Kent · England
Sand mastic for sash & case windows in Hartley, Kent
We cover Hartley for traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old material cut out, joints cleaned and sealed neatly.
- Mastic that needs renewing before redecorating
- Mastic round period door frames that has failed
- Draughts and rain around sash boxes
DIY sealant or a professional job?
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
Sealing over old silicone is the commonest DIY error. New silicone won’t bond to old, so it lifts and traps water and mould underneath. All the old material has to come out first.
How we handle sand mastic in Hartley
Sand mastic suits most period window surrounds. Newer frames usually get a flexible sealant instead, and we’ll talk through which suits your home. If you have gaps round a timber door in stone or brick and a silicone bead on a sash window that spoils the look, we can put it right, whatever the surface.
Homes around Hartley range from older properties to newer houses, and their windows range just as widely. Each frame material needs the right sealant against the right wall.
Whatever the size of the job, it’s backed by our one-year guarantee.
- Location
- Hartley (DA3)
- Region
- Kent
- Cover
- A year, on every job
- Quote
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
For landlords and businesses
If you manage several properties in or around Hartley, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs, and pictures by email help.
Housing providers, facilities teams and property managers book us too in Hartley and across Kent. We can quote a run of properties together, and we are fully insured.
Nearby places to Hartley
What else we do in Hartley
When something else is needed
We will not take on work that will not last, so here’s what sealant cannot put right:
- Cracked or broken glass
- Timber that has rotted
- Damaged stone surrounds
If you’re not sure, just ring 0345 464 0079 or email us and we will give you a straight answer.
Where we work in Hartley
- Period & listed homes
- Tenement windows
- Timber door frames
- Sash and case windows
- Stone surrounds
- Brick reveals
What sand mastic looks like in Hartley
The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day. With historic houses such as Cobham College (about 3.9 miles east) nearby, there’s older building stock in the area around Hartley as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that’s traditional sand mastic.
For landlords with property near Longfield station, any sash windows need sound mastic to keep draughts and rain out. In the older streets around Church of Saint Mary, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Hartley is about 4 miles south-west of Northfleet, in Kent. Across the DA3 area, we cover sand mastic for homes and businesses. Across Kent, we cover 922 places, Hartley among them. There’s also a page for London, about 19 miles away.
Our applicators cover all of DA3 for sand mastic. Whether your property is on Church Road, Dickens Close and Stack Lane or a nearby road, we can help. Other places close to Hartley include Longfield (1 mile north), New Barn (1 mile north-east), Longfield Hill (1 mile east), New Ash Green (1 mile south) and Nash Street (2 miles east). Further out, we also cover Maidstone (13 miles south-east), Dartford (5 miles north-west), Sevenoaks (9 miles south-west), Gravesend (4 miles north-east), Tonbridge (13 miles south) and Northfleet (4 miles north-east).
Near you in Hartley
We work in homes and buildings around Railway Tavern, Rectory Meadow and Longfield Academy. The closest station to Hartley is Longfield station, about 0.8 miles north-west of the centre. Well-known places in the area include Darent Valley Hospital (4 miles north-west) and Stone Castle (4.1 miles north). For a walk, there’s Sawyers Lake.
When to call us in Hartley
Most of it is simply age. Sand mastic is a maintenance item like any pointing and how long it lasts depends on the weather it faces.
The most common problems we see are:
- Tired mastic found when preparing windows for paint
- Mastic dropping out of the joint
- A silicone bead on a sash window that spoils the look
- Cement or filler used on old window joints that has cracked
If you look after a building such as Hartley Primary Academy, the mastic around its windows and doors needs looking after like any other building’s.
Before booking anyone
- Whether they seal over old material or remove it
- Who does the work, and how experienced they are
- What preparation is included
- What guarantee comes with the work
How to look after the new joints
After the cure time, these simple habits help:
- Do not run silicone over sand mastic
- Check with your local planning authority if your home is listed
- Clear gutters so water doesn’t pour onto the windows
- Renew mastic before redecorating the windows
Leave the new mastic alone while it firms up. It forms a skin fairly soon, but takes longer to harden fully.
Crumbling mastic lets rain into the joint. That water can reach the timber frame and the wall so early renewal protects both.
Common questions in Hartley
Is Hartley within the area you cover?
Yes, smaller places are covered as well as towns. Our work covers London and the South East. Just mention lanes, gates or anything else about the route when you book.
Can you help a landlord with a rental near Longfield station?
Yes, rental work is part of what we do. Just call 0345 464 0079 or drop us an email and tell us about the property, and we’ll send you a clear quote.
Can you work on commercial sites?
Yes. Hotels, offices and other businesses use us.
Is sand mastic better than silicone for my windows?
That depends on your windows. Period windows in stone or brick usually suit sand mastic and newer frames generally get a flexible sealant.
What should I tell you?
Tell us what needs doing and where. We will ask anything else we need to know.
Should I try DIY first?
It depends on the job. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional, while a short indoor joint may be within reach.
Do you offer different sealant colours?
We’ll suggest a colour to suit the surroundings. The product needed can limit the range.
What is sand mastic?
A traditional pointing material made from sand and a linseed-oil-based binder, used between timber frames and stone or brick.
Why act early in Hartley
Replacing sash windows is a big decision for a period home, and in listed buildings it may need consent. Where the frames are in good order, new mastic seals the surround. In a smaller place like Hartley, wherever a wall is exposed, a failed outside joint is a real source of damp. Indoors, a failed seal lets water into floors and panels as it would anywhere.
Commercial jobs are quoted on the same basis as homes: the amount of work, the access and the products needed, plus any working-time requirements on site. Ask us for a quote and we will go through it with you.
Why us?
- Fully insured
- 180+ five-star Google reviews
- 20+ years of sealant experience
- Arbo and Everbuild products
Take a look at what affects the cost or our reviews.
How it works
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. The work normally takes a few hours per window, depending on the condition of the joints. For a job in Hartley, we agree the time, the access and parking before the day. If the work is outside, the weather plays a part, as sealant needs a dry surface.
- We look at the surrounds with you and agree the joints to renew.
- We remove the old, loose mastic.
- 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.
Getting ready for the visit
- Let us know about parking restrictions
- Plan for the work area to be out of bounds to pets and children
- On commercial sites, let us know about site rules
How to get a quote
For a quick quote, get us on the phone, or email us if that is easier. Describe what needs sealing and we’ll explain what’s involved before giving you a price.