Greater London · England
External Mastic in Avery Hill
External mastic for Avery Hill, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Moss and dirt in joints with no sealant left
- Damp patches traced to an open external joint
- Leaking joints around cladding and façade panels
How we handle external mastic in Avery Hill
A movement joint is only as good as its depth. Backing rod controls how deep the sealant goes and keeps it off the back of the joint, so it bonds to the two sides only and can stretch. We are often asked to deal with panel joints letting water in and joints with sealant missing in places, on joints between brick and frames, façade panels and concrete & block.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. In Avery Hill, joints up high may need ladders or other access, which is worth talking through when you book.
Each job carries a 12-month guarantee, whatever its size.
- Where
- Avery Hill (SE9, DA15, DA16)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear price before we start
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Landlord and commercial work in Avery Hill
Water getting past a failed joint can damage the building, which matters even more when someone else lives there. Resealing at the right time is simple maintenance that we can handle for you.
Hotels need rooms back in use, so the work can be planned room by room. Hotel work is part of what we do, alongside homes and businesses.
Should I try it myself first?
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and doesn’t move well, and the joint depth matters as much as the finish.
How it works
All our tools and materials come with us in the van, so there’s nothing for you to buy. After a quick look at the joints together, we protect the area and start. It normally takes a few hours to a few days, depending on the length of joint and the access. For a job in Avery Hill, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- We prime the faces where required.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
Getting ready for the visit
- Clear items away from the joints we are working on
- Mention if the joints have been sealed before
- For business premises, tell us about site rules or sign-in
Ask for a quote
Call for a quick quote, or email us if that’s easier. Tell us about the joints that need doing and we will explain what’s involved before giving you a price.
Advice
Places near Avery Hill
More services for Avery Hill
Looking after it afterwards
Joint life depends on how it’s used and looked after. Here’s what we suggest:
- Leave the joints unpainted unless we’ve said otherwise
- Walk round the building once a year and look at the joints
- Show decorators and builders where the movement joints are
- Deal with leaking gutters that soak the joints below
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They must stay as flexible joints, never rendered or pointed over.
Small splits are the time to act. At that stage it’s a simple cut out and reseal before water has had years to get in.
Different surfaces, different methods
Joints between dissimilar materials
Each side of the joint may need its own preparation. Both surfaces are cleaned and primed as the product requires.
Render joints
Water behind render can lead to blown patches. Resealing the joints early keeps water out and protects the render itself.
Leave it or put it right?
Low-modulus sealants stretch easily, so they put less strain on the joint edges. That protects surfaces like brick, render and concrete. Too stiff a sealant can pull at the edges and break them. 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.
Commercial jobs are quoted on the same basis as homes: how much there is to do, how we reach it and what it needs, along with when we can work on site. Ask us for a quote and we’ll go through it with you.
Why book with us
- Quality sealants from Arbo and Everbuild
- We are fully insured
- 4.9 on Google from 180+ five-star reviews
- Every job guaranteed for a year
Avery Hill questions
Is parking a problem for a job in Avery Hill?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. The visit is then planned around what’s available.
Do you work for landlords with property near Falconwood station?
Yes, we work for landlords and letting agents. Just ring 0345 464 0079 or drop us an email and tell us about the property, and we’ll give you a clear quote.
Is it worth trying it myself?
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.
Why do you put foam in the joint first?
Backing rod controls the sealant depth and keeps it off the back of the joint. Then the sealant bonds to two faces and can move.
What does external mastic cost?
We do not publish prices, because the cost depends on the job: its size, the old material, access and the product needed. You will get a clear quote before work begins.
Do you work for hotels and businesses?
Yes. We’ve worked for hotels, offices and other businesses, and we are fully insured.
Can you match the colour of my brickwork?
The aim is a neat, even joint in a colour that suits the wall. Colour is agreed with you before we begin, matched as closely as the range allows.
Will you leave a mess?
Not at all. We work neatly, protect the area around the joints and tidy up afterwards.
How we quote for external mastic
You will get a clear quote before work begins. It’s based on:
- Mould in or behind the old joints
- Working hours on commercial sites
- The product the joint needs
- How easy the joints are to reach
Doing several joints on one visit normally makes better use of the time than several visits, so it’s worth mentioning everything you’d like done. We will give you a clear price for the lot.
What to tell us for a quote
A few details help us give you an accurate quote. When you get in contact, it helps to mention:
- What the problem is, such as mould, gaps, leaks or cracking
- Any previous sealing or DIY work
- Where the property is
- Photos by email, if that is easy
Need a quote? Please call 0345 464 0079 or send us an email and tell us about the job. You’ll know what we plan to do, and what it will cost, before any work begins.
External mastic in Avery Hill: local notes
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. In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts.
Schools such as Stationers' Crown Woods Academy are buildings too, and its movement joints, gutters and trims need looking after like any other building’s. Rented homes near Falconwood station change hands often, and outside joints that have cracked can let damp into a rental, so check them between lets. In the older streets around Church of Holy Trinity, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Avery Hill is about 1 mile north-east of Eltham, in Greater London. If you need external mastic in Avery Hill, it’s easy to get a quote: please call 0345 464 0079 or email us. We cover Greater London from our Crawley base. We cover 764 towns and villages across Greater London, large and small. You can also see our page for London, roughly 8 miles from Avery Hill.
Work in SE9, DA15 and DA16 is quoted and booked the same way as anywhere else. Local streets include Bexley Road, Glenure Road and Perpins Road. Avery Hill is on the A210, so it’s easy for us to get to with everything needed for external mastic. Nearby, we also carry out external mastic in Blackfen (1 mile east), Eltham (1 mile south-west), New Eltham (1 mile south), Falconwood (1 mile north-east) and Well Hall (1 mile west). Larger places within reach include London (8 miles north-west), City of Westminster (11 miles north-west), Marylebone (11 miles north-west), Kensington (12 miles west), St Pancras (10 miles north-west) and Shoreditch (8 miles north-west).
Landmarks near Avery Hill
Around Avery Hill, our work takes us to homes and buildings near Shoulder of Mutton Green and Alderwood Primary School. The closest station to Avery Hill is Falconwood station, roughly 0.6 miles north. Other landmarks nearby include Greenwich Castle (3.8 miles north-west) and Metropolitan Police Museum (1.7 miles south-east). The countryside around Avery Hill includes Summer Hill and The Tarn.