Buckinghamshire · England
External Mastic in Thornborough
Problem with your movement joints in Thornborough? We cut out the old, prepare the joints and apply the right sealant.
- Joints where the bead has come unstuck
- Movement joints filled with mortar instead of sealant
- Moss and dirt in joints with no sealant left
External mastic for homes and businesses in Thornborough
Joints in render and cladding are easy to overlook until a damp patch appears. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a matching colour. We work on brickwork movement joints, render & cladding joints and façade panels, and people most often call us about movement joints filled with mortar instead of sealant and panel joints letting water in.
Older homes in small places like Thornborough may be stone, brick or timber-framed, often with later extensions. Where one material meets another is where water normally gets in, and they need the right sealant at the right depth.
You get a 12-month guarantee, the same in Thornborough as everywhere else we work.
- Place
- Thornborough (MK18)
- Region
- Buckinghamshire
- Cover
- A year, on every job
- Price
- A clear price before we start
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Aftercare tips
No joint lasts for ever, but care makes a real difference. Our tips:
- Clear growth from the base of walls and joints
- Act on the first splits you see
- Keep movement joints as flexible joints, not mortar
- Leave the joints unpainted unless we have said otherwise
Keep the joints clear of soil, plants and climbing growth. Damp material against the sealant shortens its life.
An open movement joint lets rain into the wall every time it pours. Over time it can mean damp inside, stained render or frost-damaged brick.
Quotes for external mastic in Thornborough
We quote each job individually. These are the things that affect it:
- The amount of work
- Access and height
- Whether old sealant or filler has to be cut out
- Any working-time requirements on site
Combining jobs into one visit normally makes better use of the time than several visits. You’ll get one clear quote for the whole job.
What to tell us for a quote
To help us quote quickly, please include:
- The problem you’ve noticed
- How we’d reach the joints
- Where the job is, and your postcode
- Photos by email, if that’s easy
Asking for a quote is easy: let us know the job and the location and its rough size. Photos by email help us understand the job, and we’ll come back to you with a quote.
Common problems we fix in Thornborough
Some movement joints have been pointed up with mortar by mistake. The joint can’t move, so the wall cracks somewhere else instead.
Look out for any of the following:
- Rigid filler in a joint that should flex
- Joints with sealant missing in places
- Weathered mastic that no longer stretches
- Gaps where render, brick and frames meet
Homes close to Church of St Mary include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Questions to ask before you book
- Which colour the sealant will be
- Whether all the old sealant comes out first
- What the cure time is
- What insurance they hold
What the job involves on each surface
Render joints
Cracks along render joints let water in behind the coat. A sound joint keeps the render dry behind and protects the render itself.
Copings and trims
A failed coping joint lets water into the top of the wall. Sealing them early saves the wall below.
External mastic in Thornborough: local notes
Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Stowe House (about 4.9 miles north-west) are a reminder that the area around Thornborough 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.
If you look after a building such as Thornborough Infant School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Thornborough is about 3 miles east of Buckingham, in Buckinghamshire. For external mastic in and around Thornborough, it’s easy to get a quote: please ring 0345 464 0079 or drop us an email. We cover Buckinghamshire from our Crawley base. Thornborough is one of 263 places in Buckinghamshire where we work. We also work in Oxford, about 22 miles from Thornborough.
Here we cover the MK18 postcode area for external mastic. External mastic is available to properties on High Street, Chapel Lane and The Green and the roads around them. Other places close to Thornborough include Adstock (2 miles south), Padbury (2 miles south-west), Buckingham (3 miles west), Steeple Claydon (5 miles south-west) and East Claydon (5 miles south). Within a short drive, we also cover Aylesbury (13 miles south), Elmhurst (13 miles south), Southcourt (14 miles south), Haydon Hill (12 miles south), Turnfurlong (14 miles south) and Quarrendon Estate (12 miles south).
What’s near Thornborough
A little further out are Buckingham Castle (3.1 miles west) and Buckingham Movie Museum (3 miles west). For a walk, there’s Buckingham Sand Pit.
Nearby places to Thornborough
Other services in Thornborough
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly.
Why deal with it now?
It often makes sense to reseal all the failing joints on an elevation together. Joints of the same age tend to fail together. Older cottages and farmhouses around Thornborough can have timber floors and frames, where water from a failed joint can cause rot if it’s left.
Commercial jobs are quoted on the same basis as homes: the amount of work, how we reach it and what it needs, plus any working-time requirements on site. Call for a quick quote and we’ll explain what it covers.
Why Thornborough customers choose us
- Every job guaranteed for a year
- You choose the colour before work begins
- We’re fully insured
- 20+ years of sealant experience
See our cost guide and what customers say.
How the visit works
We work through the job in order: protection first, then preparation, sealing and a tidy-up. Typically it takes a few hours for a handful of joints, longer for a whole elevation and we leave things clean and tidy. Somewhere like Thornborough needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. 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.
- The exterior sealant is applied, tooled and checked along its length.
How to prepare
- Keep children and pets away from the work area
- Where the joints are inside, avoid wetting them before we arrive
- Let us know if you’ve seen damp or leaks
Getting a quote
We do not publish a price list. Instead, your job gets its own clear quote. To get started, phone 0345 464 0079 or drop us an email.
Related advice
Thornborough questions
Do you cover Thornborough for external mastic?
Yes. We work across London and the South East, and Thornborough is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job, and we will give you a clear price.
Will you come out to Thornborough?
Yes, smaller places are covered as well as towns. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
Can you work on commercial sites?
Yes. We work in offices, washrooms, hotels and other commercial premises. We can talk about working times when we quote.
What is backing rod for?
The foam is closed-cell backing rod. It keeps the sealant at the right depth and bonded to the sides only.
Can you seal joints between render and window frames?
Yes. Where different materials meet is one of the most common joints we seal. The sealant is chosen to bond to both sides, primed where needed.
Where is Mr Mastic based?
Mr Mastic is based in Crawley. Our applicators cover Thornborough, along with the rest of our area.
Is it OK to fill a movement joint with cement?
No. Cement or mortar cannot stretch and the joint fails. Where a joint has been mortared, it can often be raked out and sealed properly.
Are you fully insured?
Yes. We’re fully insured.