Greater London · England
External Mastic in Grange Mills
Our applicators work in Grange Mills on sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly and every job guaranteed for a year.
- Joints with sealant missing in places
- Plants rooting in failed movement joints
- Joints pointed up with cement by mistake
How we handle external mastic in Grange Mills
As ARBOMaster approved applicators, we choose exterior sealants to suit the joint and the surfaces. Porous or awkward surfaces are primed where the sealant needs it and we use one wherever it does. We work on façade panels, concrete & block and render & cladding joints, and the jobs we see most are rain getting behind render or cladding at a joint and joints pointed up with cement by mistake.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. In Grange Mills, joints up high may need ladders or other access, which is worth talking through when you book.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Location
- Grange Mills (SW12, SW4, SW2)
- Region
- Greater London
- Guarantee
- A year, on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
External mastic in Grange Mills: local notes
London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking. Historic houses like Kingswood House (about 2.9 miles east) are a reminder that the area around Grange Mills has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
Schools such as Henry Cavendish Primary School are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. Grange Mills is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. Rented homes near Balham station change hands often, and split movement joints are easy to miss on a rental until damp shows inside.
Grange Mills is about 2 miles south-west of Stockwell, in Greater London. Every kind of property in Grange Mills can book us for external mastic, old or new, large or small. Every job comes with our 12-month guarantee. Our Greater London coverage runs to 764 places, Grange Mills among them.
Here we cover the SW12, SW4 and SW2 postcode area for external mastic. If you need external mastic at a property on Lynn Road, Weir Road and Byrne Road or anywhere close by, our applicators can take on the job. Nearby, we also carry out external mastic in Hyde farm estate (1 mile south-east), Balham (1 mile south-west), Clapham Park (1 mile north-east), Streatham Hill (1 mile east) and Streatham Park (1 mile south). Larger places within reach include London (4 miles north-east), City of Westminster (5 miles north), Marylebone (5 miles north), Kensington (5 miles north-west), St Pancras (6 miles north) and Shoreditch (6 miles north-east).
Landmarks near Grange Mills
Around Grange Mills, our work takes us to homes and buildings near The Bedford pub, Waldorf School of South West London and La Retraite Roman Catholic Girls' School and the streets around them. Grange Mills has its own railway station: Balham station. A little further out are London Sewing Machine Museum (0.9 miles south-west) and St James' Hospital (0.9 miles west). Green spaces nearby include Knight's Hill and Battersea Park Lake.
How the job changes by surface
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
Cracks along render joints let water in behind the coat. Resealing the joints early keeps water out and protects the render itself.
What we cannot put right
To be straight with you, there are a few things sealant won’t fix:
- Cracked brickwork or render that needs a builder or plasterer
- Structural movement, which needs a surveyor or engineer
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
If in doubt, ring 0345 464 0079 or drop us an email and we will say what we think before booking.
Joints and surfaces we work on
- Render & cladding joints
- Joints between brick and frames
- Brickwork movement joints
- Copings & trims
- Concrete & block
- Façade panels
The process
We work through the job in order: protection first, then preparation, sealing and a tidy-up. For most jobs that takes a few hours to a few days, depending on the length of joint and the access and we leave things clean and tidy. For a job in Grange Mills, parking and access are the things to plan: let us know about parking, the floor we’ll be working on and any lift or shared entrance.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
How to prepare
- Try not to wet indoor joints just before the visit
- Mention any tricky access
- Plan for the work area to be out of bounds to pets and children
How to get a quote
For a quick quote, get us on the phone, or send an email if you’d rather. Describe what needs sealing and we will explain what’s involved and give you a clear quote.
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Can I do it myself?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
Some jobs are best left to a professional: high-level joints, fire-rated gaps, external movement joints and big jobs need the right product, the right access and the right method.
Why deal with it now?
The longer a joint stays open, the more water the wall takes in. In cold weather, frost can damage wet brick and render around the joint, so the problem grows beyond the joint itself. In a London flat, a failed joint rarely stays your problem alone: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
Combining jobs into one visit generally makes better use of the time than several visits. We’ll give you a clear price for the lot.
Why us?
- We never seal over old sealant
- Rated 4.9 stars on Google
- Every job guaranteed for a year
- Sanitary silicone with an anti-fungal additive in wet areas
Grange Mills: your questions answered
Can you help a landlord with a rental near Balham station?
Yes, rental work is part of what we do. Just call 0345 464 0079 or email us and tell us about the property, and we’ll send you a clear quote.
Is parking a problem for a job in Grange Mills?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. That way the visit can be planned around it.
Do you do commercial work?
Yes, regularly. Larger jobs can be planned room by room or area by area to suit the site.
What information do you need?
A short description and the location, plus pictures if you have them. If we need more, we will ask.
What does external mastic cost?
We don’t publish prices, because the cost depends on the job: its size, the old material, access and the product needed. We agree the price before any work begins.
Does someone need to be in?
For indoor joints, yes, someone needs to let us in. After that, you can carry on with your day.
Why do you put foam in the joint first?
Backing rod goes into deeper joints as a matter of course. It controls the depth and stops the sealant bonding to the back.
Is it OK to seal over old sealant?
No. New silicone won’t bond to old silicone, and it traps any mould or water underneath. We remove it all first.
What affects the quote in Grange Mills
Every job gets its own quote. This is what makes a difference:
- Whether there’s mould to deal with
- How many areas need sealing
- When we can work, for business premises
- Whether old sealant or filler has to be cut out
Every job is a little different, so each one gets its own quote. Size, access and the product the joint needs all play a part.
What we need to know
Photos by email are helpful but not essential. Please mention:
- Where the property is
- Pictures of the joints, sent by email
- Any previous sealing or DIY work
- Access, such as stairs, a lift or height
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and email pictures if that is easy.
Work for landlords, hotels and businesses
We work for landlords and agents as well as homeowners. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. We can quote for more than one property at once.