Wokingham · England
Knowl Hill External Mastic
Our applicators work in Knowl Hill on sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly and every job guaranteed for a year.
- Rain getting behind render or cladding at a joint
- Hard, crazed mastic that has stopped moving
- Sealant that has lost its bond to the brick or render
Why act early in Knowl Hill
Mortar or ordinary filler might look like a quick way to close an open joint, but it stops the joint moving. The wall then cracks somewhere else. The correct repair is a flexible sealant with the right backing. Older cottages and farmhouses around Knowl Hill can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
Every job is a little different, so each one gets its own quote. Size, access and the product the joint needs all play a part.
What you get with us
- Neat joints and a tidy finish
- Fully insured
- Over 20 years’ experience
- Sealant colour chosen to suit
Read how sealant jobs are priced or our reviews.
About our external mastic in Knowl Hill
We are ARBOMaster approved applicators, and each external joint gets a sealant suited to it. Some surfaces need a primer before sealing, and we do not skip that step. Common call-outs are for cracked joints where brick meets render or frames and joints with sealant missing in places, on concrete & block, brickwork movement joints and façade panels.
Older homes in small places like Knowl Hill may be stone, brick or timber-framed, often with later extensions. The joints where those materials meet are the weak points, and they need the right sealant at the right depth.
All of our work is guaranteed for twelve months, and the guarantee is the same wherever you are.
- Location
- Knowl Hill (RG10)
- Region
- Wokingham
- Cover
- A year, on every job
- Price
- A clear price before work begins
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Can I do it myself?
A careful DIYer can reseal a simple joint, 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 difference is mostly in the preparation and the product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions, then guaranteed for a year.
Keeping the joints in good condition
Simple care keeps the joints in good condition. Our advice:
- Keep soil, plants and ivy away from the joints
- Make sure movement joints aren’t pointed over
- Leave the joints unpainted unless we have said otherwise
- Tell anyone working on the walls about the movement joints
Make sure anyone working on the wall later knows where the movement joints are. They should be kept open and resealed, not filled.
Gaps, plants or missing sealant in a joint are worth getting looked at. Earlier resealing means a smaller job and a better result.
Quotes for external mastic in Knowl Hill
Every job gets its own quote. This is what makes a difference:
- Which sealant suits the joint
- How many areas need sealing
- Whether there’s mould to deal with
- Whether old sealant or filler has to be cut out
What it costs depends on how much there is to do, how much old material has to come out and how easy the joints are to reach. You will have a clear quote before any work starts, so you know where you stand.
Asking for a quote
Photos help, but a description is a good start. Try to tell us:
- Photos by email, if that is easy
- If it’s domestic, commercial or a hotel
- The rough size of the job
- Any previous sealing or DIY work
We quote each job on its own, so start by telling us what you need. Just phone 0345 464 0079 or drop us an email with the details.
What we do, step by step
All our tools and materials come with us in the van, so there’s nothing for you to buy. Once we have agreed what’s being done, we protect the area and start. Most jobs take a few hours for a handful of joints, longer for a whole elevation. Somewhere like Knowl Hill needs a little journey planning: 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.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Getting ready for the visit
- Mention any tricky access
- Move anything stored near the joints
- Tell us about any previous sealing or DIY attempts
Getting a quote
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To arrange one, ring 0345 464 0079 or drop us an email.
Related advice
Places near Knowl Hill
Other services in Knowl Hill
Questions from Knowl Hill
Is Knowl Hill in your area for external mastic?
Yes. Our work covers London and the South East, and Knowl Hill is part of that. You can call 0345 464 0079 or drop us an email and let us know what needs doing, and we’ll give you a clear quote.
I let a flat near Wargrave station. Can you help?
Yes, we work for landlords and agents. Just phone 0345 464 0079 or email us and tell us about the property, and we’ll give you a clear quote.
Can you seal over the old sealant?
No. The old sealant always comes out first, so the new joint bonds to clean surfaces.
Do you hold any approvals?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we’re part of it.
How do you reach high-level joints?
That depends on how high the joints are and the ground below. Low-level joints are straightforward; for higher ones, send details and we’ll confirm the access.
Is it worth trying it myself?
That depends on the joint. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Is there any odour?
That depends on the sealant. Some products have a noticeable smell, others very little.
Do you guarantee your work?
Yes. Every job comes with our 12-month guarantee.
What external mastic looks like in Knowl Hill
Historic houses like Harleyford Manor (about 3 miles north) are a reminder that the area around Knowl Hill 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. London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Rented homes near Wargrave station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies. In the older streets around Saint Peter, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Knowl Hill is about 4 miles west of Maidenhead, in Wokingham. We provide external mastic to homes and businesses in Knowl Hill and nearby. Our Wokingham coverage runs to 35 places, Knowl Hill among them. We also work in Reading, around 8 miles away.
Jobs for external mastic in RG10 works the same way as everywhere else we cover. If you need external mastic at a property on Star Lane, Choseley Road and Choseley Close or anywhere close by, we can help. If you’re just outside Knowl Hill, we cover Warren Row (1 mile north-west), Cold Harbour (1 mile south-east), Bowsey Hill (1 mile west), Cockpole Green (2 miles north-west) and Wargrave (2 miles west). Larger places within reach include Reading (8 miles south-west), Wokingham (7 miles south), Woodley (5 miles south-west), Earley (7 miles south-west), Crowthorne (9 miles south) and Lower Earley (7 miles south-west).
Landmarks near Knowl Hill
Locally, jobs take us to homes and businesses close to Seven Stars Public House And Attached Stables. Knowl Hill’s nearest station is Wargrave station, about 2.7 miles west of the centre. Nearby you will also find Frazer Nash Archives (3.6 miles west) and St Mark's Hospital (3.3 miles east). The countryside around Knowl Hill includes Weycock Hill and Hurley Chalk Pit.
What the job involves on each surface
Render joints
Cracks along render joints let water in behind the coat. Resealing the joints early keeps water out and helps it last.
Brickwork movement joints
Brick walls have vertical movement joints to absorb expansion. We reseal them with a low-modulus sealant over backing rod coloured to suit the wall.
What we are called out for in Knowl Hill
UV, rain and frost all age exterior sealant. In time it goes hard, crazes on the surface and stops stretching, so the next time the wall moves, it splits or pulls away.
Look out for any of the following:
- Cracked joints where brick meets render or frames
- Joints where the bead has come unstuck
- Rigid filler in a joint that should flex
- Rain getting behind render or cladding at a joint
Managing a site like Knowl Hill Church of England Primary Academy? Then its movement joints, gutters and trims need looking after like any other building’s.
Comparing quotes
- Who turns up on the day
- What preparation is included
- Which sealant they’ll use, and why
- What insurance they hold