Underhill mastic sealing
Looking for mastic sealing in Underhill? Send us the details for a fixed quote, backed by a 12-month guarantee on the work.
- Estate-wide sealant that is simply worn out
- Draught complaints from residents or tenants
- Old repairs sealed over failed mastic
Mastic sealing in Underhill
Tell us what needs sealing and where, with photos or drawings if you have them, and we’ll price it.
Mastic sealing in Underhill, done properly
Most buildings come with mastic joints nobody has looked at since handover, and it ages quietly: it sits round windows and doors, along external joints and through communal areas. When it hardens, splits or pulls away, water and draughts follow along with complaints. We work on communal entrances and stairwells, shopfronts below residential blocks and external wall and movement joints, and the failures we are asked to look at most are complaints coming in block by block and mastic failing across several blocks on an estate. Most enquiries from Underhill start with one failed joint and grow into a wider look at the building: we look at the rest while we are there and tell you what we find.
For managing agents in Underhill, resident access, notice periods and the building’s rules shape the job. We work to the agent’s notice and access plan, so residents know what’s happening.
Building owners and contractors get the same cover: twelve months on the work we carried out. It doesn’t extend to damage, faults in the building or work by others, and we’re upfront about that.
- Where
- Underhill (EN5, N20)
- Wider area
- Greater London
- Guarantee
- 12 months on every job
- Quote
- Fixed quote, scope in writing
- Phone
- 01277 525 020
- Last updated
- 3 November 2026
For owners and agents in Underhill
Seven care or nursing homes sit less than 2 miles from Underhill. Care home owners need frame and external mastic kept sound without unsettling residents. Blocks in London are normally run by managing agents, landlords or housing associations, with residents to notify and access to arrange. Our programme follows the access you agree with residents.
Landlords with units on estates such as Hadley Manor Trading Estate, 0.5 miles north of Underhill, can bring frame, door and external mastic across several units into one programme. For a school such as St Catherine's RC School, perimeter mastic on windows and doors is a holiday job.
Underhill is about 1 mile west of Barnet, in Greater London. If you are looking for mastic sealing in Underhill, we can help. We work across 764 places in Greater London. For work in that direction, see our London page (11 miles or so).
Anyone looking for mastic sealing in EN5 and N20 gets the same process as the rest of our area: send details, get a quote, we seal, guaranteed. If your site is on Park Road, May's Lane and Manor Road or close by, send details and we will quote for mastic joints. We also cover Barnet (1 mile east), New Barnet (1 mile east), Monken Hadley (1 mile north), Hadley Wood (1 mile north-east) and Cockfosters (2 miles east) for mastic joints. Nearby towns on our patch include London (11 miles south-east), City of Westminster (9 miles south), Marylebone (9 miles south), Kensington (10 miles south), St Pancras (9 miles south) and Shoreditch (10 miles south-east).
Near you in Underhill
We work on buildings around Susi Earnshaw Theatre School, Highlands Gardens and The Red Lion pub. For rail, the closest station is New Barnet station, roughly 1 mile east. Other landmarks nearby include Francis Skaryna Belarusian Library and Museum (2.2 miles south) and Barnet General Hospital (0.9 miles west). Open spaces near Underhill include Greenhill Gardens and Darland's Lake.
Different surfaces, different methods
External movement joints
Joint size and product are matched to the expected movement, often around 2:1 width to depth, as the manufacturer advises.
Commercial and mixed-use buildings
Landlords with commercial portfolios have shopfronts, office entrances and external joints to look after. We work across portfolios on a planned basis.
Cost factors for mastic joints
Sealant work doesn’t have a standard rate, since sites vary so much. What we take into account:
- Working within restricted access windows
- Site requirements such as inductions and permits
- Backing rod, priming and other preparation
- Distance, for remote addresses
The product called for affects the cost, and so does the preparation, from cutting out to priming and backing rod. Access, phasing and site requirements come into it too.
What to include in your enquiry
We can often quote from photos and a few details. It helps to include:
- The product your specification calls for
- The postcode of the building
- Whether an asbestos survey exists
- Anything awkward about access or site hours
Tell us about the building, the joints and when you need the work done, and a fixed quote will follow. The easiest way is to call the office on 01277 525 020 or use the quote form.
Common problems we fix in Underhill
Poor preparation explains many failed joints. Without clean, sound faces and a primer where the product needs one it comes away from one face.
It’s worth sending us details if you spot any of the following:
- Damp patches beside frames
- A mix of products and colours from past repairs
- Brittle perimeter mastic across a building
- No planned programme for sealant
Older community buildings, St John the Baptist Church among them, often have frames of mixed ages whose mastic varies.
Before you book anyone
- Whether their applicators hold CSCS cards
- How long is the guarantee, and what does it include?
- Proof of insurance
- How the joint faces will be prepared and primed
Site staff or a sealant specialist?
Using site staff can make sense for a small touch-up, but anything bigger is another matter: a specialist brings efficiency, a consistent finish and a 12-month guarantee.
General builders and handymen seal joints, but it isn’t their main trade. A specialist prepares properly, controls joint depth and picks a product with the right movement class, which is what makes a joint last.
What happens if it’s left?
Resealing ahead of leaks keeps it to a maintenance task. After water has got in, there may be damp, damaged plaster or decoration to put right too and occupiers notice. In Underhill, each extra visit means more notices, permits and disruption, so a proper job first time, with the old sealant fully removed, is worth it.
There’s no price list, since every building and every scope is different. For a fixed figure, call for a quote.
Why choose Mastic Doctor in Underhill
- A Constructionline member, so easy to vet
- Standard and matched colours in many product ranges
- RAL and finish matching where the product range allows
- Our applicators hold CSCS cards
See what affects the cost and our accreditations.
Questions we are asked in Underhill
Can you cope with the access rules in a London building?
Yes, most London buildings have access rules of some kind, and we plan around them. Share the building’s contractor rules and we will work to them.
Will you take on a block within reach of New Barnet station?
Yes. Blocks of any size are within what we do. We work to your notice and access arrangements.
How do you reach windows on upper floors?
It depends on the building. How upper joints are reached is agreed before work is booked so there are no surprises.
Do you guarantee the mastic work?
There is a 12-month guarantee on our workmanship and we hold public liability insurance.
Do you cover Underhill?
Yes. Sites across Underhill are covered, with one number for every area we cover.
Do you work with property factors and landlords?
Yes. Most of our mastic sealing is for agents, factors, housing associations and portfolio landlords, and we quote building by building or as a programme.
How long does a job like this take?
We plan the time on site around your programme and access. You will have an expected duration with the quote.
Towns and villages near Underhill
What else we do in Underhill
On site: what to expect
We begin with a short walk round with whoever looks after the building, agreeing which joints are in scope, where to start and what must stay open. After that, any old or failed material is removed, each joint is prepared and the new sealant goes in. All of Greater London is in the ULEZ, and kerbside space in Underhill can be scarce. Let us know about any on-site parking or loading arrangements when you send the job details.
- Each block or building is walked and the failed joints recorded with the likely cause.
- We send a fixed quote that sets out the joints, the products and the programme.
- The programme is fixed with you, including dates you can pass on to residents or tenants.
- Old sealant is stripped and each face prepared back to firm material.
- Deep joints get backing rod, faces are primed if the manufacturer specifies it, then the joint is sealed and tooled.
- Completed joints are inspected and carry a 12-month workmanship guarantee.
What we need from you
- Move anything stored against the joints
- Arrange parking or a loading space
- For older buildings, check the asbestos register before work
Get a fixed quote
Every quote starts with the facts: the joints involved, quantities, access and the product called for. Send what you have, and we will arrange a site visit if anything is unclear.