Hertfordshire · England
Window & door mastic in St Nicholas, Hertfordshire
Problem with your window and door frames in St Nicholas? We remove the old material, prepare the joints and seal them properly.
- Gaps between the frame and the inside reveal
- Untidy mastic left by window fitters
- Old mastic that has gone black or come away
Looking after it afterwards
Simple care keeps the joints in good condition. Our advice:
- Keep jet washers away from the mastic
- Wipe condensation off the frames
- Wash the frames with mild soapy water
- Check the mastic once a year
Keep sill grooves and drainage slots clear, so water can run away instead of sitting against the joint.
A small gap around a frame only grows. As old mastic keeps shrinking, the gap widens, and heat escapes around the frame. A new joint closes it up.
Window mastic for homes and businesses in St Nicholas
Mr Mastic’s applicators have more than 20 years’ experience with window and door sealants. We’re fully insured ARBOMaster approved applicators, and every job is covered by a 12-month guarantee. If you are dealing with sealant in the wrong colour for the frame and mastic that has split away from the wall, we can put it right.
Many houses in smaller places like St Nicholas have conservatories, garden rooms or patio doors. Their glazing joints and frame seals are as much a part of the job as the windows.
Whatever the size of the job, it’s backed by our 12-month guarantee.
- Location
- St Nicholas (SG1, SG2)
- Wider area
- Hertfordshire
- Guarantee
- 12 months on all our work
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
For landlords and businesses
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
Failed sealant is one of the commonest items on a check-out report. Several properties can go on one quote.
St Nicholas questions
Do older homes in St Nicholas need their sealant replacing?
Usually, yes, if it’s cracked, shrunk, mouldy or coming away. New sealant won’t stick to old, so the old bead has to come out completely first.
Can you help a landlord with a rental near Stevenage station?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or drop us an email and tell us about the property, and we will give you a clear price.
When is the sealant fully cured?
Many sealants skin over quickly but take longer to cure fully. We will tell you how long to leave the joint before we leave.
Will resealing my frames help with draughts?
Yes, if the air is getting in around the frame. If it’s through the window’s own seals or a hinge, that’s a different fix, and we’ll say so.
Do you work for hotels and businesses?
Yes, regularly. We can plan bigger jobs in stages.
Can you match the sealant to my frames?
Yes, in most cases. Mention the frame colour when you ask for a quote and we will match it as closely as we can.
Do I have to be there?
If the work is inside, we need someone to let us in. After that, you can carry on with your day.
Where do you work from?
We’re a Crawley-based firm. We work across South East England, London and Scotland.
Different surfaces, different methods
Window sills
The end joints of a sill tend to fail before the rest. A tight seal at each end keeps rain out of the wall.
Composite doors
If the door itself is draughty, the issue may be the door seals or hinges rather than the frame mastic. We will tell you if that’s what we find.
Why it’s worth doing now in St Nicholas
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. A reseal is a much smaller job. In a smaller place like St Nicholas, wherever a wall is exposed, a failed outside joint is a real source of damp. Inside, a split seal lets water into floors and panels just as it would anywhere.
Doing several joints on one visit normally makes better use of the time than several visits. You will get one clear quote for the whole job.
Why St Nicholas clients choose us
- Homes, businesses and hotels
- A 12-month guarantee on all work
- More than 20 years in sealant work
- Colour agreed with you before any work starts
Take a look at our cost guide and our reviews.
When to call us in St Nicholas
On timber frames, paint and putty build up around the joint. Old mastic gets painted over and cracks under the paint, and the wood moves with damp as well as heat.
Most people get in touch after spotting one of these:
- Black, perished sealant on frames
- Damp patches on the reveal after heavy rain
- Cracked internal joints between frame and plaster
- Cracked sealant at the sill ends
For site and facilities teams at buildings such as The Leys Primary and Nursery School, its window and door frames need their mastic kept sound, just like a home’s.
Comparing quotes
- How the surfaces are prepared before sealing
- How the colour is chosen
- How much experience the applicator has
- Is the old sealant removed completely?
Also in St Nicholas
What window mastic looks like in St Nicholas
With historic houses such as Aston Bury (about 3.3 miles south) nearby, there’s older building stock in the area around St Nicholas as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. Stevenage, which St Nicholas is part of, is one of England’s post-war new towns. Many homes date from the post-war decades, and many will have had their original windows replaced. That mastic ages as well, and sills and frame heads are where leaks start.
If you let a flat or house near Stevenage station, cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets. If you live in an older home near All Saints Church, the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
St Nicholas is about 1 mile north of Stevenage, in Hertfordshire. Homes, rented property, offices and hotels in St Nicholas can book us for window mastic, old or new, large or small. The work is guaranteed for a year. Our area takes in 381 places across Hertfordshire. London is on our list too, around 30 miles away.
We cover every part of the SG1 and SG2 postcode area for window mastic and the streets around it. Window mastic is available to properties on York Road, Ripon Road and Drury Lane. Neighbouring places we cover for window mastic include Rooks Nest (1 mile west), Pin Green (1 mile south-west), Chells (1 mile south-east), Stevenage (1 mile south) and Bedwell (1 mile south-west). Within a short drive, we also cover St Albans (14 miles south-west), Bishop's Stortford (15 miles east), Welwyn Garden City (9 miles south), Harpenden (10 miles south-west), Hitchin (4 miles north-west) and Hoddesdon (14 miles south-east).
What’s near St Nicholas
Around St Nicholas, our work takes us to homes and buildings near Church of Saint Nicholas and The Nobel School. The closest station to St Nicholas is Stevenage station, roughly 2 miles south-west of the centre. Well-known places in the area include Wymondley Castle (2.7 miles north-west) and Stevenage Museum (1.8 miles south-west). For a walk, there’s Pryor's Wood.
Quotes for window mastic in St Nicholas
Every job gets its own quote. These are the things that affect it:
- When we can work, for business premises
- Whether the work is at height
- Whether old sealant or filler has to be cut out
- How many rooms, windows or areas are involved
There are no prices on our website, because each job is priced on what it involves. Call for a quick quote.
What we need to know
To make quoting easier, please include:
- What the problem is, such as mould, gaps, leaks or cracking
- Photos by email, if that is easy
- Whether it’s a home or a business
- How many joints, rooms or windows are involved
There’s no standard price list. Instead, we give you a clear quote for your job. To get started, ring 0345 464 0079 or email us.
What we do, step by step
Good joint work is mostly preparation, so that’s where we spend the time. Joints are cleaned back and dried before anything new goes in. All told, the work takes a morning for a couple of windows and a door. For a job in St Nicholas, we agree the time, the access and parking before the day. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- Each frame is looked over and we agree which ones need resealing.
- 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.
- Every joint is tooled smooth and checked before we leave.
Before we arrive
- Where the joints are inside, avoid wetting them before we arrive
- Let us know about earlier repairs to the joints
- On commercial sites, let us know about site rules
Ask for a quote
Need a quote? Please phone 0345 464 0079 or email us and tell us about the job. We will explain what we’d do and send you a clear quote before we start.