Hertfordshire · England
Sand mastic for sash & case windows in The Flints, Hertfordshire
Traditional burnt sand mastic around sash and case windows and doors in stone and brick in The Flints, with a one-year guarantee on every job. Call for a quick quote.
- Gaps where the frame meets the masonry
- Gaps round a timber door in stone or brick
- Silicone on a period window that looks wrong
Sand mastic for homes and businesses in The Flints
Our applicators renew the sand mastic around sash and case windows and doors set in stone or brick. Out comes the old, loose mastic, and new mastic is applied and shaped by hand. We work on timber door frames, tenement windows and brick reveals, and people most often call us about mastic dropping out of the joint and mastic that needs renewing before redecorating.
Around The Flints, many homes face open ground, so their windows and doors take the full weather. That exposure dries out and cracks the mastic around frames and sills faster.
All of our work is guaranteed for twelve months, in The Flints and everywhere else we cover.
- Place
- The Flints (SG5)
- Wider area
- Hertfordshire
- Guarantee
- A year, on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
FAQs for The Flints
Do you work for landlords with property near Luton station?
Yes, landlords and agents are among the people we work for. Just call 0345 464 0079 or drop us an email with the address and what needs doing, and we will send you a clear quote.
Is The Flints within the area you cover?
Yes, we do. Our work covers London and the South East, from towns to the smallest places. The journey is planned ahead, so it helps to know about access.
Do you do commercial work?
Yes. Larger jobs can be planned room by room or area by area.
Which is right for my windows, sand mastic or modern sealant?
We will help you decide. Sand mastic suits many period homes, and modern sealants suit newer frames.
Can I add another job to the visit?
Yes. Just list everything you need and we’ll quote it together.
Can I choose the sealant colour?
Most of the time, yes. We’ll tell you which colours the right product comes in and agree one before any work starts.
What sealant do you use?
Quality sealants from brands including Arbo and Everbuild, chosen to suit the joint. We’ll tell you what we’re using and why.
Do you take out the old sealant first?
Yes. Sealing over old sealant is the main reason resealing fails early, so we never do it.
DIY versus a professional finish
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.
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
How to look after the new joints
No joint lasts for ever, but care makes a real difference. Our tips:
- Avoid heavy scraping on the mastic joint
- Leave the new mastic unpainted
- Renew mastic before redecorating the windows
- Check with your local planning authority if your home is listed
Leave the new mastic alone while it firms up. It skins over quickly but needs longer to fully harden.
Sound mastic protects the frame. Once it fails, water can sit against the timber and timber that stays wet can rot.
What the job involves on each surface
Timber door frames
A neat sand mastic joint round a front door suits a period home.
Sash and case windows
Sash windows are where we do most sand mastic work. Each joint round the box is raked out and renewed.
Frames and glazing around The Flints
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.
For landlords with property near Luton station, any sash windows need sound mastic to keep draughts and rain out. If you live in an older home near Church of St Mary Magdalene, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
The Flints is about 4 miles south-west of Hitchin, in Hertfordshire. Wherever you are in the SG5 postcode area, we can carry out sand mastic at your property. Our Hertfordshire coverage runs to 381 places, and The Flints is one of them. You can also see our page for London, about 32 miles away.
All of SG5 is within our area for sand mastic, from the main roads to the quietest streets. Close by, we work in Great Offley (1 mile east), Temple End (2 miles east) and Ley Green (2 miles south-east). Further out, we also cover Hemel Hempstead (13 miles south), Stevenage (7 miles east), St Albans (12 miles south), Welwyn Garden City (11 miles south-east), Harpenden (8 miles south) and Hitchin (4 miles north-east).
Local landmarks in The Flints
Around The Flints, our work takes us to homes and buildings near The Bull Public House. The closest station to The Flints is Luton station, roughly 4.1 miles south-west of the centre. Nearby you’ll also find Ravensburgh Castle (2.7 miles north-west) and John Dony Field Centre (2.9 miles south-west). The countryside around The Flints includes Markham's Hill and Pegsdon Hills.
The process
The work is kept neat and contained to the area we’re working on, so you can get on with your day. Expect the work to take anything from a few hours to a full day, depending on how many windows. Somewhere as small as The Flints, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- Each surround is checked first.
- 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.
Before we arrive
- Let us know about earlier repairs to the joints
- Tell us about any water getting in
- Let us know about stairs, lifts or work at height
Getting a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and email photos if that is easy.
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Towns and villages near The Flints
What else we do in The Flints
What sealant work can’t fix
We’ll always be straight with you, so here’s what new sealant will not do:
- Whether work needs listed building consent
- Crumbling stone or brickwork round the window
- Cracked or broken glass
If you’re not sure, just phone 0345 464 0079 or email us and we will give you a straight answer before you book.
Joints and surfaces we work on
- Brick reveals
- Period & listed homes
- Stone surrounds
- Timber door frames
- Tenement windows
- Sash and case windows
What we’re called out for in The Flints
Over the years, sand mastic weathers. It hardens, cracks and starts to come away from the frame or the masonry.
Look out for these signs:
- Mastic worn away on windows facing the weather
- Window mastic to renew ahead of painting
- Old cement repairs round a window that have failed
- Gaps between timber frames and stone or brick
Schools such as Offley Endowed Primary School are buildings too, and its window and door frames need their mastic kept sound, just like a home’s.
What your quote should include
- Who turns up on the day
- What product goes in the joint
- How the surfaces are prepared before sealing
- Whether all the old sealant comes out first
What affects the quote in The Flints
For a quick quote, just ask. The main things that affect it are:
- The size of the job
- Any working-time requirements on site
- Whether there’s mould to deal with
- How many areas need sealing
Combining jobs into one visit is generally more efficient than separate visits, so it’s worth mentioning everything you’d like done. We’ll give you a clear price for the lot.
Asking for a quote
When you contact us, it’s useful to know:
- Where the property is
- What the problem is, such as mould, gaps, leaks or cracking
- A few pictures by email, if you can
- Any access issues, like height or stairs
For a quote, call 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. You will have a clear quote before we start.