Hampshire · England
Knightwood Window Mastic
Specialist window mastic for Knightwood: the right sealant, proper preparation and a neat finish. Ask us for a quick quote.
- Draughty joints inside around the window
- Black, perished sealant on frames
- Rain getting in at the frame or under the sill
Window mastic in Knightwood
There are two joints on most windows. The external joint is the weather seal; inside, the joint between frame and plaster stops draughts and tidies the reveal. We seal one or both, depending on what’s needed. Typical jobs include gaps left after new windows were fitted and sealant in the wrong colour for the frame, across composite doors, patio & French doors and aluminium frames.
Houses in smaller places like Knightwood can stand more in the open than those in a built-up town. The mastic around frames on those walls tends to age faster.
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.
- Location
- Knightwood (SO53, SO52)
- Wider area
- Hampshire
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
When to call us in Knightwood
Water runs down the glass onto the sill, and the ends of the sill, where it meets the wall, are where it gets in. When that sealant fails, water gets into the wall or under the frame.
The problems people generally mention when they call are:
- Mastic that’s falling out in pieces
- Cracked sealant at the sill ends
- Cracked internal joints between frame and plaster
- Rushed sealant from a window installation
Managing a site like Knightwood Primary School? Then larger buildings have plenty of frames, and the mastic around each one ages.
Questions to ask before booking
- What the quote includes, VAT included or not
- How long to leave it before use
- What happens if they find a problem under the old sealant
- Whether all the old sealant comes out first
The process
We bring everything the job needs with us, so there’s nothing for you to buy. After a quick look at the joints together, we protect the area and start. It normally takes a morning for a couple of windows and a door. Parking around Knightwood is usually 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.
- First, we go round the frames with you and agree the list.
- The old mastic is cut out and scraped back to clean surfaces.
- Where the gap is deep, backing rod goes in first.
- The new sealant goes on in white, brown, anthracite grey, black or clear to suit.
- Every joint is tooled smooth and checked before we leave.
Preparing for the visit
- Mention if the joints have been sealed before
- Keep children and pets away from the work area
- Mention any parking rules near the property
Getting a quote
If you are in Knightwood and need window mastic, phone 0345 464 0079 or drop us an email. Tell us what the problem is and where, and you’ll get a clear quote before we start.
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What the job involves on each surface
Composite doors
If the door itself is draughty, the issue may be the door seals or hinges rather than the frame mastic. We will tell you if that’s what we find.
uPVC windows
We clean the frame edge carefully so the plastic is not marked, then the sealant goes in between frame and wall.
Looking after it afterwards
To keep the joints looking good and working properly:
- Make sure the drainage slots aren’t blocked
- Keep timber frames painted
- Check the mastic once a year
- Keep solvents and bleach off the sealant
Silicone cannot normally be painted, so if you’re planning to paint the frames or walls, tell us beforehand. We can use a paintable sealant where that matters.
A failed joint lets water into the wall a little at a time. You might not see it until plaster blows or a damp patch appears inside. Catching it early keeps the fix to a reseal.
DIY versus a professional finish
The biggest DIY mistake is sealing over old sealant. 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.
If you do try it yourself, take your time over the preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it fails, we can still redo it.
How we quote for window mastic
Every job gets its own quote. These are the things that affect it:
- Any working-time requirements on site
- How much old sealant there is and how hard it is to remove
- Whether the work is at height
- Whether there’s mould to deal with
Commercial jobs are quoted on the same basis as homes: the amount of work, the access and the products needed. Call for a quick quote and we’ll explain what it covers.
Asking for a quote
A few details help us give you an accurate quote. When you ask for a quote, tell us:
- Whether it’s a home or a business
- How many joints, rooms or windows are involved
- Any previous sealing or DIY work
- Where the property is
There’s no standard price list. Instead, we send you a clear quote for your job. To get started, phone 0345 464 0079 or email us.
Nearby places to Knightwood
What else we do in Knightwood
Knightwood questions
Will you come out to Knightwood?
Yes, we do. Our work covers London and the South East, from towns to the smallest places. The journey is planned ahead, so it helps to know about access.
Do you work for landlords with property near Chandlers Ford station?
Yes. We work for letting agents and landlords as well as homeowners. Just ring 0345 464 0079 or drop us an email with the address and what needs doing, and we will give you a clear quote.
How long does it take to reseal the windows on a house?
The work takes a few hours for a few frames, or a day or more for a whole house. Access and the amount of old mastic make the biggest difference.
Will the old sealant be removed?
Always. Sealing over the old bead is the commonest cause of early failure, so we never do it.
Do I have to be there?
For indoor joints, yes, someone needs to let us in. After that, you can carry on with your day.
Can new window sealant be painted?
Not if it’s silicone. We choose the product with your decorating in mind, so mention it when you book.
Are you fully insured?
Yes. We’re fully insured.
Do you have sealant for grey or black windows?
Yes. Anthracite grey, black, brown and white cover most frames, with clear as an option.
Frames and glazing around Knightwood
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. With historic houses such as South Stoneham House (about 3.7 miles south) nearby, there’s older building stock in the area around Knightwood as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
Letting a property close to Chandlers Ford station? Then sound mastic around windows and doors keeps out the draughts and damp that tenants notice first. For an older house near a landmark such as St Francis, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Knightwood is about 1 mile west of Chandler's Ford, in Hampshire. For window mastic in and around Knightwood, it’s easy to get a quote: please ring 0345 464 0079 or email us. We cover Hampshire from our Crawley base. 683 places in Hampshire are on our list.
Postcode districts we cover here for window mastic: SO53 and SO52. Streets in the area include Foyle Road, Harvest Road and Flexford Road, and we cover them all. If you’re just outside Knightwood, we cover Chilworth Old Village (2 miles south-west), Chilworth (2 miles south), North Baddesley (2 miles west), Toothill (3 miles south-west) and Bassett (3 miles south). Further out, we also cover Winchester (6 miles north-east), Eastleigh (3 miles south-east), Fareham (13 miles south-east), Totton (7 miles south-west), Hedge End (7 miles south-east) and Romsey (4 miles west).
What’s near Knightwood
Locally, jobs take us to homes and businesses close to Toynbee School. For rail, the closest station is Chandlers Ford station, roughly 0.8 miles south-east of the centre. Nearby you will also find Romsey Community Hospital (3.5 miles west) and Eastleigh Museum (2.5 miles south-east). Green spaces nearby include Flexford Nature Reserve.
Honest limits
Before booking, it’s worth knowing the limits too:
- Misting between the panes of a double-glazed unit (that needs a new unit)
- A door that needs adjusting, rehanging or new seals
- Penetrating damp from a failed cavity tray or render
If in doubt, call 0345 464 0079 or send us an email and we will say what we think before booking.
What we seal
- Window sills
- Composite doors
- Timber windows & doors
- Patio & French doors
- Aluminium frames
- uPVC windows