Windsor and Maidenhead · England
Sand mastic for sash & case windows in Blacknest, Windsor and Maidenhead
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for householders, landlords and businesses in Blacknest. Fully insured, ARBOMaster approved and guaranteed for a year.
- Tired mastic found when preparing windows for paint
- Crumbling sand mastic round a window
- Gaps round a timber door in stone or brick
About our sand mastic in Blacknest
We renew sand mastic around sash windows and doors in stone and brick. The old mastic is raked out, the joint is prepared and new mastic is shaped by hand. Common call-outs are for cement or filler used on old window joints that has cracked and wind and rain getting in round a sash window, across brick reveals, stone surrounds and period & listed homes.
Mastic can only go onto a dry, clean joint, so window work in Blacknest is booked around the forecast. Let us know about access to all the frames, upstairs ones included.
The work is guaranteed for twelve months. If there’s a problem with our work within the year, let us know and we’ll sort it.
- Place
- Blacknest (SL5)
- Region
- Windsor and Maidenhead
- Cover
- One year on every job
- Quote
- A clear price before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Windows and doors in Blacknest
Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. Historic houses like St Leonard's Hill (about 4.2 miles north) are a reminder that the area around Blacknest 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.
For site and facilities teams at buildings such as Holy Trinity CofE Primary School, its window and door frames need their mastic kept sound, just like a home’s. For an older house near a landmark such as Holy Trinity Church, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Blacknest is about 4 miles west of Egham, in Windsor and Maidenhead. We provide sand mastic to homes and businesses in Blacknest and nearby. Blacknest is one of 57 towns and villages in Windsor and Maidenhead we cover for sand mastic. For nearby work, see our Reading page (15 miles or so).
Jobs for sand mastic in SL5 is quoted and booked the same way as anywhere else. We cover properties on London Road and Blacknest Gate Road. Neighbouring places we cover for sand mastic include Beggar's Bush (1 mile south-west), Cheapside (1 mile north-west), Sunninghill (1 mile west), Ascot (2 miles west) and Woodside (2 miles north-west). Further out, we also cover Maidenhead (9 miles north-west), Windsor (5 miles north), Boyn Hill (9 miles north-west), North Ascot (3 miles west), Cookham (11 miles north-west) and Furze Platt (10 miles north-west).
Local landmarks in Blacknest
Around Blacknest, our work takes us to homes and buildings near The Belvedere Arms, Silwood Park and Sunningdale School and the streets around them. Blacknest’s nearest station is Sunningdale station, roughly 1.3 miles south. A little further out are Heatherwood Hospital (2.7 miles west). Open spaces near Blacknest include St Ann's Hill and Gracious Pond.
Honest limits
We won’t take on work that will not last, so these are the limits:
- Sashes that rattle, stick or will not open
- Crumbling stone or brickwork round the window
- Decayed frames that need repair
If you are not sure, just call 0345 464 0079 or email us and we will give you a straight answer.
Joints and surfaces we work on
- Sash and case windows
- Brick reveals
- Stone surrounds
- Timber door frames
- Tenement windows
- Period & listed homes
What happens on the day
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 a few hours for a single window, longer for several from start to finish. For a village or hamlet like Blacknest, the journey is planned in advance: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- Each surround is checked first.
- We rake out the old mastic and clean the joint.
- Large voids are packed out.
- We point the joint with sand mastic by hand.
- We finish the mastic to a tidy line.
Getting ready for the visit
- Tell us if parking is tricky
- For business premises, tell us about site rules or sign-in
- Try not to wet indoor joints just before the visit
How to get a quote
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we’ll explain how we’d tackle it. When it suits you, ring 0345 464 0079 or drop us an email.
Related advice
Can I do it myself?
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is chosen for how the joint moves and where it is, then guaranteed for a year.
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.
Landlord and commercial work in Blacknest
We also work for businesses, from offices to washrooms and kitchens. For commercial premises, we can talk through working times when we quote.
Housing providers, facilities teams and property managers book us too. We can quote a run of properties together, and we’re fully insured.
FAQs for Blacknest
Is Blacknest in your area for sand mastic?
Yes, Blacknest is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or email us with a few details of the job.
Do you work for landlords with property near Sunningdale station?
Yes, rental work is part of what we do. Just ring 0345 464 0079 or drop us an email and tell us about the property, and we’ll give you a clear quote.
Is it OK to seal over old sealant?
No. Fresh sealant doesn’t stick to old sealant, and it traps any mould or water underneath. We remove it all first.
Do I need permission for sand mastic on a listed building?
Yes, it’s worth checking. Ask your local planning authority whether consent is needed for work on a listed home or in a conservation area.
Can you replace silicone on a period window with sand mastic?
Yes, we do this often. The old silicone has to come out completely so the mastic can sit properly.
Should I try DIY first?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Will it make a mess?
We keep the work tidy. Nearby surfaces are protected, and the area is left clean when we finish.
Are you ARBOMaster approved?
Yes. We are an ARBOMaster approved applicator, the approved applicator scheme for Arbo sealants.
Towns and villages near Blacknest
More services for Blacknest
Different surfaces, different methods
Stone surrounds
The stone is treated with care while raking out the old mastic.
Brick reveals
Loose mastic comes out and deep gaps are packed before the new mastic goes in.
Signs you need sand mastic in Blacknest
Paint, silicone or cement used over old mastic causes problems. They do not suit the joint, and they normally need raking out.
Signs it’s time to call us include:
- Silicone on a period window that looks wrong
- Draughts and rain around sash boxes
- Crumbling sand mastic round a window
- Mastic worn away on windows facing the weather
Rented homes near Sunningdale station change hands often, and cracked sand mastic around sash windows lets in the draughts tenants complain about.
What your quote should include
- What preparation is included
- How long to leave it before use
- Whether you can choose the colour
- Who does the work, and how experienced they are
Leave it or put it right?
Replacing sash windows is a big decision for a period home and on a listed home, consent may be needed. Where the frames are in good order, new mastic seals the surround. Around Blacknest, older homes often have timber in their floors and frames, where water from a failed joint can cause rot if it’s left.
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. You’ll know the price before we begin.
Why us?
- Tidy, careful work
- More than 20 years in sealant work
- Experience in homes, commercial sites and hotels
- Full insurance on every job
Read our cost guide and customer reviews.