Kent · England
Sand Mastic in Knockholt
Traditional burnt sand mastic around sash and case windows and doors in stone and brick in Knockholt, with a 12-month guarantee on every job. Call for a quick quote.
- Gaps where the frame meets the masonry
- Mastic worn away on windows facing the weather
- Window mastic to renew ahead of painting
Signs you need sand mastic in Knockholt
Decorating can disturb tired mastic. Many people find it crumbling when they prepare the windows, which is a good time to renew it.
Keep an eye out for these signs:
- Mastic worn away on windows facing the weather
- Tired mastic found when preparing windows for paint
- Modern sealant on a period surround
- Wind and rain getting in round a sash window
For an older house near a landmark such as St Katharine's Church, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
What to look for in a quote
- Whether the sealant suits the joint
- What happens if they find a problem under the old sealant
- When the joint can take water or movement
- Who does the work, and how experienced they are
How we handle sand mastic in Knockholt
On many period windows, sand mastic looks right and suits the building. Newer frames usually get a flexible sealant instead and we’ll explain which is best for yours. If you are dealing with cement or filler used on old window joints that has cracked and tired mastic found when preparing windows for paint, we can put it right, on stone surrounds, period & listed homes and sash and case windows alike.
In a village or hamlet like Knockholt, older cottages and farmhouses often have timber windows set in stone or brick. Not every older frame suits a modern silicone bead, and sometimes a traditional sand mastic is the better choice.
Every job is covered by our 12-month guarantee.
- Place
- Knockholt (TN14)
- Region
- Kent
- Cover
- 12 months on all our work
- Price
- A clear price before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
What the job involves on each surface
Period and listed homes
Period homes look their best with traditional materials.
Sash and case windows
Most of our sand mastic work is on sash windows. Each joint round the box is raked out and renewed.
What we do, step by step
On the day, there’s very little for you to do. Point us to the joints and we’ll get on with it. The work itself takes anything from a few hours to a full day, depending on how many windows, including the tidy-up. In a small place like Knockholt, access is generally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- First we agree which joints need doing.
- Old mastic and any loose material are raked out.
- Deep gaps are packed so the mastic sits at the right depth.
- The sand mastic is mixed and pressed into the joint by hand.
- We dress the finish so it sits neatly against the masonry.
Getting ready for the visit
- For indoor joints, keep the area dry beforehand if you can
- Keep children and pets away from the work area
- Mention any leaks or damp you’ve noticed
Get a quote
If you’re in Knockholt and need sand mastic, call 0345 464 0079 or send us an email. Tell us what the problem is and where, and we will agree the price before any work begins.
Related advice
Work for landlords, hotels and businesses
Failed sealant is one of the commonest items on a check-out report. Several properties can be quoted together.
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. Hotel work is part of what we do, alongside homes and businesses.
Knockholt: your questions answered
Is Knockholt within the area you cover?
Yes, smaller places are covered as well as towns. Our work covers London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
Is Knockholt in your area for sand mastic?
Yes, Knockholt is within the area we cover. Our work covers London and the South East. Just call 0345 464 0079 or drop us an email with a few details of the job, and we’ll give you a clear quote.
Should I check with the council before work on a listed or conservation-area home?
Speak to your local planning authority before work starts. Like-for-like sand mastic is often the preferred finish, but they decide.
Are you insured?
Yes. Full insurance covers our work.
Can landlords and businesses book you?
Yes, regularly. We can quote for several properties at once.
Do you guarantee sand mastic work?
Our 12-month guarantee applies on every job.
Can I choose the sealant colour?
Generally, yes. White, clear and grey are common, and other colours are available for many products, and we agree the colour with you before any work starts.
How long does sand mastic take?
Typically it takes anything from a few hours to a full day, depending on how many windows. Bigger jobs take longer, and we will tell you how long to expect.
Nearby places to Knockholt
Other services in Knockholt
DIY versus a professional finish
Sealing over old silicone is the commonest DIY error. New silicone won’t bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.
If you are 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 fails, we can still redo it.
Sand mastic in Knockholt: local notes
Historic houses like Down House (about 2.7 miles north-west) are a reminder that the area around Knockholt has older buildings as well as new. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
If you let a flat or house near Knockholt station, older sash windows in a rental need their mastic kept sound to keep the weather out.
Knockholt is about 4 miles north-west of Sevenoaks, in Kent. We carry out sand mastic for homeowners, landlords and businesses in Knockholt, as part of our work across Kent. Knockholt is one of 922 towns and villages in Kent we cover. You can also see our page for London, about 16 miles away.
We work across the TN14 postcode area for sand mastic. Whether your property is on Main Road and Blueberry Lane or a nearby road, our applicators can take on the job. Nearby, we also carry out sand mastic in Knockholt Pound (1 mile north-east), Halstead (2 miles north-east), Sepham Heath (2 miles north-east), Pratt's Bottom (2 miles north) and Twitton (3 miles east). Further out, we also cover Dartford (11 miles north-east), Sevenoaks (4 miles south-east), Royal Tunbridge Wells (14 miles south-east), Gravesend (14 miles north-east), Tonbridge (11 miles south-east) and Northfleet (13 miles north-east).
Landmarks near Knockholt
We work in homes and buildings around The Three Horseshoes pub and the streets around them. Knockholt’s nearest station is Knockholt station, roughly 2.7 miles north-east of the centre. A little further out are Orpington Hospital (3.6 miles north) and Otford Heritage Centre (3.9 miles east). Green spaces nearby include Betsom's Hill and Downe Bank.
Why it’s worth doing now in Knockholt
Draughts round a sash window aren’t always the sashes. Open mastic joints round the box can let air in and new mastic seals them. In a small place like Knockholt, homes can be exposed to wind and rain, which finds any gap, and older walls, once damp, take a long time to dry.
Rather than a set price list, we price the job in front of us: the amount of work, the old material and the access. The price is agreed before we begin.
Why choose Mr Mastic in Knockholt
- Old sealant always removed completely
- An ARBOMaster approved applicator
- We are fully insured
- Experience in homes, commercial sites and hotels
Take a look at how sealant jobs are priced and what customers say.
How we quote for sand mastic
There’s no set price list, because no two jobs are the same. The quote depends on:
- How much old sealant there is and how hard it is to remove
- The type of sealant required
- Access and height
- How many rooms, windows or areas are involved
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all play a part, and we will explain the quote if you ask.
Asking for a quote
Photos by email are helpful but not essential. Please mention:
- Where the property is
- Any previous sealing or DIY work
- What’s wrong with the joints now
- Access, such as stairs, a lift or height
We don’t publish a price list. Instead, we send you a clear quote for your job. To arrange one, phone 0345 464 0079 or drop us an email.