Greater London · England
Sand Mastic in Harrow on the Hill
Traditional burnt sand mastic around sash and case windows and doors in stone and brick for Harrow on the Hill, backed by a 12-month guarantee. Ask us for a quote.
- Old sand mastic that has cracked, crumbled or fallen out
- Cement or filler used on old window joints that has cracked
- Gaps where the frame meets the masonry
About our sand mastic in Harrow on the Hill
On many period windows, sand mastic looks right and suits the building. Newer frames normally get a flexible sealant instead, and we will talk through which suits your home. If you’re dealing with old cement repairs round a window that have failed and failed mastic on an exposed elevation, we can help.
London homes have every kind of window, from timber sashes in period terraces to aluminium and uPVC in newer blocks. Over the years, the sealant around them shrinks, cracks and pulls away, letting in draughts and water.
Every job is covered by a one-year guarantee, wherever you are in Greater London.
- Location
- Harrow on the Hill (HA1, HA0, HA2)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Quotes
- A clear price before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Landlords, agents and businesses in Harrow on the Hill
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. Several properties can go on one quote.
Hotels need rooms back in use, so the work can be planned room by room. Hotel work is part of what we do, alongside homes and businesses.
Keeping the joints in good condition
Aftercare is simple:
- Ask a joiner to look at soft timber first
- Ask the planning authority about consent for listed or conservation-area homes
- Renew mastic before redecorating the windows
- Go gently near the mastic when preparing windows
Leave the new mastic unpainted, as traditional guidance advises. Ask us before any decorating around it.
Sound mastic protects the frame. Failed mastic lets water reach the timber and timber that stays wet can rot.
When to call us in Harrow on the Hill
Sand mastic slowly weathers. It dries out, cracks and loses its grip from the frame or the masonry.
The most common problems we see are:
- Failed mastic on an exposed elevation
- Gaps between timber frames and stone or brick
- Window mastic to renew ahead of painting
- Wind and rain getting in round a sash window
As a London address, Harrow on the Hill can be tricky for parking: tell us about permits, visitor bays or off-street space when you book.
What your quote should include
- Whether they seal over old material or remove it
- When the joint can take water or movement
- Is VAT in the price?
- What guarantee comes with the work
How the visit works
A visit follows a simple pattern: we look at the joints together, protect the area around them, do the work and clear up. It generally takes a few hours for a single window, longer for several. In Harrow on the Hill, flats, stairs and shared entrances are part of the routine. If the building has a concierge, managing agent or access rules, tell us when you book.
- First we agree which joints need doing.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- The sand mastic is mixed and pressed into the joint by hand.
- We dress the finish so it sits neatly against the masonry.
How to prepare
- On commercial sites, let us know about site rules
- Let us know about parking restrictions
- Mention any tricky access
Get a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is, and email pictures if that is easy.
Related advice
Different surfaces, different methods
Stone surrounds
Sand mastic sits naturally against stone. The finish blends with the masonry.
Brick reveals
We rake out the old mastic and pack deep voids before pointing.
Frames and glazing around Harrow on the Hill
In a converted house or block, who looks after the windows depends on the lease, so check that before you book. Historic houses like Northolt Manor (about 2.1 miles south-west) are a reminder that the area around Harrow on the Hill 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.
Rented homes near Sudbury Hill Harrow station change hands often, and any sash windows need sound mastic to keep draughts and rain out. In the older streets around Christ Church, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Harrow on the Hill is about 1 mile south-east of Harrow, in Greater London. If you need sand mastic in Harrow on the Hill, it’s easy to get a quote: please call 0345 464 0079 or drop us an email. We cover Greater London from our Crawley base, Harrow on the Hill included. We cover 764 towns and villages across Greater London, large and small. For nearby work, see our London page (11 miles or so).
We work across the HA1, HA0 and HA2 postcode area for sand mastic and the streets around it. If you need sand mastic at a property on New Road, Amery Road and London Road or anywhere close by, we can help. If you are just outside Harrow on the Hill, we cover Roxeth (1 mile west), Northwick Park (1 mile north-east), South Harrow (1 mile west), Harrow (1 mile north-west) and Sudbury (1 mile south-east). Larger places within reach include London (11 miles south-east), City of Westminster (9 miles south-east), Marylebone (9 miles east), Kensington (7 miles south-east), St Pancras (10 miles east) and Shoreditch (11 miles east).
Near you in Harrow on the Hill
Around Harrow on the Hill, our work takes us to homes and buildings near Northwick Park, St Dominic's Sixth Form College and Orley Farm School, among other places. For rail, the closest station is Sudbury Hill Harrow station, roughly 0.5 miles south. Nearby you will also find Kodak Museum (2 miles north) and Clementine Churchill Hospital (less than half a mile south-east). The countryside around Harrow on the Hill includes Middle Lake and Northala Fields.
Places near Harrow on the Hill
Also in Harrow on the Hill
Your questions about sand mastic in Harrow on the Hill
I let a flat near Sudbury Hill Harrow station. Can you help?
Yes, rental work is part of what we do. You can call 0345 464 0079 or email us with the address and a few details, and we will give you a fixed price before work begins.
Do you cover Harrow on the Hill for sand mastic?
Yes, Harrow on the Hill is within the area we cover. Our work covers London and the South East. Just phone 0345 464 0079 or email us with a few details of the job.
Are you fully insured?
Yes. Mr Mastic is fully insured.
What’s sand mastic made of?
It’s a mix of sand and a linseed-oil-based binder. It’s built up in the joint by hand and shaped to suit the surround.
Is consent needed for window work on a listed home?
It’s best to ask your local planning authority first. Sand mastic is often favoured as like for like, but they decide.
Do the sealants smell?
That depends on the sealant. Some smell for a while, some hardly at all, and any smell fades as they cure.
Do I need to be at home?
For indoor joints, yes, someone needs to let us in. Once we’ve agreed the job, you do not need to watch us work.
Should I use sand mastic or silicone?
Sand mastic usually suits period timber windows best. Modern frames normally suit a flexible sealant, and we’ll explain why.
What affects the quote in Harrow on the Hill
Call for a quick quote. The main things that affect it are:
- The type of sealant required
- When we can work, for business premises
- How much old sealant there is and how hard it is to remove
- How many rooms, windows or areas are involved
Homes and businesses are quoted the same way: the amount of work, how we reach it and what it needs, plus any working-time requirements on site. Ask us for a quote and we’ll go through it with you.
What to tell us for a quote
To help us quote quickly, please include:
- Whether it’s a home or a business
- Pictures of the joints, sent by email
- What the problem is, such as mould, gaps, leaks or cracking
- The rough size of the job
We quote each job on its own, so start by telling us what you need. Just ring 0345 464 0079 or email us with the details, and pictures are welcome.
When it is not the sealant
A few problems are outside what sealant work can do:
- Decisions on consent for listed homes
- Masonry that needs repairing
- Decayed frames that need repair
If you are not sure, just call 0345 464 0079 or send us an email and we’ll give you a straight answer.
Surfaces we seal
- Sash and case windows
- Timber door frames
- Brick reveals
- Stone surrounds
- Period & listed homes
- Tenement windows