Buckinghamshire · England
External Mastic in South Harefield
External mastic in South Harefield from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Damp patches traced to an open external joint
- Movement joints filled with mortar instead of sealant
- Failed seals between different materials
About our external mastic in South Harefield
Ground-floor and low-level joints are straightforward to reach. For joints higher up, give us some details of the building and we will confirm what’s needed to reach them safely. If you’re dealing with weathered mastic that no longer stretches and leaking joints around cladding and façade panels, we can put it right, on concrete & block, joints between brick and frames and façade panels alike.
In a village or hamlet like South Harefield, older cottages and farm buildings often stand in the open, so walls and rooflines take the full force of wind and rain. Gutter joints and wall joints there need a sealant that can flex and stay put.
We stand behind the work with a 12-month guarantee, so you’re covered after we’ve gone.
- Location
- South Harefield (UB9)
- Wider area
- Buckinghamshire
- Cover
- One year on every job
- Price
- A clear price before work begins
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Why deal with it now?
Sealing over the top of old mastic doesn’t hold for long. The new layer can’t bond properly to old, weathered material, so the old joint is cut out fully first. Where a wall is exposed, as many are in small places like South Harefield, wind-driven rain gets into any failed joint, and older walls, once damp, take a long time to dry.
Combining jobs into one visit usually makes better use of the time than several visits. We’ll send you a clear quote for the lot.
Why us?
- Approved under the ARBOMaster scheme
- White, clear, grey or another colour, product permitting
- Full insurance on every job
- We never seal over old sealant
Take a look at our cost guide or what customers say.
For landlords and businesses
Hotels need rooms back in use, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
Water getting past a failed joint can damage the building, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance that we can handle for you.
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it peels away and traps moisture behind it. Everything old must be removed 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.
The process
There’s no need to move everything out before we come, only the area right around the joints. We protect the rest, and the job takes a few hours for a handful of joints, longer for a whole elevation in most cases. For a village or hamlet like South Harefield, the journey is planned in advance: let us know about lanes, gates and parking. We bring what the job needs, so it can be finished in one trip where possible.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
Preparing for the visit
- Clear items away from the joints we are working on
- For business premises, tell us about site rules or sign-in
- Tell us about any water getting in
Get a quote
Need a quote? Please ring 0345 464 0079 or drop us an email with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
Advice
Do you need external mastic in South Harefield?
Some movement joints have been pointed up with mortar, often by someone who didn’t know what it was for. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
Common reasons people contact us are:
- Weathered mastic that no longer stretches
- Damp patches traced to an open external joint
- Joints with sealant missing in places
- Joints where the bead has come unstuck
For landlords with property near Denham station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Before booking anyone
- How long to leave it before use
- How the colour is chosen
- What the quote includes, VAT included or not
- What happens if the job turns out different
Honest limits
Honest advice matters more to us than a booking, so here’s what sealant cannot fix:
- Cutting new joints into brickwork, which is building work rather than sealant work
- Movement that’s more than a sealant joint can take
- Render that is blown, hollow or coming away
If you’re not sure, just phone 0345 464 0079 or email us and we’ll give you a straight answer before you book.
Joints and surfaces we work on
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
- Copings & trims
- Façade panels
- Concrete & block
Nearby places to South Harefield
More services for South Harefield
South Harefield: your questions answered
Will you come out to South Harefield?
Yes, we do. We work across London and the South East, and smaller places are part of that. Longer journeys are simply planned in advance.
Do you cover South Harefield for external mastic?
Yes. We work across London and the South East, and South Harefield is part of that. You can ring 0345 464 0079 or email us and let us know what needs doing, and we’ll give you a clear price.
Should I point up the gap in my brickwork?
No, not if it’s a movement joint. Pointing it stops it working. We’ll reseal it with a flexible sealant.
Can I add another job to the visit?
Yes. Just list everything you need.
Why is there a gap in my brick wall?
Walls move with heat, cold and moisture, and planned joints take up that movement. The gap is sealed with a flexible sealant over backing rod.
Does someone need to be in?
That depends on where the joints are. Inside work needs someone to give us access, and for outside work we will agree access with you when we book.
Do you do commercial work?
Yes. Commercial and hotel work is a large part of what we do, as well as homes. We can talk about working times when we quote.
Will it make a mess?
We keep the work tidy. Nearby surfaces are protected.
How the job changes by surface
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. Their movement joints are sealed over backing rod with a flexible sealant.
Joints between dissimilar materials
Joints where frames, sills or panels meet the wall are common leak points. We cut out the old sealant and reseal with a product suited to both surfaces.
South Harefield buildings and the weather
London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as Ickenham Hall (about 2.7 miles south-east) nearby, there’s older building stock in the area around South Harefield as well as newer homes. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
If you live in an older home near Church of St Mary the Virgin, old and new materials meet at the roofline and walls, which is where sealant earns its keep. Managing a site like Harefield Infant School? Then its movement joints, gutters and trims need looking after like any other building’s.
South Harefield is about 3 miles west of Ruislip, in Buckinghamshire. Whether you are in the middle of South Harefield or further out, we cover external mastic for every kind of property, from flats and houses to offices and hotels. 263 places in Buckinghamshire are on our list, from the larger towns to small villages. For nearby work, see our London page (18 miles or so).
Postcode districts we cover here for external mastic: UB9. That includes homes and businesses on Peerless Drive, Truesdale Drive and Priory Avenue. We also cover the places around South Harefield: Newyears Green (1 mile south-east), Denham (2 miles south), New Denham (3 miles south), Ickenham (3 miles south-east) and Ruislip Manor (3 miles east). Larger places within reach include High Wycombe (12 miles west), Chesham (10 miles north-west), Marlow (13 miles west), Amersham (8 miles north-west), Beaconsfield (7 miles west) and Chalfont St Peter (3 miles west).
What’s near South Harefield
In South Harefield, that means homes and buildings near The Harefield Academy, The River Garden pub and The Green. For rail, the closest station is Denham station, roughly 1 mile south-west of the centre. Nearby you’ll also find Hillingdon Museum and Archives Services (3.1 miles south) and The Pavilions (3 miles south). The countryside around South Harefield includes Horse Shoe Bay and Dews Farm Sand Pits.