Greater London · England
Window Mastic in Lessness Heath
Mastic around window and door frames, sills and patio doors for homeowners, landlords and businesses in Lessness Heath. Fully insured, ARBOMaster approved and guaranteed for a year.
- Cracked or shrunken mastic around the frame
- Sealant in the wrong colour for the frame
- Cold air getting in at the frame edge
Should I try it myself first?
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
About our window mastic in Lessness Heath
There are two joints on most windows. The external joint is the weather seal; inside, the joint between frame and plaster stops draughts and tidies the reveal. Either or both can be done. We work on composite doors, window sills and timber windows & doors, and common reasons people get in touch are draughty joints inside around the window and old mastic that has gone black or come away.
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.
The work is covered for a year after we finish. If there’s a problem with it, please phone 0345 464 0079 or drop us an email.
- Where
- Lessness Heath (DA17, DA8, DA7)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
What happens if it’s left?
Redecorating is a good moment to renew the mastic. Fresh joints finish the job neatly. In a London flat, a failed joint rarely stays your problem alone: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all play a part.
Why book with us
- 4.9 on Google from 180+ five-star reviews
- Quality sealants from Arbo and Everbuild
- Approved under the ARBOMaster scheme
- Experience in homes, commercial sites and hotels
Read our cost guide or our reviews.
Nearby places to Lessness Heath
Also in Lessness Heath
Looking after it afterwards
How long the joints last depends on use and care. Here’s what we suggest:
- Do not use solvent cleaners on the joint
- Make sure the drainage slots aren’t blocked
- Air rooms to keep condensation down around windows
- Keep jet washers away from the mastic
Keep sill grooves and drainage slots clear, so rain drains out rather than building up at the sealant.
Water gets in quietly when mastic fails. Often the first sign is a damp patch inside or flaking paint on the reveal. Early resealing stops it reaching that point.
When it isn’t the sealant
Some problems need a builder, plumber or other trade rather than us:
- A door that needs adjusting, rehanging or new seals
- A frame that has rotted at the joint
- A failed sealed unit that has misted up
If in doubt, ring 0345 464 0079 or drop us an email and we will say what we think before booking.
Surfaces we seal
- Timber windows & doors
- Window sills
- uPVC windows
- Composite doors
- Patio & French doors
- Aluminium frames
Surface by surface
uPVC windows
Some uPVC windows were sealed at fitting with a quick bead that never bonded. We cut it out, back any deep gaps and reseal properly.
Timber windows & doors
Older timber windows in stone or brick can suit sand mastic rather than modern sealant. We can talk through the options.
FAQs for Lessness Heath
Is Lessness Heath in your area for window mastic?
Yes. We work across London and the South East, and Lessness Heath is part of that. Just call 0345 464 0079 or email us with a few details of the job.
Do you work for landlords with property near Belvedere station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or email us and tell us about the property, and we will give you a clear price.
Which products do you use?
Products from Arbo and Everbuild, among others, chosen to suit the joint. We explain the product when we quote.
Do you have sealant for grey or black windows?
Yes. White, brown, anthracite grey, black and clear sealants are all available.
Where do you work from?
Mr Mastic is based in Crawley. Our applicators cover Lessness Heath.
Is the work guaranteed?
Yes. All our work carries a 12-month guarantee, and we’re fully insured.
Do you hold any approvals?
Yes. We hold ARBOMaster approved applicator status, and we’re fully insured.
How many windows can you do in a day?
That depends on the number of frames, how they’re reached and the state of the old mastic. We will tell you how long your job needs when we quote.
Windows and doors in Lessness Heath
With historic houses such as Red House (about 2.3 miles south-west) nearby, there’s older building stock in the area around Lessness Heath as well as newer homes. 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. The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
If you live in an older home near Parish Church of All Saints, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. As a London address, Lessness Heath can be tricky for parking: let us know about parking bays, permits or a driveway. Managing a site like Lessness Heath Primary School? Then its window and door frames need their mastic kept sound, just like a home’s.
Lessness Heath is about 3 miles east of Plumstead, in Greater London. For window mastic in and around Lessness Heath, it’s easy to get a quote: please call 0345 464 0079 or drop us an email. We cover Greater London from our Crawley base, Lessness Heath included. Our area takes in 764 places across Greater London, large and small. Our London page covers work nearby, about 11 miles away.
Postcode districts we cover here for window mastic: DA17, DA8 and DA7. If you need window mastic at a property on Cray Road, Clive Road and Erith Road or anywhere close by, we can help. Other places close to Lessness Heath include Belvedere (1 mile east), Erith (1 mile south-east), Northumberland Heath (1 mile south-east), West Heath (1 mile south-west) and Bexley Riverside (1 mile south-east). Larger places within reach include London (11 miles west), City of Westminster (13 miles west), Marylebone (13 miles west), Kensington (15 miles west), St Pancras (12 miles west) and Shoreditch (10 miles west).
Local landmarks in Lessness Heath
Around Lessness Heath, our work takes us to homes and buildings near Priory Club pub, Trinity Church of England School and Trinity School. Lessness Heath’s nearest station is Belvedere station, about 0.5 miles north of the centre. Nearby you will also find Broadway Shopping Centre (2.1 miles south) and Erith and District Hospital (0.9 miles south-east). Not far away are Crossness Nature Reserve.
How the visit works
Most of a good job is in the preparation, and we do not rush it. Every joint is cleaned and dried before new material goes in. In total, it usually takes most of a day for a typical house, less for a few frames. In Lessness Heath, as in most of London, parking needs a little planning. A visitor permit or a nearby bay makes the visit run more smoothly.
- We check each frame and agree which ones need doing.
- Next the failed sealant is cut away and the joint cleaned.
- Where gaps are deep, backing rod goes in first.
- New exterior sealant goes on in a matching colour and is tooled smooth.
- Finally we tidy up and check each joint.
Getting ready for the visit
- Clear items away from the joints we’re working on
- Mention any sign-in or site rules at work premises
- Tell us about any previous sealing or DIY attempts
Get a quote
For window mastic in Lessness Heath, call 0345 464 0079 or drop us an email. A short description of the job and where it is helps us quote, and you’ll get a clear quote before any work starts.
Read more
For landlords and businesses
For anyone letting property in or around Lessness Heath, jobs at different addresses can go on one quote. Send us the addresses and the work at each, and pictures by email help.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.