Hampshire · England
Sand Mastic in Horndean
Sand mastic for Horndean, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Modern sealant on a period surround
- Draughty sash windows at the surround
- Cracked mastic round a front door frame
How we handle sand mastic in Horndean
We renew sand mastic around sash windows and doors set in stone or brick. The old mastic is raked out, the joint is prepared and new mastic is shaped by hand. We work on sash and case windows, brick reveals and period & listed homes, and common reasons people get in touch are failed mastic on an exposed elevation and window mastic to renew ahead of painting.
Horndean mixes older streets, where windows have often been replaced, with newer estates fitted with uPVC. In every case, the joint between frame and wall is what keeps water out.
We stand behind the work with a 12-month guarantee.
- Location
- Horndean (PO8, PO7)
- Wider area
- Hampshire
- Cover
- A year, on every job
- Quotes
- A clear price before work begins
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Different surfaces, different methods
Brick reveals
We rake out the old mastic and pack deep voids before pointing.
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.
Horndean questions
Can you help a landlord with a rental near Rowlands Castle station?
Yes, rental work is part of what we do. Just call 0345 464 0079 or email us and tell us about the property, and we’ll give you a clear price.
What guarantee comes with sand mastic in Horndean?
Every job comes with our 12-month guarantee, wherever it is. We’re also fully insured and ARBOMaster approved.
Is it OK to seal over old sealant?
No, it won’t last. 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.
Do I need to be at home?
For indoor joints, yes, someone needs to let us in. Once we’ve agreed the job, you don’t need to watch us work.
Will you leave a mess?
Tidy work is part of the job. Nearby surfaces are protected.
What exactly is sand mastic?
It’s sand mixed with a linseed-oil-based binder, used between timber frames and stone or brick.
Is it worth trying it myself?
That depends on the joint. High-level, external movement and fire-rated joints are professional jobs, while a short indoor joint may be within reach.
Can old silicone round a sash window be swapped for sand mastic?
Usually, yes. With the silicone removed and the joint cleaned we point it with sand mastic.
Work for landlords, hotels and businesses
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. We can quote for more than one property at once.
In hotels, rooms out of use cost money, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
Can I do it myself?
If you’ve already had a go yourself, that’s fine. We remove it and do the joint properly, so just mention it when you contact us.
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
Common problems we fix in Horndean
Shallow joints are a common cause. A thin layer does not hold well so we make sure the new mastic is the right thickness.
Keep an eye out for these signs:
- Mastic dropping out of the joint
- Window mastic to renew ahead of painting
- Gaps where the frame meets the masonry
- Weathered mastic on the most exposed windows
If you look after a building such as Horndean Technology College, its window and door frames need their mastic kept sound, just like a home’s.
Questions to ask before booking
- Whether VAT is included
- When the joint can take water or movement
- How long the guarantee is
- Whether they seal over old material or remove it
How it works
We bring everything the job needs with us. After a quick look at the joints together, we protect the area and start. Most jobs take a few hours per window, depending on the condition of the joints. A visit in Horndean needs access to the work and a place to park close by. If the job is outside, mention gates, side access and anything above ground floor.
- We check the window surrounds and agree which joints need renewing.
- The loose and crumbling mastic is raked out and the joint cleaned.
- Large voids are packed out first, so the mastic is not 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.
Before we arrive
- Tell us about any water getting in
- Mention any tricky access
- Mention any sign-in or site rules at work premises
Ask for a quote
Want a quote for sand mastic? Please ring 0345 464 0079 or drop us an email with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
Advice
Frames and glazing around Horndean
Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Warblington Castle (about 4.8 miles south-east) are a reminder that the area around Horndean 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.
Homes close to Saint Wilfrid's include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint. Rented homes near Rowlands Castle station change hands often, and any sash windows need sound mastic to keep draughts and rain out.
Horndean is about 7 miles north-east of Portsmouth, in Hampshire. Across the PO8 area, we cover sand mastic for homes and businesses. Our Hampshire coverage runs to 683 places, Horndean among them. We also work in Portsmouth, around 7 miles away.
We cover every part of the PO8 and PO7 postcode area for sand mastic. We cover properties on London Road, Kings Mede and Causeway Farm and the roads around them. Being close to the A3 and A3(M), Horndean is easy for our applicators to reach. If you are just outside Horndean, we cover Lovedean (1 mile west), Wecock Farm (1 mile south-west), Catherington (2 miles north), Anmore (2 miles west) and Denmead (2 miles west). We also work in nearby towns such as Gosport (9 miles south-west), Havant (3 miles south), Eastleigh (15 miles west), Fareham (9 miles south-west), Hedge End (13 miles west) and Petersfield (7 miles north-east). Being one of Hampshire’s larger places, Horndean has every kind of property, from flats to offices.
Landmarks near Horndean
Locally, jobs take us to homes and businesses close to Horndean Infant School and Red Lion Inn. For rail, the closest station is Rowlands Castle station, roughly 2.6 miles south-east of the centre. Well-known places in the area include Havant War Memorial Hospital (3.8 miles south) and Clanfield Earthwork (3 miles north-east). For a walk, there’s Windmill Hill and Southmoor Nature Reserve.
Looking after it afterwards
How long the joints last depends on use and care. Here’s what we suggest:
- Do not paint over the new mastic
- Keep sills and gutters clear so water drains away
- Ask the planning authority about consent for listed or conservation-area homes
- Get any rot dealt with first
Keep gutters and sills clear so water runs away from the surround. Water sitting against the mastic shortens its life.
An open joint round the box lets weather through. The longer it’s left, the more the joint opens as more mastic falls out.
Nearby places to Horndean
More services for Horndean
Why deal with it now?
Cement-based fillers and modern sealants do not always suit a period surround. Sand mastic matches what was there and that can be important for listed homes. In Horndean, as anywhere, most leaks start as a small gap in a joint, and they’re far easier to fix early.
No two jobs are quite the same, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all make a difference, and we’ll explain the quote if you ask.
Why choose Mr Mastic in Horndean
- Domestic, commercial and hotel work
- 4.9 on Google from 180+ five-star reviews
- One-year guarantee on every job
- An ARBOMaster approved applicator
Take a look at our cost guide and what customers say.