Hertfordshire · England
Shephall Window Mastic
Mastic around window and door frames, sills and patio doors in Shephall, with a 12-month guarantee on every job. Call for a quick quote.
- Old mastic that has gone black or come away
- Whistling draughts around closed windows
- Gaps between the frame and the inside reveal
How we handle window mastic in Shephall
Every window and door frame has a gap around it, and mastic is what closes it. Once that seal fails, wind and rain find the gap. Our applicators cut it out and replace it with a flexible, weatherproof sealant. Common call-outs are for hard, cracked sealant around windows and cracked sealant at the sill ends, across timber windows & doors, patio & French doors and uPVC windows.
Houses in smaller places like Shephall 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.
The work is guaranteed for twelve months. If something is not right with it in that time, tell us and we will put it right.
- Where
- Shephall (SG2, SG1)
- Wider area
- Hertfordshire
- Cover
- 12 months on all our work
- Price
- Quoted before any work starts
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Should I try it myself first?
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
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.
What sealant work cannot fix
Before booking, it’s worth knowing the limits too:
- Broken hinges, locks or handles
- A failed sealed unit that has misted up
- Worn gaskets, brush seals or a door that has dropped
If in doubt, ring 0345 464 0079 or email us and we will say what we think.
Joints and surfaces we work on
- Composite doors
- Patio & French doors
- Aluminium frames
- uPVC windows
- Window sills
- Timber windows & doors
Also near Shephall
What else we do in Shephall
What we do, step by step
There’s no need to move everything out, just the space around the work. We protect the rest, and the work takes a morning for a couple of windows and a door in most cases. For a job in Shephall, 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.
- First, we confirm safe access to each frame.
- All the failed sealant is cut away, along with any loose debris.
- Frame and wall are cleaned and must be dry before sealing, and primed where the sealant calls for it.
- Backing rod fills deep voids and the sealant goes in on top.
- The joint is shaped to shed water and the area tidied.
How to prepare
- Mention any sign-in or site rules at work premises
- Keep children and pets away from the work area
- Tell us about any previous sealing or DIY attempts
How to get a quote
For a quick quote, get us on the phone, or email us if that is easier. Tell us about the joints that need doing and we’ll talk you through the work before giving you a price.
Read more
Looking after it afterwards
So the new joints stay in good condition:
- Paint up to the joint, not over it
- Keep paint and stain on wooden frames in good order
- Clear any debris from frame drain holes
- Avoid harsh chemicals near the mastic
Clean the frames with mild soapy water, and keep solvents and harsh chemicals off the joint.
On timber windows, water behind the joint can lead to rot. Rotten timber needs a joiner, not a sealant, so early resealing is worth it.
What affects the cost of window mastic
We quote each job individually. These are the things that affect it:
- Mould in or behind the old joints
- Whether the work is at height
- How much there is to do
- How many rooms, windows or areas are involved
Combining jobs into one visit usually makes better use of the time than several visits. We will give you a clear quote for the lot.
What we need to know
When you contact us, these details help:
- The rough size of the job
- Whether it’s a home or a business
- Where the property is
- What the problem is, such as mould, gaps, leaks or cracking
Every job is quoted individually, so start by telling us what you need. Simply call 0345 464 0079 or drop us an email and describe the job.
How the job changes by surface
Aluminium frames
Aluminium needs a sealant that bonds to coated metal and we avoid acetoxy silicones, which can react with some metals. We use a neutral-cure product.
Composite doors
A composite door normally sits in a plastic outer frame, so its perimeter joint is sealed much like a window. The bead is colour-matched to the frame.
Your questions about window mastic in Shephall
Do you work for landlords with property near Stevenage station?
Yes. We work for landlords and agents as well as householders. You can phone 0345 464 0079 or send us an email with the details for a clear quote.
Is it worth replacing old sealant in an older home in Shephall?
In most cases, yes, if it hasn’t been done for a while. Sealant is a maintenance item: how long it lasts depends on use, cleaning and exposure.
Can you reach windows above the ground floor?
Yes, in most cases. Access is planned before work begins, so mention the height and anything in the way.
What sealant do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Can I paint over the new sealant?
Not if it’s silicone. We choose the product with your decorating in mind, so mention it when you book.
Are you insured?
Yes. Full insurance covers our work.
Does the work come with a guarantee?
Yes, for 12 months. A yearly look at the joints helps them last.
What should I tell you?
Only a few details: the address or postcode, what’s wrong and any access issues. Then call 0345 464 0079 or email us.
What we are called out for in Shephall
Timber windows bring their own problems. Old mastic gets painted over and cracks under the paint, and timber moves with moisture as well as temperature.
These are the problems we’re asked about most:
- Cracked internal joints between frame and plaster
- Mastic that has split away from the wall
- Whistling draughts around closed windows
- White mastic on grey or black frames
Homes close to Church of Saint Mary include some older properties, and the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Before booking anyone
- How hidden problems are handled
- Whether they seal over old material or remove it
- Whether VAT is included
- How the surfaces are prepared before sealing
Windows and doors in Shephall
Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Stevenage, which Shephall is part of, is one of England’s post-war new towns. With many homes from the post-war decades, replacement windows and doors are common. That mastic ages as well, and sills and frame heads are where leaks start.
For landlords with property near Stevenage station, cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets. Managing a site like Peartree Spring Primary School? Then larger buildings have plenty of frames, and the mastic around each one ages.
Shephall is about 1 mile south of Stevenage, in Hertfordshire. Jobs in Shephall get the same care as everywhere else we work: old sealant removed completely, careful preparation and a 12-month guarantee. Our Hertfordshire coverage runs to 381 places, Shephall among them. For nearby work, see our London page, about 27 miles away.
Postcode districts we cover here for window mastic: SG2 and SG1. We cover properties on Unwin Road, Oxleys Road and Burwell Road and the roads around them. Other places close to Shephall include Aston (1 mile east), Bragbury End (1 mile south-east), Knebworth (2 miles south), Hook's Cross (2 miles south-east) and Woolmer Green (3 miles south). Further out, we also cover Hemel Hempstead (15 miles south-west), St Albans (12 miles south-west), Bishop's Stortford (14 miles east), Welwyn Garden City (6 miles south), Harpenden (9 miles south-west) and Hitchin (6 miles north-west).
Around Shephall
In Shephall, that means homes and buildings near Coopers Inn, The Heathcote School and Barnwell School and the streets around them. The nearest railway station is Stevenage station, roughly 1.4 miles north-west of the centre. A little further out are Benington Castle (2.6 miles east) and Lister Hospital (2.7 miles north-west). The countryside around Shephall includes Ridlins Mire.