Hampshire · England
External & façade joints in Knapp, Hampshire
Sealing brickwork movement joints, render, cladding and façade joints for householders, landlords and businesses in Knapp. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Rain getting behind render or cladding at a joint
- Weeds or debris growing in open joints
- Cracked joints where brick meets render or frames
Walls and rooflines in Knapp
Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Schools such as Ampfield Church of England Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing. Rented homes near Chandlers Ford station change hands often, and split movement joints are easy to miss on a rental until damp shows inside.
Knapp is about 2 miles north-west of Chandler's Ford, in Hampshire. Jobs in Knapp get the same care as everywhere else we work: old sealant removed completely, careful preparation and a one-year guarantee. Knapp is one of 683 towns and villages in Hampshire where we work. Our Southampton page covers work nearby.
Our applicators cover all of the SO51 postcode area for external mastic. Close by, we work in Ampfield (1 mile south-west), Broadgate (1 mile south-east), Gosport (1 mile south-west), Lower Slackstead (1 mile north-west) and Crampmoor (2 miles south-west). Within a short drive, we also cover Winchester (6 miles north-east), Eastleigh (5 miles south-east), Fareham (15 miles south-east), Andover (14 miles north), Totton (7 miles south-west) and Hedge End (8 miles south-east).
Landmarks near Knapp
Typical jobs here are in homes near White Horse Public House, among other places. For rail, the closest station is Chandlers Ford station, about 2.5 miles south-east. Other landmarks nearby include Romsey Community Hospital (2.9 miles south-west) and King Johns House (3.7 miles south-west). The countryside around Knapp includes Emer Bog and Baddesley Common.
About our external mastic in Knapp
For buildings in Knapp, we reseal external joints of all kinds, from brick movement joints to cladding panels. The preparation is the same whatever the wall: clean joint faces and the right depth. If you are dealing with cracked joints where brick meets render or frames and panel joints letting water in, we can put it right, whatever the surface.
Somewhere as small as Knapp, homes and farm buildings often face open ground, where walls and rooflines take the weather head on. Gutter joints and wall joints there need a sealant that can flex and stay put.
The work is guaranteed for twelve months. If something isn’t right with it in that time, tell us and we will put it right.
- Where
- Knapp (SO51)
- Wider area
- Hampshire
- Guarantee
- A year, on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
DIY sealant or a professional job?
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. Where it goes wrong is sealing over the old bead, working on a wet joint or overloading the gap.
What a professional job adds is preparation and the right product. We take joints back to clean, dry surfaces, and the sealant is chosen for how the joint moves and where it is, and the work is guaranteed for a year.
More services for Knapp
Knapp: your questions answered
Can you do external mastic in Knapp?
Yes. We work across London and the South East, and Knapp is part of that. Just call 0345 464 0079 or send us an email with a few details of the job.
I let a flat near Chandlers Ford station. Can you help?
Yes, we work for landlords and agents. You can call 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before any work starts.
What do you put in the joint?
Products from Arbo and Everbuild, among others, chosen to suit the joint. We explain the product when we quote.
Can you work on commercial sites?
Yes. We work in offices, washrooms, hotels and other commercial premises. Working times can be discussed when we quote.
What does external mastic cost?
The cost depends on the size of the job, access and how much old sealant has to come out. Call for a quick quote.
What is a movement joint?
A movement joint is a planned break in the wall that absorbs expansion and shrinkage. It should be filled with flexible sealant, never mortar.
Do you take out the old sealant first?
Yes. We cut out all the old sealant and clean the joint.
What colours does the sealant come in?
We choose a sealant colour to suit the brick, stone or render so the joint blends in. There’s a wide choice of exterior colours.
For landlords and businesses
Letting agents often deal with us directly. Tell us the address, the job and how access works.
If you manage several properties in or around Knapp, jobs at different addresses can go on one quote. Just tell us the addresses and what each one needs.
Signs you need external mastic in Knapp
Sunlight, wet weather and frost wear exterior sealant down. In time it goes hard, crazes on the surface and stops stretching, so the next time the wall moves, it splits or pulls away.
Common reasons people contact us include:
- Weathered mastic that no longer stretches
- Rigid filler in a joint that should flex
- Moss and dirt in joints with no sealant left
- Cracked joints where brick meets render or frames
For an older house near a landmark such as Church of St Mark, an extension built onto an older house moves differently, and the joint between them takes the strain.
Comparing quotes
- Whether the sealant suits the joint
- How long the guarantee is
- Are they insured?
- How much experience the applicator has
What we can’t put right
A few problems are outside what sealant work can do:
- Damp that isn’t coming from the joint
- Structural movement, which needs a surveyor or engineer
- Cracking across the wall rather than at a joint
If you are not sure, just phone 0345 464 0079 or drop us an email and we will give you a straight answer.
Where we work in Knapp
- Concrete & block
- Render & cladding joints
- Joints between brick and frames
- Brickwork movement joints
- Copings & trims
- Façade panels
Leave it or put it right?
Mortar or ordinary filler might look like a quick way to close an open joint, but it locks the joint solid. The movement then cracks the brickwork or render nearby. The correct repair is a flexible sealant with the right backing. In a small place like Knapp, homes can be exposed to wind and rain, which finds any gap, and older walls, once damp, take a long time to dry.
Leaving a failed joint generally makes the job bigger, not smaller, as water and mould keep getting in. If you are not sure whether it needs doing, ring 0345 464 0079 or email us for an honest opinion and a quote.
Why Knapp clients choose us
- An ARBOMaster approved applicator
- We’re fully insured
- Every job guaranteed for a year
- Neat joints and a tidy finish
See our cost guide or customer reviews.
What affects the quote in Knapp
Call for a quick quote. The main things that affect it are:
- Whether old sealant or filler has to be cut out
- The product the joint needs
- Any mould that needs treating
- When we can work, for business premises
We don’t show prices on the website, because the cost depends so much on the job itself. For a quick quote, please phone 0345 464 0079 or email us and we will talk you through it.
What to tell us for a quote
When you call or email, these details help:
- Pictures of the joints, sent by email
- What the problem is, such as mould, gaps, leaks or cracking
- How many joints, rooms or windows are involved
- The address or postcode of the job
Asking for a quote is easy: let us know the job and the location. Photos by email help us understand the job, and we will take it from there.
The process
We bring everything the job needs with us, so you do not need to buy or prepare anything. Once we’ve agreed what’s being done, the area is protected and the work begins. It normally takes a few hours for a handful of joints, longer for a whole elevation. Somewhere like Knapp needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. We bring what the job needs, so it can be finished in one trip where possible.
- We start by walking round the building and agreeing the joints and the access.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- We apply the sealant, tool it and check the whole run.
Getting ready for the visit
- Tell us if parking is tricky
- Let us know about earlier repairs to the joints
- Keep pets and children clear of the area while we work
Get a quote
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is, and we will explain how we’d tackle it. When it suits you, phone 0345 464 0079 or drop us an email.