Kent · England
External Mastic in Swanscombe
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Swanscombe and across Kent. Fully insured, ARBOMaster approved and guaranteed for a year.
- Panel joints letting water in
- Rigid filler in a joint that should flex
- Damp patches traced to an open external joint
External mastic in Swanscombe
As ARBOMaster approved applicators, we choose exterior sealants to suit the joint and the surfaces. Porous or awkward surfaces are primed where the sealant needs it. Common call-outs are for panel joints letting water in and rain getting behind render or cladding at a joint, across concrete & block, copings & trims and render & cladding joints.
Outbuildings, garages and conservatories around homes in places like Swanscombe add more joints to look after. Gutter ends, garage door frames and the joints where an extension meets the house are typical spots for leaks.
Every job comes with a one-year guarantee.
- Place
- Swanscombe (DA9, DA10)
- Wider area
- Kent
- Cover
- 12 months on all our work
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
How the job changes by surface
Render joints
Render has movement joints and stop beads that need sealing. They’re resealed in a sealant that suits the render.
Copings and trims
A failed coping joint lets water into the top of the wall. Resealing them is a small job that protects a lot.
Swanscombe questions
Is Swanscombe in your area for external mastic?
Yes, Swanscombe 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.
Will you come out to Swanscombe?
Yes, Swanscombe is covered. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
How long does the job take?
Typically it takes a few hours for a handful of joints, longer for a whole elevation. Bigger jobs take longer.
Why is there a gap in my brick wall?
A movement joint is a planned break in the wall that absorbs expansion and shrinkage. It should be filled with flexible sealant, never mortar.
Do you hold any approvals?
Yes. Mr Mastic is an ARBOMaster approved applicator, and we’re fully insured.
How often do external joints need resealing?
There’s no fixed answer: joints on exposed walls or with a lot of movement age sooner. A yearly look will tell you when they need doing. Every job carries our one-year guarantee.
Where are you based?
We’re a Crawley-based firm, with over 20 years’ experience. We work across South East England, London and Scotland.
Do you take out the old sealant first?
Yes, always, and completely. New silicone does not stick to old silicone, so the joint is cleaned back first.
The process
On the day, there’s very little for you to do. Point us to the joints and we will get on with it. The work itself takes a few hours for a handful of joints, longer for a whole elevation. A visit to Swanscombe is planned like any other: the time, the access and where to park are agreed in advance. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- First, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires it.
- We fit closed-cell backing rod to control the depth.
- The exterior sealant is applied, tooled and checked along its length.
Before we arrive
- Tell us about any previous sealing or DIY attempts
- On commercial sites, let us know about site rules
- Mention any parking rules near the property
Ask for a quote
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we’ll explain how we’d tackle it. When it suits you, call 0345 464 0079 or drop us an email.
Read more
Why deal with it now?
A failed movement joint lets water into the wall, behind render and cladding. Dealing with it early keeps the repair to the joint, instead of the wall and finishes around it. Homes in smaller places like Swanscombe can face more weather, and failed outside joints let damp into walls. Inside, a split seal lets water into floors and panels just as it would anywhere.
Combining jobs into one visit normally makes better use of the time than several visits. We’ll give you a clear price for the lot.
What you get with us
- Full insurance on every job
- We leave the area clean and tidy
- Arbo and Everbuild products
- We agree the colour with you first
Read our cost guide or our reviews.
Signs you need external mastic in Swanscombe
Poor preparation causes many early failures: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The sealant never bonds properly.
Any of these means the joints need attention:
- Movement joints filled with mortar instead of sealant
- Water getting into walls through failed joints
- Leaking joints around cladding and façade panels
- Plants rooting in failed movement joints
For site and facilities teams at buildings such as Knockhall Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
What your quote should include
- What happens if the job turns out different
- What preparation is included
- What guarantee comes with the work
- Is the old sealant removed completely?
Work for landlords, hotels and businesses
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. Hotel work is part of what we do, alongside homes and businesses.
Housing providers, facilities teams and property managers book us too in Swanscombe and across Kent. We can quote a run of properties together, and we are fully insured for the work.
How we quote for external mastic
The quote reflects the job in front of us. We look at:
- Whether old sealant or filler has to be cut out
- How easy the joints are to reach
- Which sealant suits the joint
- Any mould that needs treating
What it costs depends on the size of the job, how much old material has to come out and how easy the joints are to reach. We give a clear quote before we start.
Asking for a quote
A few details help us give you an accurate quote. When you get in contact, it helps to mention:
- How we’d reach the joints
- Where the job is, and your postcode
- The problem you’ve noticed
- If someone has resealed it before
For a quote, ring 0345 464 0079 or drop us an email with the location and a short description of the problem. You will have a clear quote before work begins.
DIY sealant or a professional job?
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
If you’ve already had a go yourself, that’s fine. We remove it and do the joint properly.
External mastic in Swanscombe: local notes
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.
In the older streets around Church of St Mary, old and new materials meet at the roofline and walls, which is where sealant earns its keep. For landlords with property near Greenhithe for Bluewater station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Swanscombe is about 3 miles east of Dartford, in Kent. Jobs in Swanscombe get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Swanscombe is one of 922 places in Kent where we work. You can also see our page for London, about 17 miles away.
Every address in DA9 and DA10 is within our area for external mastic, from the main roads to the quietest streets. If you need external mastic at a property on London Road, Craylands Square and High Street or anywhere close by, our applicators can take on the job. Being close to the A206 and A226, Swanscombe is simple for us to get to for external mastic. We also cover Greenhithe (1 mile north-west), Stone (1 mile west), Bean (1 mile south), West Thurrock (2 miles north) and Darenth (2 miles south-west). Larger places within reach include Dartford (3 miles west), Sevenoaks (12 miles south), Gravesend (4 miles east), Northfleet (3 miles south-east), Swanley (6 miles south-west) and Kings Hill (13 miles south).
Around Swanscombe
Around Swanscombe, our work takes us to homes and buildings near Castle Hill Park, The Ebbsfleet Academy and The Pier Hotel. The nearest railway station is Greenhithe for Bluewater station, roughly 0.5 miles west of the centre. Nearby you will also find Stone Castle (0.7 miles south-west) and Bluewater (1 mile south-west). Green spaces nearby include Sawyers Lake and Chafford Gorges Nature Park.