Knowle construction mastic
Mastic packages for new-build and refurbishment projects in Knowle. CHAS accredited, Constructionline member, with a 12-month guarantee on workmanship.
- Missed perimeter joints on a new elevation
- External joints sealed in damp or cold conditions that are now failing
- Existing joints on a refurb that need cutting out and resealing
Construction mastic across Knowle
Share the site address and what’s failing, and we’ll reply with a fixed quote or arrange a visit.
Construction mastic in Knowle, done properly
We work to the specification and the programme, not to habit. If a product is named, that’s what goes in; any alternative we suggest is put to you before anything changes. Joint widths, backing, primers and tooling follow the manufacturer’s guidance so the detail on the drawing is what ends up on site. If you have different trades sealing to different standards and new external sealant already peeling away, we can put it right, whatever the surface. One point of contact handles commercial sealant work in Knowle from the first photos to the final walk-round, for single jobs and planned programmes alike.
Sites around smaller places like Knowle can be a fair drive from suppliers, so we come with everything the package needs. Drawings, photos and the programme let us give a fixed quote.
Whoever the client is, the cover is the same: a 12-month guarantee on our workmanship. Faults in the structure, damage and other trades’ work fall outside it, and we say so plainly.
- Location
- Knowle (PO17)
- Wider area
- Hampshire
- Guarantee
- 12 months on every job
- Quotes
- Fixed quote, scope in writing
- Phone
- 01277 525 020
- Last updated
- 3 November 2026
Your questions answered
Will you plan work around the academic year at somewhere like Fareham College?
Yes. We plan campus work around teaching, exams and residence turnarounds. Any paperwork you need, from RAMS to our insurance certificate and CSCS details, is confirmed with the quote.
Would you work within a site like Knowle Hospital?
Yes, hospitals are one of the sectors we cover. Each area is agreed with the ward or department and the estates team in advance.
Can you quote from photos?
That depends on the size and complexity of the job. Simple work can often be priced from photographs, and bigger or more complex jobs typically get a visit.
Can you work while the building is occupied?
Yes, as long as we plan it. We agree a sequence with your contact so just one area at a time is disrupted.
Can you come in just for snagging?
Yes. Snag-only work is something we take on.
Will you just go over the old sealant?
No. Overlaying old sealant is a frequent cause of early failure, so everything comes out first.
Can you handle several sites?
Yes. A group of buildings can go on one quote, and you deal with one contact throughout across South East England, Greater London and Scotland.
General trades versus a specialist
Some joints are best left to specialists: fire-rated seals that must follow a tested detail, trafficked floor joints and external movement joints among them. Getting these wrong typically costs more in the end than doing them right.
Site maintenance staff can often handle a short internal joint. Where it goes wrong is preparation: sealing over old material, sealing onto damp or dusty surfaces, or a product that can’t take the movement.
Building and refurbishing in Knowle
The South East is one of the drier parts of the UK. Winter mornings still bring frost and condensation on frames and panels, which is why external dates are agreed with the site manager. A 2-mile radius around Knowle takes in several hotels. When hotels extend or refit, the work is typically squeezed between peak periods, mastic included.
Projects at schools like Orchard Lea Infant School work to term dates, so mastic is programmed tightly. For contractors at a college like Fareham College (2 miles south of Knowle), perimeters and internal sealant are timed for the holidays. New units and refits on sites such as Knowle Village Business Park, under half a mile to the north-west of Knowle, need their panel and perimeter joints sealed to the specification.
Knowle is about 2 miles north of Fareham, in Hampshire. Anywhere in PO17, it works the same way: details in, fixed quote out, then sealing and a 12-month guarantee. Our Hampshire coverage takes in 723 places, large and small. We also cover Portsmouth, around 7 miles from Knowle.
Anyone looking for construction mastic in PO17 gets the same process as the rest of our area: details, then a fixed price, then sealing and a 12-month guarantee. If your site is on Serotine Close, Boundary Walk and Park Approach or close by, send details and we’ll quote for mastic packages. We also cover Funtley (1 mile south), Tapnage (1 mile north-west), Heathfield (2 miles south), Segensworth (2 miles west) and Titchfield Park (2 miles south-west). Bigger towns within reach include 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
In Knowle, that means premises near The Miners Arms and The Henry Cort Community College and the streets around them. Knowle’s nearest station is Fareham station, roughly 2 miles south. Nearby you will also find Portchester Castle (4.9 miles south-east) and Knowle Hospital (less than half a mile north-east). Green spaces nearby include Portsdown Hill and Swanwick Lakes.
Owners, agents and contractors
Hotels, schools, healthcare sites, offices and retail units book us directly too. We plan around the way the building is used, so the building keeps working while we do.
As a CHAS accredited contractor and Constructionline member, we’re straightforward to vet for your supplier list. We are fully insured, and our insurance certificate can go with the quote.
How the job changes by surface
Fire-rated sealant where specified
Where the specification calls for fire-rated or intumescent sealant around service penetrations or linear gaps, we install it to the manufacturer’s tested detail. Fire stopping design belongs to the designer and building control and we install what’s specified.
Bathrooms, en suites and washrooms
Sanitary joints around baths, showers, basins and WCs need anti-mould sanitary silicone. Joints are cleaned, sealed and tooled neatly and baths are loaded where appropriate before sealing.
What we can’t put right
We seal joints; we don’t mend everything behind them. On its own, sealant can’t deal with:
- Faulty frames rather than failed sealant
- Joints damaged after sign-off by following trades
- Oversized gaps that need packing or adjustment by others
Not sure which it is? You can phone 01277 525 020 or send details through our quote form and we’ll tell you honestly before you book.
Surfaces we seal
- Cladding and panel joints
- Internal decorators’ caulk
- Floor and skirting junctions
- Sanitary and kitchen joints
- Window and door perimeters
- Brick and block movement joints
On site: what to expect
The first thing on site is a walk round with your contact, to confirm the scope, the order of work and any areas we must keep clear. After that, any old or failed material is removed, each joint is prepared and the new sealant goes in. If others near Knowle need work, visits can be combined. You’ll have a fixed quote before work starts.
- Drawings, specification and programme come to us.
- We take off quantities and return a fixed quote.
- The sequence is agreed with the site manager.
- Plots or floors are sealed as they’re handed over.
- Every joint is cleaned, set to depth and sealed with the specified product.
- After snagging, the work is handed over under our 12-month guarantee.
What we need from you
- Share your working hours and any access restrictions
- Share the asbestos register for older buildings
- Agree which areas must stay open
Getting a fixed quote
The quickest route to a quote is a few photographs and the site postcode. Upload them with the quote form, or give us a call on 01277 525 020 or use the quote form if you’d rather talk the job through.
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What else we do in Knowle
Looking after the joints
Your facilities or cleaning team can help the joints last. Share these points with them:
- Share drawings and the specification as soon as possible
- Use the product the specification names
- Allow flexibility for external sealing in damp or cold weather
- Keep scrapers and abrasive pads off new beads
If a joint is damaged after sealing, flag it early. Snags can be picked up in a planned close-out visit as agreed in the quote.
Frames with gaps too wide for sealant need sorting before the mastic goes on. Filling a wide gap with sealant alone sets up a failure so packing or adjustment by the installer comes first. We flag them as soon as we see them.