Greater London · England
New Build Mastic in Harrow
New build mastic for Harrow, by sealant specialists with 20+ years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Internal frame sealant that has split
- Skirting joints opening in the first winter
- Gaps behind new kitchen upstands
Work for landlords, hotels and businesses
From a single let to a portfolio, you get the same standard of work: the old material taken out, careful preparation and a 12-month guarantee.
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. Several properties can go on one quote.
About our new build mastic in Harrow
Our new-build work comes in two parts: plot mastic for developers, and putting right failed sealant for people who’ve bought a new home. In both, preparation makes the difference. Typical jobs include new-build shower sealant that has already split and sealant that never bonded to the surface, across skirting & floors, show homes and windows & doors.
Much of London’s new housing is flats in larger developments. Snagging there often goes through the developer or managing agent, and failed shower seals, open skirting joints and gaps at thresholds are typical.
A one-year guarantee comes as standard, so you are not left on your own once the job is done.
- Where
- Harrow (HA2, HA1, UB5, HA3)
- Wider area
- Greater London
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
What we’re called out for in Harrow
A new house holds a lot of water from the build, which takes a year or two to dry out. Drying timber shrinks and pulls joints apart.
Keep an eye out for these signs:
- Plot mastic for developers ahead of handover
- Kitchen sealant that has pulled off the wall
- Cracks appearing as a new home settles
- Internal frame sealant that has split
Harrow is in London, so parking needs planning: let us know about parking bays, permits or a driveway.
What to look for in a quote
- Which sealant they’ll use, and why
- What the quote includes, VAT included or not
- How the colour is chosen
- Is the old sealant removed completely?
Why act early in Harrow
Sealant done properly at handover means fewer callbacks. Every return visit for a failed seal takes time. In London conversions, one flat’s bathroom is often above another flat’s ceiling, and a slow leak from a failed seal can end up in the flat below. Dealing with it early is far simpler.
The cost depends on the size of the job, how much old material has to come out and access to the work. You’ll have a clear quote before any work starts, so you know where you stand.
Why Harrow clients choose us
- Domestic, commercial and hotel work
- Full insurance on every job
- Arbo and Everbuild products
- A choice of colours where the product allows
Take a look at what affects the cost and customer reviews.
What affects the quote in Harrow
Some jobs are bigger than they look, and some smaller. What affects the quote:
- The number of rooms or windows
- Whether there’s mould to deal with
- The type of sealant required
- Working hours on commercial sites
Homes and businesses are quoted the same way: the amount of work, the access and the products needed. Ask us for a quote and we will go through it with you.
What to tell us for a quote
There’s no need for technical detail. Just tell us:
- What the problem is, such as mould, gaps, leaks or cracking
- Whether it has been sealed before
- Where the job is, and your postcode
- The type of property
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To arrange one, ring 0345 464 0079 or drop us an email.
Looking after it afterwards
After the cure time, these simple habits help:
- Open a window or run the fan after bathing
- Follow the cure time we give you
- Clean sealant with mild detergent, not abrasives
- Watch for new gaps as the house dries out
Photograph failed sealant before it’s redone and keep the builder’s replies. It helps if anything else comes up during the warranty period.
The sooner you deal with untidy or cracking sealant, the less there is to put right. Left alone, a small crack can become a leak.
New homes and floors in Harrow
London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. Much of London’s new housing is flats in larger developments, where snagging may go through the developer or managing agent.
For new homes near Harrow-on-the-Hill station, it’s worth checking the sealant early, while snags are still fresh.
Harrow is about 7 miles south of Watford, in Greater London. Wherever you are in the HA2 postcode area, we cover new build mastic for homes and businesses. Our Greater London coverage runs to 764 places, Harrow among them. London is on our list too, around 12 miles away.
Jobs for new build mastic in HA2, HA1, UB5 and HA3 works the same way as everywhere else we cover. Local streets include High Street, London Road and Perceval Square, all of which we cover. Being close to the B457 and B458, Harrow is simple for us to get to. Close by, we work in Roxeth (1 mile south), South Harrow (1 mile south), North Harrow (1 mile north-west), Harrow on the Hill (1 mile south-east) and Rayners Lane (1 mile west). Further out, we also cover London (12 miles south-east), City of Westminster (9 miles south-east), Marylebone (10 miles south-east), Kensington (8 miles south-east), St Pancras (11 miles east) and Shoreditch (12 miles east).
Local landmarks in Harrow
Typical jobs here are in homes near Kingsfield Arms, Grange Primary School and Northwick Park. Harrow’s nearest station is Harrow-on-the-Hill station, about 0.7 miles north-east. A little further out are St. George's Shopping Centre (0.7 miles north-east) and Clementine Churchill Hospital (1 mile south-east). For a walk, there’s Islip Manor Meadows and Northala Fields.
Nearby places to Harrow
Other services in Harrow
The process
Once we are on site, we check the joints match what you told us. If we find something unexpected, we talk it through with you first. After that, the work takes a few hours in a single home. In Harrow, as in most of London, parking needs a little planning. It helps if you can point us to a visitor permit or a bay close to the door.
- We look at why each joint failed, including any movement.
- Old sealant is cut out and the joints cleaned.
- Joints are dried and primed where the product calls for it.
- New sealant goes in, with baths filled first so they’re at their heaviest.
- The finished joints are checked and the cure times given.
How to prepare
- Let us know about parking restrictions
- Let us know about earlier repairs to the joints
- Plan for the work area to be out of bounds to pets and children
Get a quote
To get a quote, call 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. You’ll have a clear quote before work begins.
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Harrow questions
Can you help a landlord with a rental near Harrow-on-the-Hill station?
Yes. We work for landlords and agents as well as householders. Just phone 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear price.
Can parking be tricky for a visit in Harrow?
It can be, so it helps to tell us about permits, visitor bays or off-street space when you book. The visit is then planned around what’s available.
Is there a guarantee?
Yes. Every job comes with a 12-month guarantee.
What sealant do you use?
It depends on the joint: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Can I do it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
Is there any odour?
Sometimes, a little. Any smell clears as the sealant cures.
Will you leave a mess?
We keep the work tidy. Nearby surfaces are protected, and we clear up when we are done.
Where are you based?
Our base is Crawley, with over 20 years’ experience. Our area covers South East England, London and Scotland.
Can I do it myself?
Not every job suits DIY: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
The difference is mostly in the preparation and the product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, then guaranteed for a year.