Hampshire · England
Window Mastic in Knowle
Mastic around window and door frames, sills and patio doors for Knowle, backed by a 12-month guarantee. Ask us for a quote.
- Cold air getting in at the frame edge
- Gaps between the frame and the inside reveal
- Black, perished sealant on frames
What window mastic looks like in Knowle
Rainfall in the South East is lower than in much of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Letting a property close to Fareham station? Then renewing tired window mastic between tenants heads off draught and damp complaints. For site and facilities teams at buildings such as Orchard Lea Infant School, its window and door frames need their mastic kept sound, just like a home’s.
Knowle is about 2 miles north of Fareham, in Hampshire. From the centre of Knowle to the outskirts, window mastic is available for homes and businesses alike. Across Hampshire, we cover 683 places, Knowle among them. Portsmouth is on our list too, about 7 miles from Knowle.
Jobs for window mastic in PO17 is quoted and booked the same way as anywhere else. That includes homes and businesses on Serotine Close, Boundary Walk and Park Approach and the roads around them. We also cover the places around Knowle: Funtley (1 mile south), Tapnage (1 mile north-west), Heathfield (2 miles south), Segensworth (2 miles west) and Titchfield Park (2 miles south-west). Within a short drive, we also cover Winchester (13 miles north), Gosport (6 miles south-east), Havant (10 miles east), Eastleigh (9 miles north-west), Horndean (9 miles east) and Totton (13 miles west).
What’s near Knowle
Typical jobs here are in homes near The Miners Arms and The Henry Cort Community College, among other places. The closest station to Knowle is Fareham station, about 2 miles south of the centre. Other landmarks nearby include Portchester Castle (4.9 miles south-east) and Knowle Hospital (under half a mile north-east). Green spaces nearby include Portsdown Hill and Swanwick Lakes.
Window mastic for homes and businesses in Knowle
A window frame and the wall around it expand and shrink at different rates. Heat and cold make frames grow and shrink against brick or render that hardly moves. That is why the joint needs a flexible, low-modulus sealant rather than something rigid. If you’re dealing with cold air getting in at the frame edge and draughty joints inside around the window, we can help.
Around Knowle, many homes face open ground, so their windows and doors take the full weather. Exposed frames and sills lose their mastic sooner than sheltered ones.
You get a one-year guarantee, the same in Knowle as everywhere else we work.
- Place
- Knowle (PO17)
- Region
- Hampshire
- Cover
- One year on every job
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
DIY versus a professional finish
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.
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
What the job involves on each surface
Timber windows & doors
Timber moves with moisture as well as heat, so a flexible sealant is essential. We seal onto sound, dry paintwork or timber.
Composite doors
Composite doors are normally hung in an uPVC-type frame, and the joint around it is sealed like a window. We match the colour to the frame.
Why act early in Knowle
Not every sealant suits a window. Decorators’ caulk and bathroom silicone aren’t designed for outside joints that move. An exterior, low-modulus sealant stays flexible in sun and frost. Around Knowle, older homes often have timber in their floors and frames, and water through a failed joint can rot timber if it’s left.
There are no prices on our website, because each job is priced on what it involves. For a quick quote, please call 0345 464 0079 or drop us an email.
Why book with us
- Experience in homes, commercial sites and hotels
- We never seal over old sealant
- Over 20 years’ experience
- Arbo and Everbuild products
When something else is needed
A few problems are outside what sealant work can do:
- Damp coming through the wall itself rather than the frame joint
- A failed sealed unit that has misted up
- A frame that has rotted at the joint
If you’re not sure, just ring 0345 464 0079 or send us an email and we will give you a straight answer before you book.
What we seal
- Aluminium frames
- Timber windows & doors
- Patio & French doors
- Composite doors
- uPVC windows
- Window sills
How it works
On the day, we look over the joints with you first, so you know exactly what we are doing. We protect the surfaces around the joints before any work begins. The work usually takes a few hours for a few frames, or a day or more for a whole house. Somewhere as small as Knowle, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We check each frame and agree which ones need doing.
- We remove the old mastic and clean the frame and the wall.
- We fit backing rod in deep gaps so the sealant is the right depth.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- Every joint is checked before we leave.
Preparing for the visit
- Plan for the work area to be out of bounds to pets and children
- Where the joints are inside, avoid wetting them before we arrive
- Mention any sign-in or site rules at work premises
How to get a quote
For a quote, ring 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. We will give you a clear quote before any work starts.
Related advice
More services for Knowle
FAQs for Knowle
Is Knowle in your area for window mastic?
Yes. We work across London and the South East, and Knowle is part of that. You can call 0345 464 0079 or send us an email and let us know what needs doing.
I let a flat near Fareham station. Can you help?
Yes, landlords and agents are among the people we work for. Just phone 0345 464 0079 or email us with the address and what needs doing, and we will send you a clear quote.
Is it worth trying it myself?
You can, for simple jobs. Preparation is everything: all the old sealant out, and a clean, dry joint. We can always put it right if it fails.
Can resealing stop a draught around my window?
It will if the frame joint is the problem. We check where the draught is before we start.
When is the sealant fully cured?
Cure times vary by product and the conditions. Before we leave, we’ll tell you the cure time.
Do you take out the old sealant first?
Yes. All of the old material is cut out and the joint cleaned before applying anything new.
Do the sealants smell?
It depends on the product. Some smell for a while, some hardly at all.
Can I paint over the new sealant?
It depends on the sealant. Some hybrid sealants can be painted; silicone cannot. Mention any painting plans before we start.
Landlords, agents and businesses in Knowle
Water getting past a failed joint can damage the building, which matters even more when someone else lives there. Resealing at the right time is simple maintenance.
We regularly work with letting and managing agents. Tell us the address, the job and how access works.
Common problems we fix in Knowle
Every frame moves through the day. A plastic or aluminium frame lengthens in sunshine and shortens as it cools, while the brick or render around it hardly moves. If the sealant cannot stretch, it splits.
The most common problems we see are:
- Cracked or shrunken mastic around the frame
- Mastic that’s falling out in pieces
- Draughty joints inside around the window
- Whistling draughts around closed windows
If you live in an older home near Church of St Francis, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
Before you book anyone
- Are they insured?
- Whether the sealant suits the joint
- What the cure time is
- What happens if they find a problem under the old sealant