Greater London · England
Blackfen New Build Mastic
Plot mastic for developers and snagging failed sealant in new homes in Blackfen, with a one-year guarantee on every job. Ask us for a quote.
- Beads laid onto grit and dust from the build
- Gaps opening as the house dries out and settles
- Cracked caulk along new skirting
New build mastic in Blackfen, done properly
We work in new homes and on new-build sites across Blackfen. One shower or a whole phase of plots, the method does not change: cut out, clean, prime where needed and reseal neatly. Typical jobs include messy sealant that spoils new finishes and shower seals failing in the first year or two, on kitchens, skirting & floors and show homes.
London homes range from new-build flats to period conversions with new floors laid over old boards. Every joint between floor, skirting and threshold has to cope with some movement, in Blackfen as anywhere.
We stand behind the work with a one-year guarantee.
- Location
- Blackfen (DA15, DA16, SE9)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
Keeping the joints in good condition
No joint lasts for ever, but care makes a real difference. A few tips:
- Ventilate bathrooms well, especially in the first year
- Photograph failed sealant before it’s redone
- Put sealant faults on your snagging list early
- Watch for new gaps as the house dries out
Follow the cure time we give you before the area gets wet. Most silicones need around a day to cure enough for use.
Mould takes hold quickly in sealant that has gaps or lifted edges. Dealing with it before it goes black keeps the job straightforward.
Different surfaces, different methods
Show homes
We seal show-home bathrooms, kitchens and frames to a tidy standard. Tell us when the home is open so we can plan around it.
Plot handovers
Taking time over preparation reduces return visits. Dust from the build is removed first and primer used where needed.
Your questions about new build mastic in Blackfen
Can you do new build mastic in Blackfen?
Yes. We work across London and the South East, and Blackfen is part of that. Just phone 0345 464 0079 or send us an email with a few details of the job.
Do you work for landlords with property near Falconwood station?
Yes, landlords and agents are among the people we work for, and several properties can be quoted together. Just ring 0345 464 0079 or drop us an email with the address and what needs doing, and we will send you a clear quote.
Why has my new-build shower seal failed already?
Lots of new homes see sealant crack early. Poor preparation at handover adds to it.
What colour sealant will you use?
That depends on what the joint meets: white or clear in most bathrooms, and a colour to suit worktops, frames and floors elsewhere. We agree the colour before any work starts.
Can I add another job to the visit?
Yes. Tell us about everything you’d like done and we will quote it together.
How long will you be here?
It depends on the size of the job, but most jobs take a few hours for most snagging lists, longer for a run of plots. We will tell you when we quote.
What does new build mastic cost?
Every job is different, so each one gets its own quote. For a quick quote, call 0345 464 0079 or send us an email with a short description of the job.
Will you leave a mess?
We keep the work tidy. Nearby surfaces are protected, and we clear up when we are done.
Joints and finishes in Blackfen homes
Many of London’s new homes are flats in bigger developments, where snags may need reporting through the developer or the managing agent. Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Blackfen is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
Blackfen is about 2 miles east of Eltham, in Greater London. Blackfen gets the same service as everywhere we cover: the old material taken out, joints prepared properly and a 12-month guarantee. Our Greater London coverage runs to 764 places, and Blackfen is one of them. For nearby work, see our London page (9 miles or so).
We work across DA15, DA16 and SE9 for new build mastic and the streets around it. That includes homes and businesses on Days Lane, Gordon Road and Kent Avenue and the roads around them. Neighbouring places we cover for new build mastic include Falconwood (1 mile north), Avery Hill (1 mile west), East Wickham (1 mile north), New Eltham (1 mile south-west) and Longlands (1 mile south). We also work in nearby towns such as London (9 miles north-west), City of Westminster (11 miles north-west), Marylebone (11 miles north-west), Kensington (13 miles west), St Pancras (10 miles north-west) and Shoreditch (9 miles north-west).
What’s near Blackfen
Typical jobs here are in homes near The George Staples pub, Harris Academy Falconwood and Shoulder of Mutton Green, among other places. For rail, the closest station is Falconwood station, roughly 0.8 miles north-west of the centre. Other landmarks nearby include Broadway Shopping Centre (2.3 miles east) and Eltham Community Hospital (1.7 miles west). The countryside around Blackfen includes Summer Hill and The Tarn.
Nearby places to Blackfen
Other services in Blackfen
How we quote for new build mastic
Your quote is based on your job. We look at:
- The size of the job
- Whether old sealant or filler has to be cut out
- How many rooms, windows or areas are involved
- Mould in or behind the old joints
Doing several joints on one visit usually makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. You will get one clear quote for the whole job.
Asking for a quote
To help us quote quickly, let us know:
- The problem you’ve noticed
- If someone has resealed it before
- Roughly how big the job is
- The address or postcode of the job
For new build mastic in Blackfen, 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 work begins.
Landlords, agents and businesses in Blackfen
We also work for businesses, from offices to washrooms and kitchens. For commercial premises, we can talk through working times when we quote.
If you manage several properties in or around Blackfen, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs.
Signs you need new build mastic in Blackfen
A new house holds a lot of water from the build, which takes a year or two to dry out. As it does, timber shrinks and joints open.
If you can see any of these, it’s time to have the joints looked at:
- Kitchen sealant that has pulled off the wall
- Joints pulling apart as timber shrinks
- Cracked sealant around new window and door frames
- Smeared, uneven beads picked up at snagging
If you’ve bought a new home near Falconwood station, the sealant around baths, showers and frames is worth checking in the first year or two.
What to look for in a quote
- The length of the guarantee
- Who does the work, and how experienced they are
- How long to leave it before use
- Whether VAT is included
When it isn’t the sealant
New sealant cannot fix everything, and we’d rather say so up front. Sealant won’t put right:
- Disputes or warranty claims with your builder
- Leaks from pipes, valves or wastes, which need a plumber
- Broken tiles or a split tray
Not sure which it is? You can ring 0345 464 0079 or send us an email and we will tell you honestly.
Surfaces we seal
- Skirting & floors
- Plot handovers
- Bathrooms & en suites
- Windows & doors
- Show homes
- Kitchens
What we do, step by step
Once we’re on site, we compare the joints with what we discussed. If we find something unexpected, we talk it through with you first. After that, the work takes a few hours for most snagging lists, longer for a run of plots. For a job in Blackfen, parking and access are the things to plan: let us know about parking, the floor we will be working on and any lift or shared entrance.
- We start by going through the snagging items or plot schedule with you.
- Every bit of the old builder’s sealant is cut out down to clean surfaces.
- We clean out the dust and grit left from the build.
- 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.
Preparing for the visit
- Tell us about access, such as stairs, a lift or high-level joints
- Tell us if parking is tricky
- For indoor joints, keep the area dry beforehand if you can
Ask for a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is.