Greater London · England
Sand mastic for sash & case windows in Sydenham, Greater London
Sand mastic for Sydenham and the surrounding area: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Mastic dropping out of the joint
- Mastic round period door frames that has failed
- Draughts and rain around sash boxes
When to call us in Sydenham
Most of it is simply age. Even well-laid mastic needs renewing in time and how long it lasts depends on the weather it faces.
Common reasons people contact us include:
- Mastic that needs renewing before redecorating
- Gaps where the frame meets the masonry
- Cement or filler used on old window joints that has cracked
- Weathered mastic on the most exposed windows
Schools such as Kirkdale School are buildings too, and larger buildings have plenty of frames, and the mastic around each one ages.
What to look for in a quote
- How long to leave it before use
- Which sealant they’ll use, and why
- How the surfaces are prepared before sealing
- How the colour is chosen
About our sand mastic in Sydenham
On many period windows, sand mastic looks right and suits the building. On modern frames we’d normally use a flexible sealant, and we’ll talk through which suits your home. We’re often asked to deal with mastic round period door frames that has failed and old cement repairs round a window that have failed, across timber door frames, period & listed homes and brick reveals.
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, and access in Sydenham is something to talk through when you book.
There’s a 12-month guarantee on every job, large or small.
- Location
- Sydenham (SE26, SE20, SE23)
- Wider area
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear price before any work starts
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Why act early in Sydenham
Cement-based fillers and modern sealants don’t always suit a period surround. Sand mastic matches what was there and that can be important for listed homes. In a flat in Sydenham, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Instead of a standard rate, we price the job in front of us: the amount of work, the old material and the access. The price is agreed before we begin.
What you get with us
- An ARBOMaster approved applicator
- Anti-fungal sanitary silicone in wet areas
- Old sealant always removed completely
- Homes, businesses and hotels
Read what affects the cost and our reviews.
Quotes for sand mastic in Sydenham
Jobs vary more than people expect. The main factors:
- Whether there’s mould to deal with
- Access and height
- How much old sealant there is and how hard it is to remove
- How much there is to do
The cost depends on the size of the job, how hard the old material is to remove and access to the work. We give a clear quote before any work starts.
What to tell us for a quote
When you contact us, it’s useful to know:
- How many joints, rooms or windows are involved
- The problem you’ve noticed
- The type of property
- How we’d reach the joints
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is. Whenever you’re ready, ring 0345 464 0079 or drop us an email.
What we cannot put right
It helps to know what we can’t do too:
- Crumbling stone or brickwork round the window
- Sashes that rattle, stick or will not open
- Putty and glazing repairs
If you’re not sure, just ring 0345 464 0079 or send us an email and we will give you a straight answer before you book.
Where we work in Sydenham
- Brick reveals
- Stone surrounds
- Tenement windows
- Timber door frames
- Sash and case windows
- Period & listed homes
How the job changes by surface
Sash and case windows
The box of a sash and case window sits in the stone or brick opening. The gap round it is pointed with sand mastic.
Stone surrounds
Sand mastic sits naturally against stone. It finishes to look like part of the surround.
What sand mastic looks like in Sydenham
With historic houses such as Kingswood House (about 1.2 miles west) nearby, there’s older building stock in the area around Sydenham as well as newer homes. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window. In a converted house or block, who looks after the windows depends on the lease, so it’s worth checking before booking.
Sydenham is in London, so parking needs planning: let us know about parking bays, permits or a driveway. For an older house near a landmark such as Church of St Bartholomew, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Sydenham is about 3 miles south-east of East Dulwich, in Greater London. Whether you’re in the middle of Sydenham or further out, sand mastic is available for homes and businesses alike. Our area takes in 764 places across Greater London, from the larger towns to small villages.
Our applicators cover all of SE26, SE20 and SE23 for sand mastic. Streets in the area include Byne Road, Lucas Road and Cator Road. Neighbouring places we cover for sand mastic include Penge (1 mile south), Crystal Palace (1 mile south-west), Sydenham Hill (1 mile north-west), Perry Vale (1 mile north-east) and Anerley (1 mile south-west). Larger places within reach include London (5 miles north), City of Westminster (7 miles north-west), Marylebone (8 miles north-west), Kensington (8 miles north-west), St Pancras (7 miles north) and Shoreditch (7 miles north).
Local landmarks in Sydenham
In Sydenham, that means homes and buildings near St Bartholomews's Church of England Primary School, Sydenham High School and Mayow Park and the streets around them. There’s a railway station in Sydenham itself: Sydenham station. Other landmarks nearby include Greenwich Castle (4.3 miles north-east) and Crystal Palace Museum (1 mile west). Not far away are Dacres Wood and Knight's Hill.
Landlord and commercial work in Sydenham
Failed sealant is one of the commonest items on a check-out report. We can quote for more than one property at once.
Housing providers, facilities teams and property managers book us too. Several sites can be quoted together.
Nearby places to Sydenham
More services for Sydenham
FAQs for Sydenham
Is parking a problem for a job in Sydenham?
In much of London, parking needs planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Do you work for landlords with property near Sydenham station?
Yes, rental work is part of what we do. You can phone 0345 464 0079 or drop us an email with the address and a few details, and we’ll give you a fixed price before any work starts.
Can I add another job to the visit?
Yes, we can. Several rooms, windows or areas can go on one quote.
Is there any odour?
There can be a smell while the sealant cures, but it fades. Ventilation helps.
Is it possible to take out silicone and use sand mastic instead?
Yes. We remove the silicone and clean the joint before the sand mastic goes in.
Do you offer different sealant colours?
We will suggest a colour to suit the surroundings, from white and clear to greys and other shades. The product needed can limit the range.
Which is right for my windows, sand mastic or modern sealant?
Sand mastic generally suits period timber windows best. On modern frames, we’d normally use a flexible sealant.
Can you seal over the old sealant?
No. We remove every bit of old sealant first.
How it works
The work is kept neat and contained to the area we are working on, so you can get on with your day. The job generally takes anything from a few hours to a full day, depending on how many windows, and we tell you how long to leave it before we go. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Sydenham. It helps if you can point us to a visitor permit or a bay close to the door.
- First we agree which joints need doing.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- We apply the mastic by hand and shape it.
- We dress the finish so it sits neatly against the masonry.
How to prepare
- Keep pets and children clear of the area while we work
- Move anything stored near the joints
- Mention any leaks or damp you’ve noticed
How to get a quote
We do not publish a price list. Instead, your job gets its own clear quote. To arrange one, call 0345 464 0079 or send us an email.