Construction Mastic in Underhill
Mastic packages for new-build and refurbishment projects across Underhill, carried out by CSCS-carded applicators. Fully insured and CHAS accredited.
- Snag items on joints that need redoing before handover
- New external sealant already peeling away
- Different trades sealing to different standards
Need construction mastic in Underhill?
Send drawings, photos or a joint schedule, or tell us about the site, and we’ll come back with a fixed quote.
Construction mastic in Underhill, done properly
Perimeter sealing outside needs a dry joint and the right temperature. Each sealant has a temperature range, and damp, frost or condensation on frames stops work, so we plan elevations with the forecast and the programme in mind. Internal areas can typically carry on while the outside waits. The enquiries we see most involve perimeter gaps outside the sealant’s range and external joints sealed in damp or cold conditions that are now failing, across sanitary and kitchen joints, floor and skirting junctions and cladding and panel joints. One point of contact handles commercial sealant work in Underhill from the first photos to the final walk-round, whether it’s one building or several.
A great deal of London construction is refurbishment of occupied or part-occupied buildings, alongside new blocks. Replacement windows, recladding and fit-outs leave perimeter and facade joints to seal, often next to people still using the building, so tidy, well-planned work matters.
Whoever the client is, the cover is the same: a 12-month guarantee on our workmanship. Faults in the structure, damage and other trades’ work fall outside it, and we say so plainly.
- Where
- Underhill (EN5, N20)
- Wider area
- Greater London
- Cover
- 12 months on our workmanship
- Quote
- Fixed quote, scope in writing
- Telephone
- 01277 525 020
- Updated
- 3 November 2026
Work for main contractors and building owners
Building owners and managing agents use us on sealant work across single buildings or whole portfolios around Underhill. Several sites can go on one quote, so there’s one set of paperwork to deal with.
We take on planned maintenance as well as one-off repairs: working through a building or an estate in stages that fit your budget. Underhill can form part of a wider programme across Greater London.
Places near Underhill
More services for Underhill
How a job runs
We schedule the visit to fit the site hours and access windows you give us. While we’re working, the area stays contained and tidy, and your contact hears from us before we move to the next area. For a job in Underhill, access comes first. Send the building rules and access times with your enquiry.
- Drawings, specification and programme come to us.
- Quantities are measured and a fixed price returned.
- The sequence is agreed with the site manager.
- Each area is sealed when it’s released.
- Joints are prepared, backed and sealed to the specification.
- After snagging, the work is handed over under our 12-month guarantee.
What we need from you
- Tell us which areas need to stay in use
- For older buildings, check the asbestos register before work
- Send your site hours and access windows
Get a fixed quote
Need a figure for a tender or a budget? We will quote against your scope and drawings that you can work with. For a chat about it beforehand, speak to us on 01277 525 020 or email drawings and photos.
Related advice
General trades versus a 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.
Putting right a botched joint often costs more than sealing it well at the start, because the whole bead must be removed and the faces cleaned back again. For that reason, many FMs and contractors use a sealant specialist from the outset.
Why deal with it now?
Sealing over damaged or contaminated new joints might save a day, but it won’t last. New sealant laid on old or dirty sealant has nothing to bond to. Damaged joints are removed and resealed from clean faces. Getting scaffold, permits or access booked in Underhill takes effort, so it makes sense to deal with every failing joint while access is in place.
Pricing mastic packages depends on quantities, condition and access, and any specification that applies. Ask us for a fixed quote.
Why us?
- 12 months’ guarantee on every job
- One contact handling all your sites
- Public liability insurance in place
- A range of standard colours, depending on the product
Take a look at our cost guide and our accreditations and insurance.
Your questions answered
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. Send the building rules and access times with your enquiry. The ULEZ covers the whole of Greater London, which we allow for
Does your area include sites such as Hadley Manor Trading Estate, near Underhill?
Yes. We cover Underhill and the area around it, including industrial estates, business parks and retail parks such as Hadley Manor Trading Estate. Photos and a short description are enough for a first look.
Which sealant will you use?
A specification, where there is one, decides it. If there isn’t one, it comes down to the joint: how much it moves, what it bonds to and whether it’s wet, trafficked or fire-rated.
How much does the work cost?
It depends on the job: the volume of work, the access, the specified product and how it’s phased. Call for a fixed quote.
Do you seal on top of existing sealant?
No. Sealing over old material is one of the classic causes of early joint failure, so everything comes out first.
Can you fit around our programme?
The programme sets the job. Tell us the sequence and we will plan applicators around it so sealing follows the trades.
What does a mastic package normally include?
Inside and out: frame perimeters, movement joints, caulk where called for, sanitary and kitchens in one fixed quote.
Construction mastic in Underhill: the local picture
As part of Greater London, Underhill is inside the ULEZ, which applies to every van on site. Add booked deliveries and tight storage, and the mastic package needs planning with the site team. There are a number of hotels within about 2 miles of Underhill. Hotel schemes tend to have fixed reopening dates, so the mastic is programmed tightly with the other trades.
For contractors refurbishing units at places like Hadley Manor Trading Estate, which lies north of Underhill, the mastic covers cladding panels, roller-door and window perimeters. On a healthcare site such as Barnet Hospital, which lies west of Underhill, new blocks and refurbishments go on while the hospital keeps running, so mastic work is sequenced carefully.
Underhill is about 1 mile west of Barnet, in Greater London. Underhill sits inside our coverage and the rest of Greater London, with the same fixed quotes and 12-month guarantee as everywhere else. We work across 764 places in Greater London, large and small. Sites around London have their own page, roughly 11 miles from Underhill.
We cover the EN5 and N20 postcode districts. Streets here include Park Road, May's Lane and Manor Road, and sites on any of them can send details for a fixed quote. 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). Bigger towns within reach 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. Underhill’s nearest 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). Green spaces nearby include Greenhill Gardens and Darland's Lake.
Do you need construction mastic in Underhill?
Frames installed with uneven gaps make perimeter sealing harder. Sealant has a range of joint widths it can cope with and gaps beyond it need packing or adjusting by the frame installer. Better to raise it at the start than seal a joint that’s bound to fail.
Typical triggers for a call:
- Perimeter gaps outside the sealant’s range
- Snag items on joints that need redoing before handover
- Caulk cracking where joints are moving more than expected
- Failed sealant in an existing building being refurbished
Building work at universities like Middlesex University, 4 miles south-west of Underhill, is often timed for the summer, mastic included.
What to look for in a quote
- What the guarantee covers, and for how long
- Do they follow the manufacturer’s priming guidance?
- Is depth set with backing rod, or bond-breaker tape in shallow joints?
- The named product and why it was chosen
What the job involves on each surface
Snagging before handover
Damaged, missed or untidy joints make up most snag lists. We price snagging as part of the package or as a separate visit.
Fire-rated sealant where specified
Fire-rated sealant is one type of fire-stopping product. Other products are used for some services and gaps, and we’ll tell you if the detail calls for something else. Record requirements are agreed with the quote.