Greater London · England
Gutter Sealing in Underhill
Our applicators work in Underhill on sealing leaking gutter joints, end caps, fascias, soffits and roofline trims. Old sealant removed completely, joints prepared properly and a 12-month guarantee.
- Open joints in fascias and soffits
- Earlier gutter repairs that have peeled off
- Internal damp traced to a gutter joint
About our gutter sealing in Underhill
Garage door frames let rain in when the sealant around them fails. We cut out the old sealant and reseal the frame with an exterior sealant. If you have trim joints where the sealant has failed and water running down the wall below the gutter, we can put it right, on uPVC fascias, garage door frames and gutter joints alike.
Working on the outside of a London home means planning access: shared paths, upper floors and parking. For a home in Underhill, tell us how high the joints are and how to reach the back of the building.
All our work is covered by a 12-month guarantee.
- Location
- Underhill (EN5, N20)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
For landlords and businesses
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements.
We work for landlords and agents as well as householders. Resealing between tenancies keeps a property looking cared for.
Should I try it myself first?
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas call for the right materials, safe access and experience.
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.
Nearby places to Underhill
Other services in Underhill
How the job changes by surface
Gutter joints
Most gutter leaks start at a joint between sections. They’re cleaned out, dried and resealed.
Garage door frames
Resealing a garage door frame keeps rain and draughts out.
Your questions about gutter sealing in Underhill
Do you cover Underhill for gutter sealing?
Yes. We work across London and the South East, and Underhill is part of that. Just phone 0345 464 0079 or drop us an email with a few details of the job, and we will send you a clear quote.
Is parking an issue for gutter sealing in Underhill?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot.
Is it messy?
Not at all. The area is protected while we work and cleaned up afterwards.
Are you ARBOMaster approved?
Yes. We hold ARBOMaster approved applicator status, and we’re fully insured.
Where is Mr Mastic based?
Our base is in Crawley, West Sussex, and we work across South East England, London and Scotland.
Will sealing fix a sagging gutter?
Not on its own. If the gutter sags, the joints keep opening so it needs refixing before sealing.
Do you replace gutters or fascias?
No. We seal joints; replacing gutters and fascias needs a gutter or roofline installer.
Will you clear out my gutters?
We clear debris near the joints, so the sealant can bond. Cleaning the whole run is a separate job.
Keeping the joints in good condition
Aftercare is simple:
- Clean out the gutters once or twice a year
- Check fascia and soffit joints for gaps
- Look for streaks or damp on the wall below gutters
- Rest ladders on the wall, not the gutter
A sagging gutter needs its brackets checked. If it drops, the joints will open.
Once roofline sealant splits, water can get behind it. Resealing early protects the boards.
Walls and rooflines in Underhill
London terraces and converted houses often share gutters, downpipes and walls, so check who is responsible for the outside before booking. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Homes close to St John the Baptist Church include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep. Underhill is in London, so parking needs planning: tell us about permits, visitor bays or off-street space when you book. Letting a property close to New Barnet station? Then a dripping gutter joint or loose fascia trim is easy to miss until damp shows inside.
Underhill is about 1 mile west of Barnet, in Greater London. Anywhere in EN5, we cover gutter sealing for homes and businesses. Underhill is one of 764 towns and villages in Greater London we cover. There’s also a page for London, roughly 11 miles from Underhill.
Here we cover the EN5 and N20 postcode area for gutter sealing. You’ll find streets such as Park Road, May's Lane and Manor Road, and we cover them all. Neighbouring places we cover for gutter sealing include 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). Within a short drive, we also cover 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).
Around Underhill
In Underhill, that means homes and buildings near Susi Earnshaw Theatre School, Highlands Gardens and The Red Lion pub, among other places. The nearest railway 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.
When something else is needed
New sealant can’t fix everything, and we’ll tell you before work begins. Sealant won’t put right:
- Problems with the roof covering
- Water backing up from a blocked pipe
- Rotten or damaged fascia boards
If you are not sure, just ring 0345 464 0079 or email us and we will give you a straight answer before you book.
Joints and surfaces we work on
- uPVC fascias
- Soffit joints
- Garage door frames
- Roofline trims
- Gutter joints
- Gutter end caps
What happens on the day
On the day, we look over the joints with you first, so you know exactly what we’re doing. We protect the surfaces around the joints before any work begins. Most jobs take an hour or two for a few joints, longer for a full run. In Underhill, flats, stairs and shared entrances are part of the routine. If the building has a concierge, managing agent or access rules, tell us when you book.
- We look at the gutters, fascias and trims and agree the joints to seal.
- We clean out each joint.
- We make sure everything is dry.
- We apply exterior or gutter sealant and finish it neatly.
- We check our work before we leave.
Getting ready for the visit
- Where the joints are inside, avoid wetting them before we arrive
- Tell us about any previous sealing or DIY attempts
- Let us know about stairs, lifts or work at height
Getting a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is, and add photos by email if you can.
Read more
Why act early in Underhill
New gutters cost far more than a few resealed joints. If the gutter is sound and the drip is a joint, resealing is the sensible fix. If it has failed, we’ll tell you. In a London flat, a failed joint rarely stays your problem alone: water can reach the neighbours below, and gaps in fire-rated joints affect the whole building.
Instead of a standard rate, we look at what your job involves: the amount of work, the old material and the access. You’ll know the price before we begin.
Why book with us
- Arbo and Everbuild products
- A sealant colour to suit the surroundings
- We are fully insured
- Every job guaranteed for a year
See our cost guide or customer reviews.