Greater London · England
Window Mastic in Well Hall
Our applicators work in Well Hall on mastic around window and door frames, sills and patio doors. Old material cut out, joints cleaned and sealed neatly and a one-year guarantee.
- Sealant in the wrong colour for the frame
- Water coming in at the bottom corners of a door
- Cold air getting in at the frame edge
About our window mastic in Well Hall
Frames and walls do not move together. Plastic and aluminium frames move with the temperature, while masonry stays fairly still. So the sealant has to stretch and recover, which is why we use a low-modulus product. If you have damp patches on the reveal after heavy rain and cracked internal joints between frame and plaster, we can put it right, on uPVC windows, patio & French doors and aluminium frames 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.
Every job is covered by our one-year guarantee, wherever you are in Greater London.
- Location
- Well Hall (SE9, SE3, SE12)
- Wider area
- Greater London
- Cover
- One year on every job
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
The process
There’s no need to move everything out before we come, only the area right around the joints. We protect the rest, and the job takes a few hours for a handful of frames, longer for a whole house for a typical job. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Well Hall. A visitor permit or a nearby bay makes the visit run more smoothly.
- We check each frame and agree which ones need doing.
- The old mastic is cut out and the surfaces cleaned back.
- Where gaps are deep, backing rod goes in first.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- We clear up and check every joint is fully closed.
Getting ready for the visit
- On commercial sites, let us know about site rules
- Tell us about access, such as stairs, a lift or high-level joints
- Where the joints are inside, avoid wetting them before we arrive
Get a quote
Asking for a quote is easy: tell us what needs doing and where. A few photos by email make the job easier to understand.
Read more
Well Hall questions
I let a flat near Eltham station. Can you help?
Yes. We work for landlords and agents as well as householders, and several properties can go on one quote. Just call 0345 464 0079 or email us with the address and what needs doing, and we’ll give you a clear price.
Can you do window mastic in Well Hall?
Yes. We work across London and the South East, and Well Hall is part of that. Just call 0345 464 0079 or drop us an email with a few details of the job.
Can resealing stop a draught around my window?
Yes, if the air is getting in around the frame. If it’s coming through the window seals, we’ll tell you.
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. If it doesn’t work out, we can redo it.
Can you quote for more than one area?
Of course. Doing several areas at once is generally more efficient.
Can new sealant go over the old?
No. Fresh sealant does not stick to old sealant, and anything trapped underneath, including mould and water, stays there. We remove it all first.
Can I paint over the new sealant?
That depends on the product. Some hybrid sealants can be painted; silicone can’t. Tell us if you are decorating and we will choose accordingly.
Do you guarantee window mastic?
Yes, for 12 months. A yearly look at the joints helps them last.
Frames and glazing around Well Hall
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. Historic houses like Eltham Palace (about 0.7 miles south) are a reminder that the area around Well Hall has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
Managing a site like Gordon Primary School? Then larger buildings have plenty of frames, and the mastic around each one ages. If you let a flat or house near Eltham station, sound mastic around windows and doors keeps out the draughts and damp that tenants notice first.
Well Hall is about 2 miles south-west of Plumstead, in Greater London. Whether you are in the middle of Well Hall or further out, we cover window mastic for every kind of property. Well Hall is one of 764 places in Greater London we cover. You can also see our page for London, about 7 miles away.
We work across SE9, SE3 and SE12 for window mastic. Local streets include Haimo Road, Lassa Road and Brome Road. We also cover the places around Well Hall: Kidbrooke (1 mile north-west), Eltham (1 mile south), Middle Park (1 mile south-west), Shooter's Hill (1 mile north-east) and Horn Park (1 mile south-west). Further out, we also cover London (7 miles north-west), City of Westminster (10 miles north-west), Marylebone (9 miles north-west), Kensington (11 miles west), St Pancras (9 miles north-west) and Shoreditch (7 miles north-west).
Near you in Well Hall
In Well Hall, that means homes and buildings near The Banker's Draft pub, Eltham Hill School and Thomas Tallis School and the streets around them. There’s a railway station in Well Hall itself: Eltham station. A little further out are Greenwich Castle (2.6 miles north-west) and Eltham Community Hospital (0.6 miles south). Open spaces near Well Hall include Birdbrook Road Nature Reserve and Summer Hill.
Aftercare tips
Aftercare is simple:
- Keep drainage slots and sill grooves clear
- Check the mastic once a year
- Avoid harsh chemicals near the mastic
- Do not paint over the silicone
Wipe the frames with soapy water when you clean the windows, and avoid solvent cleaners on the sealant.
Leaks generally show up in wet, windy weather, but sealant goes on best when frames and walls are dry. Sorting cracked mastic early means the joint is sound before the bad weather.
How the job changes by surface
Window sills
Every drop off the glass ends up on the sill, so the joints at each end and underneath matter. Each is cleaned out and resealed.
uPVC windows
uPVC expands and contracts noticeably with temperature, so the joint needs a low-modulus sealant that stays flexible. White is the usual colour, with brown, anthracite grey and black for coloured frames.
When to call us in Well Hall
Every frame moves through the day. A plastic or aluminium frame lengthens in sunshine and shortens as it cools, while the masonry beside it stays put. If the sealant cannot stretch, it splits.
People generally contact us after spotting one of these:
- Rain getting in at the frame or under the sill
- Draughty joints inside around the window
- Old mastic that has gone black or come away
- Gaps left after new windows were fitted
In the older streets around St Barnabas, the joint between an old wall and a newer frame is generally the first place rain gets in.
Before you book anyone
- Which colour the sealant will be
- How long the guarantee is
- How the joint is cleaned and prepared
- Is VAT in the price?
For landlords and businesses
For anyone letting property in or around Well Hall, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs.
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.
Leave it or put it right?
Not every sealant suits a window. Decorators’ caulk and bathroom silicone aren’t designed for outside joints that move. An exterior, low-modulus sealant stays flexible in sun and frost. In London conversions, one flat’s bathroom is often above another flat’s ceiling, 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 for homes in Well Hall.
The cost reflects the work involved, not guesswork. That’s why we ask a few questions first and give you a clear price before any work starts.
Why choose Mr Mastic in Well Hall
- Quality sealants from Arbo and Everbuild
- Experience in homes, commercial sites and hotels
- Every job guaranteed for a year
- ARBOMaster approved applicator
Read what affects the cost and customer reviews.
When something else is needed
New sealant can’t fix everything, and we will tell you before any work starts. It will not solve:
- Condensation trapped between the panes
- Draughts through the window seals rather than the frame
- A sash or casement that will not close properly
Not sure which it is? You can phone 0345 464 0079 or send us an email and we will tell you honestly.
Surfaces we seal
- Window sills
- uPVC windows
- Aluminium frames
- Composite doors
- Timber windows & doors
- Patio & French doors