Buckinghamshire · England
Knotty Green External Mastic
Professional external mastic in and around Knotty Green, with every bit of old sealant taken out first and a 12-month guarantee.
- Brick movement joints where the sealant has split
- Weathered mastic that no longer stretches
- Failed seals between different materials
Outside joints around Knotty Green
Historic houses like Cliveden (about 4.6 miles south) are a reminder that the area around Knotty Green has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you live in an older home near Church of St Michael and All Angels, old and new materials meet at the roofline and walls, which is where sealant earns its keep. Managing a site like St Mary and All Saints CofE Primary School? Then its movement joints, gutters and trims need looking after like any other building’s. Letting a property close to Beaconsfield station? Then split movement joints are easy to miss on a rental until damp shows inside.
Knotty Green is about 1 mile north of Beaconsfield, in Buckinghamshire. Jobs in Knotty Green get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Knotty Green is one of 263 towns and villages in Buckinghamshire where we work for external mastic. For nearby work, see our Reading page.
Here we cover the HP9 postcode area for external mastic. External mastic is available to properties on Penn Road, Finch Lane and Mossway. Close by, we work in Forty Green (1 mile south-west), Beaconsfield (1 mile south), Ledborough (1 mile south-east), Beacon Hill (1 mile west) and Winchmore Hill (2 miles north). Within a short drive, we also cover Aylesbury (15 miles north-west), High Wycombe (4 miles west), Chesham (6 miles north), Marlow (6 miles south-west), Amersham (4 miles north-east) and Chalfont St Peter (4 miles east).
Local landmarks in Knotty Green
We work in homes and buildings around Davenies School, The Lion of Beaconsfield pub and Beaconsfield High School, among other places. For rail, the closest station is Beaconsfield station, roughly 0.9 miles south-east. A little further out are High Wycombe Castle (4.1 miles west) and Amersham Hospital (3.2 miles north-east). The countryside around Knotty Green includes Holtspur Bank.
External mastic for homes and businesses in Knotty Green
For buildings in Knotty Green, we reseal external joints of all kinds, from brick movement joints to cladding panels. Every joint gets the same careful preparation: clean joint faces and the right depth. We work on joints between brick and frames, copings & trims and render & cladding joints, and people most often call us about plants rooting in failed movement joints and joints with sealant missing in places.
Outside joints can only be sealed when they’re dry, so work in Knotty Green is booked around the forecast. Tell us about access to all sides of the building, including outbuildings and garages.
Our work is backed for twelve months.
- Where
- Knotty Green (HP9)
- Region
- Buckinghamshire
- Cover
- One year on every job
- Price
- A clear quote up front
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
If you’re set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it doesn’t work out, we can still put it right.
Knotty Green questions
Do you work for landlords with property near Beaconsfield station?
Yes, landlords and agents are among the people we work for. You can phone 0345 464 0079 or drop us an email with the details for a clear quote.
Is Knotty Green in your area for external mastic?
Yes, Knotty Green is within the area we cover. We work across London and the South East. You can call 0345 464 0079 or send us an email and tell us what needs doing, and we’ll send you a clear quote.
Do you seal joints where cladding meets other materials?
Yes. The old joint is removed, both surfaces cleaned and primed where needed, and a flexible sealant applied. We pick a colour that works with both materials.
Can you reach joints on upper floors?
It depends on the building. Where joints can be reached safely, we’ll do them. Give us some details and we’ll confirm the access.
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.
Are you ARBOMaster approved?
Yes. We hold ARBOMaster approved applicator status, and we’re fully insured.
Will the old sealant be removed?
Yes. All of the old material is cut out and the joint cleaned before resealing.
Are you fully insured?
Yes, we are fully insured.
Towns and villages near Knotty Green
Other services in Knotty Green
How to look after the new joints
Looking after new joints is easy, and it makes a real difference:
- Act on the first splits you see
- Point out the joints to other trades
- Check the sealant is paintable before painting near it
- Avoid pressure-washing directly into sealant joints
Follow the cure time we give you before the joint is knocked or disturbed. Most exterior sealants skin fast but take longer to cure right through.
Once a joint can’t move, the wall finds another way, normally as cracking in the brickwork or render nearby. Resealing it early helps prevent that.
Landlords, agents and businesses in Knotty Green
Letting agents often deal with us directly. Tell us the address, the job and how access works and we’ll give you a quote.
Letting agents and landlords in Knotty Green can book us as well as homeowners. Sealant work between tenants keeps a property looking cared for.
What affects the quote in Knotty Green
We don’t publish a price list, because no two jobs are the same. The quote depends on:
- Whether old sealant or filler has to be cut out
- Any working-time requirements on site
- Any mould that needs treating
- Access and height
Combining jobs into one visit normally makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
Asking for a quote
Before you ask for a quote, have a think about:
- Photos by email, if that’s easy
- Access, such as stairs, a lift or height
- Whether it’s a home or a business
- Roughly how big the job is
Want a quote for external mastic? Please call 0345 464 0079 or email us with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
What happens on the day
We bring everything the job needs with us, so you don’t need to buy or prepare anything. Once we have agreed what’s being done, we protect the area and start. Most jobs take a few hours to a few days, depending on the length of joint and the access. Somewhere as small as Knotty Green, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We inspect the joints and agree which need resealing and how they’ll be reached.
- We cut out the failed sealant and rake out any dirt or growth.
- Both sides are cleaned back to sound material and primed if needed.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- We gun in a flexible exterior sealant in a colour that suits the wall and tool it neatly.
Getting ready for the visit
- Let us know about parking restrictions
- Move anything stored near the joints
- Mention if the joints have been sealed before
How to get a quote
There’s no standard price list. Instead, we give you a clear price for your job. To get started, phone 0345 464 0079 or send us an email.
Related advice
Why act early in Knotty Green
The longer a joint stays open, the more water the wall takes in. In cold weather, frost can damage wet brick and render around the joint, so the damage spreads beyond the joint. In a small place like Knotty Green, homes can be exposed to wind and rain, which finds any gap, and older walls, once damp, take a long time to dry.
The cost depends on the amount of work, how hard the old material is to remove and how easy the joints are to reach. You will have a clear quote before any work starts.
What you get with us
- White, clear, grey or coloured to suit, where the product allows
- More than 20 years in sealant work
- Colour picked to suit the job
- We’re fully insured
Take a look at our cost guide or what customers say.
When something else is needed
Before you book, it’s worth knowing the limits:
- Adding movement joints to masonry that has none
- Cracking across the wall rather than at a joint
- Movement that is more than a sealant joint can take
If you are not sure, just ring 0345 464 0079 or send us an email and we will give you a straight answer before you book.
Where we work in Knotty Green
- Render & cladding joints
- Concrete & block
- Façade panels
- Joints between brick and frames
- Brickwork movement joints
- Copings & trims