Hertfordshire · England
Sand Mastic in Northaw
Our applicators work in Northaw on traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old material cut out, joints cleaned and sealed neatly and every job guaranteed for a year.
- Mastic dropping out of the joint
- Silicone on a period window that looks wrong
- Draughty sash windows at the surround
About our sand mastic in Northaw
We work across Northaw renewing sand mastic on sash windows and doors. Each joint is raked out, prepared and pointed by hand for a neat, traditional finish. If you’re dealing with silicone on a period window that looks wrong and gaps where the frame meets the masonry, we can put it right.
Somewhere as small as Northaw, older homes often have timber frames set in stone or brickwork. Not every older frame suits a modern silicone bead, so the sealant has to be chosen to suit the building.
Big or small, it’s backed by our one-year guarantee.
- Place
- Northaw (EN6)
- Wider area
- Hertfordshire
- Cover
- One year on every job
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Do you need sand mastic in Northaw?
Water gets into small cracks in the mastic and pushes it out. Windows facing the weather tend to go first.
The most common problems we see are:
- Old sand mastic that has cracked, crumbled or fallen out
- Gaps round a timber door in stone or brick
- Old cement repairs round a window that have failed
- Failed mastic on an exposed elevation
For site and facilities teams at buildings such as Northaw Church of England Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
What your quote should include
- How hidden problems are handled
- How the joint is cleaned and prepared
- What product goes in the joint
- How much experience the applicator has
What happens on the day
We work through the job in order: protect, prepare, seal, tidy. For most jobs that takes a few hours per window, depending on the condition of the joints and we leave things clean and tidy. Somewhere as small as Northaw, access is often the only tricky part. 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.
- Old mastic and any loose material are raked out.
- Deep gaps are packed so the mastic sits at the right depth.
- The sand mastic is mixed and pressed into the joint by hand.
- The surface is finished to suit the stone or brick.
How to prepare
- Tell us if parking is tricky
- Tell us about any previous sealing or DIY attempts
- Move anything stored near the joints
Getting a quote
To get a quote, call 0345 464 0079 or email us and tell us where the job is and what the problem looks like. You’ll have a clear quote before work begins.
Advice
Nearby places to Northaw
More services for Northaw
Different surfaces, different methods
Sash and case windows
Sash windows are where we do most sand mastic work. We renew the mastic round each box.
Timber door frames
Round a period front door, sand mastic gives the right look.
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Check with your local planning authority if your home is listed
- Take care around the mastic when scraping paint
- Renew mastic before redecorating the windows
- Leave the new mastic unpainted
Don’t touch or press the mastic while it hardens. It forms a skin fairly soon but needs longer to fully harden.
Good mastic helps keep the frame dry. Failed mastic lets water reach the timber and timber that stays wet can rot.
Sand mastic in Northaw: local notes
Historic houses like Wyllyotts Manor (about 2.1 miles west) are a reminder that the area around Northaw has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. Rainfall in the South East is lower than in much of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Letting a property close to Cuffley station? Then any sash windows need sound mastic to keep draughts and rain out. Homes close to Parish Church of St Thomas A Becket include some older properties, and the joint between an old wall and a newer frame is generally the first place rain gets in.
Northaw is about 2 miles north-east of Potters Bar, in Hertfordshire. We carry out sand mastic for homeowners, landlords and businesses in Northaw, as part of our work across Hertfordshire. Northaw is one of 381 places in Hertfordshire we cover for sand mastic. For nearby work, see our London page.
Jobs for sand mastic in EN6 works the same way as everywhere else we cover. Sand mastic is available to properties on Vineyards Road, Church Lane and Northaw Road West and the roads around them. Other places close to Northaw include Cuffley (1 mile east), Brookmans Park (2 miles north-west), Newgate Street (2 miles north-east), Bell Bar (2 miles north-west) and Little Berkhamsted (3 miles north). We also work in nearby towns such as Watford (11 miles west), Hemel Hempstead (14 miles west), Stevenage (14 miles north), St Albans (8 miles west), Welwyn Garden City (7 miles north) and Harpenden (12 miles north-west).
What’s near Northaw
In Northaw, that means homes and buildings near Two Brewers Public House and Mount Grace School and the streets around them. The closest station to Northaw is Cuffley station, about 1.6 miles east of the centre. Other landmarks nearby include Potters Bar Museum (2.1 miles west) and Chase Farm Hospital (3.3 miles south-east). Open spaces near Northaw include Fir and Pond Woods.
Your questions about sand mastic in Northaw
Is Northaw in your area for sand mastic?
Yes, Northaw is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or email us with a few details of the job, and we’ll give you a clear quote.
Do you work for landlords with property near Cuffley 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’ll give you a clear price.
Do the sealants smell?
It depends on the product. Some products have a noticeable smell, others very little.
What exactly is sand mastic?
It’s a mix of sand and a linseed-oil-based binder. It’s built up in the joint by hand and shaped to suit the surround.
How do I get a quote for sand mastic in Northaw?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. You’ll get a clear quote before we start.
How long does sand mastic take to harden?
Not right away. It skins first and hardens fully later, and we will tell you what to expect.
Can you seal over the old sealant?
No, because it fails. We remove every bit of old sealant first, so the new joint bonds to clean surfaces.
Do you have insurance?
Yes. We are fully insured, and we have been doing sealant work for more than 20 years.
Honest limits
Sealant isn’t the answer to every problem, and we’d rather say so up front. It will not solve:
- Damaged stone surrounds
- Sashes that rattle, stick or will not open
- Planning or listed building consent (your local planning authority decides)
If in doubt, call 0345 464 0079 or drop us an email and we will say what we think.
Surfaces we seal
- Stone surrounds
- Sash and case windows
- Period & listed homes
- Brick reveals
- Tenement windows
- Timber door frames
What affects the cost of sand mastic
The price is agreed before any work begins. It’s based on:
- The number of rooms or windows
- Mould in or behind the old joints
- How much old sealant there is and how hard it is to remove
- Whether the work is at height
What it costs depends on how much there is to do, how hard the old material is to remove and access to the work. You will have a clear quote before any work starts, so you know where you stand.
What to tell us for a quote
A few details help us give you an accurate quote. When you ask for a quote, tell us:
- If someone has resealed it before
- Any access issues, like height or stairs
- What’s wrong with the joints now
- The type of property
For a quick quote, get us on the phone, or send an email if you’d rather. Describe what needs sealing and we will explain what’s involved and give you a clear quote.
For landlords and businesses
Hotels need rooms back in use, so we plan the work room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.