Surrey · England
External Mastic in Knaphill
External mastic across Knaphill and nearby, with old sealant always removed completely and a 12-month guarantee.
- Old sealant gone brittle and cracked
- Moss and dirt in joints with no sealant left
- Water getting into walls through failed joints
Surface by 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.
Joints between dissimilar materials
Different materials may need different primers. Both surfaces are cleaned and primed as the product requires.
External mastic for homes and businesses in Knaphill
For buildings in Knaphill, 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 render & cladding joints, joints between brick and frames and concrete & block, and the jobs we see most are plants rooting in failed movement joints and joints pointed up with cement by mistake.
Homes around Knaphill range from older cottages to newer houses, with walls and rooflines of every type. Older gutters and trims need their joints resealed; newer brick and render need their movement joints kept sound.
Our work is backed for twelve months.
- Place
- Knaphill (GU21, GU24)
- Region
- Surrey
- Cover
- A year, on every job
- Price
- A clear price before we start
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
How to look after the new joints
So the new joints stay in good condition:
- Keep high-pressure jets off the joints
- Get split or bare joints resealed while the damage is small
- Do not let climbing plants root in the sealant
- Check the sealant is paintable before painting near it
Don’t paint over the new sealant unless we have said the product is paintable. Many exterior sealants aren’t designed to be painted.
Leave a failed movement joint and water keeps getting into the wall. Over time it can mean damp inside, stained render or frost-damaged brick which cost more to put right than the joint.
Work for landlords, hotels and businesses
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Landlords and agents in Knaphill can book us as well as homeowners. Resealing between tenancies is a simple way to keep a property in good order.
Should I try it myself first?
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
Outside joints around Knaphill
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.
In the older streets around St Hugh of Lincoln's Church, old and new materials meet at the roofline and walls, which is where sealant earns its keep. If you let a flat or house near Brookwood station, outside joints that have cracked can let damp into a rental, so check them between lets. Schools such as Knaphill School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
Knaphill is about 2 miles west of Woking, in Surrey. Every kind of property in Knaphill is covered for external mastic, old or new, large or small. The work is guaranteed for a year. Our area takes in 395 places across Surrey. For nearby work, see our Reading page.
Here we cover the GU21 and GU24 postcode area for external mastic. We cover properties on Wood Lane, High Street and Barnby Road and the roads around them. We also cover Bisley (1 mile north-west), Sheet's Heath (1 mile south-west), Castle Green (1 mile north), Brookwood (1 mile south-west) and Penny Pot (1 mile north). Within a short drive, we also cover Guildford (5 miles south), Camberley (5 miles west), Epsom (15 miles east), Farnham (11 miles south-west), Egham (8 miles north) and Walton-on-Thames (10 miles north-east).
Local landmarks in Knaphill
Around Knaphill, our work takes us to homes and buildings near Anchor Inn, The Winston Churchill School A Specialist Sports College and Brookwood Lye and the streets around them. Knaphill’s nearest station is Brookwood station, roughly 1.4 miles south-west of the centre. Other landmarks nearby include The Peacocks (2.5 miles east) and Brookwood Hospital (under half a mile south). The countryside around Knaphill includes Brookwood Lye.
How the visit works
Once we’re on site, we compare the joints with what we discussed. If we find something unexpected, we talk it through with you first. After that, the work takes a few hours for a handful of joints, longer for a whole elevation. In a smaller place like Knaphill, parking is seldom the issue; lanes, gates and long drives are worth mentioning. If the job is outside, tell us about side access and how high the joints are.
- Each joint is checked and the colour of the new sealant agreed.
- We take out the old sealant until the faces are sound.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- For indoor joints, keep the area dry beforehand if you can
- On commercial sites, let us know about site rules
- Move anything stored near the joints
Getting a quote
Want a quote for external mastic? Please call 0345 464 0079 or email us with a few details. You will know what we plan to do, and what it will cost, before any work begins.
Advice
Honest limits
Before booking, it’s worth knowing the limits too:
- Loose or hollow render, which needs re-rendering
- Cracking across the wall rather than at a joint
- Damp that isn’t coming from the joint
Not sure which it is? You can ring 0345 464 0079 or send us an email and we will tell you honestly before booking.
Surfaces we seal
- Brickwork movement joints
- Façade panels
- Render & cladding joints
- Joints between brick and frames
- Copings & trims
- Concrete & block
Nearby places to Knaphill
Other services in Knaphill
Why deal with it now?
Pointing a movement joint with mortar might seem a neat fix, but it locks the joint solid. The wall then cracks somewhere else. A flexible sealant over backing rod is what the joint needs. Homes in smaller places like Knaphill can face more weather, and failed outside joints let damp into walls. Inside, a split seal lets water into floors and panels just as it would anywhere.
There are no prices on our website, because each job is priced on what it involves. Call for a quick quote.
Why choose Mr Mastic in Knaphill
- Tidy, careful work
- Colour agreed with you before we start
- 4.9 on Google from 180+ five-star reviews
- An ARBOMaster approved applicator
Read what affects the cost and customer reviews.
Your questions about external mastic in Knaphill
Is Knaphill within the area you cover?
Yes. Knaphill is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
Do you work for landlords with property near Brookwood station?
Yes. We work for landlords and agents as well as homeowners. Just call 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear price.
Do I need to be at home?
That depends on where the joints are. For work indoors, someone needs to let us in, and for outside work we’ll agree access with you when we book.
Are you insured?
Yes, we are fully insured.
What should I tell you?
Only a few details: the address or postcode, what’s wrong and any access issues. After that, simply phone 0345 464 0079 or send us an email.
Do the sealants smell?
Possibly a little. Any smell clears as the sealant cures, and ventilation helps.
Can you work on commercial sites?
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.
Where is Mr Mastic based?
Our base is Crawley. Our area covers South East England, London and Scotland.