Hertfordshire · England
Sand mastic for sash & case windows in Radlett, Hertfordshire
Sand mastic across Radlett and nearby, with every bit of old sealant taken out first and a 12-month guarantee.
- Cement or filler used on old window joints that has cracked
- Failed mastic on an exposed elevation
- Draughts and rain around sash boxes
Sand mastic in Radlett
Sand mastic suits most period window surrounds. Newer frames generally get a flexible sealant instead, and we will talk through which suits your home. Common call-outs are for mastic worn away on windows facing the weather and gaps round a timber door in stone or brick, across sash and case windows, period & listed homes and timber door frames.
Houses in smaller places like Radlett can stand more in the open than those in a built-up town, so exposed windows and doors face the weather head on. The mastic around frames on those walls tends to age faster.
Whatever the size of the job, you get the same one-year guarantee.
- Where
- Radlett (WD7)
- Wider area
- Hertfordshire
- Cover
- 12 months on all our work
- Quote
- A clear price before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Common problems we fix in Radlett
Timber swells and shrinks with the weather. The movement cracks the mastic over time.
These are the problems we’re asked about most:
- Draughty sash windows at the surround
- Mastic worn away on windows facing the weather
- Mastic dropping out of the joint
- Gaps between timber frames and stone or brick
If you live in an older home near St John, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
What to look for in a quote
- Whether they seal over old material or remove it
- How the colour is chosen
- How the surfaces are prepared before sealing
- Is VAT in the price?
How to look after the new joints
How long the joints last depends on use and care. Here’s what we suggest:
- Get any rot dealt with first
- Leave the new mastic unpainted
- Renew mastic before redecorating the windows
- Check the mastic when you check the paintwork
Check the mastic when you check the paintwork. Small cracks are easier to deal with early.
Fine cracks show the mastic is starting to fail. Renewing it then is simpler than waiting until it falls out.
Sand mastic in Radlett: local notes
With historic houses such as High Elms Manor (about 3.3 miles west) nearby, there’s older building stock in the area around Radlett as well as newer homes. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window. The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind.
For site and facilities teams at buildings such as St John's Church of England Infant and Nursery School, larger buildings have plenty of frames, and the mastic around each one ages. Letting a property close to Radlett station? Then cracked sand mastic around sash windows lets in the draughts tenants complain about.
Radlett is about 3 miles north-west of Borehamwood, in Hertfordshire. If you need sand mastic in Radlett, please phone 0345 464 0079 or email us for a quick quote. We cover Hertfordshire from our Crawley base, Radlett included. Our area takes in 381 places across Hertfordshire. London is on our list too, about 16 miles from Radlett.
Postcode districts we cover here for sand mastic: WD7. Sand mastic is available to properties on Upper Station Road, Station Road and Barn Close and the roads around them. Radlett sits on or near the B462 and A5183, so getting to you is simple. We also cover the places around Radlett: Kemprow (1 mile west), Round Bush (1 mile south-west), Letchmore Heath (1 mile south-west), Aldenham (2 miles south-west) and Patchetts Green (2 miles south-west). Further out, we also cover Watford (4 miles south-west), Hemel Hempstead (8 miles north-west), St Albans (5 miles north), Welwyn Garden City (10 miles north-east), Harpenden (9 miles north) and Hoddesdon (14 miles east).
Near you in Radlett
We work in homes and buildings around The Cat And Fiddle Public House. There’s a railway station in Radlett itself: Radlett station. Well-known places in the area include Radlett and District Museum (within half a mile south-east) and Harlequin Centre (3.7 miles south-west). The countryside around Radlett includes Verulamium Lake and Broad Colney Lakes.
What happens if it’s left?
Filling over old, loose mastic does not last. Raking out and preparing the joint gives it a sound base so the new work lasts. Homes in smaller places like Radlett can face more weather, and failed outside joints let damp into walls. Inside, a split seal lets water into floors and panels just as it would anywhere.
There are no prices on our website, because the cost depends so much on the job itself. For a quick quote, please phone 0345 464 0079 or send us an email.
What you get with us
- Approved under the ARBOMaster scheme
- 180+ five-star Google reviews
- We are fully insured
- Sanitary silicone with an anti-fungal additive in wet areas
Read our cost guide and customer reviews.
How the visit works
Before we leave, we go over the finished joints with you and tell you how long to leave it. The visit itself generally takes a few hours per window, depending on the condition of the joints, depending on the amount of work. In a smaller place like Radlett, parking is seldom the issue; lanes, gates and long drives are worth mentioning. For outside work, side access and the height of the joints help us plan.
- We start by checking each surround and agreeing the joints to renew.
- Old, loose mastic is raked out and the joint cleaned.
- Large voids are packed out first, so the mastic is not too thick.
- 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.
How to prepare
- Let us know if you’ve seen damp or leaks
- Move anything stored near the joints
- Let us know about stairs, lifts or work at height
How to get a quote
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To arrange one, call 0345 464 0079 or send us an email.
Read more
Nearby places to Radlett
What else we do in Radlett
Landlord and commercial work in Radlett
If you manage several properties in or around Radlett, several properties can go on one quote. Send us the addresses and the work at each.
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance that we can handle for you.
Surface by surface
Stone surrounds
The stone is treated with care when the old mastic comes out.
Timber door frames
Period doors in stone or brick openings are often pointed with sand mastic. We renew it the same way as on windows.
Can I do it myself?
Sealing over old silicone is the commonest DIY error. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
If you’re set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it does not work out, we can still put it right.
Common questions in Radlett
I let a flat near Radlett station. Can you help?
Yes. We work for landlords and agents as well as householders, and several properties can go on one quote. You can ring 0345 464 0079 or drop us an email with the details for a clear quote.
Can you do sand mastic in Radlett?
Yes, Radlett is within the area we cover. Our work covers London and the South East. You can ring 0345 464 0079 or send us an email and let us know what needs doing.
How much does sand mastic cost in Radlett?
We do not publish prices, because the cost depends on the job: its size, the old material, access and the product needed. You’ll get a clear quote before any work starts.
Do you remove the old sealant?
Yes. Sealing over the old bead is the commonest cause of early failure, and it’s something we never do.
What exactly is sand mastic?
It’s the traditional filler for the joint round timber windows and doors. It’s made with sand and a linseed-oil-based binder.
Do you work for hotels and businesses?
Yes. We can plan bigger jobs in stages.
How long does sand mastic take to go off?
Not straight away. The skin forms first, and the full set comes later, and we’ll tell you what to expect.
Can I add another job to the visit?
Of course. Doing several areas at once is generally more efficient, so mention them when you ask for a quote.