Hertfordshire · England
Welham Green Window Mastic
Professional window mastic in and around Welham Green, with every bit of old sealant taken out first and a 12-month guarantee.
- Old mastic that has gone black or come away
- Rushed sealant from a window installation
- Draughty joints inside around the window
Different surfaces, different methods
Composite doors
Composite doors are normally hung in an uPVC-type frame, and the joint around it is sealed like a window. We match the colour to the frame.
Timber windows & doors
Older timber windows in stone or brick can suit sand mastic rather than modern sealant. We’ll tell you which suits your home.
Window mastic for homes and businesses in Welham Green
There are two joints on most windows. The external joint is the weather seal; inside, the joint between frame and plaster stops draughts and tidies the reveal. We seal one or both, depending on what’s needed. Typical jobs include draughty joints inside around the window and cold air getting in at the frame edge, on patio & French doors, composite doors and timber windows & doors.
In smaller places like Welham Green, homes range from older cottages to newer houses, with windows to match: timber, uPVC and aluminium. Each frame material needs the right sealant against the right wall.
All our work is covered by our one-year guarantee, wherever you are in Hertfordshire.
- Location
- Welham Green (AL9, AL10)
- Region
- Hertfordshire
- Guarantee
- One year on every job
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Looking after it afterwards
Looking after new joints is easy:
- Avoid harsh chemicals near the mastic
- Keep paint and stain on wooden frames in good order
- Check the mastic once a year
- Wash the frames with mild soapy water
Check the drainage slots in the frames aren’t blocked, so water can run away instead of sitting against the joint.
Water trapped behind a failed joint can start rot in timber frames and sills. Once wood has rotted, it needs repair before it can be sealed, so early resealing is worth it.
For landlords and businesses
Mouldy or split sealant often shows up at the end of a tenancy, and it’s easy to sort out between tenants. Several properties can go on one quote.
Whether it’s one flat or a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a one-year guarantee.
Honest limits
It helps to know what we can’t do too:
- Damp problems in the wall away from the window
- A door that needs adjusting, rehanging or new seals
- Misting between the panes of a double-glazed unit (that needs a new unit)
If you’re not sure, just ring 0345 464 0079 or email us and we will give you a straight answer before booking.
Where we work in Welham Green
- Composite doors
- Patio & French doors
- Window sills
- Aluminium frames
- uPVC windows
- Timber windows & doors
What window mastic looks like in Welham Green
With historic houses such as Hatfield House (about 1.8 miles north) nearby, there’s older building stock in the area around Welham Green as well as newer homes. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window. 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.
Homes close to Church of St Mary the Virgin include some older properties, and the joint between an old wall and a newer frame is usually the first place rain gets in. Letting a property close to Welham Green station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Welham Green is about 2 miles south of Hatfield, in Hertfordshire. Jobs in Welham Green get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. We cover 381 towns and villages across Hertfordshire. We also work in London, around 17 miles away.
All of AL9 and AL10 is within our area for window mastic, from the main roads to the quietest streets. Window mastic is available to properties on Station Road, Old Farmhouse Mews and Vincenzo Close. Neighbouring places we cover for window mastic include North Mymms (1 mile south), Colney Heath (1 mile west), Hatfield (2 miles north), Sleapshyde (2 miles west) and Smallford (3 miles north-west). Further out, we also cover Watford (9 miles south-west), Hemel Hempstead (10 miles west), Stevenage (12 miles north), St Albans (5 miles west), Welwyn Garden City (4 miles north) and Harpenden (8 miles north-west).
Near you in Welham Green
Locally, jobs take us to homes and businesses close to Brookmans Park, The Hope and Anchor Public House and Chancellor's School. There’s a railway station in Welham Green itself: Welham Green station. Nearby you’ll also find Queen Elizabeth II Hospital (3.5 miles north) and The Bunker at Hatfield Police Station (2.3 miles north). Not far away are Gobions Wood.
Also near Welham Green
More services for Welham Green
The process
The work is kept neat and contained to the area we’re working on, so you can get on with your day. The job generally takes anything from an hour or two to a full day, depending on how many frames there are, and we tell you how long to leave it before we go. A visit to Welham Green is planned like any other: the time, the access and where to park are agreed in advance. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- We check how each frame can be reached safely.
- All the failed sealant is cut away.
- Frame and wall are cleaned and must be dry before sealing.
- Backing rod fills deep voids and the sealant goes in on top.
- We tool the joint so water runs off, then clear up.
Getting ready for the visit
- On commercial sites, let us know about site rules
- Tell us about any previous sealing or DIY attempts
- Let us know about stairs, lifts or work at height
How to get a quote
Need a quote? Please phone 0345 464 0079 or send us an email and tell us about the job. We’ll explain what we’d do and give you a clear price before work begins.
Related advice
What affects the quote in Welham Green
Some jobs are bigger than they look, and some smaller. What affects the quote:
- The number of rooms or windows
- The product the joint needs
- Access and height
- Mould in or behind the old joints
Leaving a failed joint generally makes the job bigger, not smaller. If you’re unsure, phone 0345 464 0079 or email us for an honest opinion and a quote.
What to tell us for a quote
When you call or email, these details help:
- The problem you’ve noticed
- Where the property is
- A few photos by email, if you can
- If someone has resealed it before
We do not publish a price list, as no two jobs are quite the same. Instead, we give you a clear price for your job. To arrange one, ring 0345 464 0079 or send us an email.
Welham Green questions
Do older homes in Welham Green need their sealant replacing?
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, and many homes in Welham Green may already be on their second or third set.
Is Welham Green within the area you cover?
Yes, we do. We work across London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Where do you work from?
We are a Crawley-based firm, with over 20 years’ experience. Our area covers South East England, London and Scotland.
Is it messy?
No. We protect the surfaces around the joints, and we tidy up before we go.
When is the sealant fully cured?
It depends on the product and the temperature. Before we leave, we will tell you the cure time.
Can you do upstairs windows?
Usually, yes. We plan safe access before the job.
Is it worth trying it myself?
It depends on the job. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional.
What should I tell you?
Where the job is, what the problem is and roughly how big it is. Photos by email help too.
What we are called out for in Welham Green
On timber frames, paint and putty build up around the joint. Mastic painted over many times cracks with the paint, and timber moves with moisture as well as temperature.
If you can see any of these, it’s time to have the joints looked at:
- A bead that does not match the frame
- Leaking joints at the ends of sills
- Rushed sealant from a window installation
- Gaps between the frame and the inside reveal
If you look after a building such as St Mary's Church of England Primary School, the mastic around its windows and doors needs looking after like any other building’s.
Comparing quotes
- What happens if the job turns out different
- Are they insured?
- How long the guarantee is
- Whether all the old sealant comes out first