Southampton · England
Window & door mastic in Thornhill, Southampton
Mastic around window and door frames, sills and patio doors in Thornhill, with a one-year guarantee on every job. Ask us for a quote.
- Rushed sealant from a window installation
- Old mastic that has gone black or come away
- Draughty joints inside around the window
What sealant work cannot fix
New sealant cannot fix everything, and we’d rather say so up front. It will not solve:
- Penetrating damp from a failed cavity tray or render
- Misting between the panes of a double-glazed unit (that needs a new unit)
- Faulty window hardware
If you’re not sure, just ring 0345 464 0079 or email us and we will give you a straight answer before booking.
Surfaces we seal
- Aluminium frames
- Window sills
- uPVC windows
- Patio & French doors
- Composite doors
- Timber windows & doors
About our window mastic in Thornhill
Mr Mastic’s applicators have more than 20 years’ experience with window and door sealants. We are fully insured ARBOMaster approved applicators, and we give a 12-month guarantee on the work. If you’re dealing with cold air getting in at the frame edge and gaps left after new windows were fitted, we can help, on patio & French doors, window sills and timber windows & doors alike.
Many houses in smaller places like Thornhill have conservatories, garden rooms or patio doors. Their glazing joints and frame seals are as much a part of the job as the windows, and any older timber or sash windows need a sealant that suits them.
We guarantee the work for a year. If there’s a problem with our work within the year, let us know and we will sort it.
- Where
- Thornhill (SO19, SO18, SO30)
- Region
- Southampton
- Guarantee
- 12 months on all our work
- Price
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Window mastic in Thornhill: local notes
Thornhill is close to the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. Both are hard on the mastic around window and door frames, which can dry out and crack sooner where a building faces the weather. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
In the older streets around St Christopher, frames set in older brick or stone need a sealant that suits the wall as well as the frame. Schools such as Thornhill Primary School are buildings too, and larger buildings have plenty of frames, and the mastic around each one ages. Letting a property close to Sholing station? Then renewing tired window mastic between tenants heads off draught and damp complaints.
Thornhill is about 2 miles east of Southampton, in Southampton. Anywhere in SO19, our applicators can take on window mastic. 40 places in Southampton are on our list.
Jobs for window mastic in SO19, SO18 and SO30 works the same way as everywhere else we cover. Streets in the area include Drove Road, Barry Road and Luton Road, and we cover them all. Main roads around Thornhill include the A334, so getting to you is simple. Neighbouring places we cover for window mastic include Harefield (1 mile north), Sholing (1 mile south-west), Bitterne (1 mile west), West End (1 mile north) and Chartwell Green (1 mile north). Larger places within reach include Shirley (4 miles west), Regents Park (4 miles west), Maybush (5 miles west), Portswood (3 miles north-west), Coxford (5 miles west) and Freemantle (4 miles west). Thornhill is one of the larger places we cover in Southampton.
Landmarks near Thornhill
Locally, jobs take us to homes and businesses close to Westwood Woodland Park, Woodlands Community College and Grove Park Business and Enterprise College. For rail, the closest station is Sholing station, about 1.4 miles south-west of the centre. Nearby you will also find Moorgreen Hospital (1.4 miles north-east) and Bitterne Local History Society Heritage And Research Centre (1.1 miles west). Not far away are Netley Common.
Work for landlords, hotels and businesses
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
We work for letting agents and landlords as well as homeowners. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
What affects the quote in Thornhill
Your quote is based on your job. We look at:
- The old material and how stubborn it is
- How many rooms, windows or areas are involved
- Any mould that needs treating
- The number and length of the joints
The cost reflects the work involved, not a rough estimate. That’s why we ask about the job first.
Asking for a quote
Before you ask for a quote, have a think about:
- How we’d reach the joints
- What’s wrong with the joints now
- The type of property
- Whether it has been sealed before
For a quick quote, get us on the phone, or email us if that is easier. Describe what needs sealing and we’ll explain what’s involved and give you a clear price.
Surface by surface
Timber windows & doors
On period timber windows, traditional sand mastic is sometimes the better choice. We’ll tell you which suits your home.
Composite doors
If the door itself is draughty, the issue may be the door seals or hinges rather than the frame mastic. We’ll tell you if that’s what we find.
How to look after the new joints
To keep the joints looking good and working properly:
- Wash the frames with mild soapy water
- Air rooms to keep condensation down around windows
- Avoid blasting the frames with a pressure washer
- Repaint timber before it’s bare
Timber frames need their paint kept up, since wood that gets wet swells and shrinks more. Paint up to the joint, not over the silicone.
Water gets in quietly when mastic fails. You might not see it until plaster blows or a damp patch appears inside. Catching it early keeps the fix to a reseal.
Places near Thornhill
More services for Thornhill
What happens on the day
We bring everything the job needs with us, so you don’t need to buy or prepare anything. After a quick look at the joints together, the area is protected and the work begins. It normally takes a few hours for a handful of frames, longer for a whole house. A visit to Thornhill is planned like any other: the time, the access and where to park are agreed in advance. If the work is outside, the weather plays a part, as sealant needs a dry surface.
- We check how each frame can be reached safely.
- Old, cracked mastic is removed completely.
- Frame and wall are cleaned and must be dry before sealing, and primed where the sealant calls for it.
- Backing rod fills deep voids and the sealant goes in on top.
- The joint is shaped to shed water and the area tidied.
Before we arrive
- Mention any parking rules near the property
- Mention any leaks or damp you’ve noticed
- Clear the area around the work
How to get a quote
If you are in Thornhill and need window mastic, phone 0345 464 0079 or send us an email. Tell us what the problem is and where, and we’ll agree the price before any work begins.
Related advice
DIY sealant or a professional job?
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and doesn’t move well, and getting the depth right matters as much as the look.
Sealing over old silicone is the commonest DIY error. New silicone will not bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
FAQs for Thornhill
Is Thornhill within the area you cover?
Yes, Thornhill is covered. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
I let a flat near Sholing station. Can you help?
Yes, landlords and agents are among the people we work for. You can phone 0345 464 0079 or drop us an email with the details for a clear quote.
Can you seal over the old sealant?
No, it will not last. It may look fine at first, but the new layer lifts away from the old one. The old sealant has to come out completely.
Which products do you use?
Products from Arbo and Everbuild, among others, chosen to suit the joint. We will tell you what we’re using and why.
What do you need from me for a quote?
Just the basics: where it is, what you’ve noticed and how we reach it. After that, simply ring 0345 464 0079 or drop us an email.
Can resealing stop a draught around my window?
Yes, where the draught is at the frame edge. We find where the air is coming from before we reseal.
Are you ARBOMaster approved?
Yes. We are ARBOMaster approved, the scheme for applicators of Arbo sealants.
Do you remove the old sealant?
Yes. Sealing over old sealant is the main reason resealing fails early, so we never do it.