Oxfordshire · England
Cumnor Sand Mastic
Our applicators work in Cumnor on traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old sealant removed completely, joints prepared properly and a one-year guarantee.
- Window mastic to renew ahead of painting
- Modern sealant on a period surround
- Gaps round a timber door in stone or brick
Signs you need sand mastic in Cumnor
Rain on the window surround works into any crack and loosens it further. Exposed elevations usually fail first.
If you can see any of these, it’s time to have the joints looked at:
- Cracked mastic round a front door frame
- Patchy fillers round a sash window
- Crumbling sand mastic round a window
- A silicone bead on a sash window that spoils the look
If you look after a building such as Cumnor Church of England School (Voluntary Controlled), its window and door frames need their mastic kept sound, just like a home’s.
Comparing quotes
- What guarantee comes with the work
- What insurance they hold
- Which sealant they’ll use, and why
- How much experience the applicator has
How we handle sand mastic in Cumnor
Sand mastic doesn’t last for ever, leaving gaps round the window. We rake it out and renew it and tidies the surround. We work on sash and case windows, timber door frames and brick reveals, and people most often call us about crumbling sand mastic round a window and cement or filler used on old window joints that has cracked.
Somewhere as small as Cumnor, 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 one-year guarantee comes as standard, so you are covered after we have gone.
- Where
- Cumnor (OX2)
- Wider area
- Oxfordshire
- Guarantee
- 12 months on all our work
- Price
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
FAQs for Cumnor
Will you come out to Cumnor?
Yes, we do. Our work covers London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
I let a flat near Oxford station. Can you help?
Yes, rental work is part of what we do. Just ring 0345 464 0079 or email us and tell us about the property, and we will give you a clear price.
Can I do it myself?
Sometimes. The key is preparation: remove all the old material and work on a clean, dry joint. If it does not work out, we can redo it.
Do you hold any approvals?
Yes. We’re ARBOMaster approved, the scheme for applicators of Arbo sealants.
Will there be a smell?
It depends on the product. Some products have a noticeable smell, others very little, and any smell fades as they cure.
What’s sand mastic made of?
A traditional pointing material made from sand and a linseed-oil-based binder for the joint between timber frames and masonry.
Do I need permission for sand mastic on a listed building?
Speak to your local planning authority before work starts. Like-for-like sand mastic is often the preferred finish but the decision is theirs.
How long does sand mastic take to go off?
A skin forms quite soon, but full hardening takes longer. We’ll tell you what to expect for your job.
Why deal with it now?
If you’re redecorating, renew the mastic first. Paint over cracked mastic will not stop the gaps, and the new mastic is traditionally left unpainted. In a small place like Cumnor, homes can be exposed to wind and rain, which finds any gap, and older walls, once damp, take a long time to dry.
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all make a difference, and we will explain the quote if you ask.
Why Cumnor clients choose us
- Over 20 years’ experience
- Domestic, commercial and hotel work
- We never seal over old sealant
- Full insurance on every job
What we do, step by step
When we arrive, we look over the joints with you first, so you know exactly what we’re doing. We protect the surfaces around the joints before any work begins. Most jobs take a few hours for a single window, longer for several. For a village or hamlet like Cumnor, the journey is planned in advance: tell us about narrow lanes, gates, long drives and where we can park. We bring what the job needs, so it can be finished in one trip where possible.
- First we agree which joints need doing.
- We remove the old, loose mastic.
- Deep gaps are packed so the mastic sits at the right depth.
- The sand mastic is mixed and pressed into the joint by hand.
- We dress the finish so it sits neatly against the masonry.
Preparing for the visit
- Tell us about any previous sealing or DIY attempts
- For indoor joints, keep the area dry beforehand if you can
- For business premises, tell us about site rules or sign-in
How to get a quote
Every job is quoted individually, so start by telling us what you need. Just ring 0345 464 0079 or drop us an email with the details.
Read more
DIY versus a professional finish
A DIY attempt does not rule out a professional job. We remove it and do the joint properly, so just mention it when you contact us.
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
Nearby places to Cumnor
Also in Cumnor
Quotes for sand mastic in Cumnor
You will get a clear quote before we start. It’s based on:
- How many areas need sealing
- Access and height
- Any working-time requirements on site
- Any mould that needs treating
Homes and businesses are quoted the same way: the amount of work, the access and the products needed, along with when we can work on site. Call for a quick quote and we will explain what it covers.
What to tell us for a quote
When you call or email, it’s useful to know:
- Where the property is
- If it’s domestic, commercial or a hotel
- How many joints, rooms or windows are involved
- Access, such as stairs, a lift or height
If you are in Cumnor and need sand mastic, ring 0345 464 0079 or drop us an email. A short description of the job and where it is helps us quote, and you’ll get a clear quote before work begins.
Sand mastic in Cumnor: local notes
With historic houses such as Appleton Manor (about 1.9 miles south-west) nearby, there’s older building stock in the area around Cumnor 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. 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.
In the older streets around Church of St Michael, frames set in older brick or stone need a sealant that suits the wall as well as the frame. If you let a flat or house near Oxford station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
Cumnor is about 4 miles north-west of Abingdon-on-Thames, in Oxfordshire. From the centre of Cumnor to the outskirts, sand mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Cumnor is one of 443 places in Oxfordshire where we work.
Work in OX2 works the same way as everywhere else we cover. That includes homes and businesses on High Street, The Park and The Winnyards and the roads around them. Neighbouring places we cover for sand mastic include Chawley (1 mile north-east), Filchampstead (1 mile north-west), Henwood (1 mile south-east), Dean Court (2 miles north-east) and Botley (2 miles north-east). Larger places within reach include Oxford (5 miles east), Didcot (9 miles south-east), Bicester (14 miles north-east), Abingdon-on-Thames (4 miles south-east), Witney (8 miles north-west) and Carterton (11 miles west).
Local landmarks in Cumnor
We work in homes and buildings around The Vine Inn and Matthew Arnold School and the streets around them. The nearest railway station is Oxford station, about 3.1 miles north-east of the centre. Well-known places in the area include Westgate Shopping Centre (3.3 miles north-east) and Radcliffe Infirmary (3.6 miles north-east). For a walk, there’s Lashford Lane Fen and Cumnor Hill.
Keeping the joints in good condition
How long the joints last depends on use and care. Here’s what we suggest:
- Plan mastic work ahead of painting
- Avoid heavy scraping on the mastic joint
- Make sure water runs off the sill
- Keep modern sealant off the mastic
Avoid sealing over the mastic with silicone. If you see a crack, ask us to take a look rather than patching it.
Good mastic helps keep the frame dry. Failed mastic lets water reach the timber, which can lead to rot.
Surface by surface
Brick reveals
Loose mastic comes out and deep gaps are packed before the new mastic goes in.
Stone surrounds
Stone openings are rarely perfectly straight, so the joint varies in width. Sand mastic is shaped by hand to suit.