Greater London · England
Window Mastic in North Harrow
Specialist window mastic for North Harrow: careful preparation, the right product and tidy work. Call for a quick quote.
- Damp patches on the reveal after heavy rain
- A bead that does not match the frame
- Black, perished sealant on frames
Work for landlords, hotels and businesses
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.
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance.
Window mastic for homes and businesses in North Harrow
If you can feel air around a shut window, the gap is often at the frame. Resealing that joint can make a room feel noticeably less draughty. If the draught is through the window seals instead, we will tell you. If you are dealing with draughty joints inside around the window and sealant in the wrong colour for the frame, we can help, on composite doors, timber windows & doors and patio & French doors alike.
London has a lot of flats and conversions, where windows are often on upper floors. In a converted house or block, the lease generally says who is responsible for the windows, so it’s worth checking before booking, and access in North Harrow is something to talk through when you book.
A one-year guarantee comes as standard, so you are not left on your own once the job is done.
- Place
- North Harrow (HA2, HA1, HA5)
- Region
- Greater London
- Guarantee
- A year, on every job
- Quote
- A clear price before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Questions from North Harrow
Do you work for landlords with property near Harrow-on-the-Hill station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or drop us an email and tell us about the property, and we’ll give you a clear price.
Do you cover North Harrow for window mastic?
Yes, North Harrow is within the area we cover. Our work covers London and the South East. Just call 0345 464 0079 or email us with a few details of the job.
Can you work on commercial sites?
Yes. We work in offices, washrooms, hotels and other commercial premises. Working times can be discussed when we quote.
Can I add another job to the visit?
Yes. More than one area can be quoted together.
Do you hold any approvals?
Yes. We’re an ARBOMaster approved applicator, which is run for the Arbo sealant brand.
Is it worth trying it myself?
You can, for simple jobs. The key is preparation: remove all the old material and work on a clean, dry joint. We can always put it right if it fails.
Is the new sealant paintable?
Silicone generally will not take paint. If you plan to paint, tell us first and we can use a paintable sealant where it suits the joint.
Do you take out the old sealant first?
Yes, always, and completely. New sealant will not bond properly to old, so the joint is cleaned back first.
How to look after the new joints
To keep the joints looking good and working properly:
- Check the mastic once a year
- Keep timber frames painted
- Wipe condensation off the frames
- Do not aim a pressure washer at the joints
Wipe the frames with soapy water when you clean the windows, and keep solvents and harsh chemicals off the joint.
Draughts get worse, not better. As old mastic keeps shrinking, the gap widens, and heat escapes around the frame. A new joint closes it up.
Do you need window mastic in North Harrow?
Sun, frost and rain wear sealant out. UV light hardens the outside of the bead, until it loses its stretch and starts to crack.
Any of these means the joints need attention:
- Gaps where the sill meets the wall
- Whistling draughts around closed windows
- Old mastic that has gone black or come away
- White mastic on grey or black frames
For an older house near a landmark such as Church of St Alban, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
What to look for in a quote
- How the colour is chosen
- How hidden problems are handled
- Whether all the old sealant comes out first
- What the cure time is
How we quote for window mastic
There’s no set price list. What we look at:
- Working hours on commercial sites
- The size of the job
- The product the joint needs
- How easy the joints are to reach
What it costs depends on how much there is to do, how much old material has to come out and how easy the joints are to reach. You’ll have a clear quote before any work starts, so you know where you stand.
Helping us quote
What to tell us when you ask for a quote:
- Whether it’s a home or a business
- Access, such as stairs, a lift or height
- The address or postcode of the job
- Photos by email, if that is easy
The more we know about the job, the more useful the quote. Let us know the location, the problem and roughly how many joints.
Windows and doors in North Harrow
With historic houses such as Headstone Manor (about 0.8 miles north-east) nearby, there’s older building stock in the area around North Harrow 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. In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking.
Managing a site like Longfield Primary School? Then the mastic around its windows and doors needs looking after like any other building’s. North Harrow is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
North Harrow is about 1 mile north-west of Harrow, in Greater London. Across the HA2 area, our applicators can take on window mastic. North Harrow is one of 764 towns and villages in Greater London we cover. We also work in London, about 13 miles from North Harrow.
Here we cover the HA2, HA1 and HA5 postcode area for window mastic. If you need window mastic at a property on The Avenue, Pinner Road and Durham Road or a nearby road, we can help. Nearby, we also carry out window mastic in Rayners Lane (1 mile south-west), Harrow (1 mile south-east), Roxbourne (1 mile south-west), Eastcote (1 mile west) and Greenhill (1 mile east). Within a short drive, we also cover London (13 miles south-east), City of Westminster (10 miles south-east), Marylebone (10 miles south-east), Kensington (9 miles south-east), St Pancras (11 miles east) and Shoreditch (13 miles east).
Near you in North Harrow
Typical jobs here are in homes near Nower Hill High School, Heathfield School and Headstone Manor Recreation Ground and the streets around them. The closest station to North Harrow is Harrow-on-the-Hill station, roughly 1.2 miles east of the centre. Well-known places in the area include St. George's Shopping Centre (1 mile east) and Hilfield Castle (5 miles north). Green spaces nearby include Northala Fields and Islip Manor Meadows.
Honest limits
Some problems need a builder, plumber or other trade rather than us:
- A failed sealed unit that has misted up
- A frame that has rotted at the joint
- Damp coming through the wall itself rather than the frame joint
Not sure which it is? You can call 0345 464 0079 or send us an email and we will tell you honestly before you book.
What we seal
- Window sills
- Aluminium frames
- Timber windows & doors
- Patio & French doors
- uPVC windows
- Composite doors
Why deal with it now?
Working on frames from a ladder with a sealant gun isn’t easy, especially upstairs. We cut out properly, back deep gaps and tool every joint neatly, in a sealant suited to the wall. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Dealing with it early is far simpler.
Homes and businesses are quoted the same way: the amount of work, the access and the products needed. Call for a quick quote and we’ll go through it with you.
Why us?
- We never seal over old sealant
- Colour picked to suit the job
- ARBOMaster approved applicator
- A choice of colours where the product allows
See our cost guide or what customers say.
How it works
The work is kept neat and contained to the joints we are treating. The job usually takes most of a day for a typical house, less for a few frames, and we explain the cure time before we leave. In North Harrow, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- We check how each frame can be reached safely.
- All the failed sealant is cut away, along with any loose debris.
- The surfaces are cleaned and left dry, and primed where the sealant calls for it.
- Deep voids are backed, then the sealant is gunned in.
- We tool the joint so water runs off, then clear up.
Preparing for the visit
- Mention any parking rules near the property
- Mention any leaks or damp you’ve noticed
- Clear items away from the joints we are working on
Ask for a quote
We quote each job on its own, so the first step is telling us about yours. Just call 0345 464 0079 or email us with the details.