Hertfordshire · England
Astrope External Mastic
Problem with your movement joints in Astrope? We remove the old material, prepare the joints and seal them properly.
- Gaps where render, brick and frames meet
- Brick movement joints where the sealant has split
- Sealant that has lost its bond to the brick or render
External mastic in Astrope
Ground-floor and low-level joints are straightforward to reach. Where joints are higher up, tell us about the building when you get in touch and we’ll confirm what access is needed. If you have weathered mastic that no longer stretches and movement joints with cracked, split or missing sealant, we can put it right, whatever the surface.
Somewhere as small as Astrope, homes and farm buildings often face open ground, where walls and rooflines take the weather head on. Gutter joints and wall joints there need a sealant that can flex and stay put.
Each job carries a 12-month guarantee, whatever its size.
- Where
- Astrope (HP23)
- Region
- Hertfordshire
- Cover
- A year, on every job
- Quote
- Quoted before any work starts
- Phone
- 0345 464 0079
- Last updated
- 26 October 2026
FAQs for Astrope
Is Astrope within the area you cover?
Yes. Astrope 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 Cheddington station. Can you help?
Yes. We work for letting agents and landlords as well as householders, and several properties can go on one quote. You can ring 0345 464 0079 or send us an email with the details for a clear quote.
What is backing rod for?
We fit closed-cell backing rod wherever the joint depth needs controlling. It controls the depth and stops the sealant bonding to the back, so the joint can move.
What is a movement joint?
It’s a deliberate gap that lets the wall expand and contract without cracking. It’s sealed with a flexible sealant, not mortar.
How much does external mastic cost in Astrope?
We do not publish prices, because the cost depends on the job: its size, the old material, access and the product needed. You’ll get a clear quote before work begins.
When is the sealant fully cured?
Most sealants are touch-dry well before they’re fully cured. We will give you the cure time for the product we used before we leave.
Do you work for hotels and businesses?
Yes, regularly. We can plan bigger jobs in stages to suit the site.
Do you work at height?
It depends on the height and the site. Ground-floor joints are simple; for higher work, tell us about the building and we’ll confirm what’s needed.
Work for landlords, hotels and businesses
We work for landlords and letting agents as well as householders. Sealant work between tenants is a simple way to keep a property in good order before the next move-in.
If you manage several properties in or around Astrope, several properties can be quoted together. Send us the addresses and the work at each.
Outside joints around Astrope
The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Ascott House (about 4.8 miles north) are a reminder that the area around Astrope has older buildings as well as new. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
For site and facilities teams at buildings such as Long Marston VA Church of England Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s. If you live in an older home near Church of St Mary (Church of England), old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Astrope is about 5 miles east of Aylesbury, in Hertfordshire. For external mastic in and around Astrope, it’s easy to get a quote: please phone 0345 464 0079 or drop us an email. We’re based in Crawley and cover Hertfordshire. Astrope is one of 381 places in Hertfordshire we cover. There’s also a page for Oxford, about 23 miles away.
We cover every part of the HP23 postcode area for external mastic. We also cover the places around Astrope: Puttenham (1 mile west), Long Marston (1 mile north), Buckland (2 miles south), Aston Clinton (2 miles south-west) and Broughton (3 miles west). Further out, we also cover Hemel Hempstead (12 miles south-east), Harpenden (15 miles east), Berkhamsted (7 miles south-east), Tring (3 miles south-east), Chorleywood (15 miles south-east) and Grovehill (11 miles south-east).
Around Astrope
We work in homes and buildings around The Half Moon Public House and the streets around them. The closest station to Astrope is Cheddington station, about 2.9 miles north-east of the centre. Other landmarks nearby include Tindal Centre (4.2 miles west) and Pitstone Green Museum (2.8 miles east). Not far away are Haddington Hill and College Lake nature reserve.
Surface by surface
Joints between dissimilar materials
Each side of the joint may need its own preparation. Both surfaces are cleaned and primed as the product requires.
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. Where one has been mortared, we cut it out and reseal it with sealant.
Also near Astrope
Also in Astrope
DIY sealant or a professional job?
If you’ve already had a go yourself, that’s fine. We remove it and do the joint properly, so tell us about it when you ask for a quote.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Why deal with it now?
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. Where a wall is exposed, as many are in small places like Astrope, wind-driven rain gets into any failed joint, and damp in older walls is slow to dry out.
Doing several joints on one visit usually makes better use of the time than several visits. You will get one clear quote for the whole job.
Why us?
- Quality sealants from Arbo and Everbuild
- We leave the area clean and tidy
- White, clear, grey or coloured to suit, where the product allows
- Rated 4.9 stars on Google
See our cost guide and our reviews.
What we’re called out for in Astrope
Many joints fail because they were sealed too deep or with nothing behind them. Sealant bonded to three sides has nowhere to go and tears as soon as the joint widens.
These are the problems we’re asked about most:
- Movement joints filled with mortar instead of sealant
- Joints where the bead has come unstuck
- Cracked joints where brick meets render or frames
- Water getting into walls through failed joints
Letting a property close to Cheddington station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What your quote should include
- What happens if the job turns out different
- Which colour the sealant will be
- What product goes in the joint
- Is the old sealant removed completely?
How the visit works
There’s no need to move everything out before we come, only the area right around the joints. We protect the rest, and the work takes anything from a few hours to several days, depending on the building in most cases. Somewhere like Astrope needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. Everything for the job comes with us, so a second trip is avoided where possible.
- We start by walking round the building and agreeing the joints and the access.
- 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.
- We fit closed-cell backing rod to control the depth.
- The exterior sealant is applied, tooled and checked along its length.
Before we arrive
- Try not to wet indoor joints just before the visit
- Let us know about earlier repairs to the joints
- For business premises, tell us about site rules or sign-in
Getting a quote
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is, and we’ll talk you through what we’d do. When it suits you, call 0345 464 0079 or drop us an email.
Read more
How we quote for external mastic
Some jobs are bigger than they look, and some smaller. The main factors:
- Mould in or behind the old joints
- The size of the job
- Working hours on commercial sites
- How many areas need sealing
Homes and businesses are quoted the same way: the amount of work, the access and the products needed, plus any working-time requirements on site. Ask us for a quote and we will explain what it covers.
What we need to know
Photos by email are helpful but not essential. Please mention:
- Pictures of the joints, sent by email
- What’s wrong with the joints now
- Whether it’s a home or a business
- How we’d reach the joints
For a quote, phone 0345 464 0079 or email us and tell us where the job is and what the problem looks like. We will give you a clear price before any work starts.