Buckinghamshire · England
Longwick External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Longwick and across Buckinghamshire. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Sealant that has lost its bond to the brick or render
- Gaps where render, brick and frames meet
- Joints pointed up with cement by mistake
External mastic in Longwick
External mastic is a job where short cuts show quickly. New sealant over old, joints packed with mortar and beads with no backing rarely last long. We take the old material out and do it properly. We work on concrete & block, joints between brick and frames and façade panels, and the jobs we see most are brick movement joints where the sealant has split and rain getting behind render or cladding at a joint.
Homes around Longwick range from older cottages to newer houses, with walls and rooflines of every type. Older homes need their gutter and trim joints kept tight, newer ones their movement joints.
You are covered for a year from the day we finish. If anything isn’t right with it, phone 0345 464 0079 or email us.
- Where
- Longwick (HP27)
- Wider area
- Buckinghamshire
- Guarantee
- A year, on every job
- Quotes
- Quoted before any work starts
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
DIY sealant or a professional job?
The biggest DIY mistake is sealing over old sealant. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Walls and rooflines in Longwick
Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Managing a site like Longwick Church of England Combined School? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. Rented homes near Monks Risborough station change hands often, and outside joints that have cracked can let damp into a rental, so check them between lets.
Longwick is about 5 miles east of Thame, in Buckinghamshire. Across the HP27 area, we can carry out external mastic at your property. Our area takes in 263 places across Buckinghamshire, large and small. For nearby work, see our Oxford page (16 miles or so).
We work across the HP27 postcode area for external mastic. Streets in the area include Headland End, Wickfields and Furrow Drive. Close by, we work in Owlswick (1 mile north), Alscot (1 mile east), Pitch Green (1 mile south-west), Ilmer (1 mile north-west) and Horsenden (1 mile south). We also work in nearby towns such as Aylesbury (6 miles north), High Wycombe (9 miles south-east), Chesham (11 miles east), Marlow (12 miles south), Amersham (12 miles east) and Beaconsfield (13 miles south-east).
Local landmarks in Longwick
In Longwick, that means homes and buildings near Princes Risborough School and The Red Lion Public House. For rail, the closest station is Monks Risborough station, about 1.3 miles east. Other landmarks nearby include Great Kimble Dial Hill (2.4 miles east) and St John's Hospital (4.6 miles north). Not far away are Brush Hill Local Nature Reserve and Beacon Hill.
Towns and villages near Longwick
Other services in Longwick
What we do, step by step
Most of a good job is in the preparation, so that’s where we spend the time. Joints are cleaned back and dried before anything new goes in. In total, it generally takes a few hours to a few days, depending on the length of joint and the access. For a job in Longwick, we agree the time, the access and parking before the day. If the work is outside, the weather plays a part, as sealant needs a dry surface.
- 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.
How to prepare
- Let us know if you’ve seen damp or leaks
- For business premises, tell us about site rules or sign-in
- Tell us about any previous sealing or DIY attempts
Ask for a quote
Need a quote? Please ring 0345 464 0079 or send us an email with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
Read more
Why act early in Longwick
Water gets in through a failed movement joint and can run behind render or cladding. Resealing early keeps the job to the joint itself, rather than the wall around it. In an older home around Longwick, damp from a failed joint can get into timber and plaster, and that is a much bigger job than renewing the sealant.
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. You will know the price before we begin.
What you get with us
- Arbo and Everbuild products
- A 12-month guarantee on all work
- Homes, businesses and hotels
- A choice of colours where the product allows
What the job involves on each surface
Cladding and façade panels
Panels heat up and cool down quickly, so the joint sealant has to cope with frequent movement. The sealant is chosen with that in mind.
Joints between dissimilar materials
Each side of the joint may need its own preparation. We prepare both faces so the sealant bonds properly.
For landlords and businesses
In hotels, rooms out of use cost money, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
From a single let to a portfolio, you get the same standard of work: the old material taken out, careful preparation and a 12-month guarantee.
Your questions about external mastic in Longwick
Do you cover smaller places like Longwick?
Yes, Longwick is covered. Our work covers London and the South East, and smaller places are part of that. Longer journeys are simply planned in advance.
Do you work for landlords with property near Monks Risborough station?
Yes, rental work is part of what we do. You can ring 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before any work starts.
Can I add another job to the visit?
Yes, and it often makes sense. Doing several areas at once is generally more efficient, so mention them when you ask for a quote.
Is it OK to seal over old sealant?
No, it will not last. It may look fine at first, but the new bead soon lifts. Removing the old sealant completely is the only lasting way.
What sealant do you use?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. Brands we use include Arbo and Everbuild.
What is backing rod for?
We fit closed-cell backing rod wherever the joint depth needs controlling. It controls the depth and stops the sealant bonding to the back, so the joint can move.
Where is Mr Mastic based?
Our base is in Crawley, and we cover South East England, London and all of Scotland.
How long should I leave it?
Cure times vary by product and the temperature. We tell you how long to leave it before we go.
Do you need external mastic in Longwick?
Sunlight, wet weather and frost wear exterior sealant down. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
Look out for any of the following:
- Failed sealant between panels on a façade
- Moss and dirt in joints with no sealant left
- Sealant that has lost its bond to the brick or render
- Joints pointed up with cement by mistake
If you live in an older home near Owlswick Chapel, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Before you book anyone
- What happens if they find a problem under the old sealant
- What the quote includes, VAT included or not
- What insurance they hold
- Whether you can choose the colour
Looking after it afterwards
To keep the joints looking good and working properly:
- Tell anyone working on the walls about the movement joints
- Deal with leaking gutters that soak the joints below
- Get split or bare joints resealed while the damage is small
- 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.
A joint that has stopped moving pushes the movement elsewhere, often as cracks near the joint. Catch it early and you reduce the risk.