Hertfordshire · England
Window & door mastic in Newnham, Hertfordshire
Problem with your window and door frames in Newnham? We remove the old material, prepare the joints and seal them properly.
- Draughty joints inside around the window
- Draughts coming in around windows and doors
- Untidy mastic left by window fitters
Leave it or put it right?
A cracked joint around a frame lets rain into the wall. Left long enough, it can stain inside walls, spoil plaster and rot wooden frames. Resealing now is a small job by comparison. Older cottages and farmhouses around Newnham can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
Instead of a standard rate, we price the job in front of us: the amount of work, the old material and the access. You will know the price before we begin.
Why us?
- Old sealant always removed completely
- Rated 4.9 stars on Google
- White, clear, grey or another colour, product permitting
- An ARBOMaster approved applicator
Take a look at how sealant jobs are priced and our reviews.
About our window mastic in Newnham
Frames and walls don’t move together. Plastic and aluminium frames move with the temperature, while masonry stays fairly still. That’s why the joint needs a flexible, low-modulus sealant rather than something rigid. If you have cracked or shrunken mastic around the frame and rain getting in at the frame or under the sill, we can put it right, whatever the surface.
In a village or hamlet like Newnham, older cottages and farmhouses often have timber windows set in stone or brick. Not every older frame suits a modern silicone bead, and sometimes a traditional sand mastic is the better choice.
You get a one-year guarantee, the same in Newnham as everywhere else we work.
- Location
- Newnham (SG7)
- Region
- Hertfordshire
- Cover
- 12 months on all our work
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Windows and doors in Newnham
With historic houses such as Hinxworth Place (about 1.4 miles north) nearby, there’s older building stock in the area around Newnham as well as newer homes. In older buildings, older timber frames in brick or stone need a different approach from a modern uPVC window. Rainfall in the South East is lower than in much of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Managing a site like The Knights Templar School? Then its window and door frames need their mastic kept sound, just like a home’s. In the older streets around Church of St Vincent, frames set in older brick or stone need a sealant that suits the wall as well as the frame. For landlords with property near Baldock station, cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Newnham is about 3 miles north-east of Letchworth, in Hertfordshire. Every kind of property in Newnham is covered for window mastic. The work is guaranteed for a year. Across Hertfordshire, we cover 381 places, and Newnham is one of them. Our Chelmsford page covers work nearby (35 miles or so).
Every address in SG7 is covered for window mastic, from the main roads to the quietest streets. Local streets include Ashwell Road and Caldecote Road, and we cover them all. Other places close to Newnham include Caldecote (1 mile north-west), Bygrave (2 miles south-east), Ashwell End (2 miles north), Bury End (2 miles north) and Ashwell (2 miles north-east). Larger places within reach include Stevenage (8 miles south), Welwyn Garden City (15 miles south), Hitchin (6 miles south-west), Letchworth (4 miles south-west), Letchworth Garden City (4 miles south-west) and Benslow (6 miles south-west).
Near you in Newnham
For rail, the closest station is Baldock station, roughly 2 miles south of the centre. Well-known places in the area include Bygrave House (1.5 miles south-east) and Fairfield Hospital (3 miles south-west). For a walk, there’s Arlesey Old Moat and Glebe Meadows.
DIY sealant or a professional job?
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and doesn’t move well, and getting the depth right matters as much as the look.
If you’re set on DIY, put the effort into preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it doesn’t work out, we can still put it right.
What affects the cost of window mastic
There’s no set price list. The quote depends on:
- The size of the job
- Access and height
- Which sealant suits the joint
- Mould in or behind the old joints
What it costs depends on the size of the job, how much old material has to come out and access to the work. You will have a clear quote before any work starts, so you know where you stand.
Asking for a quote
You don’t need to know the technical terms. Just tell us:
- How we’d reach the joints
- If someone has resealed it before
- Where the job is, and your postcode
- What the problem is, such as mould, gaps, leaks or cracking
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is, and we will explain how we’d tackle it. Whenever you’re ready, call 0345 464 0079 or send us an email.
Surface by surface
Composite doors
An exposed front door gets wind-driven rain. Those corners get the most care.
Aluminium frames
Coated aluminium needs a compatible sealant, and acetoxy silicones aren’t used, as they can attack some metals. We use a neutral-cure product.
For landlords and businesses
For anyone letting property in or around Newnham, jobs at different addresses can be quoted together. Send us the addresses and the work at each, and pictures by email help.
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements and we will give you a quote.
Questions from Newnham
Do you cover smaller places like Newnham?
Yes, Newnham is covered. We work across London and the South East, from towns to the smallest places. The journey is planned ahead, so it helps to know about access.
Can you do window mastic in Newnham?
Yes. Our work covers London and the South East, and Newnham is part of that. You can ring 0345 464 0079 or email us and let us know what needs doing, and we’ll give you a clear quote.
Can tenants book the work?
Yes, but check with your landlord or agent first. Many landlords are glad to have it sorted.
Can you get sealant to suit coloured frames?
Normally, yes. Mention the frame colour when you ask for a quote and we’ll use the nearest match.
Do I have to be there?
That depends on where the joints are. For work indoors, someone needs to let us in.
Where do you work from?
Mr Mastic is based in Crawley. We cover Newnham and the rest of Hertfordshire.
Do you work for landlords and businesses?
Yes. As well as homeowners, we work for landlords, agents, businesses and hotels in Newnham.
Do the sealants smell?
Sometimes, a little. Any smell clears as the sealant cures, and ventilation helps.
What happens on the day
At the end, we look at the finished work together and explain the cure time. The work normally takes a morning for a couple of windows and a door, depending on the size of the job. Somewhere as small as Newnham, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We start by checking each window and door with you.
- The old mastic is cut out and the surfaces cleaned back.
- We fit backing rod in deep gaps so the sealant is the right depth.
- New exterior sealant goes on in a matching colour and is tooled smooth.
- We clear up and check every joint is fully closed.
Preparing for the visit
- Let us know about stairs, lifts or work at height
- Let us know if you’ve seen damp or leaks
- Tell us about any previous sealing or DIY attempts
Ask for a quote
There’s no standard price list, as no two jobs are quite the same. Instead, we send you a clear quote for your job. To arrange one, ring 0345 464 0079 or email us.
Read more
Keeping the joints in good condition
Aftercare is simple:
- Clear any debris from frame drain holes
- Paint up to the joint, not over it
- Air rooms to keep condensation down around windows
- Do not aim a pressure washer at the joints
Clean the frames with mild soapy water, and avoid solvent cleaners on the sealant.
On timber windows, water behind the joint can lead to rot. Once wood has rotted, it needs repair before it can be sealed, so it pays to reseal before that happens.