Greater London · England
Isleworth Sand Mastic
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for Isleworth, backed by a 12-month guarantee. Ask us for a quote.
- Gaps round a timber door in stone or brick
- Mastic dropping out of the joint
- Draughty sash windows at the surround
Why deal with it now?
Replacing sash windows is a big decision for a period home, and in listed buildings it may need consent. If the frames are sound, renewing the mastic deals with gaps and draughts at the surround. Converted houses in London often have a bathroom above someone else’s living room, and a slow leak from a failed seal can end up in the flat below. Putting it right early is much less trouble.
What you pay reflects the work, not guesswork. That is why we ask about the job first and agree the price before starting.
Why choose Mr Mastic in Isleworth
- Anti-fungal silicone where joints get wet
- 12-month guarantee on every job
- 180+ five-star Google reviews
- Fully insured
How we handle sand mastic in Isleworth
Sand mastic has long been used to fill the joint between timber frames and masonry. It’s made from sand and a linseed-oil-based binder and built up by hand. On period homes, it looks right where silicone wouldn’t. We work on period & listed homes, tenement windows and brick reveals, and the jobs we see most are gaps round a timber door in stone or brick and modern sealant on a period surround.
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.
All of our work is guaranteed for twelve months, in Isleworth and everywhere else we cover.
- Place
- Isleworth (TW7, TW1, TW3)
- Region
- Greater London
- Cover
- One year on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
FAQs for Isleworth
Is parking a problem for a job in Isleworth?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. The visit is then planned around what’s available.
Is Isleworth in your area for sand mastic?
Yes. Our work covers London and the South East, and Isleworth is part of that. Just ring 0345 464 0079 or send us an email with a few details of the job.
Is sand mastic better than silicone for my windows?
We will talk it through with you. Period homes often look best with sand mastic, and modern sealants suit newer frames.
Do you guarantee sand mastic work?
Our 12-month guarantee covers every job.
Are you fully insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Do you work for letting agents?
Yes. We work for homeowners, landlords, letting agents, businesses and hotels in Isleworth.
Can I do it myself?
It depends on the job. High-level, external movement and fire-rated joints are professional jobs.
When will the new mastic be hard?
The surface skins quite quickly, then hardens over a longer period. The weather and joint depth both affect it.
How it works
At the end, we look at the finished work together and explain the cure time. The visit itself normally takes anything from a few hours to a full day, depending on how many windows, depending on the amount of work. 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.
- We start by checking each surround and agreeing the joints to renew.
- Old, loose mastic is raked out and the joint cleaned.
- Large voids are packed out first, so the mastic isn’t too thick.
- Sand mastic is mixed and applied by hand, then shaped to the joint.
- The mastic is finished to sit tidily against the stone or brick.
Preparing for the visit
- Let us know about parking restrictions
- Try not to wet indoor joints just before the visit
- Plan for the work area to be out of bounds to pets and children
How to get a quote
If you are in Isleworth and need sand mastic, ring 0345 464 0079 or email us. A short description of the job and where it is helps us quote, and you will get a clear quote before we start.
Related advice
What the job involves on each surface
Sash and case windows
The box of a sash and case window sits in the stone or brick opening. The gap round it is pointed with sand mastic.
Timber door frames
Sand mastic is used round timber door frames too. The method is the same as for windows.
Places near Isleworth
What else we do in Isleworth
Can I do it myself?
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
What we’re called out for in Isleworth
Most of it is simply age. Even well-laid mastic needs renewing in time and how long it lasts depends on the weather it faces.
It’s worth asking for a quote if you see:
- Mastic dropping out of the joint
- Mastic worn away on windows facing the weather
- A silicone bead on a sash window that spoils the look
- Cement or filler used on old window joints that has cracked
For an older house near a landmark such as Church of All Saints, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
What to look for in a quote
- How the joint is cleaned and prepared
- What guarantee comes with the work
- Whether all the old sealant comes out first
- Which colour the sealant will be
How to look after the new joints
Looking after new joints is easy, and it makes a real difference:
- Avoid heavy scraping on the mastic joint
- Ask us before painting near the mastic
- Renew mastic before redecorating the windows
- Inspect the joints round the windows every year or so
Leave the new mastic unpainted, as traditional guidance advises. Ask us before any decorating around it.
Renewing mastic before redecorating saves doing it twice. Paint over cracked mastic only covers it up.
Frames and glazing around Isleworth
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. Historic houses like Syon House (about 0.9 miles north-east) are a reminder that the area around Isleworth has older buildings as well as new. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window.
As a London address, Isleworth can be tricky for parking: let us know about parking bays, permits or a driveway. Schools such as St Mary's Catholic Primary School are buildings too, and larger buildings have plenty of frames, and the mastic around each one ages.
Isleworth is about 2 miles north of Twickenham, in Greater London. Jobs in Isleworth get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Isleworth is one of 764 places in Greater London where we work. You can also see our page for London, roughly 10 miles from Isleworth.
Postcode districts we cover here for sand mastic: TW7, TW1 and TW3. You will find streets such as Upper Square, London Road and Shire Horse Way, and we cover them all. Nearby, we also carry out sand mastic in Woodlands (1 mile west), St Margarets (1 mile south-east), Ivybridge (1 mile south-west), Spring Grove (1 mile north-west) and Hounslow (1 mile west). Larger places within reach include London (10 miles east), City of Westminster (8 miles east), Marylebone (9 miles north-east), Kensington (6 miles east), St Pancras (10 miles north-east) and Shoreditch (12 miles east).
What’s near Isleworth
Typical jobs here are in homes near The George Inn, Kneller Hall Junior School and Gumley House RC Convent School and the streets around them. Isleworth has its own railway station: Isleworth station. A little further out are West Middlesex University Hospital (within half a mile north-east) and Museum of Army Music (1.4 miles south-west). Green spaces nearby include Richmond Hill and Kew Gardens Lake.
How we quote for sand mastic
We do not publish a price list. The quote depends on:
- Which sealant suits the joint
- The old material and how stubborn it is
- How many areas need sealing
- When we can work, for business premises
Every job is a little different, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all play a part, and we’ll explain the quote if you ask.
Asking for a quote
There’s no need for technical detail. Just tell us:
- The type of property
- Access, such as stairs, a lift or height
- Where the property is
- The rough size of the job
Need a quote? Please call 0345 464 0079 or email us and tell us about the job. You’ll know what we plan to do, and what it will cost, before any work begins.