Greater London · England
Pratt's Bottom External Mastic
Specialist external mastic for Pratt's Bottom: the right sealant, proper preparation and a neat finish. Call for a quick quote.
- Failed seals between different materials
- Joints with sealant missing in places
- Joints pointed up with cement by mistake
How we handle external mastic in Pratt's Bottom
Low-level joints can usually be done from the ground. Where joints are higher up, tell us about the building when you get in touch and we’ll confirm what access is needed. We’re often asked to deal with sealant pulling away from one side of the joint and panel joints letting water in, on concrete & block, façade panels and joints between brick and frames.
Modern London flats rely on sealed movement joints and cladding joints. Period houses have different weak points, such as gutter joints, trims and the line where an extension meets the old wall, and both kinds of building are found across London.
Big or small, you get the same 12-month guarantee in Pratt's Bottom and across Greater London.
- Where
- Pratt's Bottom (BR6, TN14)
- Wider area
- Greater London
- Cover
- A year, on every job
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Updated
- 26 October 2026
Pratt's Bottom: your questions answered
Can you help a landlord with a rental near Knockholt station?
Yes, we work for landlords and agents. Just call 0345 464 0079 or drop us an email and tell us about the property, and we will give you a clear quote.
Can parking be tricky for a visit in Pratt's Bottom?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Do the sealants smell?
There can be a smell while the sealant cures, but it fades. Opening a window helps.
Are you an approved applicator?
Yes. We are approved under the ARBOMaster scheme, the approved applicator scheme for Arbo sealants.
Are you fully insured?
Yes. We’re fully insured.
Can you seal over the old sealant?
No. Fresh sealant does not stick to old sealant, and it traps any mould or water underneath. It all has to come out first.
Do you work at height?
It depends on the building. We work on joints that can be reached safely. Tell us about the building and we will confirm what access is needed.
Will it make a mess?
No. We work neatly, protect the area around the joints and tidy up afterwards.
Outside joints around Pratt's Bottom
Compared with the north and west, the South East gets less rain, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. London terraces and converted houses often share gutters, downpipes and walls, so it’s worth agreeing who is responsible before work starts.
Managing a site like Pratts Bottom Primary School? Then larger buildings have long runs of movement joint that eventually need resealing. For an older house near a landmark such as All Souls' Church, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Pratt's Bottom is about 3 miles south of Orpington, in Greater London. Pratt's Bottom gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. Our Greater London coverage runs to 764 places, and Pratt's Bottom is one of them. Our London page covers work nearby.
Every address in BR6 and TN14 is covered for external mastic, from the main roads to the quietest streets. That includes homes and businesses on Orchard Road, Runciman Close and Downs View Close. Nearby, we also carry out external mastic in Halstead (1 mile south-east), Chelsfield (1 mile north-east), Bopeep (1 mile north-east), Badgers Mount (1 mile east) and Maypole (1 mile north-east). Further out, we also cover London (14 miles north-west), Shoreditch (15 miles north-west), Whitechapel (14 miles north-west), Stockwell (13 miles north-west), Orpington (3 miles north) and Wimbledon (15 miles west).
Around Pratt's Bottom
We work in homes and buildings around Hewitt's Chalk Bank and Green Street Green Primary School. The closest station to Pratt's Bottom is Knockholt station, roughly 0.8 miles east of the centre. Well-known places in the area include Crofton Roman Villa (2.4 miles north-west) and Lullingstone Castle (3.8 miles east). The countryside around Pratt's Bottom includes Betsom's Hill and Downe Bank Nature Reserve.
Also near Pratt's Bottom
Also in Pratt's Bottom
Why deal with it now?
A low-modulus sealant is chosen because it moves without pulling hard at the edges. That matters on brick, render and concrete, which can be weaker at the face. A stiffer product can damage the joint edge as it fails. Damp from a failed joint spreads quietly in older London brickwork and timber, and once it shows in Pratt's Bottom, the repair is bigger than a sealant job.
Leaving a failed joint usually makes the job bigger, not smaller, because water and mould keep working on it. If you’re unsure, phone 0345 464 0079 or send us an email and we will give you an honest view and a quote.
Why Pratt's Bottom clients choose us
- Colour picked to suit the job
- Anti-fungal silicone where joints get wet
- Rated 4.9 stars on Google
- Domestic, commercial and hotel work
Common problems we fix in Pratt's Bottom
The wrong product in a moving joint is a classic cause. A high-modulus or general-purpose sealant can be too rigid for a busy joint, and it tears off the sides.
People normally contact us after spotting one of these:
- Sealant pulling away from one side of the joint
- Joints pointed up with cement by mistake
- Hard, crazed mastic that has stopped moving
- Weeds or debris growing in open joints
Pratt's Bottom is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
Questions to ask before you book
- How long to leave it before use
- Whether the sealant suits the joint
- The length of the guarantee
- What insurance they hold
When it is not the sealant
Some problems need a builder, plumber or other trade rather than us:
- Adding movement joints to masonry that has none
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Render that’s blown, hollow or coming away
If you are not sure, just call 0345 464 0079 or drop us an email and we’ll give you a straight answer before booking.
Surfaces we seal
- Copings & trims
- Façade panels
- Concrete & block
- Render & cladding joints
- Joints between brick and frames
- Brickwork movement joints
Landlord and commercial work in Pratt's Bottom
If you manage several properties in or around Pratt's Bottom, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs, and photos by email help.
We also work for property managers and facilities teams. Several sites can go on one quote.
How it works
On the day, we start by going over the job with you. Surfaces next to the work are protected before any work begins. The work usually takes a few hours for a handful of joints, longer for a whole elevation. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. Mention any building rules, key holders or managing agents when you book.
- 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.
- We clean both faces of the joint and prime them where the product calls for it.
- We push in closed-cell backing rod so the sealant is the right depth and bonds to the sides only.
- The new sealant, chosen to suit the brick or render, is applied and tooled to a neat finish.
Before we arrive
- Let us know about stairs, lifts or work at height
- Plan for the work area to be out of bounds to pets and children
- Mention any leaks or damp you’ve noticed
How to get a quote
For external mastic in Pratt's Bottom, call 0345 464 0079 or email us. Tell us what the problem is and where, and we’ll agree the price before any work begins.
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How to look after the new joints
After the cure time, these simple habits help:
- Ask before painting over external sealant
- Keep water from gutters off the wall
- Tell anyone working on the walls about the movement joints
- Check external joints each spring
Do not paint over the new sealant unless we have said the product is paintable. Paint can crack on a flexible joint.
An open movement joint lets rain into the wall every time it pours. That can lead to damp patches, staining and frost damage, all bigger jobs than a reseal.
DIY sealant or a professional job?
A DIY attempt does not rule out a professional job. We remove it and do the joint properly.
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.