Oxfordshire · England
Dorchester Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for Dorchester, backed by a 12-month guarantee. Ask us for a quote.
- Draughts and rain around sash boxes
- Window mastic to renew ahead of painting
- Cracked mastic round a front door frame
What we do, step by step
We bring everything the job needs with us, so you don’t need to buy or prepare anything. Once we have agreed what’s being done, we protect the area and start. Most jobs take a few hours for a single window, longer for several. In a small place like Dorchester, access is normally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- We check each window surround and the condition of the joint.
- The joint is raked out and cleaned.
- Large voids are packed out.
- We point the joint with sand mastic by hand.
- The finish is dressed neatly.
Before we arrive
- Try not to wet indoor joints just before the visit
- On commercial sites, let us know about site rules
- Tell us about any previous sealing or DIY attempts
Get a quote
Asking for a quote is easy: let us know what needs doing and where and its rough size. A few pictures by email make the job easier to understand, and we will take it from there.
Related advice
Sand mastic in Dorchester
Sand mastic has long been used to fill the joint between timber frames and masonry. It’s a mix of sand and a linseed-oil-based binder, applied by hand. On older homes, it suits the building far better than silicone. We work on period & listed homes, stone surrounds and sash and case windows, and the jobs we see most are wind and rain getting in round a sash window and gaps between timber frames and stone or brick.
In a village or hamlet like Dorchester, older cottages and farmhouses often have timber windows set in stone or brick. Older buildings like these don’t always suit modern silicone, and sometimes a traditional sand mastic is the better choice.
Every job comes with a one-year guarantee.
- Location
- Dorchester (OX10)
- Region
- Oxfordshire
- Guarantee
- 12 months on all our work
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Work for landlords, hotels and businesses
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements.
For anyone letting property in or around Dorchester, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs.
How the job changes by surface
Stone surrounds
The stone is treated with care when the old mastic comes out.
Sash and case windows
Sash windows are where we do most sand mastic work. We renew the mastic round each box.
Dorchester: your questions answered
Do you work for landlords with property near Culham station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or email us and tell us about the property, and we will send you a clear quote.
Can you do sand mastic in Dorchester?
Yes. Our work covers London and the South East, and Dorchester is part of that. You can ring 0345 464 0079 or send us an email and let us know what needs doing, and we will give you a clear price.
Do you hold any approvals?
Yes. We are approved under the ARBOMaster scheme.
Is it worth trying it myself?
It depends on the job. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional.
What do you need from me for a quote?
Only a few details: the address or postcode, what’s wrong and any access issues. After that, simply phone 0345 464 0079 or drop us an email.
Can new sealant go over the old?
No. The old sealant always comes out first.
When will the new mastic be hard?
Not straight away. The skin forms first, and the full set comes later and we will give you an idea for your job.
What does sand mastic cost?
Size, access and the old material all affect the cost. Call for a quick quote.
Windows and doors in Dorchester
With historic houses such as Clifton Hampden Manor (about 2 miles west) nearby, there’s older building stock in the area around Dorchester 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. Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
For an older house near a landmark such as Dorchester Abbey, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. If you look after a building such as Dorchester St Birinus Church of England School, larger buildings have plenty of frames, and the mastic around each one ages.
Dorchester is about 4 miles north-east of Didcot, in Oxfordshire. Wherever you are in the OX10 postcode area, our applicators can take on sand mastic. Dorchester is one of 443 places in Oxfordshire we cover. Oxford is on our list too, around 8 miles away.
Our applicators cover all of the OX10 postcode area for sand mastic. That includes homes and businesses on High Street, Queen Street and Queens Close and the roads around them. If you’re just outside Dorchester, we cover Burcot (1 mile north-west), Little Wittenham (1 mile south-west), Berinsfield (1 mile north), Warborough (1 mile east) and Shillingford (1 mile south-east). Further out, we also cover Oxford (8 miles north), Didcot (4 miles south-west), Abingdon-on-Thames (5 miles north-west), Thame (11 miles north-east), Wantage (12 miles west) and Henley-on-Thames (14 miles south-east).
Near you in Dorchester
We work in homes and buildings around The White Hart Hotel Bar and the streets around them. For rail, the closest station is Culham station, roughly 3.1 miles west of the centre. Other landmarks nearby include Brightwell Castle (2.3 miles south) and Littlemore Hospital (5.6 miles north-west). For a walk, there’s Ewelme Watercress Beds and Wittenham Clumps.
When to call us in Dorchester
Timber swells and shrinks with the weather. The movement cracks the mastic over time.
The most common problems we see are:
- Cement or filler used on old window joints that has cracked
- Window mastic to renew ahead of painting
- Open joints round the window box
- A silicone bead on a sash window that spoils the look
If you let a flat or house near Culham station, older sash windows in a rental need their mastic kept sound to keep the weather out.
Comparing quotes
- Are they insured?
- Whether they seal over old material or remove it
- What the quote includes, VAT included or not
- How long the guarantee is
Can I do it myself?
The biggest DIY mistake is sealing over old sealant. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Nearby places to Dorchester
Other services in Dorchester
Why deal with it now?
Before painting the windows, it pays to renew the mastic. Paint over cracked mastic will not stop the gaps and traditional guidance is to leave the new mastic unpainted. Where a wall is exposed, as many are in small places like Dorchester, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
We do not show prices on the website, because each job is priced on what it involves. Call for a quick quote.
Why choose Mr Mastic in Dorchester
- Approved under the ARBOMaster scheme
- Old sealant always removed completely
- Anti-fungal silicone where joints get wet
- We leave the area clean and tidy
See what affects the cost and our reviews.
Looking after it afterwards
After the cure time, these simple habits help:
- Have rotten timber repaired before new mastic goes in
- Check with your local planning authority if your home is listed
- Ask us before painting near the mastic
- Avoid patching sand mastic with silicone
Leave the new mastic alone while it firms up. It skins over quickly, but takes longer to harden fully.
Good mastic helps keep the frame dry. Once it fails, water can sit against the timber, which can lead to rot.