Hertfordshire · England
St Nicholas External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for St Nicholas, backed by a one-year guarantee. Call for a quick quote.
- Old sealant gone brittle and cracked
- Sealant pulling away from one side of the joint
- Joints pointed up with cement by mistake
External mastic in St Nicholas, done properly
Joints in render and cladding are easy to overlook until a damp patch appears. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant. Typical jobs include old sealant gone brittle and cracked and movement joints filled with mortar instead of sealant, on façade panels, brickwork movement joints and concrete & block.
In and around St Nicholas, older properties sit alongside newer ones, each with its own outside joints. Older homes need their gutter and trim joints kept tight, newer ones their movement joints.
We stand behind the work with a 12-month guarantee.
- Where
- St Nicholas (SG1, SG2)
- Wider area
- Hertfordshire
- Guarantee
- A year, on every job
- Price
- A clear price before work begins
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
External mastic in St Nicholas: local notes
St Nicholas is part of Stevenage, one of the post-war new towns. Many homes date from the post-war decades and were built in phases, so whole streets can have gutters, trims and wall joints reaching the end of their life together. Compared with the north and west, the South East gets less rain, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you live in an older home near All Saints Church, an extension built onto an older house moves differently, and the joint between them takes the strain. Rented homes near Stevenage station change hands often, and split movement joints are easy to miss on a rental until damp shows inside.
St Nicholas is about 1 mile north of Stevenage, in Hertfordshire. Anywhere in SG1, our applicators can take on external mastic. We cover 381 towns and villages across Hertfordshire, from the larger towns to small villages. There’s also a page for London, roughly 30 miles from St Nicholas.
Jobs for external mastic in SG1 and SG2 works the same way as everywhere else we cover. External mastic is available to properties on York Road, Ripon Road and Drury Lane and the roads around them. Nearby, we also carry out external mastic in 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).
Local landmarks in St Nicholas
Typical jobs here are in homes near Church of Saint Nicholas and The Nobel School, among other places. St Nicholas’s nearest station is Stevenage station, roughly 2 miles south-west of the centre. A little further out are Wymondley Castle (2.7 miles north-west) and Stevenage Museum (1.8 miles south-west). The countryside around St Nicholas includes Pryor's Wood.
Different surfaces, different methods
Cladding and façade panels
If the façade has a specified sealant, that is what we use or an approved alternative. Send us any details you have about the façade.
Brickwork movement joints
Vertical joints in long brick walls let the brickwork expand without cracking. We reseal them with a low-modulus sealant over backing rod.
Also in St Nicholas
For landlords and businesses
We also work for businesses, from offices to washrooms and kitchens. For commercial premises, we can talk through working times when we quote.
We work for landlords and letting agents as well as homeowners. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
How it works
There’s no need to move everything out before we come, only the area right around the joints. Everything nearby is protected, and the work takes anything from a few hours to several days, depending on the building in most cases. For a job in St Nicholas, 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.
- We start by walking round the building and agreeing the joints and the access.
- We cut out the old mastic and rake out anything in the joint.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Before we arrive
- Keep children and pets away from the work area
- Tell us if parking is tricky
- Mention any leaks or damp you’ve noticed
Get a quote
Getting a quote is simple: let us know the job and the location and its rough size. Photos by email help us understand the job, and we’ll take it from there.
Related advice
Signs you need external mastic in St Nicholas
Weeds, moss and debris in a joint are a sign the sealant has gone. Dirt and roots then trap moisture in the joint and speed up the damage.
Common reasons people contact us are:
- Rigid filler in a joint that should flex
- Weeds or debris growing in open joints
- Leaking joints around cladding and façade panels
- Movement joints with cracked, split or missing sealant
For site and facilities teams at buildings such as The Leys Primary and Nursery School, larger buildings have long runs of movement joint that eventually need resealing.
Comparing quotes
- What the cure time is
- What insurance they hold
- Who turns up on the day
- Whether you can choose the colour
Looking after it afterwards
How long the joints last depends on use and care. We suggest:
- Keep movement joints as flexible joints, not mortar
- Ask before painting over external sealant
- Show decorators and builders where the movement joints are
- Avoid pressure-washing directly into sealant joints
Keep pressure washers away from the sealant. A strong jet can damage the edges of the bead over time.
Act while the splits are small. At that stage it’s a simple cut out and reseal.
Why it’s worth doing now in St Nicholas
Mortar or ordinary filler might look like a quick way to close an open joint, but it locks the joint solid. The wall then cracks somewhere else. A flexible sealant over backing rod is what the joint needs. In an older home around St Nicholas, damp from a failed joint can get into timber and plaster, and that’s a much bigger job than renewing the sealant.
What it costs depends on how much there is to do, how much old material has to come out and how easy the joints are to reach. We give a clear quote before we start, so you know where you stand.
Why us?
- Tidy, careful work
- 12-month guarantee on every job
- White, clear, grey or another colour, product permitting
- Anti-fungal silicone where joints get wet
Take a look at how sealant jobs are priced or what customers say.
St Nicholas questions
Do you cover smaller places like St Nicholas?
Yes. St Nicholas is within the area we cover, which takes in towns, villages and rural addresses. Our work covers London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
I let a flat near Stevenage station. Can you help?
Yes, we work for landlords and letting agents. Just phone 0345 464 0079 or email us and tell us about the property, and we will send you a clear quote.
How often do external joints need resealing?
It varies from wall to wall: joints on exposed walls or with a lot of movement age sooner. Check them each year and reseal when they split or harden. Our work comes with a 12-month guarantee.
Does someone need to be in?
For indoor joints, yes, someone needs to let us in. Once we have agreed the job, you don’t need to watch us work.
What do you put in the joint?
Each joint gets the product that suits it. Movement, water and weather all affect the choice, and we’ll explain our choice.
What does external mastic cost?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. You will get a clear quote before any work starts.
Do you have insurance?
Yes. We are fully insured.
Can you reach joints on upper floors?
It depends on the height and the site. Ground-floor joints are simple; for higher work, tell us about the building and we will confirm what’s needed.
When something else is needed
In fairness, there are a few things sealant won’t fix:
- Render that’s blown, hollow or coming away
- Cracked brickwork or render that needs a builder or plasterer
- Cutting new joints into brickwork, which is building work rather than sealant work
If you are not sure, just ring 0345 464 0079 or email us and we will give you a straight answer.
Where we work in St Nicholas
- Concrete & block
- Brickwork movement joints
- Joints between brick and frames
- Render & cladding joints
- Copings & trims
- Façade panels