Hertfordshire · England
External & façade joints in Bromley, Hertfordshire
Sealing brickwork movement joints, render, cladding and façade joints for homes and businesses in Bromley and across Hertfordshire. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Rigid filler in a joint that should flex
- Rain getting behind render or cladding at a joint
- Sealant that has lost its bond to the brick or render
DIY versus a professional finish
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
If you’ve already had a go yourself, that’s fine. We cut it out and start again, so just mention it when you contact us.
About our external mastic in Bromley
External mastic is a job where short cuts show quickly. New sealant over old, joints packed with mortar and beads with no backing rarely last long. We take the old material out and do it properly. We work on copings & trims, façade panels and render & cladding joints, and the jobs we see most are moss and dirt in joints with no sealant left and joints with sealant missing in places.
Older homes in small places like Bromley may be stone, brick or timber-framed, often with later extensions. Where one material meets another is where water generally gets in, and they need the right sealant at the right depth.
Our work is backed for twelve months.
- Where
- Bromley (SG11)
- Region
- Hertfordshire
- Guarantee
- A year, on every job
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Walls and rooflines in Bromley
Historic houses like Much Hadham Palace (about 1.4 miles south-east) are a reminder that the area around Bromley has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material. London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
Historic houses such as Much Hadham Palace, about 1.4 miles south-east, show how far back building around Bromley goes, and older homes nearby need a sealant that suits their walls.
Bromley is about 4 miles west of Bishop's Stortford, in Hertfordshire. We provide external mastic to householders, landlords and businesses in Bromley and nearby. Bromley is one of 381 towns and villages in Hertfordshire where we work for external mastic. Chelmsford is on our list too, around 21 miles away.
Postcode districts we cover here for external mastic: SG11. Neighbouring places we cover for external mastic include Standon (1 mile north-west), Hadham Ford (1 mile east), Much Hadham (1 mile south-east), Puckeridge (2 miles north-west) and Hadham Cross (2 miles south). Within a short drive, we also cover Stevenage (10 miles west), Bishop's Stortford (4 miles east), Welwyn Garden City (12 miles south-west), Hitchin (15 miles west), Hoddesdon (9 miles south) and Cheshunt (12 miles south).
What’s near Bromley
Locally, jobs take us to homes and businesses close to The Fox And Hounds pub, among other places. The closest station to Bromley is Bishops Stortford station, about 4.8 miles east. A little further out are Henry Moore Studios and Gardens (2.8 miles south-east) and Moated mound (2.7 miles north-east).
How to look after the new joints
Aftercare is simple, and it makes a real difference:
- Point out the joints to other trades
- Clear growth from the base of walls and joints
- Keep movement joints as flexible joints, not mortar
- Get split or bare joints resealed while the damage is small
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They should be kept open and resealed, not filled.
Water getting behind cladding or render can go unnoticed for a long time. When it finally shows inside, the joint may have been open for years.
Other services in Bromley
How we quote for external mastic
For a quick quote, just ask. The main things that affect it are:
- Mould in or behind the old joints
- The size of the job
- Which sealant suits the joint
- When we can work, for business premises
What you pay reflects the work, not a rough estimate. That is why we ask about the job first and agree the price before starting.
What to tell us for a quote
The more you tell us, the more accurate the quote. When you get in contact, it helps to mention:
- Whether it’s a home or a business
- Any previous sealing or DIY work
- What the problem is, such as mould, gaps, leaks or cracking
- Pictures of the joints, sent by email
For external mastic in Bromley, phone 0345 464 0079 or send us an email. Tell us what the problem is and where, and we will agree the price before any work begins.
What we are called out for in Bromley
Some movement joints have been pointed up with mortar. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
Look out for any of the following:
- Brick movement joints where the sealant has split
- Cracked joints where brick meets render or frames
- Rigid filler in a joint that should flex
- Rain getting behind render or cladding at a joint
For landlords with property near Bishops Stortford station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Before you book anyone
- What preparation is included
- How the colour is chosen
- The length of the guarantee
- What the cure time is
Questions from Bromley
Is Bromley in your area for external mastic?
Yes, Bromley is within the area we cover. We work across London and the South East. You can ring 0345 464 0079 or drop us an email and tell us what needs doing, and we will send you a clear quote.
Is Bromley within the area you cover?
Yes, we do. Our work covers London and the South East, and smaller places are part of that. Longer journeys are simply planned in advance.
Can you seal over the old sealant?
No, and we never do. It may look fine at first, but the new bead soon lifts. The old sealant has to come out completely.
Which products do you use?
We choose the sealant for the joint, not the other way round. Where it moves, gets wet or faces the weather makes a difference, and we’ll explain our choice.
How much does external mastic cost in Bromley?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. You will get a clear quote before we start.
Are you an approved applicator?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we are part of it.
How long does external mastic take?
As a guide, most jobs take a few hours to a few days, depending on the length of joint and the access. Larger jobs naturally take longer.
I rent my home. Can I book you?
We can work for tenants, landlords or agents. Get your landlord’s agreement first.
Why act early in Bromley
A properly done movement joint is an even line in a colour that suits the wall. A hurried job with smeared edges and no backing looks worse and fails sooner so it’s worth doing right. In a small place like Bromley, homes can be exposed to wind and rain, which finds any gap, and damp in older walls is slow to dry out.
Combining jobs into one visit is normally more efficient than separate visits, so it’s worth mentioning everything you’d like done. You’ll get one clear quote for the whole job.
Why us?
- Anti-fungal silicone where joints get wet
- White, clear, grey or another colour, product permitting
- 12-month guarantee on every job
- Domestic, commercial and hotel work
Take a look at what affects the cost and customer reviews.
The process
Our applicators work methodically: protect, prepare, seal, tidy. Typically it takes a few hours to a few days, depending on the length of joint and the access, and the area is left clean. Somewhere like Bromley 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 checking each joint, agreeing the ones to redo and how we’ll reach them.
- The old mastic and anything lodged in the joint is removed.
- Both sides are cleaned back to sound material and primed if needed.
- Closed-cell backing rod is fitted to set the depth and stop three-sided bonding.
- 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 parking restrictions
- Keep pets and children clear of the area while we work
- Let us know about stairs, lifts or work at height
Getting a quote
Getting a quote is simple: tell us what needs doing and where, and roughly how big it is. A few photos by email make the job easier to understand.
Advice
Surface by surface
Render joints
The face of render can be soft, so a low-modulus sealant is kinder to the joint edges. Priming is done where the sealant calls for it.
Joints between dissimilar materials
Joints where frames, sills or panels meet the wall are common leak points. The old joint is removed and a sealant that bonds to both sides goes in.