Greater London · England
Sand mastic for sash & case windows in Hounslow, Greater London
Sand mastic for Hounslow and the surrounding area: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Cement or filler used on old window joints that has cracked
- Weathered mastic on the most exposed windows
- Draughts and rain around sash boxes
About our sand mastic in Hounslow
Sand mastic suits most period window surrounds. On modern frames we’d normally use a flexible sealant, and we’ll talk through which suits your home. If you have draughty sash windows at the surround and silicone on a period window that looks wrong, we can help.
Many London homes are flats, with windows high above the street. Who looks after the outside of the frames can depend on the lease, so check that first.
We guarantee the work for a year. If something is not right with it in that time, tell us and we will put it right.
- Place
- Hounslow (TW3, TW7, TW2)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
For landlords and businesses
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance that we can handle for you.
If you manage several properties in or around Hounslow, jobs at different addresses can go on one quote. Send us the addresses and the work at each, and photos by email help.
What the job involves on each surface
Sash and case windows
Sash windows are where we do most sand mastic work. Each joint round the box is raked out and renewed.
Period and listed homes
A traditional finish suits a period property.
DIY versus a professional finish
Sealing over old silicone is the commonest DIY error. Silicone does not stick to old silicone, so it peels away and traps moisture behind it. All the old material has to come out 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.
Hounslow homes and the weather
In London conversions and blocks, the lease decides who is responsible for the frames, so it’s worth checking before booking. Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Hounslow 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 Church of St Mary the Virgin, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall. If you look after a building such as Chatsworth Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Hounslow is about 9 miles west of City of Westminster, in Greater London. We carry out sand mastic for householders, landlords and businesses in Hounslow and the surrounding area. 764 places in Greater London are on our list, from the larger towns to small villages. For nearby work, see our London page.
Every address in TW3, TW7 and TW2 is covered for sand mastic. Whether your property is on New Road, Ivy Road and Bell Road or anywhere close by, our applicators can take on the job. If you’re just outside Hounslow, we cover Woodlands (1 mile north-east), Ivybridge (1 mile south-east), Lampton (1 mile north-west), Isleworth (1 mile east) and Spring Grove (1 mile north). Within a short drive, we also cover London (11 miles east), City of Westminster (9 miles east), Marylebone (9 miles east), Kensington (7 miles east), St Pancras (11 miles east) and Shoreditch (12 miles east).
What’s near Hounslow
In Hounslow, that means homes and buildings near Moon Under Water pub, Kingsley Academy and Inwood Park. Hounslow’s nearest station is Hounslow station, roughly 0.6 miles south-west. Well-known places in the area include Museum of Army Music (0.8 miles south) and South Middlesex Hospital (0.9 miles south-east). For a walk, there’s Garden Lake and Richmond Hill.
What happens if it’s left?
Replacing sash windows is a big decision for a period home, and in listed buildings it may need consent. Where the frames are in good order, new mastic seals the surround. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in Hounslow, the repair is bigger than a sealant job.
A failed joint rarely gets cheaper to fix by waiting, because water and mould keep working on it. If you are unsure, ring 0345 464 0079 or send us an email for an honest opinion and a quote.
What you get with us
- Over 20 years’ experience
- We’re fully insured
- Homes, businesses and hotels
- Any old sealant cut out fully, not covered over
Take a look at our cost guide or what customers say.
How to look after the new joints
To keep the joints looking good and working properly:
- Clear gutters so water doesn’t pour onto the windows
- Avoid heavy scraping on the mastic joint
- Leave the new mastic unpainted
- Don’t run silicone over sand mastic
Make sure water drains away from the window surround. Water sitting against the mastic shortens its life.
Gaps round a sash box let in draughts and rain. The longer it’s left, the more the joint opens.
Hounslow questions
Is Hounslow in your area for sand mastic?
Yes, Hounslow is within the area we cover. We work across London and the South East. Just call 0345 464 0079 or send us an email with a few details of the job, and we’ll send you a clear quote.
I let a flat near Hounslow station. Can you help?
Yes, we work for landlords and letting agents. Just call 0345 464 0079 or email us and tell us about the property, and we will give you a clear quote.
Is there any odour?
Sometimes, a little. It fades as the sealant cures, and ventilation helps.
Does someone need to be in?
It depends on the job. For work indoors, someone needs to let us in, and for outside work we’ll agree access with you when we book.
How long will you be here?
That depends on the amount of work, but as a guide it takes a few hours per window, depending on the condition of the joints. We will give you a better idea when we quote.
How long does sand mastic take to go off?
It forms a skin fairly soon, then hardens over a longer period. Timing depends on the weather and the joint.
Where do you work from?
Mr Mastic is based in Crawley. We cover Hounslow and the rest of Greater London, along with the rest of our area.
Can you match the sealant colour?
Normally, yes. White, clear and grey are common, and other colours are available, and we will agree it with you first.
The process
Once we are on site, we compare the joints with what we discussed. If anything is different, we explain it before carrying on. Most jobs then take a few hours per window, depending on the condition of the joints. For a job in Hounslow, parking and access are the things to plan: tell us about permits, visitor bays or off-street space, which floor we are working on and whether there’s a lift.
- Each surround is checked first.
- The joint is raked out and cleaned.
- Large voids are packed out.
- New sand mastic is applied and shaped by hand.
- We finish the mastic to a tidy line.
Getting ready for the visit
- Let us know if you’ve seen damp or leaks
- Let us know about parking restrictions
- Mention any tricky access
Getting a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints.
Read more
What we can’t put right
New sealant can’t fix everything, and we’d rather say so up front. Sealant won’t put right:
- Sashes that rattle, stick or won’t open
- Damaged stone surrounds
- Broken panes
Not sure which it is? You can call 0345 464 0079 or send us an email and we will tell you honestly before booking.
Where we work in Hounslow
- Stone surrounds
- Timber door frames
- Sash and case windows
- Brick reveals
- Period & listed homes
- Tenement windows