Hertfordshire · England
Sand Mastic in Colney Street
Window and door surrounds in Colney Street need attention? We cut out the old, prepare the joints and apply the right sealant.
- Tired mastic found when preparing windows for paint
- Mastic round period door frames that has failed
- Open joints round the window box
Different surfaces, different methods
Sash and case windows
The box of a sash and case window sits in the stone or brick opening. The gap round it is pointed with sand mastic.
Brick reveals
We rake out the old mastic and pack deep voids before the new mastic goes in.
How we handle sand mastic in Colney Street
Sand mastic has long been used to fill the joint between timber frames and masonry. It’s made from sand and a linseed-oil-based binder and built up by hand. On older homes, it suits the building far better than silicone. If you are dealing with cracked mastic round a front door frame and mastic that needs renewing before redecorating, we can put it right.
Somewhere as small as Colney Street, older homes often have timber frames set in stone or brickwork. Not every older frame suits a modern silicone bead, and sometimes a traditional sand mastic is the better choice.
A 12-month guarantee comes with the work, just as it does everywhere we cover.
- Location
- Colney Street (AL2, WD7)
- Wider area
- Hertfordshire
- Guarantee
- 12 months on all our work
- Price
- A clear quote up front
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Work for landlords, hotels and businesses
Letting agents and landlords in Colney Street can book us as well as homeowners. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
What happens on the day
There is not much for you to do on the day. Point us to the joints and we will get on with it. The job generally takes a few hours for a single window, longer for several, including the tidy-up. In a small place like Colney Street, access is generally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First, we look at the surrounds with you and agree what needs doing.
- We rake out the old mastic and clean the joint.
- Deep voids are packed so the mastic is the right thickness.
- We mix the sand mastic and apply it by hand, shaping it to the joint.
- We dress the surface so it sits neatly against the masonry.
Preparing for the visit
- Mention any leaks or damp you’ve noticed
- Plan for the work area to be out of bounds to pets and children
- Mention any sign-in or site rules at work premises
Get a quote
Asking for a quote is easy: let us know the job and the location. A few pictures by email make the job easier to understand, and we will take it from there.
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Sand mastic in Colney Street: local notes
London and the South East are among the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. With historic houses such as High Elms Manor (about 2.9 miles west) nearby, there’s older building stock in the area around Colney Street as well as newer homes. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window.
For landlords with property near How Wood station, older sash windows in a rental need their mastic kept sound to keep the weather out. For site and facilities teams at buildings such as Park Street Church of England Voluntary Aided Primary School, the mastic around its windows and doors needs looking after like any other building’s. Homes close to Church of the Holy Trinity include some older properties, and replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Colney Street is about 3 miles south of St Albans, in Hertfordshire. Every kind of property in Colney Street can book us for sand mastic. The work is guaranteed for a year. Our area takes in 381 places across Hertfordshire. We also work in London, about 18 miles from Colney Street.
Postcode districts we cover here for sand mastic: AL2 and WD7. Whether your property is on Old Parkbury Lane, Ventura Park and Radlett Road or a nearby road, we can help. We also cover the places around Colney Street: Frogmore (1 mile north-west), Park Street (1 mile north-west), How Wood (1 mile north-west), Bricket Wood (2 miles west) and Chiswell Green (2 miles north-west). Further out, we also cover Watford (4 miles south-west), Hemel Hempstead (6 miles north-west), Stevenage (15 miles north-east), St Albans (3 miles north), Welwyn Garden City (8 miles north-east) and Harpenden (8 miles north).
Near you in Colney Street
We work in homes and buildings around The George and Dragon Public House and Samuel Ryder Academy and the streets around them. The nearest railway station is How Wood station, roughly 1 mile north-west. Other landmarks nearby include Kingsley Green (1 mile east) and The Maltings (2.9 miles north). Open spaces near Colney Street include Verulamium Lake and Broad Colney Lakes.
Can I do it myself?
If you are set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it doesn’t work out, we can still put it right.
Sealing over old silicone is the commonest DIY error. New silicone won’t bond to old, so it peels away and traps moisture behind it. All the old material has to come out first.
How to look after the new joints
Aftercare is simple:
- Leave the new mastic unpainted
- Clear gutters so water doesn’t pour onto the windows
- Check the mastic when you check the paintwork
- Have rotten timber repaired before new mastic goes in
Avoid sealing over the mastic with silicone. If you see a crack, ask us to take a look rather than patching it.
Once mastic starts to crumble, rain gets in. That water can reach the timber frame and the wall so early renewal protects both.
Quotes for sand mastic in Colney Street
We don’t publish a price list. What we look at:
- Mould in or behind the old joints
- Access and height
- The type of sealant required
- The old material and how stubborn it is
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all make a difference.
What to tell us for a quote
What to tell us when you ask for a quote:
- Pictures of the joints, sent by email
- How many joints, rooms or windows are involved
- The address or postcode of the job
- Whether it has been sealed before
If you’re in Colney Street and need sand mastic, ring 0345 464 0079 or drop us an email. A short description of the job and where it is helps us quote, and you’ll get a clear quote before we start.
What happens if it’s left?
New mastic over crumbling mastic will not hold. We remove the loose material first so the new mastic stays put. Where a wall is exposed, as many are in small places like Colney Street, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
Some things make a job bigger or smaller: the old material and how easily it comes out, any mould to treat, and whether the work is at height. Your quote takes all of that into account.
Why us?
- Any old sealant cut out fully, not covered over
- An ARBOMaster approved applicator
- A 12-month guarantee on all work
- 20+ years of sealant experience
Take a look at what affects the cost or our reviews.
FAQs for Colney Street
Can you do sand mastic in Colney Street?
Yes, Colney Street is within the area we cover. We work across London and the South East. Just phone 0345 464 0079 or send us an email with a few details of the job.
Do you work for landlords with property near How Wood station?
Yes. We work for landlords and letting agents as well as householders. Just call 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear price.
Do you have insurance?
Yes. We are fully insured.
What do you put in the joint?
Each joint gets the product that suits it. Where it moves, gets wet or faces the weather makes a difference.
Do you take out the old sealant first?
Yes, every time. New silicone does not stick to old silicone, so any old material comes out before anything new goes in.
Where do you work from?
Our base is Crawley. We work across South East England, London and Scotland.
Can old silicone round a sash window be swapped for sand mastic?
Often, yes. With the silicone removed and the joint cleaned we point it with sand mastic.
What do you need from me for a quote?
The location, the problem and the rough size of the job. If you can, email a few photos.