Kent · England
Comp Sand Mastic
Specialist sand mastic for Comp: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Weathered mastic on the most exposed windows
- Gaps round a timber door in stone or brick
- Tired mastic found when preparing windows for paint
Should I try it myself first?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is.
Sealing over old silicone is the commonest DIY error. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
About our sand mastic in Comp
Sand mastic skins over fairly quickly, but it takes longer to harden fully. Traditional guidance is not to paint over it and we’ll advise if you are redecorating. We work on sash and case windows, stone surrounds and brick reveals, and the jobs we see most are gaps round a timber door in stone or brick and window mastic to renew ahead of painting.
Homes in small places like Comp often stand in the open, with little to shelter their windows from wind and rain. Exposed frames and sills lose their mastic sooner than sheltered ones.
A 12-month guarantee comes with the work, just as it does everywhere we cover.
- Location
- Comp (TN15)
- Wider area
- Kent
- Cover
- 12 months on all our work
- Quote
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Also in Comp
What affects the quote in Comp
The price is agreed before any work begins. It’s based on:
- Whether the work is at height
- The number of rooms or windows
- The old material and how stubborn it is
- Which sealant suits the joint
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please phone 0345 464 0079 or send us an email.
What we need to know
What to tell us when you ask for a quote:
- Any previous sealing or DIY work
- What the problem is, such as mould, gaps, leaks or cracking
- Whether it’s a home or a business
- A few photos by email, if you can
For a quote, phone 0345 464 0079 or drop us an email with the location and a short description of the problem. You’ll have a clear quote before work begins.
Keeping the joints in good condition
No joint lasts for ever, but care makes a real difference. A few tips:
- Avoid heavy scraping on the mastic joint
- Renew mastic before redecorating the windows
- Avoid patching sand mastic with silicone
- Find out about consent before window work on a listed home
Keep paint scrapers and sanders off the mastic when redecorating. Hard scraping can loosen it.
Crumbling mastic lets rain into the joint. That water can reach the timber frame and the wall so early renewal protects both.
Work for landlords, hotels and businesses
If you manage several properties in or around Comp, several properties can go on one quote. Send us the addresses and the work at each.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. Several properties can be quoted together.
Sand mastic in Comp: local notes
London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as Old Soar Manor (about 1.7 miles south-west) nearby, there’s older building stock in the area around Comp as well as newer homes. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window.
Letting a property close to Borough Green & Wrotham station? Then cracked sand mastic around sash windows lets in the draughts tenants complain about. If you look after a building such as Platt Church of England Voluntary Aided Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Comp is about 3 miles west of Kings Hill, in Kent. Anywhere in TN15, we cover sand mastic for homes and businesses. We cover 922 towns and villages across Kent, large and small. London is on our list too, about 24 miles from Comp.
Here we cover the TN15 postcode area for sand mastic. We also cover Platt (1 mile north-west), Wrotham Heath (1 mile north-east), Crouch (1 mile south-west), Claygate Cross (1 mile south-west) and Borough Green (1 mile west). We also work in nearby towns such as Maidstone (8 miles east), Dartford (12 miles north-west), Sevenoaks (7 miles west), Royal Tunbridge Wells (11 miles south), Gravesend (10 miles north) and Tonbridge (7 miles south-west).
Near you in Comp
Typical jobs here are in homes near The Blue Anchor pub and Wrotham School and the streets around them. Comp’s nearest station is Borough Green & Wrotham station, roughly 1.5 miles west. Nearby you’ll also find Ightham Court (2.3 miles west) and Beechin Wood Archery Museum (less than half a mile west).
Why deal with it now?
Silicone might seem the quicker option, but on period stone or brick it often looks out of place. Sand mastic suits the building and blends with the stone or brick. Older cottages and farmhouses around Comp can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
What it costs depends on the amount of work, how much old material has to come out and how easy the joints are to reach. We give a clear quote before any work starts, so you know where you stand.
Why book with us
- More than 20 years in sealant work
- Fully insured
- Rated 4.9 stars on Google
- Neat joints and a tidy finish
Read our cost guide and our reviews.
Comp: your questions answered
Can you do sand mastic in Comp?
Yes, Comp is within the area we cover. We work across London and the South East. You can call 0345 464 0079 or drop us an email and tell us what needs doing.
Will you come out to Comp?
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.
Where is Mr Mastic based?
We’re a Crawley-based firm. We work across South East England, London and Scotland.
What should I tell you?
Just the basics: where it is, what you’ve noticed and how we reach it. Then phone 0345 464 0079 or drop us an email.
Is consent needed for window work on a listed home?
Speak to your local planning authority before work starts. Like-for-like sand mastic is often the preferred finish but the decision is theirs.
Does someone need to be in?
We need access to the joints, so we’ll agree that with you when we book. Indoors, that normally means someone at home.
Can new sealant go over the old?
No, and we never do. It may look fine at first, but the new layer lifts away from the old one. The old sealant has to come out completely.
Do you guarantee sand mastic work?
Our 12-month guarantee applies on every job.
What happens on the day
Our applicators work methodically: protect, prepare, seal, tidy. Typically it takes a few hours for a single window, longer for several. Somewhere as small as Comp, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We start by checking each surround and agreeing the joints to renew.
- Old, loose mastic is raked out and the joint cleaned.
- 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.
- We dress the surface so it sits neatly against the masonry.
Getting ready for the visit
- Tell us about access, such as stairs, a lift or high-level joints
- Try not to wet indoor joints just before the visit
- Mention any parking rules near the property
Ask for a quote
Call for a quick quote, or email us if that’s easier. Tell us about the joints that need doing and we’ll talk you through the work before giving you a price.
Advice
What we are called out for in Comp
Timber swells and shrinks with the weather. That movement opens up the mastic joint over time.
Any of these means the joints need attention:
- Crumbling sand mastic round a window
- Window mastic to renew ahead of painting
- Draughty sash windows at the surround
- Open joints round the window box
In the older streets around Church of St Mary, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Comparing quotes
- How the colour is chosen
- How the joint is cleaned and prepared
- What the cure time is
- What product goes in the joint