. Thong’s nearest station is Sole Street station, about 2.2 miles south-west of the centre. Well-known places in the area include Rochester Castle (4.5 miles east) and Gravesham Museum (2.6 miles north-west). Not far away are Rede Common and Gad's Hill.
What happens on the day
We keep the work tidy and contained to the area we’re working on, so you can carry on as normal. Expect the work to take a few hours to a few days, depending on the length of joint and the access, and we explain the cure time before we leave. For a village or hamlet like Thong, the journey is planned in advance: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- Each joint is checked and the colour of the new sealant agreed.
- We take out the old sealant until the faces are sound.
- Backing rod goes in so the sealant can stretch between the two faces.
- We prime the faces where required.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
Before we arrive
- Move anything stored near the joints
- Let us know if you’ve seen damp or leaks
- Tell us about any previous sealing or DIY attempts
Get a quote
Every job is quoted individually, so the first step is telling us about yours. Just call 0345 464 0079 or drop us an email with the details, and pictures are welcome.
Related advice
Also in Thong
Different surfaces, different methods
Joints between dissimilar materials
Where a frame or panel meets masonry, water often finds a way in. The old joint is removed and a sealant that bonds to both sides goes in.
Brickwork movement joints
Clay brickwork grows slightly over its life and moves with the weather. The movement joint takes that up, so its sealant has to stay flexible.
Aftercare tips
A little care helps the new joints last. We recommend:
- Avoid pressure-washing directly into sealant joints
- Keep movement joints as flexible joints, not mortar
- Deal with leaking gutters that soak the joints below
- Do not let climbing plants root in the sealant
Have a quick look at the joints each spring. Watch for splits, edges coming away or growth in the joint.
Gaps, plants or missing sealant in a joint are worth getting looked at. Early work is quicker and leaves a better finish.
For landlords and businesses
From a single let to a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a one-year guarantee.
For anyone letting property in or around Thong, jobs at different addresses can be quoted together. Send us the addresses and the work at each.
FAQs for Thong
Does living near the coast affect external mastic in Thong?
Coastal weather is harder on outside sealant: there’s more wind-driven rain and, closer to the shore, salt in the air. Choosing the right sealant for the frame and wall, laid at the right depth, helps it last.
Will you come out to Thong?
Yes, Thong is covered. Our work covers London and the South East, and smaller places are part of that. Longer journeys are simply planned in advance.
How long should I leave it?
It depends on the product and the temperature. We tell you how long to leave it before we go.
Can new sealant go over the old?
No, it won’t last. It may look fine at first, but the new layer lifts away from the old one. Removing the old sealant completely is the only lasting way.
Can I do it myself?
Sometimes. Preparation is everything: all the old sealant out, and a clean, dry joint. If it does not work out, we can redo it.
Is it messy?
Very little: the area around the joints is protected first, and we tidy up before we go.
Can tenants book the work?
Yes. Check with your landlord; we can send the quote to them too.
Do you take out the old sealant first?
Always. Sealing over the old bead is the commonest cause of early failure, so we never do it.
What affects the cost of external mastic
Call for a quick quote. What matters most is:
- Whether there’s mould to deal with
- How much there is to do
- Which sealant suits the joint
- How easy the joints are to reach
Doing several joints on one visit is generally more efficient than separate visits, so tell us about everything that needs sealing. You will get one clear quote for the whole job.
What to tell us for a quote
A few details help us give you an accurate quote. When you get in contact, it helps to mention:
- The problem you’ve noticed
- Roughly how big the job is
- Any previous sealing or DIY work
- Any access issues, like height or stairs
To get a quote, phone 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. We’ll give you a clear quote before any work starts.