Southampton · England
Swaythling Window Mastic
Our applicators work in Swaythling on mastic around window and door frames, sills and patio doors. Old material cut out, joints cleaned and sealed neatly and a one-year guarantee.
- Cold air getting in at the frame edge
- Water coming in at the bottom corners of a door
- Mastic that is falling out in pieces
Window mastic in Swaythling
The mastic around a window or door seals the gap between the frame and the wall. When it cracks, hardens or pulls away, draughts and rain get in. Our applicators cut it out and replace it with a flexible, weatherproof sealant. We work on aluminium frames, timber windows & doors and composite doors, and people most often call us about damp patches on the reveal after heavy rain and black, perished sealant on frames.
In smaller places like Swaythling, homes range from older cottages to newer houses, with windows to match: timber, uPVC and aluminium. The right sealant depends on the frame and on what it sits in.
You get a 12-month guarantee, the same in Swaythling as everywhere else we work.
- Where
- Swaythling (SO16, SO18, SO17)
- Wider area
- Southampton
- Cover
- A year, on every job
- Quote
- A clear price before work begins
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
What sealant work can’t fix
We’ll always be straight with you, so here’s what sealant can’t fix:
- A frame that has rotted at the joint
- A sash or casement that will not close properly
- Penetrating damp from a failed cavity tray or render
If in doubt, call 0345 464 0079 or drop us an email and we’ll say what we think before booking.
Where we work in Swaythling
- Aluminium frames
- Window sills
- Timber windows & doors
- uPVC windows
- Patio & French doors
- Composite doors
Swaythling homes and the weather
Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. With historic houses such as South Stoneham House (about 0.3 miles south-east) nearby, there’s older building stock in the area around Swaythling as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic.
For landlords with property near Swaythling station, sound mastic around windows and doors keeps out the draughts and damp that tenants notice first. Schools such as Mansbridge Primary School are buildings too, and larger buildings have plenty of frames, and the mastic around each one ages.
Swaythling is about 2 miles north of Southampton, in Southampton. Our applicators cover window mastic for homes and businesses in Swaythling and the surrounding area, as part of our work across Southampton. Our area takes in 40 places across Southampton, from the larger towns to small villages.
We cover every part of the SO16, SO18 and SO17 postcode area for window mastic. Whether your property is on High Road, Wide Lane and Lilac Road or anywhere close by, our applicators can take on the job. Close by, we work in Bassett Green (1 mile west), Mansbridge (1 mile east), North Stoneham (1 mile north), Portswood (1 mile south-west) and St Denys (1 mile south). We also work in nearby towns such as Shirley (3 miles south-west), Regents Park (3 miles south-west), Thornhill (3 miles south-east), Itchen (3 miles south), Sholing (3 miles south) and Maybush (3 miles west).
What’s near Swaythling
We work in homes and buildings around Saint George Catholic Voluntary Aided College Southampton, Riverside Park and Saint George Catholic Voluntary Aided College Southampton, among other places. Swaythling has its own railway station: Swaythling station. A little further out are Marlands Shopping Centre (2.6 miles south-west) and Bitterne Local History Society Heritage And Research Centre (1.9 miles south). Open spaces near Swaythling include Netley Common.
Common problems we fix in Swaythling
Frames are never completely still. Sun on a frame makes it expand, and it contracts again overnight, while the masonry beside it stays put. If the sealant can’t stretch, it splits.
These are the problems we’re asked about most:
- Rain getting in at the frame or under the sill
- Gaps where the sill meets the wall
- Cracked or shrunken mastic around the frame
- Gaps between the frame and the inside reveal
In the older streets around St. Mary's Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Questions to ask before you book
- What the quote includes, VAT included or not
- Is the old sealant removed completely?
- How the joint is cleaned and prepared
- Whether the sealant suits the joint
DIY sealant or a professional job?
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
Sealing over old silicone is the commonest DIY error. Silicone doesn’t stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
What the job involves on each surface
Composite doors
Composite doors are normally hung in an uPVC-type frame, so its perimeter joint is sealed much like a window. We match the colour to the frame.
Patio & French doors
Not every patio door leak is a mastic problem: worn seals, blocked drainage slots or a poor threshold detail can be the cause. We check before we reseal.
Also near Swaythling
Also in Swaythling
What affects the cost of window mastic
We do not publish a price list. The quote depends on:
- How many areas need sealing
- The size of the job
- Working hours on commercial sites
- How easy the joints are to reach
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please phone 0345 464 0079 or send us an email.
Asking for a quote
When you call or email, it’s useful to know:
- Any access issues, like height or stairs
- Where the job is, and your postcode
- Photos by email, if that’s easy
- If someone has resealed it before
For window mastic in Swaythling, phone 0345 464 0079 or email us. A short description of the job and where it is helps us quote, and we will agree the price before any work begins.
What we do, step by step
We bring everything the job needs with us. Once we have agreed what’s being done, we protect the area and start. It normally takes most of a day for a typical house, less for a few frames. Parking around Swaythling is normally easier than in a town centre, but mention any lanes, gates or long drives. If the job is outside, tell us about side access and how high the joints are.
- We start by checking each window and door with you.
- We remove the old mastic and clean the frame and the wall.
- Deep gaps are filled with backing rod to set the depth.
- New exterior sealant goes on in a matching colour and is tooled smooth.
- Finally we tidy up and check each joint.
Getting ready for the visit
- Mention any leaks or damp you’ve noticed
- Tell us about any previous sealing or DIY attempts
- Let us know about stairs, lifts or work at height
How to get a quote
Need a quote? Please phone 0345 464 0079 or drop us an email with a few details. We’ll explain what we’d do and give you a clear quote before work begins.
Read more
Swaythling questions
Do you cover Swaythling for window mastic?
Yes. We work across London and the South East, and Swaythling is part of that. Just phone 0345 464 0079 or drop us an email with a few details of the job.
Can you help a landlord with a rental near Swaythling station?
Yes, rental work is part of what we do. Just ring 0345 464 0079 or email us and tell us about the property, and we will give you a clear price.
Can you seal the gap between the frame and the plaster indoors?
Yes. Indoors, we seal between the frame and the plaster or reveal.
Do you have sealant for grey or black windows?
Yes. White, brown, anthracite grey, black and clear sealants are all available, so the joint suits the frame.
How many windows can you do in a day?
A handful of frames is a short visit, while a whole house takes longer. You’ll get a timescale with the quote.
Does someone need to be in?
We need access to the joints, so we’ll agree that with you when we book. Indoors, that normally means someone at home.
Are you ARBOMaster approved?
Yes. We’re ARBOMaster approved, the scheme for applicators of Arbo sealants.
Can I paint over the new sealant?
Not normally, if it’s silicone. We choose the product with your decorating in mind, so mention it when you book.
Aftercare tips
So the new joints stay in good condition:
- Avoid blasting the frames with a pressure washer
- Use gentle cleaners on frames and sealant
- Air rooms to keep condensation down around windows
- Keep drainage slots and sill grooves clear
Wipe the frames with soapy water when you clean the windows, and keep solvents and harsh chemicals off the joint.
Signs to watch for: split or missing mastic, gaps, damp patches inside or black mould on the reveal. If you notice one, it’s time to get the joint looked at.