Greater London · England
Window & door mastic in South Harrow, Greater London
Window mastic for South Harrow and the surrounding area: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Cracked internal joints between frame and plaster
- Rain getting in at the frame or under the sill
- White mastic on grey or black frames
Looking after it afterwards
No joint lasts for ever, but care makes a real difference. Our tips:
- Clear any debris from frame drain holes
- Ventilate rooms so frames do not stay wet inside
- Look round the frames every year or so
- Paint up to the joint, not over it
Clean the frames with mild soapy water, and keep solvents and harsh chemicals off the joint.
Signs to watch for: split or missing mastic, gaps, damp patches inside or black mould on the reveal. Any of these is worth a call.
About our window mastic in South Harrow
Every window and door frame has a gap around it, and mastic is what closes it. Once that seal fails, wind and rain find the gap. The old mastic is removed and the joint resealed with a flexible exterior sealant. Typical jobs include cold air getting in at the frame edge and untidy mastic left by window fitters, on patio & French doors, uPVC windows and composite doors.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Either way, the mastic between frame and brickwork is what stops draughts and rain getting in.
Whatever the size of the job, it’s backed by our 12-month guarantee in South Harrow and across Greater London.
- Place
- South Harrow (HA2, HA1, UB5)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
South Harrow homes and the weather
In London conversions and blocks, the lease decides who is responsible for the frames, so check that before booking. Historic houses like Northolt Manor (about 1.5 miles south-west) are a reminder that the area around South Harrow has older buildings as well as new. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window.
Letting a property close to Northolt Park station? Then renewing tired window mastic between tenants heads off draught and damp complaints. South Harrow is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
South Harrow is about 1 mile south of Harrow, in Greater London. Homes, rented property, offices and hotels in South Harrow can book us for window mastic, old or new, large or small. Every job comes with our 12-month guarantee. Our Greater London coverage runs to 764 places, South Harrow among them. There’s also a page for London, roughly 12 miles from South Harrow.
We cover every part of the HA2, HA1 and UB5 postcode area for window mastic. Whether your property is on Park Lane, Grange Road and Dudley Road or a nearby road, we can help. Nearby, we also carry out window mastic in Roxeth (1 mile north-east), Harrow (1 mile north), Harrow on the Hill (1 mile east), Rayners Lane (1 mile north-west) and Northolt (1 mile south-west). Further out, we also cover London (12 miles east), City of Westminster (9 miles east), Marylebone (9 miles east), Kensington (8 miles south-east), St Pancras (10 miles east) and Shoreditch (12 miles east).
Around South Harrow
We work in homes and buildings around Orley Farm School, Northwick Park and St Dominic's Sixth Form College and the streets around them. South Harrow’s nearest station is Northolt Park station, roughly 0.5 miles south-west. Well-known places in the area include St. George's Shopping Centre (1.3 miles north-east) and Kodak Museum (2 miles north). Not far away are Middle Lake and Northala Fields.
Work for landlords, hotels and businesses
If you manage several properties in or around South Harrow, jobs at different addresses can go on one quote. Send us the addresses and the work at each.
We regularly work with letting and managing agents. Tell us the address, the job and how access works and we’ll give you a quote.
Different surfaces, different methods
uPVC windows
Some uPVC windows were sealed at fitting with a quick bead that never bonded. It comes out, deep gaps get backing rod and the joint is resealed.
Composite doors
A composite door usually sits in a plastic outer frame, so its perimeter joint is sealed much like a window. The bead is colour-matched to the frame.
DIY versus a professional finish
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
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.
When it isn’t the sealant
Some problems need a builder, plumber or other trade rather than us:
- Rotten timber, which needs a joiner first
- Damp coming through the wall itself rather than the frame joint
- Misting between the panes of a double-glazed unit (that needs a new unit)
If in doubt, ring 0345 464 0079 or send us an email and we’ll say what we think.
Where we work in South Harrow
- Aluminium frames
- Patio & French doors
- uPVC windows
- Window sills
- Timber windows & doors
- Composite doors
South Harrow: your questions answered
Do you work for landlords with property near Northolt Park station?
Yes, landlords and agents are among the people we work for. You can call 0345 464 0079 or send us an email with the details for a clear quote.
Is parking a problem for a job in South Harrow?
Parking in South Harrow, as in most of London, takes a little planning: a visitor permit or a bay close to the door helps a lot.
Can I do it myself?
That depends on the joint. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Will new mastic stop draughts?
In many cases. Air often gets in between the frame and the wall, and sealing the inside and outside joints closes that path.
Can I add another job to the visit?
Of course. Combining jobs makes good use of the visit.
What do you put in the joint?
Each joint gets the product that suits it. Movement, water and weather all affect the choice, and we will explain our choice.
Do the sealants smell?
That depends on the sealant. Some smell for a while, some hardly at all.
How do I get a quote for window mastic in South Harrow?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. You will get a clear quote before any work starts.
Places near South Harrow
More services for South Harrow
What happens on the day
When we get to you, we check the joints match what you told us. If we find something unexpected, we talk it through with you first. After that, the work takes a few hours for a handful of frames, longer for a whole house. In a London area like South Harrow, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- We check each frame and agree which ones need doing.
- Next the failed sealant is cut away and the joint cleaned.
- We fit backing rod in deep gaps so the sealant is the right depth.
- A flexible, weatherproof sealant is applied in a colour to suit the frame.
- We clear up and check every joint is fully closed.
Getting ready for the visit
- For business premises, tell us about site rules or sign-in
- Where the joints are inside, avoid wetting them before we arrive
- Mention any tricky access
Get a quote
We quote each job on its own, so the first step is telling us about yours. Simply ring 0345 464 0079 or email us and describe the job and send photos if you have them.
Related advice
When to call us in South Harrow
Some failures date back to when the windows were fitted. Sealant run over dust, wet brick or loose mortar didn’t grip properly, so it comes away long before its time.
Look out for any of the following:
- Rain getting in at the frame or under the sill
- Draughty joints inside around the window
- Cracked or shrunken mastic around the frame
- Untidy mastic left by window fitters
For site and facilities teams at buildings such as The Welldon Park Academy, larger buildings have plenty of frames, and the mastic around each one ages.
Comparing quotes
- How much experience the applicator has
- How the colour is chosen
- What happens if they find a problem under the old sealant
- How long the guarantee is