West Berkshire · England
External Mastic in Colthrop
We cover Colthrop for sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly.
- Failed sealant between panels on a façade
- Joints pointed up with cement by mistake
- Old sealant gone brittle and cracked
How to look after the new joints
To keep the joints looking good and working properly:
- Get split or bare joints resealed while the damage is small
- Keep movement joints as flexible joints, not mortar
- Keep water from gutters off the wall
- Check external joints each spring
Give the sealant the cure time we tell you before anything rubs against it. Most exterior sealants skin fast but take longer to cure right through.
If you can see gaps, plants or bare sections in a joint, have it checked. Early work is quicker and leaves a better finish.
External mastic in Colthrop
A movement joint is only as good as its depth. Closed-cell backing rod sets the depth and stops the sealant sticking to the back, so it bonds to the two sides only and can stretch. If you’re dealing with sealant that has lost its bond to the brick or render and water getting into walls through failed joints, we can help, whatever the surface.
Outside joints can only be sealed when they’re dry, so work in Colthrop is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
Your job is guaranteed for a year, as with all our work.
- Place
- Colthrop (RG19, RG18)
- Wider area
- West Berkshire
- Cover
- A year, on every job
- Price
- A clear price before we start
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
How the job changes by surface
Brickwork movement joints
Vertical joints in long brick walls let the brickwork expand without cracking. We reseal them with a low-modulus sealant over backing rod coloured to suit the wall.
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. Their movement joints are sealed over backing rod with a flexible sealant.
Common problems we fix in Colthrop
Sometimes a movement joint was filled with mortar or a rigid filler by mistake. The joint can’t move, so the wall cracks somewhere else instead.
Common reasons people contact us are:
- Joints where the bead has come unstuck
- Hard, crazed mastic that has stopped moving
- Moss and dirt in joints with no sealant left
- Rain getting behind render or cladding at a joint
If you let a flat or house near Thatcham station, split movement joints are easy to miss on a rental until damp shows inside.
Questions to ask before you book
- Is VAT in the price?
- How the surfaces are prepared before sealing
- When the joint can take water or movement
- What guarantee comes with the work
Also near Colthrop
What else we do in Colthrop
Quotes for external mastic in Colthrop
There’s no set price list, because no two jobs are the same. The quote depends on:
- The old material and how stubborn it is
- The amount of work
- The number of rooms or windows
- Mould in or behind the old joints
The cost depends on the size of the job, how hard the old material is to remove and how easy the joints are to reach. You will have a clear quote before any work starts, so you know where you stand.
What we need to know
Photos help, but a description is a good start. Try to tell us:
- Access, such as stairs, a lift or height
- How many joints, rooms or windows are involved
- Any previous sealing or DIY work
- A few pictures by email, if you can
For a quick quote, get us on the phone, or send an email if you’d rather. Tell us about the joints that need doing and we will talk you through the work and give you a clear price.
Honest limits
In fairness, there are a few things sealant will not fix:
- Structural movement, which needs a surveyor or engineer
- Cutting new joints into brickwork, which is building work rather than sealant work
- Loose or hollow render, which needs re-rendering
If you’re not sure, just phone 0345 464 0079 or send us an email and we’ll give you a straight answer before booking.
Where we work in Colthrop
- Render & cladding joints
- Joints between brick and frames
- Copings & trims
- Concrete & block
- Façade panels
- Brickwork movement joints
For landlords and businesses
For anyone letting property in or around Colthrop, several properties can be quoted together. Send us the addresses and the work at each, and photos by email help.
We also work for property managers and facilities teams in Colthrop and across West Berkshire. We can quote a run of properties together, and we are fully insured for the work.
How it works
On the day, there’s very little for you to do. Show us the job and we’ll take it from there. The work itself takes a few hours for a handful of joints, longer for a whole elevation. Somewhere like Colthrop needs a little journey planning: let us know about lanes, gates and parking. We bring what the job needs, so it can be finished in one trip where possible.
- We start by checking each joint, agreeing the ones to redo and how we will reach them.
- We cut out the failed sealant and rake out any dirt or growth.
- Both sides are cleaned back to sound material and primed if needed.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- A flexible exterior sealant is applied and tooled in a colour to suit the wall.
How to prepare
- Tell us if parking is tricky
- Let us know if you’ve seen damp or leaks
- For business premises, tell us about site rules or sign-in
Ask for a quote
Every job is quoted individually, so the first step is telling us about yours. Just phone 0345 464 0079 or send us an email with the details and send pictures if you have them.
Read more
What external mastic looks like in Colthrop
With historic houses such as Shaw House (about 3.5 miles west) nearby, there’s older building stock in the area around Colthrop as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material. Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
For an older house near a landmark such as St Mary's Church, older walls, gutters and the joints where extensions meet them need a flexible sealant. Schools such as Francis Baily Primary School are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Colthrop is about 1 mile east of Thatcham, in West Berkshire. Anywhere in RG19, we cover external mastic for homes and businesses. Our area takes in 155 places across West Berkshire. Our Reading page covers work nearby (12 miles or so).
We work across the RG19 and RG18 postcode area for external mastic and the streets around it. Whether your property is on Bath Road, Ashman Road and Fokerham Road or anywhere close by, our applicators can take on the job. If you’re just outside Colthrop, we cover Crookham (2 miles south-east), Hyde End (2 miles south-east), Heads Hill (2 miles south-west), Mill Green (2 miles south) and Goose Hill (3 miles south). Further out, we also cover Newbury (4 miles west), Burghfield Common (8 miles east), Speenhamland (4 miles west), Hungerford (12 miles west), Spencers Wood (12 miles east) and Calcot (9 miles east).
Landmarks near Colthrop
Typical jobs here are in homes near The Swan pub and Kennet School, among other places. The closest station to Colthrop is Thatcham station, about 0.5 miles south-west of the centre. Nearby you’ll also find Old Chapel Textile Centre (2.6 miles south-west) and Donnington Castle (4.6 miles west). Green spaces nearby include Thatcham Reed Beds.
Common questions in Colthrop
Do you cover smaller places like Colthrop?
Yes. Colthrop is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
Is Colthrop in your area for external mastic?
Yes, Colthrop is within the area we cover. Our work covers London and the South East. You can call 0345 464 0079 or send us an email and let us know what needs doing.
How long should I leave it?
It depends on the product and the temperature. Before we leave, we’ll tell you the cure time.
Which products do you use?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. We use products from Arbo and Everbuild.
Does someone need to be in?
That depends on where the joints are. Inside work needs someone to give us access, and for outside work we’ll agree access with you when we book.
What information do you need?
The location, the problem and the rough size of the job. If you can, email a few pictures.
How long does external mastic take?
It depends on the size of the job, but most jobs take a few hours for a handful of joints, longer for a whole elevation. We’ll give you a better idea when we quote.
Where is Mr Mastic based?
We work from Crawley. We cover Colthrop and the rest of West Berkshire.