Oxfordshire · England
Sand mastic for sash & case windows in Merton, Oxfordshire
Our applicators work in Merton on traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old material cut out, joints cleaned and sealed neatly and a 12-month guarantee.
- Crumbling sand mastic round a window
- Window mastic to renew ahead of painting
- Patchy fillers round a sash window
Sand mastic in Merton, done properly
A silicone bead around a sash window can look out of place and does not suit the building. Sand mastic is the traditional choice, and we can replace one with the other. We are often asked to deal with modern sealant on a period surround and mastic dropping out of the joint, across sash and case windows, stone surrounds and tenement windows.
In a village or hamlet like Merton, older cottages and farmhouses often have timber windows set in stone or brick. Older buildings like these don’t always suit modern silicone, so the sealant has to be chosen to suit the building.
Whatever the size of the job, it’s backed by our 12-month guarantee in Merton and across Oxfordshire.
- Where
- Merton (OX25)
- Wider area
- Oxfordshire
- Cover
- One year on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Why act early in Merton
New mastic over crumbling mastic won’t hold. Raking out and preparing the joint gives it a sound base so the new work lasts. In a small place like Merton, homes can be exposed to wind and rain, which finds any gap, and damp in older walls is slow to dry out.
Homes and businesses are quoted the same way: the amount of work, the access and the products needed, plus any working-time requirements on site. Ask us for a quote and we will explain what it covers.
What you get with us
- Trusted Arbo and Everbuild sealants
- Homes, businesses and hotels
- ARBOMaster approved applicator
- Anti-fungal sanitary silicone in wet areas
Read our cost guide and our reviews.
How to look after the new joints
After the cure time, these simple habits help:
- Take care around the mastic when scraping paint
- Inspect the joints round the windows every year or so
- Plan mastic work ahead of painting
- Make sure water runs off the sill
Avoid painting over the new mastic, which is the traditional advice. If you’re redecorating, ask us first.
It’s best to renew mastic before painting the windows. Paint over cracked mastic only covers it up.
Signs you need sand mastic in Merton
Timber swells and shrinks with the weather. The movement cracks the mastic little by little.
Keep an eye out for these signs:
- Failed mastic on an exposed elevation
- Modern sealant on a period surround
- Window mastic to renew ahead of painting
- Cement or filler used on old window joints that has cracked
Letting a property close to Bicester Village station? Then any sash windows need sound mastic to keep draughts and rain out.
What your quote should include
- How the colour is chosen
- What preparation is included
- Whether all the old sealant comes out first
- How much experience the applicator has
Common questions in Merton
Do you work for landlords with property near Bicester Village station?
Yes. We work for letting agents and landlords as well as homeowners, and several properties can be quoted together. You can call 0345 464 0079 or send us an email with the details for a clear quote.
Will you come out to Merton?
Yes, Merton is covered. We work across London and the South East, and smaller places are part of that. The journey is planned ahead, so it helps to know about access.
Is it possible to take out silicone and use sand mastic instead?
Often, yes. Once the silicone is out and the joint prepared, sand mastic is applied by hand.
Do I need permission for sand mastic on a listed building?
Your local planning authority is the one to ask. They decide whether consent is needed.
Will it make a mess?
No. We protect the surfaces around the joints, and we tidy up before we go.
How much does sand mastic cost in Merton?
It depends on the job, so we quote each one individually. To get one, call 0345 464 0079 or email us with a short description of the job.
What’s sand mastic made of?
It’s the traditional filler for the joint round timber windows and doors. It combines sand with a linseed-oil-based binder.
What guarantee comes with the work?
Every job comes with our 12-month guarantee.
Nearby places to Merton
What else we do in Merton
How we quote for sand mastic
Your quote is based on your job. We take into account:
- How much old sealant there is and how hard it is to remove
- The number and length of the joints
- Mould in or behind the old joints
- When we can work, for business premises
What it costs depends on the size of the job, how hard the old material is to remove and how easy the joints are to reach. We give a clear quote before work begins, so you know where you stand.
Helping us quote
The more you tell us, the more accurate the quote. When you ask for a quote, tell us:
- Pictures of the joints, sent by email
- Any access issues, like height or stairs
- Where the property is
- If someone has resealed it before
For a quick quote, get us on the phone, or email us if that is easier. Describe what needs sealing and we’ll explain what’s involved.
The process
Every visit runs the same way: we look at the joints together, protect the area around them, carry out the job and clear up. It normally takes a few hours per window, depending on the condition of the joints. Somewhere as small as Merton, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We check the window surrounds and agree which joints need renewing.
- The loose and crumbling mastic is raked out and the joint cleaned.
- Large voids are packed out first, so the mastic is not 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.
Preparing for the visit
- For indoor joints, keep the area dry beforehand if you can
- Let us know if you’ve seen damp or leaks
- Mention any parking rules near the property
Getting a quote
There’s no standard price list, as no two jobs are quite the same. Instead, your job gets its own clear quote. To arrange one, ring 0345 464 0079 or drop us an email.
Related advice
Different surfaces, different methods
Stone surrounds
Stone openings are rarely perfectly straight, so the joint varies in width. Sand mastic is shaped by hand to suit.
Period and listed homes
Sand mastic is the like-for-like choice for many period homes. On listed buildings, check with your planning authority first.
Merton homes and the weather
London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Boarstall Tower (about 3.7 miles south-east) are a reminder that the area around Merton 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.
Homes close to Church of St Swithin include some older properties, and the joint between an old wall and a newer frame is usually the first place rain gets in.
Merton is about 3 miles south of Bicester, in Oxfordshire. Merton gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a one-year guarantee. We cover 443 towns and villages across Oxfordshire, from the larger towns to small villages. Oxford is on our list too, about 8 miles from Merton.
Postcode districts we cover here for sand mastic: OX25. If you’re just outside Merton, we cover Fencott (1 mile south), Murcott (1 mile south-east), Charlton-on-Otmoor (1 mile south-west), Wendlebury (2 miles north-west) and Lower Arncott (2 miles east). We also work in nearby towns such as Oxford (8 miles south), Bicester (3 miles north), Abingdon-on-Thames (13 miles south), Witney (15 miles west), Thame (11 miles south-east) and Kidlington (6 miles south-west).
Local landmarks in Merton
We work in homes and buildings around The Old Plough pub, among other places. For rail, the closest station is Bicester Village station, about 2.7 miles north of the centre. A little further out are Bicester Community Hospital (2.9 miles north) and Bicester Avenue (2.3 miles north). For a walk, there’s Graven Hill and Woodsides Meadow.
DIY versus a professional finish
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.