Hertfordshire · England
Window & door mastic in Northaw, Hertfordshire
Window and door frames in Northaw need attention? We remove the old material, prepare the joints and seal them properly, and the work is guaranteed for a year.
- Water coming in at the bottom corners of a door
- Rushed sealant from a window installation
- Leaking joints at the ends of sills
What we’re called out for in Northaw
Water runs down the glass onto the sill, so the sill ends and the joint below the frame are common leak points. When that sealant fails, water gets into the wall or under the frame.
Most people get in touch after spotting one of these:
- White mastic on grey or black frames
- Water coming in at the bottom corners of a door
- Draughty joints inside around the window
- Rushed sealant from a window installation
Letting a property close to Cuffley station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Questions to ask before you book
- What happens if the job turns out different
- How the colour is chosen
- What insurance they hold
- Who turns up on the day
Window mastic in Northaw
Colour matters on a frame. White, brown, anthracite grey, black and clear sealants are all available, so the line suits the frame instead of standing out. We work on composite doors, timber windows & doors and aluminium frames, and people most often call us about rushed sealant from a window installation and cracked internal joints between frame and plaster.
In a village or hamlet like Northaw, older cottages and farmhouses often have timber windows set in stone or brick. Older buildings like these don’t always suit modern silicone, and sometimes a traditional sand mastic is the better choice.
The work is covered for a year after we finish. If anything is not right with it, call 0345 464 0079 or email us.
- Location
- Northaw (EN6)
- Wider area
- Hertfordshire
- Cover
- A year, on every job
- Quotes
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Northaw homes and the weather
With historic houses such as Wyllyotts Manor (about 2.1 miles west) nearby, there’s older building stock in the area around Northaw as well as newer homes. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you live in an older home near Parish Church of St Thomas A Becket, frames set in older brick or stone need a sealant that suits the wall as well as the frame. Managing a site like Northaw Church of England Primary School? Then the mastic around its windows and doors needs looking after like any other building’s.
Northaw is about 2 miles north-east of Potters Bar, in Hertfordshire. Homes, rented property, offices and hotels in Northaw is covered for window mastic. Every job comes with our 12-month guarantee. Across Hertfordshire, we cover 381 places, Northaw among them. Our London page covers work nearby, about 14 miles away.
Our applicators cover all of EN6 for window mastic and the streets around it. Streets in the area include Vineyards Road, Church Lane and Northaw Road West. Nearby, we also carry out window mastic in 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). Larger places within reach include 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).
Landmarks near Northaw
Locally, jobs take us to homes and businesses close to Two Brewers Public House and Mount Grace School. The nearest railway station is Cuffley station, roughly 1.6 miles east. Nearby you’ll also find Potters Bar Museum (2.1 miles west) and Chase Farm Hospital (3.3 miles south-east). Not far away are Fir and Pond Woods.
Aftercare tips
Looking after new joints is easy, and it makes a real difference:
- Keep paint and stain on wooden frames in good order
- Do not use solvent cleaners on the joint
- Avoid blasting the frames with a pressure washer
- Ventilate rooms so frames don’t stay wet inside
Check the drainage slots in the frames aren’t blocked, so rain drains out rather than building up at the sealant.
Look out for the warning signs: cracks in the mastic, gaps you can see light through, damp on the reveal or mould around the inside of the frame. If you notice one, it’s time to get the joint looked at.
Towns and villages near Northaw
Also in Northaw
Why it’s worth doing now in Northaw
A cracked joint around a frame lets rain into the wall. Left long enough, it can stain inside walls, spoil plaster and rot wooden frames. Resealing now is a small job by comparison. Where a wall is exposed, as many are in small places like Northaw, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
Combining jobs into one visit is usually more efficient than separate visits, so it’s worth mentioning everything you’d like done. We will give you a clear quote for the lot.
Why book with us
- Any old sealant cut out fully, not covered over
- Homes, businesses and hotels
- 180+ five-star Google reviews
- A sealant colour to suit the surroundings
See our cost guide and our reviews.
What affects the cost of window mastic
We don’t publish a price list, because jobs vary so much. What we look at:
- Any working-time requirements on site
- The number and length of the joints
- Access and height
- How many areas need sealing
The cost depends on the size of the job, how hard the old material is to remove and how easy the joints are to reach. We give a clear quote before any work starts.
What we need to know
To make quoting easier, please include:
- The rough size of the job
- Where the job is, and your postcode
- Pictures of the joints, sent by email
- If someone has resealed it before
Every job is quoted individually, so the first step is telling us about yours. Simply phone 0345 464 0079 or send us an email and describe the job.
Should I try it myself first?
Sealing over old silicone is the commonest DIY error. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. Everything old must be removed first.
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
Northaw questions
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 email us with the address and what needs doing, and we will give you a clear quote.
Is Northaw in your area for window mastic?
Yes, Northaw is within the area we cover. We work across London and the South East. Just call 0345 464 0079 or drop us an email with a few details of the job, and we will send you a clear quote.
Can new sealant go over the old?
No, it won’t last. It can look neat for a few weeks, but the new layer lifts away from the old one. The old sealant has to come out completely.
How long should I leave it?
Cure times vary by product and the temperature. Before we leave, we will tell you the cure time.
Do you have insurance?
Yes. Full insurance covers our work.
How long does it take to reseal the windows on a house?
A few frames take a few hours. You will get a timescale with the quote.
Where do you work from?
We work from Crawley. We cover Northaw and the rest of Hertfordshire.
Can I add another job to the visit?
Yes. Just list everything you need and we will quote it together.
How it works
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. It normally takes most of a day for a typical house, less for a few frames. Somewhere as small as Northaw, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We start by checking each window and door with you.
- We remove the old mastic and clean the frame and the wall.
- Deep gaps are filled with backing rod to set the depth.
- New exterior sealant goes on in a matching colour and is tooled smooth.
- Every joint is checked before we leave.
Preparing for the visit
- Let us know about parking restrictions
- Tell us about any water getting in
- For indoor joints, keep the area dry beforehand if you can
Get a quote
Call for a quick quote, or send an email if you’d rather. Describe what needs sealing and we will talk you through the work.
Read more
When something else is needed
We won’t take on work that won’t last, so here’s what sealant can’t put right:
- Rotten timber, which needs a joiner first
- Faulty window hardware
- Damp coming through the wall itself rather than the frame joint
If in doubt, call 0345 464 0079 or send us an email and we will say what we think.
Surfaces we seal
- Timber windows & doors
- Composite doors
- Aluminium frames
- Patio & French doors
- uPVC windows
- Window sills