Greater London · England
New-build mastic & snagging in Sydenham, Greater London
New-build sealant joints in Sydenham need attention? We remove the old material, prepare the joints and seal them properly.
- Sealant applied over dusty or wet surfaces
- Joints pulling apart as timber shrinks
- Cracked sealant around new window and door frames
New build mastic in Sydenham
Dust is the enemy of new-build sealant. Each joint is cleaned of dust and primed where the product calls for it, so the new bead bonds properly rather than sitting on a layer of grit. We work on plot handovers, show homes and bathrooms & en suites, and common reasons people get in touch are beads laid onto grit and dust from the build and second-fix sealing on new plots.
Across London, commercial floors have movement joints that break down under heavy foot traffic, and new homes need their plot mastic finished properly before handover.
The work is guaranteed for twelve months. If there’s a problem with our work within the year, let us know and we will sort it.
- Location
- Sydenham (SE26, SE20, SE23)
- Wider area
- Greater London
- Guarantee
- A year, on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
How we quote for new build mastic
You’ll get a clear quote before any work starts. It takes into account:
- How easy the joints are to reach
- The number of rooms or windows
- Working hours on commercial sites
- The size of the job
There are no prices on our website, because each job is priced on what it involves. For a quick quote, please phone 0345 464 0079 or drop us an email and we will talk you through it.
What to tell us for a quote
To make quoting easier, let us know:
- What the problem is, such as mould, gaps, leaks or cracking
- Whether it has been sealed before
- Where the job is, and your postcode
- Whether it’s a home or a business
There’s no standard price list, because every job is different. Instead, we give you a clear price for your job. To arrange one, call 0345 464 0079 or email us.
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Check bath and shower seals every few months as the house settles
- Ventilate bathrooms well, especially in the first year
- Report sealant problems to your builder during the snagging period
- Do not wait for the house to settle if water is getting through
Leave the sealant for the cure time we give you before showering or bathing. Silicone is normally left for about a day to cure enough for use.
Mould takes hold quickly in sealant that has gaps or lifted edges. Resealing before mould gets in saves a harder job later.
For landlords and businesses
In hotels, rooms out of use cost money, so the work can be planned room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
We regularly work with letting and managing agents. Tell us the address, the job and how access works and we’ll quote.
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 matched to the joint and its conditions.
Sealing over old silicone is the commonest DIY error. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
Your questions about new build mastic in Sydenham
I let a flat near Sydenham station. Can you help?
Yes, rental work is part of what we do. You can call 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before any work starts.
Is Sydenham in your area for new build mastic?
Yes, Sydenham is within the area we cover. We work across London and the South East. You can ring 0345 464 0079 or email us and let us know what needs doing.
Do you have insurance?
Yes. We are fully insured, and we have been doing sealant work for more than 20 years.
Should I try DIY first?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. Most DIY failures come from sealing over old material, wet joints or too much sealant.
Can I send you my snagging list?
Yes. We often work straight from a snagging list. We agree the sealant items with you before any work starts.
Will there be a smell?
Some sealants have a smell while they cure, but it fades. Ventilation helps.
Does someone need to be in?
If the work is inside, we need someone to let us in. After that, you can carry on with your day.
Where do you work from?
We work from Crawley. We cover Sydenham and the rest of Greater London.
Leave it or put it right?
For developers, getting the sealant right first time saves return visits. Every return visit for a failed seal takes time. Converted houses in London often have a bathroom above someone else’s living room, and a slow leak from a failed seal can end up in the flat below. Dealing with it early is far simpler for homes in Sydenham.
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. The price is agreed before we begin.
What you get with us
- Colour agreed with you before any work starts
- 180+ five-star Google reviews
- A 12-month guarantee on all work
- We never seal over old sealant
Read our cost guide and customer reviews.
Nearby places to Sydenham
Also in Sydenham
Do you need new build mastic in Sydenham?
Baths and trays settle under load once the home is lived in. If a bath wasn’t filled when it was sealed, the bead is stretched the first time it’s used.
Signs it’s time to call us include:
- Beads laid onto grit and dust from the build
- Plot mastic for developers ahead of handover
- Shower seals failing in the first year or two
- Gaps opening as the house dries out and settles
Sydenham is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Questions to ask before you book
- Whether they seal over old material or remove it
- How hidden problems are handled
- What insurance they hold
- How the surfaces are prepared before sealing
How it works
Every visit runs the same way: we check the joints, mask and protect the surrounding surfaces, carry out the job and clear up. Most jobs take a few hours for most snagging lists, longer for a run of plots. In Sydenham, as in most of London, parking needs a little planning. A visitor permit or a nearby bay makes the visit run more smoothly.
- We start by going through the snagging items or plot schedule with you.
- The failed sealant is removed completely.
- Joints are vacuumed and cleaned of building dust.
- Primer goes on where the surface and product need it, then the new sealant.
- We tool every joint neatly and tell you when each area can be used.
How to prepare
- Tell us about access, such as stairs, a lift or high-level joints
- Let us know if you’ve seen damp or leaks
- Tell us if parking is tricky
Getting a quote
Want a quote for new build mastic? Please call 0345 464 0079 or email us and tell us about the job. We’ll explain what we’d do and give you a clear quote before work begins.
Read more
What new build mastic looks like in Sydenham
Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Many of London’s new homes are flats in bigger developments, where snags may need reporting through the developer or the managing agent.
If you’ve bought a new home near Sydenham station, the sealant around baths, showers and frames is worth checking in the first year or two.
Sydenham is about 3 miles south-east of East Dulwich, in Greater London. Across the SE26 area, we cover new build mastic for homes and businesses. 764 places in Greater London are on our list, large and small.
Here we cover the SE26, SE20 and SE23 postcode area for new build mastic. You will find streets such as Byne Road, Lucas Road and Cator Road, and we cover them all. If you’re just outside Sydenham, we cover 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). Further out, we also cover 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).
Near you in Sydenham
We work in homes and buildings around St Bartholomews's Church of England Primary School, Sydenham High School and Mayow Park, among other places. There’s a railway station in Sydenham itself: Sydenham station. Well-known places in the area include Greenwich Castle (4.3 miles north-east) and Crystal Palace Museum (1 mile west). Green spaces nearby include Dacres Wood and Knight's Hill.