Hertfordshire · England
Sand mastic for sash & case windows in Newnham, Hertfordshire
Sand mastic across Newnham and nearby, with old sealant always removed completely and a 12-month guarantee.
- Silicone on a period window that looks wrong
- Mastic round period door frames that has failed
- Old sand mastic that has cracked, crumbled or fallen out
Sand mastic for homes and businesses in Newnham
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, period & listed homes and timber door frames, and the jobs we see most are draughts and rain around sash boxes and a silicone bead on a sash window that spoils the look.
Homes in small places like Newnham often stand in the open, with little to shelter their windows from wind and rain. Exposed frames and sills lose their mastic sooner than sheltered ones.
Each job carries a 12-month guarantee, large or small.
- Place
- Newnham (SG7)
- Region
- Hertfordshire
- Guarantee
- A year, on every job
- Quote
- A clear price before work begins
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Your questions about sand mastic in Newnham
Will you come out to Newnham?
Yes, Newnham is covered. 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 cover Newnham for sand mastic?
Yes, Newnham is within the area we cover. We work across London and the South East. You can phone 0345 464 0079 or drop us an email and let us know what needs doing, and we’ll give you a clear price.
Do you take out the old sealant first?
Yes. All of the old material is cut out and the joint cleaned before resealing.
Can sand mastic be painted?
Traditional guidance is not to paint over sand mastic. If you’re redecorating the window, ask us first and we will talk you through it.
Are you an approved applicator?
Yes. We’re ARBOMaster approved, the scheme for applicators of Arbo sealants.
Can landlords and businesses book you?
Yes. We work in homes, commercial premises and hotels, and we’re fully insured.
When will the new mastic be hard?
The surface skins quite quickly, then hardens over a longer period. The weather and joint depth both affect it.
What do you put in the joint?
Quality sealants from brands including Arbo and Everbuild, picked for each joint. We will tell you what we are using and why.
Frames and glazing around Newnham
The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. With historic houses such as Hinxworth Place (about 1.4 miles north) nearby, there’s older building stock in the area around Newnham as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
Homes close to Church of St Vincent include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint. If you let a flat or house near Baldock station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
Newnham is about 3 miles north-east of Letchworth, in Hertfordshire. Jobs in Newnham get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. We cover 381 towns and villages across Hertfordshire, large and small. Chelmsford is on our list too, around 35 miles away.
Here we cover the SG7 postcode area for sand mastic. Streets in the area include Ashwell Road and Caldecote Road, all of which we cover. Other places close to Newnham include Caldecote (1 mile north-west), Bygrave (2 miles south-east), Ashwell End (2 miles north), Bury End (2 miles north) and Ashwell (2 miles north-east). Larger places within reach include Stevenage (8 miles south), Welwyn Garden City (15 miles south), Hitchin (6 miles south-west), Letchworth (4 miles south-west), Letchworth Garden City (4 miles south-west) and Benslow (6 miles south-west).
Local landmarks in Newnham
Newnham’s nearest station is Baldock station, roughly 2 miles south. Well-known places in the area include Bygrave House (1.5 miles south-east) and Fairfield Hospital (3 miles south-west). The countryside around Newnham includes Arlesey Old Moat and Glebe Meadows.
How we quote for sand mastic
We don’t publish a price list, because jobs vary so much. What we look at:
- How much old sealant there is and how hard it is to remove
- Whether the work is at height
- Which sealant suits the joint
- Whether there’s mould to deal with
Some things make a job bigger or smaller: the old material and how easily it comes out, whether mould needs treating, and whether we need extra access for height. Your quote takes all of that into account.
What to tell us for a quote
When you contact us, these details help:
- How many joints, rooms or windows are involved
- Photos by email, if that’s easy
- Any previous sealing or DIY work
- How we’d reach the joints
Need a quote? Please phone 0345 464 0079 or drop us an email with a few details. You will know what we plan to do, and what it will cost, before any work begins.
The process
On the day, we look over the joints with you first. Surfaces next to the work are protected before any work begins. Most jobs take anything from a few hours to a full day, depending on how many windows. For a village or hamlet like Newnham, the journey is planned in advance: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- Each surround is checked first.
- We rake out the old mastic and clean the joint.
- We fill deep gaps so the new mastic is not too thick.
- We point the joint with sand mastic by hand.
- The finish is dressed neatly.
Preparing for the visit
- Tell us about any water getting in
- Move anything stored near the joints
- For business premises, tell us about site rules or sign-in
Ask for a quote
For a quote, phone 0345 464 0079 or send us an email and tell us where the job is and what the problem looks like. You’ll have a clear quote before any work starts.
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Landlords, agents and businesses in Newnham
We regularly work with letting and managing agents. Tell us the address, the job and how access works.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. Several properties can be quoted together.
DIY versus a professional finish
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
If you do try it yourself, take your time over the preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
Common problems we fix in Newnham
Water gets into small cracks in the mastic and loosens it further. Windows facing the weather tend to go first.
The problems people normally mention when they call are:
- Mastic that needs renewing before redecorating
- Gaps between timber frames and stone or brick
- Draughts and rain around sash boxes
- A silicone bead on a sash window that spoils the look
For site and facilities teams at buildings such as The Knights Templar School, larger buildings have plenty of frames, and the mastic around each one ages.
Comparing quotes
- Who does the work, and how experienced they are
- Whether VAT is included
- What insurance they hold
- Which colour the sealant will be
What sealant work can’t fix
Some problems need a builder, plumber or other trade rather than us:
- Decisions on consent for listed homes
- Damaged stone surrounds
- Timber that has rotted
Not sure which it is? You can phone 0345 464 0079 or email us and we’ll tell you honestly.
Where we work in Newnham
- Stone surrounds
- Timber door frames
- Tenement windows
- Brick reveals
- Sash and case windows
- Period & listed homes
Surface by surface
Stone surrounds
We take care not to mark the stone when the old mastic comes out.
Timber door frames
Sand mastic is used round timber door frames too. The method is the same as for windows.