Greater London · England
Sand Mastic in Roundshaw
Professional sand mastic in and around Roundshaw, with old sealant always removed completely and a 12-month guarantee.
- Cracked mastic round a front door frame
- Mastic dropping out of the joint
- Weathered mastic on the most exposed windows
How we handle sand mastic in Roundshaw
Old sand mastic cracks, crumbles and falls out over time, leaving gaps round the window. Renewing it closes the gap so the surround looks right again. If you’re dealing with gaps between timber frames and stone or brick and patchy fillers round a sash window, we can put it right.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Either way, the mastic between frame and brickwork is what stops draughts and rain getting in.
Whatever the size of the job, you get the same one-year guarantee.
- Location
- Roundshaw (SM6, CR8, CR0)
- Region
- Greater London
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
When it isn’t the sealant
We’d rather tell you now than do work that won’t last, so here’s what sealant can’t put right:
- Sashes that need overhauling
- Crumbling stone or brickwork round the window
- Whether work needs listed building consent
If you’re not sure, just ring 0345 464 0079 or send us an email and we will give you a straight answer before you book.
Joints and surfaces we work on
- Stone surrounds
- Period & listed homes
- Sash and case windows
- Brick reveals
- Tenement windows
- Timber door frames
The process
A visit follows a simple pattern: we look at the joints together, protect the area around them, do the work and clear up. It usually takes anything from a few hours to a full day, depending on how many windows. In a London area like Roundshaw, the main things to plan are parking and access: tell us about permits, visitor bays or off-street space, which floor we’re working on and whether there’s a lift.
- Each surround is checked first.
- We rake out the old mastic and clean the joint.
- We fill deep gaps so the new mastic is not too thick.
- We point the joint with sand mastic by hand.
- We finish the mastic to a tidy line.
Before we arrive
- Let us know about stairs, lifts or work at height
- Mention any parking rules near the property
- For indoor joints, keep the area dry beforehand if you can
Get a quote
We quote each job on its own, so the first step is telling us about yours. Just call 0345 464 0079 or send us an email with the details.
Advice
FAQs for Roundshaw
Can parking be tricky for a visit in Roundshaw?
Parking in Roundshaw, as in most of London, takes a little planning: a visitor permit or a nearby bay makes the day run more smoothly.
Do you cover Roundshaw for sand mastic?
Yes. We work across London and the South East, and Roundshaw is part of that. Just call 0345 464 0079 or email us with a few details of the job.
Do you guarantee sand mastic work?
There’s a 12-month guarantee on every job, sand mastic included.
Is sand mastic better than silicone for my windows?
We will help you decide. Period homes often look best with sand mastic and newer frames suit modern sealant.
Do I have to be there?
Access is agreed with you when the job is booked. Indoors, that usually means someone at home.
Is it worth trying it myself?
That depends on the joint. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional.
I rent my home. Can I book you?
We’re happy to deal with the tenant, landlord or agent. Just make sure your landlord agrees.
Are you insured?
Yes. We are fully insured.
Leave it or put it right?
If you are redecorating, renew the mastic first. Paint over cracked mastic will not stop the gaps, and the new mastic is traditionally left unpainted. In older London homes, water behind a failed joint soaks into brick and timber without much sign, and by the time it shows on a wall or ceiling in Roundshaw, the repair is bigger than the sealant job would have been.
Doing several joints on one visit is generally more efficient than separate visits, so tell us about everything that needs sealing. We will give you a clear price for the lot.
Why choose Mr Mastic in Roundshaw
- Experience in homes, commercial sites and hotels
- Neat joints and a tidy finish
- 4.9 on Google from 180+ five-star reviews
- More than 20 years in sealant work
Take a look at how sealant jobs are priced or our reviews.
DIY sealant or a professional job?
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
Landlords, agents and businesses in Roundshaw
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance that we can handle for you.
What sand mastic looks like in Roundshaw
In a converted house or block, who looks after the windows depends on the lease, so check that before booking. Historic houses like Addington Palace (about 3.9 miles east) are a reminder that the area around Roundshaw has older buildings as well as new. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
For landlords with property near Wallington station, cracked sand mastic around sash windows lets in the draughts tenants complain about. If you look after a building such as Wallington Primary Academy, larger buildings have plenty of frames, and the mastic around each one ages. For an older house near a landmark such as St. Paul's, the joint between an old wall and a newer frame is normally the first place rain gets in.
Roundshaw is about 2 miles south-west of Croydon, in Greater London. Every kind of property in Roundshaw is covered for sand mastic, old or new, large or small. The work is guaranteed for a year. Roundshaw is one of 764 towns and villages in Greater London where we work. London is on our list too, around 10 miles away.
We work across SM6, CR8 and CR0 for sand mastic and the streets around it. If you need sand mastic at a property on Link Lane, Milton Road and Redwing Road or anywhere close by, we can help. Other places close to Roundshaw include Russell Hill (1 mile east), Bandonhill (1 mile north), Peaks Hill (1 mile south), Waddon (1 mile north-east) and Wallington (1 mile north-west). Within a short drive, we also cover London (10 miles north), City of Westminster (11 miles north), Marylebone (11 miles north), Kensington (11 miles north), St Pancras (12 miles north) and Shoreditch (12 miles north).
Landmarks near Roundshaw
In Roundshaw, that means homes and buildings near Wilson's School, Waddon Ponds and The John Fisher School. The nearest railway station is Wallington station, roughly 0.9 miles north-west. Nearby you’ll also find Purley War Memorial Hospital (1.2 miles south-east) and Croydon Airport Visitor Centre (0.6 miles east). Open spaces near Roundshaw include Roundshaw Downs and Duppas Hill.
Towns and villages near Roundshaw
What else we do in Roundshaw
How we quote for sand mastic
Every job gets its own quote. These are the things that affect it:
- Which sealant suits the joint
- Whether old sealant or filler has to be cut out
- The number and length of the joints
- Any working-time requirements on site
No two jobs are quite the same, so we quote each one individually. Size, access and the product the joint needs all play a part, and we’ll explain the quote if you ask.
Asking for a quote
Before you ask for a quote, have a think about:
- Access, such as stairs, a lift or height
- The problem you’ve noticed
- The rough size of the job
- Pictures of the joints, sent by email
Asking for a quote is easy: tell us what needs doing and where. A few pictures by email make the job easier to understand, and we’ll come back to you with a quote.
How to look after the new joints
To keep the joints looking good and working properly:
- Renew mastic before redecorating the windows
- Ask us before painting near the mastic
- Inspect the joints round the windows every year or so
- Avoid heavy scraping on the mastic joint
Don’t run silicone over the new mastic. If anything cracks, get it looked at rather than patching it.
Crumbling mastic lets rain into the joint. That water can reach the timber frame and the wall, so renewing it early is worth it.