Greater London · England
Window & door mastic in Harefield, Greater London
Window mastic across Harefield and nearby, with every bit of old sealant taken out first and a 12-month guarantee.
- Untidy mastic left by window fitters
- Cold air getting in at the frame edge
- White mastic on grey or black frames
Frames and glazing around Harefield
Historic houses like Ickenham Hall (about 3.4 miles south-east) are a reminder that the area around Harefield has older buildings as well as new. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. 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.
Schools such as Harefield Infant School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s. Homes close to Harefield Baptist Church include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Harefield is about 3 miles south of Rickmansworth, in Greater London. Jobs in Harefield get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Our area takes in 786 places across Greater London, from the larger towns to small villages.
Postcode districts we cover here for window mastic: UB9. Window mastic is available to properties on High Street, Vernon Drive and New Park Road. Neighbouring places we cover for window mastic include Hill End (1 mile north), Woodcock Hill (1 mile north-east), Batchworth Heath (2 miles north-east), Batchworth (2 miles north-east) and Mill End (2 miles north). Within a short drive, we also cover City of Westminster (15 miles south-east), Kensington (14 miles south-east), Hampstead (13 miles east), Ruislip (4 miles south-east), Ealing (10 miles south-east) and Hayes (7 miles south-east).
Near you in Harefield
In Harefield, that means homes and buildings near The King's Arms Public House, The Green and The Harefield Academy, among other places. For rail, the closest station is Denham station, roughly 2 miles south. A little further out are Chiltern Open Air Museum (3.4 miles north-west) and Harefield Hospital (within half a mile north-west). Not far away are Dews Farm Sand Pits and Horse Shoe Bay.
Window mastic in Harefield, done properly
Behind a thin line of old mastic there’s sometimes a deep void. Filling it with sealant alone leaves a joint that can’t move properly, so we fit backing rod to set the right depth. The sealant then grips the two sides it should. We work on composite doors, timber windows & doors and window sills, and people most often call us about gaps where the sill meets the wall and gaps left after new windows were fitted. As mastic and silicone sealant specialists, we take on window mastic and every other kind of sealant job in Harefield.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. The mastic around them dries out and cracks with age, letting in draughts and water.
Each job carries a 12-month guarantee, whatever its size.
- Place
- Harefield (UB9)
- Wider area
- Greater London
- Guarantee
- 12 months on all our work
- Price
- A clear quote up front
- Phone
- 07833 053749
- Last updated
- 26 October 2026
Looking after it afterwards
Simple care keeps the joints in good condition. We recommend:
- Do not aim a pressure washer at the joints
- Keep solvents and bleach off the sealant
- Repaint timber before it’s bare
- Paint up to the joint, not over it
Clean the frames with mild soapy water, and avoid solvent cleaners on the sealant.
A small gap around a frame only grows. As old mastic keeps shrinking, the gap widens, and heat escapes around the frame. Resealing closes it.
Why act early in Harefield
Redecorating is a good moment to renew the mastic. Fresh joints finish the job neatly. In London conversions, one flat’s bathroom is often above another flat’s ceiling, and a slow leak from a failed seal can end up in the flat below. Putting it right early is much less trouble for homes in Harefield.
No two jobs are quite the same, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all play a part, and we will explain the quote if you ask.
Why us?
- Experience in homes, commercial sites and hotels
- Sealant colour chosen to suit
- White, clear, grey or another colour, product permitting
- Neat joints and a tidy finish
Take a look at how sealant jobs are priced and what customers say.
When something else is needed
Honest advice matters more to us than a booking, so here’s what sealant cannot fix:
- A sash or casement that will not close properly
- Draughts through the window seals rather than the frame
- A frame that has rotted at the joint
If in doubt, ring 07833 053749 or email us and we will say what we think.
Joints and surfaces we work on
- Aluminium frames
- Timber windows & doors
- Window sills
- uPVC windows
- Composite doors
- Patio & French doors
How it works
When we arrive, we start by going over the job with you. Surfaces next to the work are protected before we start. The work normally takes a morning for a couple of windows and a door. For a job in Harefield, parking and access are the things to plan: let us know about parking, the floor we’ll be working on and any lift or shared entrance.
- First, we confirm safe access to each frame.
- Old, cracked mastic is removed completely, along with any loose debris.
- Frame and wall are cleaned and must be dry before sealing.
- Backing rod fills deep voids and the sealant goes in on top.
- The joint is shaped to shed water and the area tidied.
Getting ready for the visit
- On commercial sites, let us know about site rules
- Tell us about any water getting in
- For indoor joints, keep the area dry beforehand if you can
Get a quote
Quotes start with a quick conversation. Describe the problem, the location and the size of the job, and we will talk you through what we’d do. When it suits you, call 07833 053749 or email us.
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Common problems we fix in Harefield
Joint shape matters as much as the product. A thin smear across a wide gap has nothing to it, and a gap filled solid can’t flex. That is what backing rod is for.
People usually contact us after spotting something like this:
- Cracked or shrunken mastic around the frame
- Cracked sealant at the sill ends
- Draughty joints inside around the window
- A bead that doesn’t match the frame
Harefield is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Before you book anyone
- Is VAT in the price?
- Are they insured?
- The length of the guarantee
- Whether all the old sealant comes out first
Your questions about window mastic in Harefield
Do you cover Harefield for window mastic?
Yes, Harefield is within the area we cover. We work across London and the South East. You can ring 07833 053749 or email us and let us know what needs doing, and we will give you a clear price.
I let a flat near Denham station. Can you help?
Yes, rental work is part of what we do. You can phone 07833 053749 or send us an email with the address and a few details, and we will give you a fixed price before work begins.
How many windows can you do in a day?
Allow anything from an hour or two to a full day, depending on how many frames there are. Access and the amount of old mastic make the biggest difference.
Will there be a smell?
Sometimes, a little. It fades as the sealant cures, and ventilation helps.
Will the old sealant be removed?
Yes, always, and completely. New sealant will not bond properly to old, so the joint is cleaned back first.
Can new window sealant be painted?
It depends on the sealant. Silicone is not paintable, but some hybrid sealants are. Tell us if you’re decorating and we’ll choose accordingly.
How do I get a quote for window mastic in Harefield?
The cost depends on the size of the job, access and how much old sealant has to come out. Ask us for a quote and we will talk you through it.
Can you do several jobs on one visit?
Yes. Tell us about everything you’d like done and we’ll quote it together.
Towns and villages near Harefield
Also in Harefield
Surface by surface
Timber windows & doors
Timber moves with moisture as well as heat, so the joint must stay flexible. We seal onto sound, dry paintwork or timber.
uPVC windows
The frame is cleaned with a product that won’t harm the plastic, then the sealant goes in between frame and wall.
Should I try it myself first?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.