Hertfordshire · England
High Wych Sand Mastic
Sand mastic in High Wych from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Mastic round period door frames that has failed
- Failed mastic on an exposed elevation
- Modern sealant on a period surround
What happens if it’s left?
New mastic over crumbling mastic will not hold. Raking out and preparing the joint gives it a sound base so the new work lasts. Around High Wych, older homes often have timber in their floors and frames, and water through a failed joint can rot timber if it’s left.
What it costs depends on the amount of work, how much old material has to come out and how easy the joints are to reach. We give a clear quote before any work starts, so you know where you stand.
Why us?
- Anti-fungal sanitary silicone in wet areas
- We never seal over old sealant
- Arbo and Everbuild products
- An ARBOMaster approved applicator
Sand mastic in High Wych
We renew sand mastic around sash windows and doors set in stone or brick. The old mastic is raked out, the joint is prepared and new mastic is shaped by hand. We work on brick reveals, sash and case windows and tenement windows, and people most often call us about mastic round period door frames that has failed and modern sealant on a period surround.
Homes in small places like High Wych 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.
Whatever the size of the job, you get the same 12-month guarantee in High Wych and across Hertfordshire.
- Place
- High Wych (CM21)
- Region
- Hertfordshire
- Cover
- A year, on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Updated
- 26 October 2026
High Wych homes and the weather
With historic houses such as Much Hadham Palace (about 3.9 miles north-west) nearby, there’s older building stock in the area around High Wych as well as newer homes. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window. 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.
Rented homes near Harlow Mill station change hands often, and cracked sand mastic around sash windows lets in the draughts tenants complain about. Schools such as High Wych Church of England Primary School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
High Wych is about 3 miles north of Harlow, in Hertfordshire. Anywhere in CM21, we cover sand mastic for homes and businesses. High Wych is one of 381 places in Hertfordshire we cover for sand mastic. We also work in Chelmsford, about 16 miles from High Wych.
We work across CM21 for sand mastic and the streets around it. You’ll find streets such as Mansfield, High Wych Lane and Broadfields, and we cover them all. We also cover Sawbridgeworth (1 mile east), Lower Sheering (2 miles east), Allen's Green (2 miles north), Spellbrook (2 miles north-east) and Sheering (3 miles east). We also work in nearby towns such as Stevenage (15 miles north-west), Bishop's Stortford (4 miles north), Welwyn Garden City (14 miles west), Hoddesdon (7 miles south-west), Cheshunt (10 miles south-west) and Hatfield (15 miles west).
Near you in High Wych
Locally, jobs take us to homes and businesses close to The Half Moon Public House, Leventhorpe and Gibberd Garden, among other places. High Wych’s nearest station is Harlow Mill station, about 1.3 miles south of the centre. A little further out are Harlow Mill (1.3 miles south) and Princess Alexandra Hospital (3 miles south-west). Not far away are Sawbridgeworth Marsh.
Keeping the joints in good condition
How long the joints last depends on use and care. We suggest:
- Ask a joiner to look at soft timber first
- Check with your local planning authority if your home is listed
- Check the mastic when you check the paintwork
- Ask us before painting near the mastic
Don’t touch or press the mastic while it hardens. It forms a skin fairly soon, but takes longer to harden fully.
Once mastic starts to crumble, rain gets in. That water can reach the timber frame and the wall, so renewing it early is worth it.
High Wych: your questions answered
Do you work for landlords with property near Harlow Mill station?
Yes. We work for landlords and letting agents as well as homeowners. Just ring 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear quote.
Is High Wych within the area you cover?
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.
Can you replace silicone on a period window with sand mastic?
Yes. The silicone is cut out and the joint cleaned before the sand mastic goes in.
Where do you work from?
Our base is Crawley. Our area covers South East England, London and Scotland.
Do you remove the old sealant?
Always. Sealing over old sealant is the main reason resealing fails early, so we never do it.
How long will you be here?
Typically it takes a few hours for a single window, longer for several. Larger jobs naturally take longer.
Is it OK to seal over old sealant?
No. The old sealant always comes out first.
Can you do several jobs on one visit?
Yes, we can. More than one area can be quoted together.
Common problems we fix in High Wych
Paint, silicone or cement used over old mastic causes problems. They don’t move with the timber, and they usually need raking out.
Look out for these signs:
- Draughts and rain around sash boxes
- Crumbling sand mastic round a window
- Gaps round a timber door in stone or brick
- Old cement repairs round a window that have failed
In the older streets around Parish Church of St James the Great, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Before booking anyone
- How hidden problems are handled
- How long to leave it before use
- Whether they’re fully insured
- How the colour is chosen
Honest limits
We’d rather tell you now than do work that will not last, so these are the limits:
- Sash cords, weights and draught-proofing of the sashes
- Planning or listed building consent (your local planning authority decides)
- Broken panes
Not sure which it is? You can ring 0345 464 0079 or drop us an email and we’ll tell you honestly before you book.
What we seal
- Timber door frames
- Stone surrounds
- Period & listed homes
- Sash and case windows
- Brick reveals
- Tenement windows
What affects the cost of sand mastic
The quote reflects the job in front of us. We take into account:
- Access and height
- Any mould that needs treating
- Which sealant suits the joint
- Any working-time requirements on site
Some things make a job bigger or smaller: how much old sealant there is and how stubborn it is, any mould to treat, and whether we need extra access for height. We take all of that into account in your quote.
Helping us quote
To help us quote quickly, please include:
- Pictures of the joints, sent by email
- Where the property is
- If someone has resealed it before
- Roughly how big the job is
Every job is quoted individually, so the first step is telling us about yours. Just phone 0345 464 0079 or email us with the details, and pictures are welcome.
Work for landlords, hotels and businesses
Letting agents often deal with us directly. Tell us the address, the job and how access works and we’ll give you a quote.
Whether it’s one flat or a portfolio, you get the same standard of work: the old material taken out, careful preparation and a 12-month guarantee.
How it works
When we get to you, we compare the joints with what we discussed. If anything is different, we explain it before carrying on. Most jobs then take anything from a few hours to a full day, depending on how many windows. In a small place like High Wych, access is usually the main thing to plan. 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.
How to prepare
- Tell us about any previous sealing or DIY attempts
- For business premises, tell us about site rules or sign-in
- Mention any parking rules near the property
How to get a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is, and add photos by email if you can.