Hertfordshire · England
External Mastic in Great Offley
We cover Great Offley for sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly and a one-year guarantee.
- Panel joints letting water in
- Joints pointed up with cement by mistake
- Sealant pulling away from one side of the joint
Why act early in Great Offley
The longer a joint stays open, the more water the wall takes in. In cold weather, frost can damage wet brick and render around the joint, so the problem grows beyond the joint itself. Older cottages and farmhouses around Great Offley can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
Homes and businesses are quoted the same way: how much there is to do, how we reach it and what it needs. Ask us for a quote and we will explain what it covers.
Why Great Offley customers choose us
- 4.9 on Google from 180+ five-star reviews
- 20+ years of sealant experience
- A sealant colour to suit the surroundings
- White, clear, grey or another colour, product permitting
Take a look at what affects the cost and our reviews.
About our external mastic in Great Offley
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. We pick a colour that sits well with the wall so the joint doesn’t stand out. Typical jobs include movement joints with cracked, split or missing sealant and failed sealant between panels on a façade, across render & cladding joints, copings & trims and façade panels.
External sealant needs dry, clean surfaces, so work around Great Offley is planned for dry weather. Tell us about access to all sides of the building, including outbuildings and garages.
We stand behind the work with a one-year guarantee.
- Location
- Great Offley (SG5)
- Wider area
- Hertfordshire
- Guarantee
- One year on every job
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
DIY sealant or a professional job?
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly, so just mention it when you contact us.
Some sealant jobs are within reach of a careful DIYer, like a short, easy-to-reach joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
How the job changes by surface
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. The movement joint takes that up, so the sealant in it must stay soft and stretchy.
Concrete and blockwork
The face of concrete or block is often dusty, so cleaning and priming matter. We prime where the sealant needs it before the bead.
How to look after the new joints
After the cure time, these simple habits help:
- Clear growth from the base of walls and joints
- Check the sealant is paintable before painting near it
- Never let anyone fill a movement joint with mortar
- Keep high-pressure jets off the joints
Do not paint over the new sealant unless we’ve said the product is paintable. Paint can crack on a flexible joint and spoil the finish.
Act while the splits are small. Then it’s a straightforward cut-out and reseal with no damage behind it to deal with.
External mastic in Great Offley: local notes
London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
Homes close to Church of St Mary Magdalene include some older properties, and older walls, gutters and the joints where extensions meet them need a flexible sealant. Schools such as Offley Endowed Primary School are buildings too, and movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Great Offley is about 3 miles south-west of Hitchin, in Hertfordshire. We provide external mastic to homeowners, landlords and businesses in Great Offley and the surrounding area, as part of our work across Hertfordshire. 381 places in Hertfordshire are on our list. There’s also a page for London, roughly 32 miles from Great Offley.
Jobs for external mastic in SG5 is quoted and booked the same way as anywhere else. Whether your property is on High Street, Garden Fields and John Hall Court or a nearby road, our applicators can take on the job. Close by, we work in The Flints (1 mile west), Temple End (2 miles east), Ley Green (2 miles south-east) and Pegsdon (2 miles north-west). Further out, we also cover Hemel Hempstead (13 miles south-west), Stevenage (7 miles east), St Albans (12 miles south), Welwyn Garden City (11 miles south-east), Harpenden (8 miles south) and Hitchin (3 miles north-east).
What’s near Great Offley
Typical jobs here are in homes near The Bull Public House. For rail, the closest station is Hitchin station, roughly 3.7 miles north-east of the centre. A little further out are Ravensburgh Castle (3.1 miles north-west) and Keech Hospice Care (4.2 miles west). For a walk, there’s Pegsdon Hills and Markham's Hill.
Common problems we fix in Great Offley
A lot of failed joints come down to preparation: joint faces that were dusty or damp, unprimed where they needed it, or still carrying old sealant. The new sealant then lets go long before it should.
Signs it’s time to call us include:
- Rain getting behind render or cladding at a joint
- Sealant pulling away from one side of the joint
- Moss and dirt in joints with no sealant left
- Movement joints filled with mortar instead of sealant
For landlords with property near Hitchin station, outside joints that have cracked can let damp into a rental, so check them between lets.
What your quote should include
- What the cure time is
- Are they insured?
- Which sealant they’ll use, and why
- Whether you can choose the colour
The process
All our tools and materials come with us in the van, so there’s nothing for you to buy. After a quick look at the joints together, we protect the area and start. It normally takes a few hours for a handful of joints, longer for a whole elevation. In a small place like Great Offley, access is usually the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
Getting ready for the visit
- Mention any parking rules near the property
- Mention if the joints have been sealed before
- Tell us about access, such as stairs, a lift or high-level joints
Getting a quote
We quote each job on its own, so start by telling us what you need. Simply ring 0345 464 0079 or drop us an email and describe the job and send photos if you have them.
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For landlords and businesses
We also work for property managers and facilities teams. We can quote a run of properties together.
Whether it’s one flat or a portfolio, you get the same standard of work: the old material taken out, careful preparation and a 12-month guarantee.
Your questions about external mastic in Great Offley
I let a flat near Hitchin station. Can you help?
Yes, rental work is part of what we do. You can call 0345 464 0079 or send us an email with the address and a few details, and we will give you a fixed price before we start.
Is Great Offley within the area you cover?
Yes, smaller places are covered as well as towns. We work across London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
What sealant do you use?
We choose the sealant for the joint, not the other way round. Where it moves, gets wet or faces the weather makes a difference, and we will tell you what we are using.
What is backing rod for?
Backing rod goes into deeper joints as a matter of course. It controls the depth and stops the sealant bonding to the back.
How do I get a quote for external mastic in Great Offley?
There’s no set price, as it depends on the job: how much there is, what’s there now, how we reach it and what it needs. We agree the price before any work begins.
Will there be a smell?
It depends on the product. Some smell for a while, some hardly at all, and any smell fades as they cure.
Can I do it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
Do you seal joints where cladding meets other materials?
Yes. Joints between dissimilar materials are a big part of external work. The sealant is chosen to bond to both sides, primed where needed.