Greater London · England

Sand Mastic in Belgravia

Traditional burnt sand mastic around sash and case windows and doors in stone and brick for householders, landlords and businesses in Belgravia. Fully insured, ARBOMaster approved and guaranteed for a year.

Gaps where the frame meets the masonry
Tired mastic found when preparing windows for paint
Wind and rain getting in round a sash window

Book sand mastic in Belgravia

Call 0345 464 0079

Get a quick quote

How we handle sand mastic in Belgravia

Old sand mastic cracks, crumbles and falls out over time and gaps open up round the frame. We rake it out and renew it so the surround looks right again. We are often asked to deal with window mastic to renew ahead of painting and mastic worn away on windows facing the weather, across period & listed homes, sash and case windows and brick reveals.

London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. The mastic around them dries out and cracks with age, which is when draughts and damp patches appear in homes in Belgravia.

There’s a 12-month guarantee on every job, large or small.

Location: Belgravia (SW3, SW1X, SW1W)
Wider area: Greater London
Cover: A year, on every job
Quotes: A clear price before any work starts
Call: 0345 464 0079
Updated: 26 October 2026

Mr Mastic applicator sealing the top of a white uPVC door frame on a red-brick house

Surface by surface

Period and listed homes

On a listed home or in a conservation area, the right material matters. Like-for-like sand mastic is usually favoured.

Stone surrounds

Stone openings are rarely perfectly straight, so the gap is not the same all the way round. We shape it by hand to follow the stone.

DIY sealant or a professional job?

Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.

A DIY attempt doesn’t rule out a professional job. We cut it out and start again, so just mention it when you contact us.

Belgravia: your questions answered

Is parking a problem for a job in Belgravia?

London parking needs a little planning, so let us know about permits, bays or a driveway when you book. That way the visit can be planned around it.

Can you do sand mastic in Belgravia?

Yes, Belgravia is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or drop us an email and let us know what needs doing, and we’ll give you a clear price.

Will you leave a mess?

Tidy work is part of the job. Nearby surfaces are protected.

How much does sand mastic cost in Belgravia?

The cost depends on the size of the job, access and how much old sealant has to come out. Ask us for a quote.

What should I tell you?

Just the basics: where it is, what you’ve noticed and how we reach it. After that, simply phone 0345 464 0079 or send us an email.

Where is Mr Mastic based?

We are a Crawley-based firm. Our area covers South East England, London and Scotland.

Which is right for my windows, sand mastic or modern sealant?

We will talk it through with you. Sand mastic suits many period homes, and modern sealants suit newer frames.

Do you have insurance?

Yes. We’re fully insured, and we can confirm the details when we quote.

For landlords and businesses

We also work for property managers and facilities teams. Several sites can be quoted together, and we are fully insured for the work.

Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.

Windows and doors in Belgravia

In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking. Historic houses like Apsley House (about 0.4 miles north) are a reminder that the area around Belgravia has older buildings as well as new. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window.

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 St Peter's Church, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.

Belgravia is about 1 mile south of City of Westminster, in Greater London. Belgravia gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a one-year guarantee. Our area takes in 764 places across Greater London.

All of SW3, SW1X and SW1W is within our area for sand mastic. We cover properties on Hans Road, Eaton Lane and Gerald Road. Belgravia is on the A3214 and A3217, so it’s easy for us to get to with everything needed for sand mastic. We also cover the places around Belgravia: Brompton (1 mile south-west), Victoria (1 mile south-east), Chelsea (1 mile south-west), Pimlico (1 mile south-east) and Westminster (1 mile east). Larger places within reach include London (3 miles east), St Pancras (3 miles north-east), Shoreditch (4 miles north-east), Walthamstow (8 miles north-east), Hoxton (4 miles north-east) and Whitechapel (4 miles east).

Near you in Belgravia

Typical jobs here are in homes near Saint Thomas More Language College, Green Park and Natural History Museum Library and Archives. Other local landmarks include Star Tavern (less than half a mile north-west) and Inchbald School of Design (under half a mile south). For rail, the closest station is London Victoria station, roughly 0.5 miles south-east of the centre. Nearby you’ll also find Health Exhibition Centre (less than half a mile south-east) and Harrods (less than half a mile west). The countryside around Belgravia includes Campden Hill and Serpentine.

Map of Belgravia © OpenStreetMap contributors

What we do, step by step

Before we leave, we go over the finished joints with you and tell you how long to leave it. The work normally takes a few hours per window, depending on the condition of the joints, depending on the size of the job. In Belgravia, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.

We start by checking each surround and agreeing the joints to renew.
Old, loose mastic is raked out and the joint cleaned.
Large voids are packed out first, so the mastic isn’t too thick.
Sand mastic is mixed and applied by hand, then shaped to the joint.
The finish is dressed so it sits neatly against the stone or brick.

Getting ready for the visit

Clear the area around the work
Mention if the joints have been sealed before
Keep children and pets away from the work area

How to get a quote

For sand mastic in Belgravia, call 0345 464 0079 or email us. Tell us what the problem is and where, and you will get a clear quote before we start.

Ask for a quote

Related advice

How we quote for sand mastic

Your quote is based on your job. We look at:

The type of sealant required
Access and height
How many rooms, windows or areas are involved
When we can work, for business premises

Commercial jobs are quoted on the same basis as homes: the amount of work, the access and the products needed, plus any working-time requirements on site. Call for a quick quote and we will go through it with you.

What to tell us for a quote

A few details help us give you an accurate quote. When you get in contact, it helps to mention:

Any access issues, like height or stairs
The address or postcode of the job
The problem you’ve noticed
How many joints, rooms or windows are involved

It all starts with a short chat. 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.

What happens if it’s left?

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. In older London homes, water behind a failed joint soaks into brick and timber without much sign, and by the time it shows on a wall or ceiling in Belgravia, the repair is bigger than the sealant job would have been.

The cost 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 work begins, so you know where you stand.