Southampton · England
Window Mastic in Portswood
Problem with your window and door frames in Portswood? We cut out the old, prepare the joints and apply the right sealant, and the work is guaranteed for a year.
- Gaps between the frame and the inside reveal
- Water coming in at the bottom corners of a door
- Whistling draughts around closed windows
Aftercare tips
Good habits help new joints last longer. Our tips:
- Keep timber frames painted
- Clear any debris from frame drain holes
- Check the mastic once a year
- Keep jet washers away from the mastic
Wipe the frames with soapy water when you clean the windows, and keep solvents and harsh chemicals off the joint.
A small gap around a frame only grows. As the old mastic shrinks further, more air gets through, and a cold room gets colder. A new joint closes it up.
Window mastic in Portswood, done properly
Over two decades of sealing frames has taught us which products suit which walls. We are ARBOMaster approved and fully insured, and we give a one-year guarantee on the work. If you are dealing with rushed sealant from a window installation and whistling draughts around closed windows, we can help, whatever the surface.
In smaller places like Portswood, homes range from older cottages to newer houses, with windows to match: timber, uPVC and aluminium. Each frame material needs the right sealant against the right wall.
A one-year guarantee comes with the work, just as it does everywhere we cover.
- Location
- Portswood (SO17, SO14, SO18)
- Wider area
- Southampton
- Guarantee
- A year, on every job
- Quotes
- A clear quote up front
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
The process
All our tools and materials come with us in the van, so you do not need to buy or prepare anything. Once we have agreed what’s being done, the area is protected and the work begins. It normally takes a few hours for a handful of frames, longer for a whole house. In a smaller place like Portswood, parking is seldom the issue; lanes, gates and long drives are worth mentioning. If the job is outside, tell us about side access and how high the joints are.
- We check each frame and agree which ones need doing.
- The old mastic is cut out and the surfaces cleaned back.
- Deep gaps are filled with backing rod to set the depth.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- Every joint is checked before we leave.
Getting ready for the visit
- Tell us about any water getting in
- Let us know about parking restrictions
- Mention any sign-in or site rules at work premises
How to get a quote
For window mastic in Portswood, call 0345 464 0079 or send us an email. A short description of the job and where it is helps us quote, and we’ll agree the price before any work begins.
Read more
When something else is needed
Sealant is not the answer to every problem, and we’ll tell you before any work starts. It will not solve:
- Draughts through the window seals rather than the frame
- A failed sealed unit that has misted up
- Damp problems in the wall away from the window
If you’re not sure, just ring 0345 464 0079 or email us and we will give you a straight answer before you book.
Joints and surfaces we work on
- Composite doors
- Window sills
- uPVC windows
- Aluminium frames
- Timber windows & doors
- Patio & French doors
How the job changes by surface
Window sills
The end joints of a sill tend to fail before the rest. A tight seal at each end keeps rain out of the wall.
Patio & French doors
Heavy door frames can move more than windows. The sealant must cope with it.
Common problems we fix in Portswood
Plenty of failed mastic was poorly applied in the first place. Mastic laid onto dusty, damp or crumbling surfaces never bonded as it should, so it comes away long before its time.
Keep an eye out for these signs:
- Draughty joints inside around the window
- Leaking joints at the ends of sills
- Cracked or shrunken mastic around the frame
- Water coming in at the bottom corners of a door
Managing a site like St Denys Primary School? Then the mastic around its windows and doors needs looking after like any other building’s.
Comparing quotes
- Which colour the sealant will be
- What the cure time is
- How long the guarantee is
- Whether VAT is included
Portswood: your questions answered
Do you work for landlords with property near St Denys station?
Yes, landlords and agents are among the people we work for. Just phone 0345 464 0079 or send us an email with the address and what needs doing, and we will send you a clear quote.
Is window mastic in a coastal place like Portswood any different?
Coastal weather is harder on outside sealant: there’s more wind-driven rain and, closer to the shore, salt in the air. Choosing the right sealant for the frame and wall, laid at the right depth, helps it last.
Do I have to be there?
That depends on where the joints are. For work indoors, someone needs to let us in, while outside work can sometimes be arranged differently.
Do the sealants smell?
It depends on the product. Some smell for a while, some hardly at all.
Can new sealant go over the old?
No. New silicone won’t bond to old silicone, and anything trapped underneath, including mould and water, stays there. We remove it all first.
Can you match the sealant to my frames?
Yes. Anthracite grey, black, brown and white cover most frames, with clear as an option.
Where is Mr Mastic based?
Our base is Crawley. We work across South East England, London and Scotland.
Do you hold any approvals?
Yes. We hold ARBOMaster approved applicator status.
What happens if it’s left?
If you are painting or rendering, reseal at the same time. A clean new bead makes new paint or render look finished. In an older home around Portswood, damp from a failed joint can get into timber and plaster, which is far harder to put right than the sealant itself.
Rather than a set price list, we look at what your job involves: the amount of work, the old material and the access. You will know the price before we begin.
Why us?
- ARBOMaster approved applicator
- White, clear, grey or coloured to suit, where the product allows
- More than 20 years in sealant work
- We agree the colour with you first
Read how sealant jobs are priced or our reviews.
Window mastic in Portswood: local notes
Portswood is within about 2 miles of the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. Both are hard on the mastic around window and door frames, which can dry out and crack sooner where a building faces the weather. Historic houses like South Stoneham House (about 1 mile north-east) are a reminder that the area around Portswood 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.
Letting a property close to St Denys station? Then sound mastic around windows and doors keeps out the draughts and damp that tenants notice first. Homes close to Highfield Church include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Portswood is about 1 mile north of Southampton, in Southampton. Homes, rented property, offices and hotels in Portswood can book us for window mastic. The work is guaranteed for a year. Portswood is one of 40 places in Southampton we cover.
Jobs for window mastic in SO17, SO14 and SO18 is quoted and booked the same way as anywhere else. You’ll find streets such as Ivy Road, Alma Road and Lawn Road, and we cover them all. With the A335 and A3035 close by, Portswood is easy for our applicators to reach for window mastic. Other places close to Portswood include St Denys (1 mile south-east), Southampton (1 mile south), Inner Avenue (1 mile south-west), Bitterne Manor (1 mile south-east) and Bitterne Park (1 mile east). Further out, we also cover Thornhill (3 miles south-east), Maybush (3 miles west), Eling (4 miles west), Rownhams (3 miles north-west), Millbrook (3 miles west) and Weston (3 miles south).
Near you in Portswood
Typical jobs here are in homes near St Anne's Catholic School, St Mary's Independent School and South Western Arms. There’s a railway station in Portswood itself: St Denys station. Well-known places in the area include Marlands Shopping Centre (1.5 miles south) and Royal South Hants Hospital (0.9 miles south). Green spaces nearby include Netley Common.
Places near Portswood
Other services in Portswood
Work for landlords, hotels and businesses
If you manage several properties in or around Portswood, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs, and photos by email help.
Mouldy or split sealant often shows up at the end of a tenancy. We can quote for more than one property at once.