Hertfordshire · England
Borehamwood External Mastic
Specialist external mastic for Borehamwood: careful preparation, the right product and tidy work. Ask us for a quick quote.
- Failed seals between different materials
- Weeds or debris growing in open joints
- Movement joints with cracked, split or missing sealant
Can I do it myself?
Sealing over old silicone is the commonest DIY error. New silicone won’t bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
About our external mastic in Borehamwood
A movement joint is only as good as its depth. Backing rod controls how deep the sealant goes and keeps it off the back of the joint, leaving it bonded to two faces so it can move with the wall. If you have movement joints with cracked, split or missing sealant and weeds or debris growing in open joints, we can put it right, whatever the surface.
Extensions are a common sight on houses around Borehamwood, and the joint where new wall meets old is a classic place for water to get in. Sealing it properly means the right joint depth and a flexible sealant, not a quick bead.
A 12-month guarantee comes as standard, so you are not left on your own once the job is done.
- Where
- Borehamwood (WD6)
- Wider area
- Hertfordshire
- Guarantee
- One year on every job
- Quote
- A clear quote up front
- Call
- 0345 464 0079
- Updated
- 26 October 2026
What sealant work can’t fix
Before booking, it’s worth knowing the limits too:
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Structural movement, which needs a surveyor or engineer
- Cracked brickwork or render that needs a builder or plasterer
Not sure which it is? You can ring 0345 464 0079 or drop us an email and we’ll tell you honestly.
Joints and surfaces we work on
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
- Copings & trims
- Façade panels
- Concrete & block
Quotes for external mastic in Borehamwood
Your quote is based on your job. We look at:
- The number and length of the joints
- Working hours on commercial sites
- The product the joint needs
- How easy the joints are to reach
The cost depends on the amount of work, how hard the old material is to remove and how easy the joints are to reach. We give a clear quote before we start, so you know where you stand.
Asking for a quote
When you contact us, these details help:
- Where the property is
- Whether it’s a home or a business
- Pictures of the joints, sent by email
- Roughly how big the job is
Asking for a quote is easy: let us know the job and the location and its rough size. A few photos by email make the job easier to understand, and we’ll come back to you with a quote.
Towns and villages near Borehamwood
More services for Borehamwood
Outside joints around Borehamwood
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. With historic houses such as Wyllyotts Manor (about 4.3 miles north-east) nearby, there’s older building stock in the area around Borehamwood as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
Letting a property close to Elstree & Borehamwood station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies. In the older streets around All Saints church, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Borehamwood is about 5 miles east of Watford, in Hertfordshire. We provide external mastic to householders, landlords and businesses in Borehamwood, as part of our work across Hertfordshire. Across Hertfordshire, we cover 381 places, and Borehamwood is one of them. Our London page covers work nearby (14 miles or so).
Work in WD6 is quoted and booked the same way as anywhere else. If you need external mastic at a property on Station Road, Canterbury Road and Eldon Avenue or a nearby road, we can help. Being close to the A1 and A5135, Borehamwood is easy for our applicators to reach for external mastic. We also cover Well End (1 mile north-east), Green Street (1 mile north), Deacon's Hill (1 mile south), Rowley Green (1 mile east) and Elstree (2 miles south-west). Larger places within reach include Watford (5 miles west), Hemel Hempstead (10 miles north-west), St Albans (7 miles north), Welwyn Garden City (10 miles north), Harpenden (11 miles north) and Hoddesdon (13 miles north-east).
Around Borehamwood
In Borehamwood, that means homes and buildings near Aldenham Country Park, The Pick & Shovel pub and Yavneh College, among other places. The closest station to Borehamwood is Elstree & Borehamwood station, about 0.6 miles south-west. Nearby you will also find Royal National Orthopaedic Hospital (2.4 miles south-west) and Spires Shopping Centre (3.1 miles east). Not far away are Darland's Lake and Rowley Lodge Field.
Common problems we fix in Borehamwood
Every building moves. Clay bricks expand slightly over their life, concrete and block shrink, and everything moves with temperature and wet. All of that ends up in the joint sealant.
People usually contact us when they notice something like this:
- Old sealant gone brittle and cracked
- Cracked joints where brick meets render or frames
- Joints pointed up with cement by mistake
- Plants rooting in failed movement joints
Schools such as St Teresa Catholic Primary School are buildings too, and larger buildings have long runs of movement joint that eventually need resealing.
What your quote should include
- Whether all the old sealant comes out first
- Which colour the sealant will be
- What preparation is included
- Whether the sealant suits the joint
What happens on the day
When we arrive, we start by going over the job with you, so you know exactly what we are doing. Surfaces next to the work are protected before work begins. The work usually takes anything from a few hours to several days, depending on the building. Parking in a town like Borehamwood is normally straightforward, but tell us if there’s a driveway or any restrictions, and mention if the work is upstairs, in a flat or high on the outside.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- Plan for the work area to be out of bounds to pets and children
- Let us know about parking restrictions
- Mention any tricky access
Ask for a quote
For external mastic in Borehamwood, phone 0345 464 0079 or email us. A short description of the job and where it is helps us quote, and we will agree the price before any work begins.
Related advice
Leave it or put it right?
The longer a joint stays open, the more water the wall takes in. In cold weather, frost can damage wet brick and render near the open joint, so the problem grows beyond the joint itself. Draughts from a gap round a frame, damp under a sill or water behind a bath panel all start small, and they’re far easier to fix early.
Some things make a job bigger or smaller: the old material and how easily it comes out, whether mould needs treating, and whether the work is at height. Your quote takes all of that into account.
What you get with us
- We never seal over old sealant
- Full insurance on every job
- Sanitary silicone with an anti-fungal additive in wet areas
- Over 20 years’ experience
Take a look at what affects the cost or our reviews.
Borehamwood questions
Do you cover Borehamwood for external mastic?
Yes. Our work covers London and the South East, and Borehamwood is part of that. You can ring 0345 464 0079 or email us and tell us what needs doing, and we will give you a clear quote.
Do you work for landlords with property near Elstree & Borehamwood station?
Yes, landlords and agents are among the people we work for. Just ring 0345 464 0079 or email us with the address and what needs doing, and we will give you a clear quote.
How do you reach high-level joints?
That depends on the building and the joints. We work on joints that can be reached safely. Give us some details and we will confirm the access.
What do you need from me for a quote?
A short description and the location, with photos by email if possible. If we need more, we’ll ask.
How long will you be here?
That depends on the amount of work, but most jobs take a few hours to a few days, depending on the length of joint and the access. We will give you a better idea when we quote.
Do you remove the old sealant?
Yes. We cut out all the old sealant and clean the joint.
Why do you put foam in the joint first?
The foam is closed-cell backing rod. It stops the sealant going in too deep and bonding to three sides.
Is it messy?
We keep the work tidy. We protect what’s around the joints, and the area is left clean when we finish.
Landlord and commercial work in Borehamwood
If you manage several properties in or around Borehamwood, jobs at different addresses can go on one quote. Send us the addresses and the work at each, and photos by email help.
A neglected joint can let water reach the structure, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance that we can handle for you.