Greater London · England
Northolt External Mastic
External mastic for Northolt and the surrounding area: careful preparation, the right product and tidy work. Call for a quick quote.
- Sealant pulling away from one side of the joint
- Leaking joints around cladding and façade panels
- Gaps where render, brick and frames meet
What sealant work cannot fix
Honest advice matters more to us than a booking, so here’s what sealant can’t fix:
- Cutting new joints into brickwork, which is building work rather than sealant work
- Loose or hollow render, which needs re-rendering
- Subsidence or other structural problems
Not sure which it is? You can ring 0345 464 0079 or email us and we will tell you honestly.
Joints and surfaces we work on
- Façade panels
- Joints between brick and frames
- Concrete & block
- Brickwork movement joints
- Copings & trims
- Render & cladding joints
External mastic in Northolt
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, so it bonds to the two sides only and can stretch. If you have failed seals between different materials and weeds or debris growing in open joints, we can help.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. In Northolt, joints up high may need ladders or other access, which is worth talking through when you book.
Our work is backed for twelve months, and the guarantee is the same wherever you are.
- Where
- Northolt (UB5, UB6)
- Region
- Greater London
- Guarantee
- 12 months on all our work
- Price
- Quoted before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
How to look after the new joints
Simple care keeps the joints in good condition. Our advice:
- Keep water from gutters off the wall
- Look over the joints every year, ideally after winter
- Keep movement joints as flexible joints, not mortar
- Have failed joints looked at early
Keep the joints clear of soil, plants and climbing growth. Damp material against the sealant shortens its life.
A joint that has stopped moving pushes the movement elsewhere, usually as cracking in the brickwork or render nearby. Catch it early and you reduce the risk.
Why it’s worth doing now in Northolt
Sealing over the top of old mastic doesn’t hold for long. New sealant does not bond well to old, weathered sealant, so we always take the old sealant out. Converted houses in London often have a bathroom above someone else’s living room, so a small leak from tired sealant can mean a neighbour’s ceiling and a lot of disruption. Putting it right early is much less trouble.
Doing several joints on one visit is normally more efficient than separate visits. We will send you a clear quote for the lot.
Why Northolt clients choose us
- Trusted Arbo and Everbuild sealants
- Experience in homes, commercial sites and hotels
- Any old sealant cut out fully, not covered over
- Tidy, careful work
See our cost guide and what customers say.
Places near Northolt
More services for Northolt
What the job involves on each surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. Each is resealed with a weatherproof, flexible sealant.
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. The movement joint takes that up, so the sealant in it must stay soft and stretchy.
Outside joints around Northolt
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. In terraces and conversions, gutters and walls are often shared with the neighbours, so check who is responsible for the outside before booking.
Northolt is in London, so parking needs planning: let us know about parking bays, permits or a driveway. Letting a property close to Northolt Park station? Then outside joints that have cracked can let damp into a rental, so check them between lets. Homes close to St Richard's Church include some older properties, and an extension built onto an older house moves differently, and the joint between them takes the strain.
Northolt is about 2 miles south-west of Harrow, in Greater London. Whether you are in the middle of Northolt or further out, we cover external mastic for every kind of property. We cover 764 towns and villages across Greater London. You can also see our page for London, roughly 12 miles from Northolt.
Jobs for external mastic in UB5 and UB6 is quoted and booked the same way as anywhere else. We cover properties on Church Road, Eastcote Lane North and Tenby Gardens and the roads around them. We also cover the places around Northolt: South Ruislip (1 mile north-west), Greenford (1 mile south-east), South Harrow (1 mile north-east), Yeading (2 miles south-west) and Yiewsley (2 miles south-west). Larger places within reach include London (12 miles east), City of Westminster (10 miles east), Marylebone (10 miles east), Kensington (8 miles south-east), St Pancras (11 miles east) and Shoreditch (13 miles east).
What’s near Northolt
Typical jobs here are in homes near Northala Fields, The Greenwood Public House and Northolt High School, among other places. The closest station to Northolt is Northolt Park station, about 0.7 miles north-east of the centre. Nearby you will also find Heath Robinson Museum (3.1 miles north) and Clementine Churchill Hospital (2 miles north-east). Green spaces nearby include Islip Manor Meadows and Northala Fields.
Should I try it myself first?
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
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. All the old material has to come out first.
The process
At the end, we look at the finished work together. The work normally takes a few hours for a handful of joints, longer for a whole elevation, depending on the amount of work. Parking in much of London is by permit or pay-and-display, so it helps to know what’s near you in Northolt. A visitor permit or a nearby bay makes the visit run more smoothly.
- We start by checking each joint, agreeing the ones to redo and how we’ll reach them.
- Old sealant and any debris are cut and raked out.
- 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.
Getting ready for the visit
- Mention if the joints have been sealed before
- Let us know about parking restrictions
- Let us know if you’ve seen damp or leaks
Ask for a quote
We quote each job on its own, so start by telling us what you need. Just call 0345 464 0079 or send us an email with the details.
Advice
Common questions in Northolt
I let a flat near Northolt Park station. Can you help?
Yes, we work for letting agents and landlords. You can phone 0345 464 0079 or send us an email with the address and a few details, and we will give you a fixed price before any work starts.
Can parking be tricky for a visit in Northolt?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot, so mention what’s available when you book.
When will the joints need doing again?
That depends on the wall, the weather and the movement. Signs to watch for are cracking, hardening and gaps at the edges, and reseal at that point.
How do you reach high-level joints?
It depends on the building. Send us pictures and a rough idea of the height, and we will confirm what access is needed.
Will you leave a mess?
Tidy work is part of the job. We protect what’s around the joints, and the area is left clean when we finish.
Do you come to Northolt?
Yes, we do. Our applicators work in Northolt.
Do you hold any approvals?
Yes. We are approved under the ARBOMaster scheme.
Do you take out the old sealant first?
Yes. Sealing over the old bead is the commonest cause of early failure, and it’s something we never do.
Quotes for external mastic in Northolt
Jobs vary more than people expect. What affects the quote:
- Any working-time requirements on site
- How much old sealant there is and how hard it is to remove
- The type of sealant required
- The number of rooms or windows
Rather than a set price list, we look at what your job involves: how many joints, what’s in them now and how we reach them. The price is agreed before we begin.
What we need to know
To help us quote quickly, let us know:
- How many joints, rooms or windows are involved
- The problem you’ve noticed
- Photos by email, if that’s easy
- Whether it has been sealed before
For external mastic in Northolt, phone 0345 464 0079 or drop us an email. Tell us what the problem is and where, and you will get a clear quote before any work starts.