Surrey · England
External Mastic in South Merstham
External mastic in South Merstham from a team with over 20 years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Weeds or debris growing in open joints
- Hard, crazed mastic that has stopped moving
- Water getting into walls through failed joints
How we handle external mastic in South Merstham
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. We pick a colour that sits well with the wall. If you have sealant that has lost its bond to the brick or render and hard, crazed mastic that has stopped moving, we can put it right, whatever the surface.
Houses in smaller places like South Merstham can stand more in the open than those in a built-up town, and walls and rooflines facing the weather take the worst of it. That’s where gutter joints and wall joints tend to fail first.
We stand behind the work with a 12-month guarantee, so you’re not left on your own once the job is done.
- Where
- South Merstham (RH1)
- Region
- Surrey
- Guarantee
- A year, on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
What affects the cost of external mastic
Some jobs are bigger than they look, and some smaller. What affects the quote:
- Whether the work is at height
- How many areas need sealing
- Mould in or behind the old joints
- Which sealant suits the joint
Rather than a set price list, we price the job in front of us: how many joints, what’s in them now and how we reach them. The price is agreed before we begin.
What we need to know
Photos help, but a description is a good start. Try to tell us:
- Whether it’s a home or a business
- How many joints, rooms or windows are involved
- The problem you’ve noticed
- Access, such as stairs, a lift or height
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.
FAQs for South Merstham
Is South Merstham within the area you cover?
Yes, South Merstham is covered. Our work covers London and the South East, and smaller places are part of that. The journey is planned ahead, so it helps to know about access.
Can you help a landlord with a rental near Merstham station?
Yes, rental work is part of what we do. You can phone 0345 464 0079 or email us with the address and a few details, and we’ll give you a fixed price before any work starts.
Can you seal over the old sealant?
No, and we never do. It can look neat for a few weeks, but the new layer lifts away from the old one. Removing the old sealant completely is the only lasting way.
What is backing rod for?
We fit closed-cell backing rod wherever the joint depth needs controlling. It controls the depth and stops the sealant bonding to the back, so the joint can move.
How long before the joint can be used?
Many sealants skin over quickly but take longer to cure fully. We’ll give you the cure time for the product we used.
Can you quote for more than one area?
Of course. Combining jobs makes good use of the visit, so mention them when you ask for a quote.
Is it worth trying it myself?
Sometimes. The key is preparation: remove all the old material and work on a clean, dry joint. We can always put it right if it fails.
How long will you be here?
Typically it takes a few hours for a handful of joints, longer for a whole elevation. Larger jobs naturally take longer, and we will tell you how long to expect.
What we’re called out for in South Merstham
Every building moves. Clay bricks expand slightly over their life, concrete and block shrink, and everything moves with temperature and wet. The sealant in the movement joints takes that strain.
It’s worth asking for a quote if you see:
- Moss and dirt in joints with no sealant left
- Gaps where render, brick and frames meet
- Panel joints letting water in
- Old sealant gone brittle and cracked
In the older streets around All Saints', old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Before you book anyone
- Whether they’re fully insured
- What guarantee comes with the work
- Is the old sealant removed completely?
- What the quote includes, VAT included or not
Looking after it afterwards
After the cure time, these simple habits help:
- Keep movement joints as flexible joints, not mortar
- Avoid pressure-washing directly into sealant joints
- Check the sealant is paintable before painting near it
- Fix overflowing gutters above sealed joints
Give the sealant the cure time we tell you before anything rubs against it. Most exterior sealants skin fast but take longer to cure right through.
Gaps, plants or missing sealant in a joint are worth getting looked at. Early work is quicker and leaves a better finish.
How it works
A visit follows a simple pattern: we look at the joints together, protect the area around them, carry out the job and tidy away. Most jobs take a few hours to a few days, depending on the length of joint and the access. For a job in South Merstham, we agree the time, the access and parking before the day. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- Each joint is checked and the colour of the new sealant agreed.
- Failed sealant is removed back to clean, sound faces.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- Primer is applied wherever the sealant needs it.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
How to prepare
- Plan for the work area to be out of bounds to pets and children
- Tell us about any previous sealing or DIY attempts
- Move anything stored near the joints
Getting a quote
For a quote, call 0345 464 0079 or send us an email and tell us where the job is and what the problem looks like. We’ll give you a clear quote before any work starts.
Related advice
How the job changes by surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. We reseal them with an exterior sealant suited to the material.
Cladding and façade panels
If the façade has a specified sealant, that’s what we use, or one the system allows. Tell us what the building has when you get in touch.
Should I try it myself first?
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
Towns and villages near South Merstham
Also in South Merstham
When something else is needed
Sealant isn’t the answer to every problem, and we’d rather say so up front. Sealant will not put right:
- Cracks in the bricks or render themselves, away from the joints
- Failed render or damaged cladding panels
- Walls that need new movement joints cut into them
If in doubt, ring 0345 464 0079 or email us and we’ll say what we think before you book.
What we seal
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
- Concrete & block
- Copings & trims
- Façade panels
What external mastic looks like in South Merstham
London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Schools such as Merstham Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing. Rented homes near Merstham station change hands often, and failed wall and movement joints let damp in, so they’re worth checking between tenancies.
South Merstham is about 2 miles north-east of Redhill, in Surrey. Jobs in South Merstham get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. We cover 395 towns and villages across Surrey. For nearby work, see our Crawley page, about 10 miles away.
Work in RH1 is quoted and booked the same way as anywhere else. Streets in the area include Station Road South, London Road South and Station Road, and we cover them all. Other places close to South Merstham include Merstham (1 mile north), Holmethorpe (1 mile south-west), Gatton (1 mile west), Nutfield (2 miles south-east) and Redhill (2 miles south-west). We also work in nearby towns such as Epsom (7 miles north-west), Horley (6 miles south), Ewell (8 miles north-west), Reigate (3 miles south-west), Walton-on-Thames (14 miles north-west) and Caterham (3 miles north-east).
Around South Merstham
Locally, jobs take us to homes and businesses close to Merstham Park School, Nutfield Marshes and East Surrey College and the streets around them. There’s a railway station in South Merstham itself: Merstham station. Well-known places in the area include Bletchingley Castle (2.3 miles south-east) and The Belfry (1.7 miles south-west). Not far away are Colley Hill and Mercers Lake.