Windsor and Maidenhead · England
Sand mastic for sash & case windows in Cold Harbour, Windsor and Maidenhead
Problem with your window and door surrounds in Cold Harbour? We cut out the old, prepare the joints and apply the right sealant, with a 12-month guarantee.
- Patchy fillers round a sash window
- Mastic dropping out of the joint
- Gaps where the frame meets the masonry
About our sand mastic in Cold Harbour
For a listed home or one in a conservation area, ask your local planning authority whether consent is needed for work to windows. Like-for-like sand mastic is often the preferred finish. We work on stone surrounds, tenement windows and sash and case windows, and the jobs we see most are crumbling sand mastic round a window and draughty sash windows at the surround.
Somewhere as small as Cold Harbour, older homes often have timber frames set in stone or brickwork. Older buildings like these do not always suit modern silicone, and sometimes a traditional sand mastic is the better choice.
A 12-month guarantee comes as standard, so you are covered after we have gone.
- Where
- Cold Harbour (SL6)
- Region
- Windsor and Maidenhead
- Guarantee
- One year on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Why act early in Cold Harbour
New sash windows are a major, costly change and on a listed home, consent may be needed. Where the frames are in good order, new mastic seals the surround. Where a wall is exposed, as many are in small places like Cold Harbour, wind-driven rain gets into any failed joint, and older walls, once damp, take a long time to dry.
Doing several joints on one visit usually makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
Why us?
- A 12-month guarantee on all work
- Approved under the ARBOMaster scheme
- Old sealant always removed completely
- We leave the area clean and tidy
Read what affects the cost or customer reviews.
Places near Cold Harbour
Also in Cold Harbour
How it works
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. Somewhere as small as Cold Harbour, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First we agree which joints need doing.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
How to prepare
- Move anything stored near the joints
- Let us know if you’ve seen damp or leaks
- Tell us about access, such as stairs, a lift or high-level joints
Ask for a quote
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To get started, ring 0345 464 0079 or email us.
Related advice
DIY versus a professional finish
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and doesn’t move well, and getting the depth right matters as much as the look.
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
Looking after it afterwards
After the cure time, these simple habits help:
- Ask a joiner to look at soft timber first
- Leave the new mastic unpainted
- Ask the planning authority about consent for listed or conservation-area homes
- Make sure water runs off the sill
Don’t touch or press the mastic while it hardens. It skins over quickly but needs longer to fully harden.
Gaps round a sash box let in draughts and rain. The longer it’s left, the more the joint opens.
When to call us in Cold Harbour
Over the years, sand mastic weathers. It hardens, cracks and starts to come away from the frame or the masonry.
The problems people usually mention when they call are:
- Tired mastic found when preparing windows for paint
- Weathered mastic on the most exposed windows
- Old cement repairs round a window that have failed
- Crumbling sand mastic round a window
For site and facilities teams at buildings such as Knowl Hill Church of England Primary Academy, its window and door frames need their mastic kept sound, just like a home’s.
What your quote should include
- What the quote includes, VAT included or not
- What happens if the job turns out different
- What the cure time is
- Whether you can choose the colour
When it is not the sealant
We will always be straight with you, so here’s what sealant can’t fix:
- Crumbling stone or brickwork round the window
- Decisions on consent for listed homes
- Sash cords, weights and draught-proofing of the sashes
Not sure which it is? You can phone 0345 464 0079 or email us and we’ll tell you honestly.
Joints and surfaces we work on
- Period & listed homes
- Tenement windows
- Sash and case windows
- Brick reveals
- Timber door frames
- Stone surrounds
Different surfaces, different methods
Stone surrounds
Old stone surrounds are often uneven, so the joint varies in width. We shape it by hand to follow the stone.
Period and listed homes
Many older homes were built with sand mastic round the windows. On listed buildings, check with your planning authority first.
Cold Harbour questions
I let a flat near Wargrave station. Can you help?
Yes, rental work is part of what we do. You can ring 0345 464 0079 or send us an email with the address and a few details, and we’ll give you a fixed price before we start.
Is Cold Harbour within the area you cover?
Yes, Cold Harbour is covered. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Which is right for my windows, sand mastic or modern sealant?
We will help you decide. Sand mastic suits many period homes and newer frames suit modern sealant.
Do I have to be there?
We need access to the joints, so we will agree that with you when we book. For inside work, that normally means someone being in.
Is it messy?
We keep the work tidy. We protect what’s around the joints, and we clear up when we’re done.
Can I add another job to the visit?
Yes, and it often makes sense. Doing several areas at once is generally more efficient.
Which products do you use?
Products from Arbo and Everbuild, among others, chosen to suit the joint. We will tell you what we are using and why.
Do you hold any approvals?
Yes. We’re ARBOMaster approved, the scheme for applicators of Arbo sealants.
What sand mastic looks like in Cold Harbour
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. With historic houses such as Harleyford Manor (about 3.3 miles north) nearby, there’s older building stock in the area around Cold Harbour 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.
Rented homes near Wargrave station change hands often, and cracked sand mastic around sash windows lets in the draughts tenants complain about. If you live in an older home near Saint Peter, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Cold Harbour is about 3 miles west of Maidenhead, in Windsor and Maidenhead. We provide sand mastic to homes and businesses in Cold Harbour, as part of our work across Windsor and Maidenhead. We cover 57 towns and villages across Windsor and Maidenhead, from the larger towns to small villages. Reading is on our list too, about 9 miles from Cold Harbour.
Postcode districts we cover here for sand mastic: SL6. If you’re just outside Cold Harbour, we cover Knowl Hill (1 mile north-west), Warren Row (1 mile north-west), Bowsey Hill (2 miles west), Cockpole Green (3 miles north-west) and Wargrave (3 miles west). We also work in nearby towns such as Maidenhead (3 miles east), Windsor (8 miles east), Boyn Hill (3 miles east), North Ascot (8 miles south-east), Cookham (5 miles north-east) and Furze Platt (3 miles north-east).
Local landmarks in Cold Harbour
We work in homes and buildings around Cox Green School and The Royal Oak pub, among other places. Cold Harbour’s nearest station is Wargrave station, about 3.3 miles west of the centre. Nearby you’ll also find St Mark's Hospital (2.8 miles north-east). Not far away are Hurley Chalk Pit and Taplow Lake.