Greater London · England
External & façade joints in Dartmouth Park, Greater London
Professional external mastic in and around Dartmouth Park, with old sealant always removed completely.
- Failed sealant between panels on a façade
- Plants rooting in failed movement joints
- Sealant that has lost its bond to the brick or render
How we handle external mastic in Dartmouth Park
Movement joints let brickwork, render and cladding expand and shrink without cracking. The sealant in it has to stretch and squeeze for years, so once it splits or hardens, the joint stops working and water gets in. Common call-outs are for weathered mastic that no longer stretches and rain getting behind render or cladding at a joint, on joints between brick and frames, render & cladding joints and brickwork movement joints.
Modern London flats rely on sealed movement joints and cladding joints. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall.
All of our work is guaranteed for twelve months.
- Place
- Dartmouth Park (NW5, N19, N7)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Honest limits
Sealant is not the answer to every problem, and we’ll tell you before any work starts. Sealant won’t put right:
- Adding movement joints to masonry that has none
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Cracked brickwork or render that needs a builder or plasterer
Not sure which it is? You can call 0345 464 0079 or send us an email and we’ll tell you honestly before booking.
Joints and surfaces we work on
- Copings & trims
- Brickwork movement joints
- Joints between brick and frames
- Concrete & block
- Render & cladding joints
- Façade panels
Quotes for external mastic in Dartmouth Park
Call for a quick quote. What matters most is:
- The old material and how stubborn it is
- How much there is to do
- How many rooms, windows or areas are involved
- Whether the work is at height
What it costs depends on the size of the job, how much old material has to come out and access to the work. You’ll have a clear quote before any work starts, so you know where you stand.
What we need to know
Photos by email are helpful but not essential. Try to tell us:
- The type of property
- Any access issues, like height or stairs
- The problem you’ve noticed
- Any previous sealing or DIY work
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints.
Questions from Dartmouth Park
Is Dartmouth Park in your area for external mastic?
Yes, Dartmouth Park is within the area we cover. Our work covers London and the South East. You can call 0345 464 0079 or drop us an email and let us know what needs doing.
Is parking a problem for a job in Dartmouth Park?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot.
When will the joints need doing again?
That varies with the weather the wall faces, how much it moves and the sealant used. Treat it as a maintenance item and look at it yearly and renew it when it starts to fail.
Can you reach joints on upper floors?
That depends on the building and the joints. Where joints can be reached safely, we’ll do them. Give us some details and we will confirm the access.
Is it worth trying it myself?
That depends on the joint. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
What is a movement joint?
It’s a deliberate gap that lets the wall expand and contract without cracking. It should be filled with flexible sealant, never mortar.
Can you seal joints between two different materials?
Yes. The old joint is removed, both surfaces cleaned and primed where needed, and a flexible sealant applied. We pick a colour that works with both materials.
Can new sealant go over the old?
No. We remove every bit of old sealant first.
What the job involves on each surface
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. We reseal their joints with backing rod and a flexible product.
Copings and trims
A failed coping joint lets water into the top of the wall. Resealing them is a small job that protects a lot.
What we do, step by step
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. Typically it takes a few hours to a few days, depending on the length of joint and the access. In Dartmouth Park, flats, stairs and shared entrances are part of the routine. If the building has a concierge, managing agent or access rules, tell us when you book.
- First, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Before we arrive
- Let us know about earlier repairs to the joints
- For indoor joints, keep the area dry beforehand if you can
- Mention any tricky access
Ask for a quote
For a quote, ring 0345 464 0079 or email us with the location and a short description of the problem. We will give you a clear quote before any work starts.
Read more
Work for landlords, hotels and businesses
Hotels need rooms back in use, so we plan the work room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
For anyone letting property in or around Dartmouth Park, jobs at different addresses can go on one quote. Just tell us the addresses and what each one needs.
Nearby places to Dartmouth Park
More services for Dartmouth Park
Walls and rooflines in Dartmouth Park
London terraces and converted houses often share gutters, downpipes and walls, so it’s worth agreeing who is responsible before work starts. 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.
If you let a flat or house near Gospel Oak station, split movement joints are easy to miss on a rental until damp shows inside. Managing a site like Acland Burghley School? Then larger buildings have long runs of movement joint that eventually need resealing.
Dartmouth Park is about 2 miles east of Hampstead, in Greater London. Every kind of property in Dartmouth Park is covered for external mastic, old or new, large or small. The work is guaranteed for a year. Across Greater London, we cover 764 places, and Dartmouth Park is one of them.
Here we cover the NW5, N19 and N7 postcode area for external mastic. Whether your property is on Hugo Road, Ward Road and Anson Road or a nearby road, we can help. If you’re just outside Dartmouth Park, we cover Lissenden Gardens (1 mile south-west), Tufnell Park (1 mile east), Gospel Oak (1 mile south-west), Upper Holloway (1 mile north-east) and Highgate (1 mile north). We also work in nearby towns such as London (5 miles south-east), City of Westminster (3 miles south), Marylebone (3 miles south), Kensington (5 miles south-west), St Pancras (3 miles south-east) and Shoreditch (4 miles south-east).
What’s near Dartmouth Park
Around Dartmouth Park, our work takes us to homes and buildings near The Dartmouth Arms, Whittington Park and Brookfield Primary School, among other places. Also close by are Asanté Academy of Chinese Medicine (1.4 miles north) and Vaughan Williams Memorial Library (1.5 miles south). For rail, the closest station is Gospel Oak station, about 0.5 miles south-west. Nearby you’ll also find O2 Centre (1.8 miles south-west) and Isokon Gallery (1 mile south-west). Not far away are Belsize Wood and Dartmouth Park Hill.
Do you need external mastic in Dartmouth Park?
Poor preparation causes many early failures: dusty or wet faces, no primer where one was needed, or old sealant left in. The new sealant then lets go long before it should.
Common reasons people contact us are:
- Joints where the bead has come unstuck
- Brick movement joints where the sealant has split
- Old sealant gone brittle and cracked
- Weeds or debris growing in open joints
Dartmouth Park is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book.
What to look for in a quote
- What insurance they hold
- Whether you can choose the colour
- How hidden problems are handled
- Who turns up on the day
DIY versus a professional finish
A DIY attempt does not rule out a professional job. We remove it and do the joint properly, so tell us about it when you ask for a quote.
If you’re 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.