Greater London · England
Sand Mastic in College Park
Professional sand mastic in and around College Park, with every bit of old sealant taken out first.
- Cement or filler used on old window joints that has cracked
- Modern sealant on a period surround
- Gaps between timber frames and stone or brick
About our sand mastic in College Park
Sand mastic skins over fairly quickly, but it takes longer to harden fully. Traditional guidance is not to paint over it and we will advise if you’re redecorating. Typical jobs include gaps between timber frames and stone or brick and draughty sash windows at the surround, on period & listed homes, tenement windows and brick reveals.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Either way, the mastic between frame and brickwork is what stops draughts and rain getting in.
Big or small, you get the same 12-month guarantee in College Park and across Greater London.
- Where
- College Park (NW10, W10, NW26)
- Region
- Greater London
- Cover
- 12 months on all our work
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Frames and glazing around College Park
Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. With historic houses such as Leighton House (about 2.6 miles south-east) nearby, there’s older building stock in the area around College Park as well as newer homes. In older buildings, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
Schools such as Kenmont Primary School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s. For landlords with property near Willesden Junction station, cracked sand mastic around sash windows lets in the draughts tenants complain about.
College Park is about 1 mile south-east of Harlesden, in Greater London. College Park gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a one-year guarantee. College Park is one of 764 towns and villages in Greater London we cover. You can also see our page for London, roughly 6 miles from College Park.
We work across the NW10, W10 and NW26 postcode area for sand mastic and the streets around it. Streets in the area include Tubbs Road, Waldo Road and Hythe Road. We also cover the places around College Park: Kensal Green (1 mile east), Old Oak Common (1 mile south-west), Harlesden (1 mile north-west), Willesden Green (1 mile north) and Kensal Rise (1 mile east). Within a short drive, we also cover London (6 miles east), City of Westminster (4 miles east), Marylebone (4 miles east), Kensington (3 miles south-east), St Pancras (5 miles east) and Shoreditch (7 miles east).
Around College Park
Locally, jobs take us to homes and businesses close to Newman Catholic College, Brondesbury College and Little Wormwood Scrubs. College Park has its own railway station: Willesden Junction station. Nearby you’ll also find Westfield London (1.7 miles south) and Brent Museum and Archives (1.1 miles north). Open spaces near College Park include Westbere Copse and The Long Water.
Also near College Park
Other services in College Park
When to call us in College Park
Paint, silicone or cement used over old mastic causes problems. They do not move with the timber and we normally remove them.
Any of these means the joints need attention:
- Mastic worn away on windows facing the weather
- Tired mastic found when preparing windows for paint
- Gaps where the frame meets the masonry
- Old cement repairs round a window that have failed
If you live in an older home near Saint Mark's, frames set in older brick or stone need a sealant that suits the wall as well as the frame.
What to look for in a quote
- How long the guarantee is
- Which colour the sealant will be
- How much experience the applicator has
- What product goes in the joint
Can I do it myself?
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it lifts and traps water and mould underneath. Everything old must be removed first.
Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.
What the job involves on each surface
Stone surrounds
Stone surrounds suit sand mastic well. The finish blends with the masonry.
Tenement and terrace windows
Windows above ground floor need the right access. Tell us the height and we’ll confirm what’s needed.
The process
On the day, we start by going over the job with you, so you know exactly what we’re doing. We protect the surfaces around the joints before we start. The work generally takes a few hours per window, depending on the condition of the joints. In College Park, 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 the surrounds with you and agree the joints to renew.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- The sand mastic is mixed and pressed into the joint by hand.
- We dress the finish so it sits neatly against the masonry.
Before we arrive
- For indoor joints, keep the area dry beforehand if you can
- Let us know about stairs, lifts or work at height
- Plan for the work area to be out of bounds to pets and children
Getting a quote
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is, and we’ll talk you through what we’d do. Whenever you’re ready, phone 0345 464 0079 or email us.
Related advice
How to look after the new joints
After the cure time, these simple habits help:
- Ask us before painting near the mastic
- Ask the planning authority about consent for listed or conservation-area homes
- Sort the mastic before the decorators arrive
- Avoid heavy scraping on the mastic joint
When preparing windows for paint, take care around the mastic. Hard scraping can loosen it.
Gaps round a sash box let in draughts and rain. Left, the gap tends to get bigger as more mastic falls out.
Honest limits
To be straight with you, there are a few things sealant won’t fix:
- Decayed frames that need repair
- Sash cords, weights and draught-proofing of the sashes
- Cracked or broken glass
If in doubt, ring 0345 464 0079 or email us and we will say what we think before booking.
Surfaces we seal
- Sash and case windows
- Tenement windows
- Period & listed homes
- Brick reveals
- Stone surrounds
- Timber door frames
Why deal with it now?
New mastic over crumbling mastic won’t hold. We remove the loose material first so the new work lasts. In a flat in College Park, failed sealant seldom stays inside your own four walls: water from a shower or window joint can reach the flat below, and gaps in fire-stopping matter to everyone in the building.
What you pay reflects the work, not guesswork. That’s why we ask a few questions first and agree the price before starting.
Why book with us
- Any old sealant cut out fully, not covered over
- 4.9 on Google from 180+ five-star reviews
- Trusted Arbo and Everbuild sealants
- Over 20 years’ experience
Questions from College Park
Can parking be tricky for a visit in College Park?
London parking needs a little planning, so let us know about permits, bays or a driveway when you book. That way the visit can be planned around it.
Is College Park in your area for sand mastic?
Yes. Our work covers London and the South East, and College Park is part of that. You can ring 0345 464 0079 or send us an email and tell us what needs doing, and we will give you a clear quote.
Is it OK to seal over old sealant?
No. New silicone won’t bond to old silicone, and it traps any mould or water underneath. We remove it all first.
Do you do commercial work?
Yes. Larger jobs can be planned room by room or area by area.
Do I have to be there?
We need access to the joints, so we will agree that with you when we book. Indoors, that usually means someone at home.
Do you have insurance?
Yes, we are fully insured for every job we do.
Can I paint the new mastic?
Traditional guidance is not to paint over sand mastic. If you are redecorating the window, ask us first and we will advise.
Can you replace silicone on a period window with sand mastic?
Yes, we do this often. The old silicone has to come out completely so the mastic can sit properly.