Greater London · England
Petersham External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for homeowners, landlords and businesses in Petersham. ARBOMaster approved applicators, fully insured, with a 12-month guarantee.
- Weeds or debris growing in open joints
- Movement joints with cracked, split or missing sealant
- Rain getting behind render or cladding at a joint
How to look after the new joints
Joint life depends on how it’s used and looked after. We suggest:
- Tell anyone working on the walls about the movement joints
- Leave the joints unpainted unless we’ve said otherwise
- Make sure movement joints are not pointed over
- Check external joints each spring
Make sure anyone working on the wall later knows where the movement joints are. They must stay as flexible joints, never rendered or pointed over.
Leave a failed movement joint and water keeps getting into the wall. That can lead to damp patches, staining and frost damage, all bigger jobs than a reseal.
About our external mastic in Petersham
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible sealant bridges the two where mortar or filler would crack. We work on copings & trims, brickwork movement joints and joints between brick and frames, and people most often call us about plants rooting in failed movement joints and rain getting behind render or cladding at a joint.
London’s terraces and conversions often share walls, gutters and downpipes with their neighbours, so a leaking gutter joint or failed wall joint can affect more than one home. In a converted house in Petersham, it’s worth checking who is responsible for the outside before booking.
All of our work is guaranteed for twelve months.
- Location
- Petersham (TW10, TW1)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Also near Petersham
Other services in Petersham
Petersham: your questions answered
Is parking an issue for external mastic in Petersham?
Parking in Petersham, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly, so mention what’s available when you book.
Can you help a landlord with a rental near St Margarets (London) station?
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 work begins.
What colours does the sealant come in?
The sealant colour is picked to suit the wall, so the joint sits quietly in the wall. Exterior sealants come in a good range of colours.
What is backing rod for?
The foam is closed-cell backing rod. It keeps the sealant at the right depth and bonded to the sides only so it can flex with the joint.
Where is Mr Mastic based?
Our base is in Crawley, West Sussex, and we cover South East England, London and all of Scotland.
Will there be a smell?
Possibly a little. Any smell clears as the sealant cures.
Do you seal joints where cladding meets other 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.
Do you work in Petersham?
Yes. We work in Petersham and the rest of Greater London, as part of our work across South East England, London and Scotland. To book, ring 0345 464 0079 or email us.
Quotes for external mastic in Petersham
The price is agreed before any work begins. It’s based on:
- Access and height
- Whether there’s mould to deal with
- How much there is to do
- Any working-time requirements on site
Combining jobs into one visit is usually more efficient than separate visits, so it’s worth mentioning everything you’d like done. We’ll send you a clear quote for the lot.
Helping us quote
Photos by email are helpful but not essential. Please mention:
- How we’d reach the joints
- The address or postcode of the job
- Roughly how big the job is
- What’s wrong with the joints now
Asking for a quote is easy: let us know the job and the location. A few photos by email make the job easier to understand, and we’ll take it from there.
Do you need external mastic in Petersham?
The wrong product in a moving joint is a classic cause. A stiff, general-purpose sealant can’t cope with a joint that moves a lot, and it tears off the sides.
Any of these means the joints need attention:
- Joints with sealant missing in places
- Old sealant gone brittle and cracked
- Damp patches traced to an open external joint
- Movement joints filled with mortar instead of sealant
If you let a flat or house near St Margarets (London) station, outside joints that have cracked can let damp into a rental, so check them between lets.
What to look for in a quote
- Is the old sealant removed completely?
- What the cure time is
- Whether you can choose the colour
- What insurance they hold
What we do, step by step
Good joint work is mostly preparation, so that’s where we spend the time. Every joint is cleaned and dried before new material goes in. In total, it normally takes anything from a few hours to several days, depending on the building. In Petersham, flats, stairs and shared entrances are part of the routine. Mention any building rules, key holders or managing agents when you book.
- We start by checking each joint, agreeing the ones to redo and how we’ll reach them.
- The old mastic and anything lodged in the joint is removed.
- The joint faces are cleaned and primed where the sealant needs it.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
Getting ready for the visit
- Tell us about any water getting in
- Plan for the work area to be out of bounds to pets and children
- Mention if the joints have been sealed before
How to get a quote
Call for a quick quote, or email us if that is easier. Describe what needs sealing and we’ll explain what’s involved and give you a clear price.
Read more
What happens if it’s left?
A failed movement joint lets water into the wall. Resealing early keeps the job to the joint itself, instead of the wall and finishes around it. In a flat in Petersham, 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.
Rather than a set price list, we look at what your job involves: how many joints, what’s in them now and how we reach them. You will know the price before we begin.
Why us?
- 4.9 on Google from 180+ five-star reviews
- Domestic, commercial and hotel work
- You choose the colour before work begins
- Trusted Arbo and Everbuild sealants
Take a look at what affects the cost and customer reviews.
Surface by surface
Render joints
Rendered walls have joints at beads, openings and changes of material. They’re resealed in a sealant that suits the render.
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. Where one has been mortared, we cut it out and reseal it with sealant where it can be done safely.
External mastic in Petersham: local notes
In terraces and conversions, gutters and walls are often shared with the neighbours, so it’s worth agreeing who is responsible before work starts. With historic houses such as Pembroke Lodge (about 0.5 miles south-east) nearby, there’s older building stock in the area around Petersham as well as newer homes. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Petersham is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. For an older house near a landmark such as St Peter's Church, old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Petersham is about 1 mile south of Richmond, in Greater London. If you need external mastic in Petersham, please call 0345 464 0079 or email us for a quick quote. We cover Greater London from our Crawley base. We cover 764 towns and villages across Greater London, from the larger towns to small villages. There’s also a page for London, about 10 miles away.
All of TW10 and TW1 is covered for external mastic. That includes homes and businesses on Sandy Lane, River Lane and Arosa Road and the roads around them. Neighbouring places we cover for external mastic include Richmond (1 mile north), Ham (1 mile south), Eel Pie Island (1 mile west), St Margarets (1 mile north-west) and Strawberry Hill (1 mile south-west). We also work in nearby towns such as London (10 miles east), City of Westminster (8 miles north-east), Marylebone (8 miles north-east), Kensington (6 miles north-east), St Pancras (10 miles north-east) and Shoreditch (11 miles north-east).
Local landmarks in Petersham
Around Petersham, our work takes us to homes and buildings near St Catherine's School, Grey Court School and Marble Hill Park, among other places. The closest station to Petersham is St Margarets (London) station, about 0.9 miles north-west. Well-known places in the area include Bentall Centre (2.4 miles south) and Eel Pie Island Museum (1 mile west). Open spaces near Petersham include Kew Gardens Lake and Richmond Hill.
Honest limits
We’d rather tell you now than do work that won’t last, so these are the limits:
- Cutting new joints into brickwork, which is building work rather than sealant work
- Subsidence or other structural problems
- Render that is blown, hollow or coming away
If in doubt, phone 0345 464 0079 or send us an email and we will say what we think before booking.
Where we work in Petersham
- Copings & trims
- Concrete & block
- Brickwork movement joints
- Joints between brick and frames
- Render & cladding joints
- Façade panels