Hertfordshire · England
Sand mastic for sash & case windows in Allen's Green, Hertfordshire
Sand mastic for Allen's Green, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Wind and rain getting in round a sash window
- Gaps where the frame meets the masonry
- Crumbling sand mastic round a window
How we handle sand mastic in Allen's Green
Silicone on a period window often looks wrong and isn’t always the right material. Sand mastic gives a finish that matches the age of the house and we can swap the silicone for it. We work on brick reveals, timber door frames and period & listed homes, and the jobs we see most are tired mastic found when preparing windows for paint and gaps round a timber door in stone or brick.
Around Allen's Green, 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.
Big or small, it’s backed by our one-year guarantee in Allen's Green and across Hertfordshire.
- Where
- Allen's Green (CM21)
- Region
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Your questions about sand mastic in Allen's Green
Do you work for landlords with property near Sawbridgeworth station?
Yes. We work for landlords and agents as well as householders, and several properties can go on one quote. Just phone 0345 464 0079 or send us an email with the address and what needs doing, and we will give you a clear price.
Is Allen's Green in your area for sand mastic?
Yes, Allen's Green is within the area we cover. Our work covers London and the South East. You can ring 0345 464 0079 or send us an email and let us know what needs doing, and we will send you a clear quote.
Are you insured?
Yes. We’re fully insured.
Where do you work from?
Our base is in Crawley, and we work across South East England, London and Scotland.
Is it possible to take out silicone and use sand mastic instead?
Usually, yes. With the silicone removed and the joint cleaned we point it with sand mastic.
How long does the job take?
It depends on the size of the job, but as a guide it takes a few hours per window, depending on the condition of the joints. We will tell you when we quote.
Does someone need to be in?
That depends on where the joints are. For work indoors, someone needs to let us in, while outside work can sometimes be arranged differently.
Is the work guaranteed?
All our work has a 12-month guarantee.
For landlords and businesses
If you manage several properties in or around Allen's Green, several properties can go on one quote. Send us the addresses and the work at each.
Housing providers, facilities teams and property managers book us too in Allen's Green and across Hertfordshire. Several sites can go on one quote, and we are fully insured.
Places near Allen's Green
What else we do in Allen's Green
Can I do it myself?
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Different surfaces, different methods
Brick reveals
We rake out the old mastic and pack deep voids before the new mastic goes in.
Period and listed homes
A traditional finish suits a period property.
What affects the quote in Allen's Green
There’s no set price list. The quote depends on:
- How easy the joints are to reach
- Working hours on commercial sites
- The type of sealant required
- Mould in or behind the old joints
Instead of a standard rate, we price the job in front of us: the amount of work, the old material and the access. The price is agreed before we begin.
Asking for a quote
Photos help, but a description is a good start. Try to tell us:
- Pictures of the joints, sent by email
- The problem you’ve noticed
- If someone has resealed it before
- Roughly how big the job is
If you’re in Allen's Green and need sand mastic, call 0345 464 0079 or send us an email. A short description of the job and where it is helps us quote, and you will get a clear quote before any work starts.
Frames and glazing around Allen's Green
With historic houses such as Much Hadham Palace (about 2.2 miles north-west) nearby, there’s older building stock in the area around Allen's Green 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. London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
If you live in an older home near Former Church of St Anne, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Allen's Green is about 3 miles south-west of Bishop's Stortford, in Hertfordshire. Every kind of property in Allen's Green can book us for sand mastic, old or new, large or small. The work is guaranteed for a year. 381 places in Hertfordshire are on our list, from the larger towns to small villages. Chelmsford is on our list too, about 17 miles from Allen's Green.
All of CM21 is within our area for sand mastic, from the main roads to the quietest streets. Neighbouring places we cover for sand mastic include Thorley (2 miles north-east), High Wych (2 miles south), Spellbrook (2 miles east), Sawbridgeworth (2 miles south-east) and Thorley Street (2 miles north-east). Larger places within reach include Stevenage (13 miles west), Bishop's Stortford (3 miles north-east), Welwyn Garden City (13 miles west), Hoddesdon (8 miles south-west), Cheshunt (11 miles south-west) and Hatfield (15 miles west).
Local landmarks in Allen's Green
For rail, the closest station is Sawbridgeworth station, about 2.5 miles south-east. Well-known places in the area include Herts and Essex Hospital (3.4 miles north-east) and Harlow Mill (3.2 miles south). Open spaces near Allen's Green include Thorley Wash nature reserve.
Signs you need sand mastic in Allen's Green
Rain on the window surround works into any crack and loosens it further. Windows facing the weather tend to go first.
The most common problems we see are:
- Mastic round period door frames that has failed
- Crumbling sand mastic round a window
- Window mastic to renew ahead of painting
- Wind and rain getting in round a sash window
For landlords with property near Sawbridgeworth station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
What to look for in a quote
- When the joint can take water or movement
- Whether they seal over old material or remove it
- What preparation is included
- What happens if the job turns out different
Looking after it afterwards
Good habits help new joints last longer. A few tips:
- Do not paint over the new mastic
- Check with your local planning authority if your home is listed
- Don’t run silicone over sand mastic
- Look over the window mastic once a year
Do not run silicone over the new mastic. If you see a crack, ask us to take a look before trying a quick fix.
It’s best to renew mastic before painting the windows. Paint over cracked mastic only covers it up.
What we do, step by step
Once we’re on site, we check the joints match what you told us. If we find something unexpected, we talk it through with you first. Most jobs then take a few hours per window, depending on the condition of the joints. In a small place like Allen's Green, access is normally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- We look at the surrounds with you and agree the joints to renew.
- We remove the old, loose mastic.
- We pack any deep voids first.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
Before we arrive
- Clear the area around the work
- Mention any tricky access
- Keep pets and children clear of the area while we work
Get a quote
For a quick quote, get us on the phone, or email us if that’s easier. Describe what needs sealing and we’ll talk you through the work before giving you a price.