Greater London · England
External Mastic specialist in Harold Wood
External mastic across Harold Wood and nearby, with every bit of old sealant taken out first.
- Leaking joints around cladding and façade panels
- Damp patches traced to an open external joint
- Moss and dirt in joints with no sealant left
How we handle external mastic in Harold Wood
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible exterior sealant takes up that movement where a rigid filler would soon crack. If you have moss and dirt in joints with no sealant left and failed seals between different materials, we can put it right. We are sealant specialists rather than general builders, which means external mastic in Harold Wood is done by people who seal joints every day.
London’s terraces and conversions often share walls, gutters and downpipes with their neighbours, so one failed joint can cause damp for more than one household. For a flat in Harold Wood, check the lease for who looks after the outside.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Where
- Harold Wood (RM3, RM11, RM2)
- Region
- Greater London
- Cover
- One year on every job
- Quote
- Quoted before any work starts
- Phone
- 07833 053749
- Last updated
- 26 October 2026
How the job changes by surface
Brickwork movement joints
Brick movement joints are often mistaken for a missing mortar line. If that is happened, we rake it out and reseal it properly where it can be done safely.
Joints between dissimilar materials
Different materials may need different primers. We prepare both faces so the sealant bonds properly.
How to look after the new joints
Simple care keeps the joints in good condition. We recommend:
- Act on the first splits you see
- Walk round the building once a year and look at the joints
- Never let anyone fill a movement joint with mortar
- Ask before painting over external sealant
Have a quick look at the joints each spring. Splits, gaps at the edges or plants in the joint are early warning signs.
Water getting behind cladding or render can go unnoticed for a long time. When it finally shows inside, the joint may have been open for years so early resealing is worth it.
How we quote for external mastic
Every job gets its own quote. These are the things that affect it:
- How much there is to do
- How much old sealant there is and how hard it is to remove
- Access and height
- Which sealant suits the joint
We do not show prices on the website, because the cost depends so much on the job itself. Call for a quick quote.
Asking for a quote
You do not need to know the technical terms. It helps if you can tell us:
- Any access issues, like height or stairs
- The type of property
- Roughly how big the job is
- What the problem is, such as mould, gaps, leaks or cracking
Call for a quick quote, or send an email if you’d rather. Tell us about the joints that need doing and we will talk you through the work before giving you a price.
Do you need external mastic in Harold Wood?
Sunlight, wet weather and frost wear exterior sealant down. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
People normally contact us when they notice something like this:
- Rain getting behind render or cladding at a joint
- Old sealant gone brittle and cracked
- Movement joints filled with mortar instead of sealant
- Brick movement joints where the sealant has split
For an older house near a landmark such as Saint Peter, older walls, gutters and the joints where extensions meet them need a flexible sealant.
Before you book anyone
- What guarantee comes with the work
- Who does the work, and how experienced they are
- What the cure time is
- How the joint is cleaned and prepared
Places near Harold Wood
What else we do in Harold Wood
Outside joints around Harold Wood
With historic houses such as Hare Hall (about 1 mile south-west) nearby, there’s older building stock in the area around Harold Wood as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth. London terraces and converted houses often share gutters, downpipes and walls, so it’s worth agreeing who is responsible before work starts.
As a London address, Harold Wood can be tricky for parking: tell us about permits, visitor bays or off-street space when you book. If you let a flat or house near Harold Wood station, split movement joints are easy to miss on a rental until damp shows inside.
Harold Wood is about 2 miles north-east of Romford, in Greater London. For external mastic in and around Harold Wood, please call 07833 053749 or drop us an email for a quick quote. We cover Greater London from our Crawley base, Harold Wood included. Our Greater London coverage runs to 786 places, Harold Wood among them.
Work in RM3, RM11 and RM2 works the same way as everywhere else we cover. That includes homes and businesses on Oak Road, Ewan Road and Holt Road and the roads around them. Nearby, we also carry out external mastic in Gallows Corner (1 mile west), Ardleigh Green (1 mile south-west), Gidea Park (1 mile west), Emerson Park (1 mile south) and Heath Park (2 miles south-west). Within a short drive, we also cover London (15 miles south-west), Shoreditch (14 miles west), Walthamstow (11 miles west), Hoxton (14 miles west), Whitechapel (14 miles west) and Orpington (15 miles south).
Near you in Harold Wood
In Harold Wood, that means homes and buildings near Havering College of Further and Higher Education, Harold Wood Primary School and The Morris Dancer Public House. There’s a railway station in Harold Wood itself: Harold Wood station. A little further out are The Mercury Mall (2.1 miles south-west) and Upminster Tithe Barn Museum of Nostalgia (2.1 miles south-east). For a walk, there’s Hornchurch Cutting.
Why act early in Harold Wood
Low-modulus sealants stretch easily, so they put less strain on the joint edges. That protects surfaces like brick, render and concrete. A stiffer product can damage the joint edge as it fails. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble.
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all make a difference.
Why choose Mr Mastic in Harold Wood
- Old sealant always removed completely
- White, clear, grey or another colour, product permitting
- Anti-fungal sanitary silicone in wet areas
- A 12-month guarantee on all work
Take a look at our cost guide and our reviews.
How it works
Before we leave, we go over the finished joints with you. The visit itself generally takes a few hours for a handful of joints, longer for a whole elevation, depending on the size of the job. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents 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.
Preparing for the visit
- Where the joints are inside, avoid wetting them before we arrive
- Tell us about access, such as stairs, a lift or high-level joints
- Let us know if you’ve seen damp or leaks
Getting a quote
For external mastic in Harold Wood, ring 07833 053749 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.
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Your questions about external mastic in Harold Wood
Is Harold Wood in your area for external mastic?
Yes, Harold Wood is within the area we cover. Our work covers London and the South East. Just phone 07833 053749 or email us with a few details of the job.
Do you work for landlords with property near Harold Wood station?
Yes. We work for letting agents and landlords as well as homeowners, and several properties can be quoted together. Just phone 07833 053749 or send us an email with the address and what needs doing, and we’ll send you a clear quote.
Can you do several jobs on one visit?
Yes. Tell us about everything you’d like done.
How long does external mastic last?
That depends on the wall, the weather and the movement. Look for splits, hardening or edges coming away and have them redone then.
Is it OK to fill a movement joint with cement?
No, not if it’s a movement joint. Filling it with mortar defeats its purpose. We’ll reseal it with a flexible sealant.
Are you insured?
Yes. Full insurance covers our work, and we can confirm the details when we quote.
Do I have to be there?
We need access to the joints, so we will agree that with you when we book. For inside work, that normally means someone being in.
Will there be a smell?
Possibly a little. Any smell clears as the sealant cures.
When it is not the sealant
Sealant isn’t the answer to every problem, and we will tell you before we start. It won’t solve:
- Render that’s blown, hollow or coming away
- Structural movement, which needs a surveyor or engineer
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
Not sure which it is? You can phone 07833 053749 or email us and we’ll tell you honestly.
Where we work in Harold Wood
- Copings & trims
- Render & cladding joints
- Joints between brick and frames
- Façade panels
- Concrete & block
- Brickwork movement joints