Kent · England
Sand mastic for sash & case windows in How Green, Kent
Specialist sand mastic for How Green: careful preparation, the right product and tidy work. Call for a quick quote.
- Cracked mastic round a front door frame
- Draughty sash windows at the surround
- Weathered mastic on the most exposed windows
How we handle sand mastic in How Green
A silicone bead around a sash window can look out of place and doesn’t suit the building. Sand mastic gives a finish that matches the age of the house and we can swap the silicone for it. If you are dealing with window mastic to renew ahead of painting and crumbling sand mastic round a window, we can help, whatever the surface.
Mastic can only go onto a dry, clean joint, so window work in How Green is booked around the forecast. Let us know about access to all the frames, upstairs ones included.
All our work is covered by a 12-month guarantee, wherever you are in Kent.
- Where
- How Green (TN8)
- Wider area
- Kent
- Guarantee
- One year on every job
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Why deal with it now?
Silicone might seem the quicker option, but it can look wrong on a period surround. Sand mastic suits the building and blends with the stone or brick. Where a wall is exposed, as many are in small places like How Green, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
The cost depends on the amount of work, how hard the old material is to remove and access to the work. We give a clear quote before any work starts.
Why book with us
- More than 20 years in sealant work
- We are fully insured
- ARBOMaster approved applicator
- Anti-fungal sanitary silicone in wet areas
Towns and villages near How Green
Also in How Green
FAQs for How Green
Will you come out to How Green?
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.
Can you help a landlord with a rental near Hever station?
Yes, rental work is part of what we do. You can phone 0345 464 0079 or email us with the address and a few details, and we’ll give you a fixed price before work begins.
How long does the job take?
As a guide, most jobs take a few hours per window, depending on the condition of the joints. Larger jobs naturally take longer.
Does someone need to be in?
For indoor joints, yes, someone needs to let us in. After that, you can carry on with your day.
Can you quote for more than one area?
Of course. Doing several areas at once is usually more efficient, so mention them when you ask for a quote.
Can I paint the new mastic?
Traditional guidance is not to paint over sand mastic. Ask us before you decorate around it and we will advise.
Are you insured?
Yes, we’re fully insured for every job we do.
Where is Mr Mastic based?
We’re based in Crawley, and we cover South East England, London and all of Scotland.
Do you need sand mastic in How Green?
Scraping and sanding before painting can loosen old mastic. It’s often found when windows are being prepared for paint, which is a good time to renew it.
People normally contact us after spotting one of these:
- Tired mastic found when preparing windows for paint
- Wind and rain getting in round a sash window
- Cement or filler used on old window joints that has cracked
- Gaps where the frame meets the masonry
For site and facilities teams at buildings such as Hever Church of England Voluntary Aided Primary School, the mastic around its windows and doors needs looking after like any other building’s.
Questions to ask before booking
- Are they insured?
- Whether they seal over old material or remove it
- What guarantee comes with the work
- How long to leave it before use
Work for landlords, hotels and businesses
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
If you manage several properties in or around How Green, several properties can go on one quote. Send us the addresses and the work at each.
Keeping the joints in good condition
Looking after new joints is easy:
- Look over the window mastic once a year
- Avoid heavy scraping on the mastic joint
- Clear gutters so water doesn’t pour onto the windows
- Don’t paint over the new mastic
Leave the new mastic alone while it firms up. It skins over quickly but needs longer to fully harden.
Renewing mastic before redecorating saves doing it twice. Paint over cracked mastic only covers it up.
What happens on the day
There’s no need to move everything out, just the space around the work. We protect the rest, and the job takes anything from a few hours to a full day, depending on how many windows in most cases. Somewhere like How Green needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. We bring what the job needs, so it can be finished in one trip where possible.
- We start by checking each surround and agreeing the joints to renew.
- We rake out the old mastic and clean the joint.
- We pack any deep gaps so the mastic sits at the right depth.
- The mastic is mixed, pressed into the joint by hand and shaped.
- The mastic is finished to sit tidily against the stone or brick.
How to prepare
- Clear items away from the joints we are working on
- Let us know if you’ve seen damp or leaks
- Let us know about stairs, lifts or work at height
Get a quote
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we will explain how we’d tackle it. When it suits you, phone 0345 464 0079 or send us an email.
Related advice
When something else is needed
Before you book, it’s worth knowing the limits too:
- Rotten sashes, sills or window boxes (a joiner’s job)
- Sash cords, weights and draught-proofing of the sashes
- Broken panes
If in doubt, call 0345 464 0079 or drop us an email and we will say what we think.
Surfaces we seal
- Stone surrounds
- Sash and case windows
- Tenement windows
- Period & listed homes
- Brick reveals
- Timber door frames
How Green homes and the weather
Historic houses like Hever Castle (about 0.7 miles south) are a reminder that the area around How Green has older buildings as well as new. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window. The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Rented homes near Hever station change hands often, and older sash windows in a rental need their mastic kept sound to keep the weather out. For an older house near a landmark such as Church of St Peter, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
How Green is about 7 miles south-west of Sevenoaks, in Kent. From the centre of How Green to the outskirts, we cover sand mastic for every kind of property. How Green is one of 922 towns and villages in Kent we cover. For nearby work, see our Crawley page.
Here we cover the TN8 postcode area for sand mastic. If you need sand mastic at a property on Hever Road and How Green Lane or a nearby road, we can help. Nearby, we also carry out sand mastic in Hever (1 mile south), Newtown (2 miles south), Markbeech (2 miles south), Chiddingstone Causeway (3 miles east) and Chiddingstone Hoath (3 miles south-east). Within a short drive, we also cover Sevenoaks (7 miles north-east), Royal Tunbridge Wells (8 miles south-east), Tonbridge (7 miles east), Swanley (14 miles north), Kings Hill (14 miles east) and Paddock Wood (12 miles east).
Local landmarks in How Green
Locally, jobs take us to homes and businesses close to The Wheatsheaf Public House and Chiddingstone Castle Park and Gardens, among other places. The nearest railway station is Hever station, about 1.3 miles south-west of the centre. Well-known places in the area include Tandridge Priory (5.4 miles north-west) and Hever Castle (0.7 miles south).
What affects the cost of sand mastic
Jobs vary more than people expect. The main factors:
- Whether the work is at height
- Whether old sealant or filler has to be cut out
- The product the joint needs
- How much there is to do
No two jobs are quite the same, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all play a part, and we’ll explain the quote if you ask.
What we need to know
There’s no need for technical detail. Just tell us:
- The address or postcode of the job
- Any previous sealing or DIY work
- The problem you’ve noticed
- Any access issues, like height or stairs
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is, and add photos by email if you can.