Hertfordshire · England
Window Mastic in Letchworth Garden City
Mastic around window and door frames, sills and patio doors for homes and businesses in Letchworth Garden City and across Hertfordshire. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Water coming in at the bottom corners of a door
- Cold air getting in at the frame edge
- Black, perished sealant on frames
Letchworth Garden City: your questions answered
Should the sealant in an older Letchworth Garden City home be renewed?
Usually, yes, if it’s cracked, shrunk, mouldy or coming away. The key is cutting all the old sealant out, as new sealant will not bond to it.
Can you help a landlord with a rental near Letchworth Garden City station?
Yes, we work for letting agents and landlords. You can ring 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before any work starts.
Do you work for hotels and businesses?
Yes. We work in offices, washrooms, hotels and other commercial premises. Working times can be discussed when we quote.
How long does it take to reseal the windows on a house?
A few frames take a few hours. We confirm the timing with your quote.
Are you insured?
Yes. Full insurance covers our work, and we can confirm the details when we quote.
What sealant do you use?
Products from Arbo and Everbuild, among others, picked for each joint. We’ll tell you what we are using and why.
Can resealing stop a draught around my window?
If the draught is coming in around the frame, yes. If it’s through the window’s own seals or a hinge, that is a different fix, and we’ll say so.
Can you do the inside joint as well?
Yes. Draughts often come through the inside gap too, so it can be worth sealing both.
How we handle window mastic in Letchworth Garden City
Around Letchworth Garden City we seal all kinds of frames: uPVC, aluminium, timber and composite, plus patio doors, French doors and sills. The sealant is chosen to suit the frame material and the wall. Typical jobs include whistling draughts around closed windows and untidy mastic left by window fitters, on composite doors, patio & French doors and aluminium frames.
Around Letchworth Garden City, many houses have gained conservatories, French doors or replacement windows over time. Each one adds more joints to look after, and those joints age at different rates. Sills, frame heads and glazing joints are where leaks normally start.
Our work is backed for twelve months, in Letchworth Garden City and everywhere else we cover.
- Where
- Letchworth Garden City (SG6, SG7)
- Region
- Hertfordshire
- Guarantee
- One year on every job
- Quotes
- A clear quote up front
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
Aftercare tips
Once the sealant has cured, a few habits help it last:
- Do not use solvent cleaners on the joint
- Clear any debris from frame drain holes
- Keep jet washers away from the mastic
- Walk round the house once a year and look at the joints
Timber frames need their paint kept up, because bare, wet timber moves more and pulls at the joint. Keep paint off the silicone itself.
On timber windows, water behind the joint can lead to rot. Rotten timber needs a joiner, not a sealant, so it pays to reseal before that happens.
What we cannot put right
We’d rather tell you now than do work that won’t last, so here’s what sealant cannot put right:
- Penetrating damp from a failed cavity tray or render
- Condensation trapped between the panes
- Draughts through the window seals rather than the frame
If you’re not sure, just call 0345 464 0079 or email us and we’ll give you a straight answer.
Surfaces we seal
- Composite doors
- uPVC windows
- Timber windows & doors
- Aluminium frames
- Patio & French doors
- Window sills
How the visit works
At the end, we look at the finished work together and tell you how long to leave it. The work normally takes a morning for a couple of windows and a door, depending on the amount of work. In Letchworth Garden City, parking is rarely complicated, though it helps to know about driveways or restrictions, and mention if the work is upstairs, in a flat or high on the outside.
- First, we go round the frames with you and agree the list.
- The old mastic is cut out and scraped back to clean surfaces.
- Deep gaps get closed-cell backing rod to set the depth.
- A flexible exterior sealant is applied in a colour to suit the frame.
- We tool each bead neatly and check every joint is closed.
Preparing for the visit
- Tell us about any previous sealing or DIY attempts
- Where the joints are inside, avoid wetting them before we arrive
- Let us know about stairs, lifts or work at height
Get a quote
The more we know about the job, the more useful the quote. Tell us where the job is, what’s wrong and how much there is, and email pictures if that is easy.
Advice
Work for landlords, hotels and businesses
Housing providers, facilities teams and property managers book us too in Letchworth Garden City and across Hertfordshire. Several sites can be quoted together, and we’re fully insured.
If you manage several properties in or around Letchworth Garden City, jobs at different addresses can be quoted together. Just tell us the addresses and what each one needs, and photos by email help.
Why deal with it now?
Not every sealant suits a window. Decorators’ caulk and bathroom silicone aren’t designed for outside joints that move. An exterior, low-modulus sealant stays flexible in sun and frost. Draughts from a gap round a frame, damp under a sill or water behind a bath panel all start small, and early is when they’re cheapest and quickest to sort.
What you pay reflects the work, not a rough estimate. That is why we ask a few questions first.
Why Letchworth Garden City clients choose us
- A choice of colours where the product allows
- Sealant colour chosen to suit
- 20+ years of sealant experience
- Every job guaranteed for a year
Window mastic in Letchworth Garden City: local notes
Letchworth Garden City is one of England’s garden cities, planned in the early twentieth century. Some older homes may keep timber windows; many others have had replacements. Either way, the joint between frame and wall needs a sound bead. Historic houses like Hinxworth Place (about 4.6 miles north) are a reminder that the area around Letchworth Garden City has older buildings as well as new. Where a home is older, older timber frames in brick or stone need a different approach from a modern uPVC window.
Managing a site like Pixmore Junior School? Then its window and door frames need their mastic kept sound, just like a home’s. Letting a property close to Letchworth Garden City station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Letchworth Garden City is about 5 miles north-west of Stevenage, in Hertfordshire. Jobs in Letchworth Garden City get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Our Hertfordshire coverage runs to 381 places, and Letchworth Garden City is one of them. London is on our list too, around 34 miles away.
Our applicators cover all of SG6 and SG7 for window mastic and the streets around it. You’ll find streets such as Pix Road, Field Lane and Ridge Road. Main roads around Letchworth Garden City include the A505. Nearby, we also carry out window mastic in Letchworth (1 mile east), Willian (1 mile south), Norton (1 mile north-east), Walsworth (2 miles south-west) and Ickleford (2 miles west). We also work in nearby towns such as Stevenage (5 miles south-east), Welwyn Garden City (13 miles south), Harpenden (12 miles south-west), Hitchin (3 miles south-west), Hatfield (15 miles south) and Hertford (14 miles south-east).
Local landmarks in Letchworth Garden City
In Letchworth Garden City, that means homes and buildings near Norton School, Three Magnets pub and Church of St Paul, among other places. There’s a railway station in Letchworth Garden City itself: Letchworth Garden City station. Other landmarks nearby include Wymondley Castle (2.5 miles south) and Fairfield Hospital (1.8 miles north-west). The countryside around Letchworth Garden City includes Purwell Ninesprings.
Different surfaces, different methods
Aluminium frames
Metal frames expand in the sun and are often slim, with little room for error. A tidy bead in anthracite grey, black or a matching colour suits the frame.
Patio & French doors
Not every patio door leak is a mastic problem: worn seals, blocked drainage slots or a poor threshold detail can be the cause. We check before we reseal.
Places near Letchworth Garden City
Other services in Letchworth Garden City
Do you need window mastic in Letchworth Garden City?
Frames are never completely still. A plastic or aluminium frame lengthens in sunshine and shortens as it cools, while the brick or render around it hardly moves. If the sealant can’t stretch, it splits.
Common reasons people contact us are:
- Mastic that has split away from the wall
- Cracked internal joints between frame and plaster
- Mastic that’s falling out in pieces
- Cracked sealant at the sill ends
If you live in an older home near St Michael, the joint between an old wall and a newer frame is generally the first place rain gets in.
What to look for in a quote
- What happens if they find a problem under the old sealant
- Whether all the old sealant comes out first
- What preparation is included
- What the cure time is