Hertfordshire · England
Sand mastic for sash & case windows in Farnham, Hertfordshire
Sand mastic for Farnham, by sealant specialists with 20+ years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Silicone on a period window that looks wrong
- Wind and rain getting in round a sash window
- Cracked mastic round a front door frame
How it works
The work is kept neat and contained to the area we’re working on, so you can carry on as normal. The job normally takes a few hours for a single window, longer for several, and we explain the cure time before we leave. Somewhere as small as Farnham, access is often the only tricky part. 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.
- We rake out the old mastic and clean the joint.
- Large voids are packed out.
- We point the joint with sand mastic by hand.
- The finish is dressed neatly.
Preparing for the visit
- Let us know about earlier repairs to the joints
- Mention any sign-in or site rules at work premises
- Let us know about stairs, lifts or work at height
Get a quote
For sand mastic in Farnham, ring 0345 464 0079 or send us an email. A short description of the job and where it is helps us quote, and we will agree the price before any work begins.
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How we handle sand mastic in Farnham
Burnt sand mastic is a traditional material blends with stone and brick surrounds. It suits period and listed homes, where modern sealant can look out of place. We work on stone surrounds, sash and case windows and period & listed homes, and people most often call us about old cement repairs round a window that have failed and mastic that needs renewing before redecorating.
Homes in small places like Farnham often stand in the open, with little to shelter their windows from wind and rain. That exposure dries out and cracks the mastic around frames and sills faster.
The work is guaranteed for twelve months. If there’s a problem with our work within the year, let us know and we will sort it.
- Place
- Farnham (CM23)
- Wider area
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Looking after it afterwards
Aftercare is simple:
- Check with your local planning authority if your home is listed
- Don’t run silicone over sand mastic
- Take care around the mastic when scraping paint
- Check the mastic when you check the paintwork
Check the mastic when you check the paintwork. Small cracks are easier to deal with early.
Sound mastic protects the frame. Once it fails, water can sit against the timber, which can lead to rot.
Farnham questions
Do you cover Farnham for sand mastic?
Yes. We work across London and the South East, and Farnham is part of that. Just phone 0345 464 0079 or send us an email with a few details of the job.
Do you cover smaller places like Farnham?
Yes, smaller places are covered as well as towns. Our work covers London and the South East. Just mention lanes, gates or anything else about the route when you book.
Do you work for letting agents?
Yes. As well as householders, we work for landlords, agents, businesses and hotels across Hertfordshire.
Is it worth trying it myself?
Some simple jobs can be done by a careful DIYer. Most DIY failures come from sealing over old material, wet joints or too much sealant.
Can sand mastic be painted?
Traditional guidance is not to paint over sand mastic. Ask us before you decorate around it and we’ll talk you through it.
Do you work for hotels and businesses?
Yes. We work in offices, washrooms, hotels and other commercial premises. We can talk about working times when we quote.
Is it OK to seal over old sealant?
No. We remove every bit of old sealant first, so the new joint bonds to clean surfaces.
Do you offer different sealant colours?
Usually, yes. Sealants come in white, clear, grey and other colours, and we will agree it with you first.
Towns and villages near Farnham
Also in Farnham
What we can’t put right
A few problems are outside what sealant work can do:
- Sash cords, weights and draught-proofing of the sashes
- Rotten sashes, sills or window boxes (a joiner’s job)
- Decisions on consent for listed homes
If in doubt, phone 0345 464 0079 or drop us an email and we will say what we think.
Where we work in Farnham
- Stone surrounds
- Brick reveals
- Sash and case windows
- Period & listed homes
- Tenement windows
- Timber door frames
When to call us in Farnham
Paint, silicone or cement used over old mastic causes problems. They don’t suit the joint, and they normally need raking out.
The most common problems we see are:
- Failed mastic on an exposed elevation
- Modern sealant on a period surround
- Draughty sash windows at the surround
- Cracked mastic round a front door frame
For site and facilities teams at buildings such as Farnham Church of England Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Comparing quotes
- What the quote includes, VAT included or not
- Is the old sealant removed completely?
- How the joint is cleaned and prepared
- How long to leave it before use
What affects the cost of sand mastic
There’s no set price list, because no two jobs are the same. What we look at:
- The old material and how stubborn it is
- Mould in or behind the old joints
- When we can work, for business premises
- The number and length of the joints
The cost reflects the work involved, not guesswork. That is why we ask a few questions first and agree the price before starting.
Asking for a quote
To make quoting easier, please include:
- Any previous sealing or DIY work
- Where the property is
- Pictures of the joints, sent by email
- Roughly how big the job is
Want a quote for sand mastic? Please ring 0345 464 0079 or send us an email and tell us about the job. We’ll explain what we’d do and give you a clear quote before work begins.
For landlords and businesses
Mouldy or split sealant often shows up at the end of a tenancy. We can quote for more than one property at once.
Letting agents often deal with us directly. Tell us the address, the job and how access works and we’ll give you a quote.
DIY versus a professional finish
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and does not move well, and getting the depth right matters as much as the look.
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
What sand mastic looks like in Farnham
Historic houses like Much Hadham Palace (about 4.2 miles south-west) are a reminder that the area around Farnham has older buildings as well as new. 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, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
For an older house near a landmark such as Church of St Mary the Virgin, 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 Stansted Mountfitchet station, older sash windows in a rental need their mastic kept sound to keep the weather out.
Farnham is about 2 miles north of Bishop's Stortford, in Hertfordshire. Whether you’re in the middle of Farnham or further out, sand mastic is available for homes and businesses alike. Our Hertfordshire coverage runs to 381 places, Farnham among them. Our Chelmsford page covers work nearby.
Postcode districts we cover here for sand mastic: CM23. If you’re just outside Farnham, we cover Uppend (1 mile north), Mount Pleasant (1 mile north), Manuden (2 miles north-east), Bentfield Green (2 miles east) and Stansted Mountfitchet (2 miles east). Larger places within reach include Stevenage (14 miles west), Hoddesdon (12 miles south-west), Hertford (12 miles south-west), Ware (10 miles south-west), Baldock (15 miles north-west) and Broxbourne (13 miles south-west).
Around Farnham
Typical jobs here are in homes near St Mary's Catholic School, among other places. Farnham’s nearest station is Stansted Mountfitchet station, roughly 2.4 miles east. A little further out are Moated mound (1.7 miles south-west) and Herts and Essex Hospital (2.8 miles south-east). For a walk, there’s Portingbury Hills and Aubrey Buxton Nature Reserve.