Hertfordshire · England
Hertford Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for householders, landlords and businesses in Hertford. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Old sand mastic that has cracked, crumbled or fallen out
- Cracked mastic round a front door frame
- Draughty sash windows at the surround
Sand mastic in Hertford, done properly
Silicone on a period window often looks wrong and is not always the right material. Sand mastic is the traditional choice and we can swap the silicone for it. If you are dealing with crumbling sand mastic round a window and open joints round the window box, we can help, whatever the surface.
Around Hertford, many houses have gained conservatories, French doors or replacement windows over time. Each one adds more joints to look after, and those joints age at different rates. Leaks usually start at a sill, a frame head or a glazing joint.
We stand behind the work with a 12-month guarantee, so you are not left on your own once the job is done.
- Place
- Hertford (SG14, SG13)
- Region
- Hertfordshire
- Cover
- 12 months on all our work
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Keeping the joints in good condition
Joint life depends on how it’s used and looked after. Here’s what we suggest:
- Avoid heavy scraping on the mastic joint
- Make sure water runs off the sill
- Ask us before painting near the mastic
- Do not run silicone over sand mastic
Keep gutters and sills clear so water runs away from the surround. Water sitting against the mastic shortens its life.
Once mastic starts to crumble, rain gets in. That water can reach the timber frame and the wall so early renewal protects both.
Nearby places to Hertford
What else we do in Hertford
When to call us in Hertford
Rain on the window surround works into any crack and loosens it further. Windows facing the weather tend to go first.
Common reasons people contact us are:
- Gaps where the frame meets the masonry
- Silicone on a period window that looks wrong
- Weathered mastic on the most exposed windows
- Cracked mastic round a front door frame
Homes close to Hertford United Reform Church include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Comparing quotes
- What happens if they find a problem under the old sealant
- How long the guarantee is
- Whether all the old sealant comes out first
- Which colour the sealant will be
Why act early in Hertford
Gaps round a sash window let in rain and draughts. Left, water can reach the timber and the wall, so dealing with it now protects both. Black mould and gaps in sealant do not fix themselves, and in a busy household in Hertford they spread with every shower and every downpour. Replacing the sealant now is the simplest fix.
We do not show prices on the website, because the cost depends so much on the job itself. For a quick quote, please call 0345 464 0079 or drop us an email.
Why us?
- Anti-fungal silicone where joints get wet
- Rated 4.9 stars on Google
- Arbo and Everbuild products
- Fully insured
Read how sealant jobs are priced and customer reviews.
DIY sealant or a professional job?
A careful DIYer can reseal a simple joint, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
If you’ve already had a go yourself, that’s fine. We remove it and do the joint properly.
The process
All our tools and materials come with us in the van, so you don’t need to buy or prepare anything. Once we have agreed what’s being done, the area is protected and the work begins. Most jobs take a few hours per window, depending on the condition of the joints. A visit in Hertford needs access to the work and a place to park close by. If the job is outside, mention gates, side access and anything above ground floor.
- Each surround is checked first.
- The joint is raked out and cleaned.
- Large voids are packed out.
- New sand mastic is applied and shaped by hand.
- The finish is dressed neatly.
Before we arrive
- On commercial sites, let us know about site rules
- Keep pets and children clear of the area while we work
- Mention if the joints have been sealed before
How to get a quote
For a quick quote, get us on the phone, or send an email if you’d rather. Tell us about the joints that need doing and we will talk you through the work.
Related advice
Different surfaces, different methods
Tenement and terrace windows
In shared buildings, the windows may be part of a wider repair so it’s worth checking responsibilities.
Sash and case windows
Sash windows are where we do most sand mastic work. We renew the mastic round each box.
Questions from Hertford
Do you work for landlords with property near Hertford East station?
Yes, landlords and agents are among the people we work for. You can phone 0345 464 0079 or send us an email with the details for a clear quote.
Is there a guarantee on sand mastic in Hertford?
All our work, in Hertford and everywhere else, comes with a 12-month guarantee. We are fully insured, and an ARBOMaster approved applicator.
What information do you need?
Tell us what needs doing and where. We will ask anything else we need to know.
How long does the job take?
As a guide, most jobs take a few hours per window, depending on the condition of the joints. Larger jobs naturally take longer.
Can you do several jobs on one visit?
Yes, and it often makes sense. Combining jobs makes good use of the visit.
Is it possible to paint over sand mastic?
The usual advice is to leave sand mastic unpainted. Ask us before you decorate around it and we will talk you through it.
Is it OK to seal over old sealant?
No. New silicone will not bond to old silicone, and anything trapped underneath, including mould and water, stays there. It all has to come out first.
Are you an approved applicator?
Yes. We are an ARBOMaster approved applicator, which is run for the Arbo sealant brand.
Quotes for sand mastic in Hertford
Jobs vary more than people expect. What affects the quote:
- Whether there’s mould to deal with
- The size of the job
- Access and height
- Any working-time requirements on site
Doing several joints on one visit usually makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You will get one clear quote for the whole job.
What we need to know
When you call or email, it’s useful to know:
- Access, such as stairs, a lift or height
- What’s wrong with the joints now
- The address or postcode of the job
- Any previous sealing or DIY work
Asking for a quote is easy: let us know what needs doing and where and its rough size. A few photos by email make the job easier to understand, and we will come back to you with a quote.
Frames and glazing around Hertford
London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Letting a property close to Hertford East station? Then cracked sand mastic around sash windows lets in the draughts tenants complain about. For site and facilities teams at buildings such as Mill Mead Primary School, its window and door frames need their mastic kept sound, just like a home’s.
Hertford is about 9 miles south-east of Stevenage, in Hertfordshire. We provide sand mastic to householders, landlords and businesses in Hertford and nearby, as part of our work across Hertfordshire. Our area takes in 381 places across Hertfordshire, from the larger towns to small villages. You can also see our page for London, about 21 miles away.
We cover every part of SG14 and SG13 for sand mastic. Whether your property is on Salisbury Square, Market Street and Parliament Square or anywhere close by, we can help. Being close to the A10 and A119, Hertford is easy for our applicators to reach for sand mastic. Other places close to Hertford include Horns Mill (1 mile south), Foxholes (1 mile east), Rush Green (2 miles east), Hertford Heath (2 miles south-east) and Little Amwell (2 miles south-east). Within a short drive, we also cover Stevenage (9 miles north-west), St Albans (11 miles west), Bishop's Stortford (11 miles north-east), Welwyn Garden City (5 miles west), Harpenden (12 miles west) and Hitchin (13 miles north-west).
Around Hertford
In Hertford, that means homes and buildings near The Old Barge pub and Richard Hale School and the streets around them. Hertford has its own railway station: Hertford East station. Well-known places in the area include Hertford County Hospital (under half a mile south-west) and Mcmullen & Sons Brewery Museum (under half a mile south-west). Green spaces nearby include Willowmead.