Hertfordshire · England
External Mastic in Allen's Green
Our applicators work in Allen's Green on sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly and every job guaranteed for a year.
- Water getting into walls through failed joints
- Joints where the bead has come unstuck
- Plants rooting in failed movement joints
Allen's Green questions
Can you do external mastic in Allen's Green?
Yes, Allen's Green is within the area we cover. We work across London and the South East. Just call 0345 464 0079 or email us with a few details of the job, and we’ll send you a clear quote.
I let a flat near Sawbridgeworth station. Can you help?
Yes, rental work is part of what we do. Just phone 0345 464 0079 or send us an email and tell us about the property, and we’ll give you a clear price.
Which products do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Do the sealants smell?
Possibly a little. Any smell clears as the sealant cures, and ventilation helps.
Do you take out the old sealant first?
Yes. Sealing over old sealant is the main reason resealing fails early, so we never do it.
Do you do commercial work?
Yes. We work in offices, washrooms, hotels and other commercial premises, as well as homes. Working times can be discussed when we quote.
Do I need to be at home?
That depends on where the joints are. Inside work needs someone to give us access, while outside work can sometimes be arranged differently.
Is the work guaranteed?
Yes. Every job comes with our 12-month guarantee.
External mastic in Allen's Green, done properly
Many failed façade joints only get noticed once there’s a stain or a damp patch inside. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a colour to suit. If you’re dealing with weathered mastic that no longer stretches and movement joints with cracked, split or missing sealant, we can help.
Older homes in small places like Allen's Green may be stone, brick or timber-framed, often with later extensions. Where one material meets another is where water generally gets in.
Every job is covered by a 12-month guarantee.
- Where
- Allen's Green (CM21)
- Region
- Hertfordshire
- Guarantee
- A year, on every job
- Price
- A clear price before work begins
- Call
- 0345 464 0079
- Last updated
- 26 October 2026
Surface by surface
Render joints
The face of render can be soft, so a low-modulus sealant is kinder to the joint edges. We prime where the product needs it.
Joints between dissimilar materials
Joints where frames, sills or panels meet the wall are common leak points. We cut out the old sealant and reseal with a product suited to both surfaces.
When to call us in Allen's Green
Joints sealed without backing rod, or far too deep, rarely last. Sealant bonded to three sides has nowhere to go and rips as the joint opens.
Look out for any of the following:
- Moss and dirt in joints with no sealant left
- Movement joints filled with mortar instead of sealant
- Sealant pulling away from one side of the joint
- Gaps where render, brick and frames meet
Homes close to Former Church of St Anne include some older properties, and old and new materials meet at the roofline and walls, which is where sealant earns its keep.
Before booking anyone
- Whether the sealant suits the joint
- What preparation is included
- The length of the guarantee
- How hidden problems are handled
Why it’s worth doing now in Allen's Green
An open joint keeps letting water into the wall with every downpour. Wet masonry is more easily damaged by frost, so the damage spreads beyond the joint. Older cottages and farmhouses around Allen's Green can have timber floors and frames, and water through a failed joint can rot timber if it’s left.
There are no prices on our website, because the cost depends so much on the job itself. Call for a quick quote.
What you get with us
- Every job guaranteed for a year
- Any old sealant cut out fully, not covered over
- Fully insured
- White, clear, grey or coloured to suit, where the product allows
Read what affects the cost and what customers say.
Keeping the joints in good condition
Once the sealant has cured, a few habits help it last:
- Fix overflowing gutters above sealed joints
- Clear growth from the base of walls and joints
- Look over the joints every year, ideally after winter
- Make sure movement joints aren’t pointed over
Do not paint over the new sealant unless we’ve said the product is paintable. Many exterior sealants aren’t designed to be painted.
Water getting behind cladding or render can go unnoticed for a long time. When it finally shows inside, the joint may have been open for years so early resealing is worth it.
Outside joints around Allen's Green
With historic houses such as Much Hadham Palace (about 2.2 miles north-west) nearby, there’s older building stock in the area around Allen's Green as well as newer homes. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth. 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.
If you let a flat or house near Sawbridgeworth station, failed wall and movement joints let damp in, so they’re worth checking between tenancies.
Allen's Green is about 3 miles south-west of Bishop's Stortford, in Hertfordshire. Allen's Green gets the same service as everywhere we cover: the old material taken out, joints prepared properly and a 12-month guarantee. 381 places in Hertfordshire are on our list, from the larger towns to small villages. There’s also a page for Chelmsford, about 17 miles away.
Jobs for external mastic in CM21 is quoted and booked the same way as anywhere else. Other places close to Allen's Green include Thorley (2 miles north-east), High Wych (2 miles south), Spellbrook (2 miles east), Sawbridgeworth (2 miles south-east) and Thorley Street (2 miles north-east). Further out, we also cover Stevenage (13 miles west), Bishop's Stortford (3 miles north-east), Welwyn Garden City (13 miles west), Hoddesdon (8 miles south-west), Cheshunt (11 miles south-west) and Hatfield (15 miles west).
What’s near Allen's Green
The nearest railway station is Sawbridgeworth station, roughly 2.5 miles south-east of the centre. Well-known places in the area include Herts and Essex Hospital (3.4 miles north-east) and Harlow Mill (3.2 miles south). Not far away are Thorley Wash nature reserve.
Towns and villages near Allen's Green
More services for Allen's Green
For landlords and businesses
Housing providers, facilities teams and property managers book us too in Allen's Green and across Hertfordshire. We can quote a run of properties together.
We also work for businesses, from offices to washrooms and kitchens. On commercial sites, working times can be discussed when we quote.
The process
Our applicators work methodically: protect, prepare, seal, tidy. Typically it takes anything from a few hours to several days, depending on the building. Somewhere like Allen's Green needs a little journey planning: let us know about lanes, gates and parking. 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.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control 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
- Where the joints are inside, avoid wetting them before we arrive
- Move anything stored near the joints
How to get a quote
For a quick quote, get us on the phone, or send an email if you’d rather. Describe what needs sealing and we will talk you through the work before giving you a price.
Related advice
What sealant work can’t fix
Before booking, it’s worth knowing the limits:
- Rising or penetrating damp from elsewhere in the wall
- Walls that need new movement joints cut into them
- Cracks in the bricks or render themselves, away from the joints
If you’re not sure, just ring 0345 464 0079 or drop us an email and we’ll give you a straight answer before booking.
Where we work in Allen's Green
- Joints between brick and frames
- Façade panels
- Copings & trims
- Render & cladding joints
- Concrete & block
- Brickwork movement joints