Greater London · England
Window Mastic in Crystal Palace
Mastic around window and door frames, sills and patio doors for homeowners, landlords and businesses in Crystal Palace. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Gaps left after new windows were fitted
- Gaps between the frame and the inside reveal
- Water coming in at the bottom corners of a door
How we handle window mastic in Crystal Palace
Most frames have an outside joint and an inside one. Outside, the mastic keeps rain out; the internal joint closes the gap to the plaster and stops draughts. Either or both can be done. We are often asked to deal with cold air getting in at the frame edge and cracked internal joints between frame and plaster, on uPVC windows, timber windows & doors and composite doors.
London has a lot of flats and conversions, where windows are often on upper floors. Who looks after the outside of the frames can depend on the lease, so check that first.
Our work is backed for twelve months, in Crystal Palace and everywhere else we cover.
- Location
- Crystal Palace (SE19, SE20, SE26)
- Region
- Greater London
- Guarantee
- One year on every job
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Can I do it myself?
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, and the work is guaranteed for a year.
If you are set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it does not work out, we can still put it right.
The process
There is not much for you to do on the day. Show us the job and we will take it from there. The job generally takes a morning for a couple of windows and a door, including the tidy-up. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- First, we go round the frames with you and agree the list.
- The old mastic is cut out and scraped back to clean surfaces.
- Deep gaps get closed-cell backing rod to set the depth.
- A flexible exterior sealant is applied in a colour to suit the frame.
- Every joint is tooled smooth and checked before we leave.
Getting ready for the visit
- Tell us about any water getting in
- Tell us about any previous sealing or DIY attempts
- Let us know about parking restrictions
How to get a quote
Getting a quote is simple: let us know the job and the location. A few pictures by email make the job easier to understand, and we’ll come back to you with a quote.
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Crystal Palace questions
Can parking be tricky for a visit in Crystal Palace?
Parking in Crystal Palace, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Do you cover Crystal Palace for window mastic?
Yes. Our work covers London and the South East, and Crystal Palace is part of that. You can call 0345 464 0079 or email us and let us know what needs doing, and we’ll give you a clear price.
Is it messy?
No. We protect the surfaces around the joints, and we tidy up before we go.
Do you do commercial work?
Yes, regularly. We can plan bigger jobs in stages.
What do you put in the joint?
Quality sealants from brands including Arbo and Everbuild, picked for each joint. We explain the product when we quote.
Can landlords and businesses book you?
Yes, we do. Domestic, commercial and hotel work are all part of what we do, and we’re fully insured.
What should I tell you?
Only a few details: the address or postcode, what’s wrong and any access issues. After that, simply call 0345 464 0079 or send us an email.
Can you do several jobs on one visit?
Yes. Several rooms, windows or areas can go on one quote.
Keeping the joints in good condition
Once the sealant has cured, a few habits help it last:
- Keep jet washers away from the mastic
- Ventilate rooms so frames don’t stay wet inside
- Paint up to the joint, not over it
- Use gentle cleaners on frames and sealant
Timber frames need their paint kept up, since wood that gets wet swells and shrinks more. Keep paint off the silicone itself.
Water trapped behind a failed joint can start rot in timber frames and sills. Rotten timber needs a joiner, not a sealant, so early resealing is worth it.
Leave it or put it right?
A cracked joint around a frame lets rain into the wall. Left long enough, it can stain inside walls, spoil plaster and rot wooden frames. A reseal is a much smaller job. 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.
The cost depends on how much there is to do, how hard the old material is to remove and access to the work. You’ll have a clear quote before any work starts.
What you get with us
- Sealant colour chosen to suit
- Experience in homes, commercial sites and hotels
- Quality sealants from Arbo and Everbuild
- Approved under the ARBOMaster scheme
How the job changes by surface
Composite doors
An exposed front door gets wind-driven rain. We pay most attention there.
Aluminium frames
Aluminium needs a sealant that bonds to coated metal, and acetoxy silicones are not used, as they can attack some metals. Neutral-cure sealant is the safe choice.
When it isn’t the sealant
Before booking, it’s worth knowing the limits:
- Damp problems in the wall away from the window
- A frame that has rotted at the joint
- Faulty window hardware
Not sure which it is? You can call 0345 464 0079 or send us an email and we’ll tell you honestly.
What we seal
- uPVC windows
- Aluminium frames
- Patio & French doors
- Window sills
- Timber windows & doors
- Composite doors
Do you need window mastic in Crystal Palace?
Sills take more water than any other part of a window, and the ends of the sill, where it meets the wall, are where it gets in. Failed sealant there lets rain into the wall or behind the frame.
Common reasons people contact us include:
- Cracked internal joints between frame and plaster
- Mastic that is falling out in pieces
- Hard, cracked sealant around windows
- Leaking joints at the ends of sills
In the older streets around St Paul's, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
What to look for in a quote
- Is VAT in the price?
- Whether they seal over old material or remove it
- Whether you can choose the colour
- What insurance they hold
Nearby places to Crystal Palace
Other services in Crystal Palace
Window mastic in Crystal Palace: local notes
The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. In London conversions and blocks, the lease decides who is responsible for the frames, so check that before you book.
Letting a property close to Crystal Palace station? Then renewing tired window mastic between tenants heads off draught and damp complaints. Crystal Palace is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Crystal Palace is about 2 miles north-east of Thornton Heath, in Greater London. Anywhere in SE19, we cover window mastic for homes and businesses. Our area takes in 764 places across Greater London. For nearby work, see our London page.
Work in SE19, SE20 and SE26 works the same way as everywhere else we cover. Local streets include Tudor Road, Colby Road and Church Road, and we cover them all. Neighbouring places we cover for window mastic include Anerley (1 mile south), Penge (1 mile south-east), Gipsy Hill (1 mile west), Upper Norwood (1 mile west) and Sydenham (1 mile north-east). Larger places within reach include London (6 miles north), City of Westminster (7 miles north-west), Marylebone (7 miles north-west), Kensington (8 miles north-west), St Pancras (8 miles north) and Shoreditch (7 miles north).
Near you in Crystal Palace
Locally, jobs take us to homes and businesses close to The Grape & Grain pub, Crystal Palace Park and Sydenham High School, among other places. There’s a railway station in Crystal Palace itself: Crystal Palace station. Nearby you’ll also find Greenwich Castle (5 miles north-east) and Whitgift Centre (3.3 miles south-west). Not far away are Dulwich Upper Wood and Knight's Hill.