Hertfordshire · England
External Mastic in Letty Green
Movement joints in Letty Green need attention? We cut out the old, prepare the joints and apply the right sealant, and the work is guaranteed for a year.
- Joints where the bead has come unstuck
- Water getting into walls through failed joints
- Joints pointed up with cement by mistake
Letty Green questions
Is Letty Green in your area for external mastic?
Yes, Letty Green is within the area we cover. Our work covers London and the South East. Just ring 0345 464 0079 or send us an email with a few details of the job, and we’ll send you a clear quote.
Will you come out to Letty Green?
Yes, Letty Green is covered. Our work covers London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Do the sealants smell?
Sometimes, a little. Any smell clears as the sealant cures.
Do you do commercial work?
Yes. Larger jobs can be planned room by room or area by area to suit the site.
Where do you work from?
We work from Crawley. We cover Letty Green and the rest of Hertfordshire, along with the rest of our area.
How long before the joint can be used?
Cure times vary by product. Before we leave, we will tell you the cure time.
Can a movement joint be filled with mortar?
No. Cement or mortar can’t stretch, so the joint stops doing its job. Where a joint has been mortared, it can often be raked out and sealed properly.
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.
External mastic in Letty Green, done properly
External mastic is a job where short cuts show quickly. New sealant over old, joints packed with mortar and beads with no backing all tend to fail early. We take the old material out and do it properly. Common call-outs are for old sealant gone brittle and cracked and moss and dirt in joints with no sealant left, across concrete & block, joints between brick and frames and render & cladding joints.
Around Letty Green, older buildings can be stone, brick or timber-framed, many with extensions added later. Where one material meets another is where water generally gets in.
Your job is guaranteed for a year, as with all our work.
- Location
- Letty Green (SG14)
- Wider area
- Hertfordshire
- Cover
- 12 months on all our work
- Quote
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What happens on the day
Good joint work is mostly preparation, and we do not rush it. Joints are cleaned back and dried before anything new goes in. All told, the work takes a few hours to a few days, depending on the length of joint and the access. Somewhere as small as Letty Green, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- We look at every joint and agree a colour to suit the wall.
- Failed sealant is removed back to clean, sound faces.
- Backing rod goes in so the sealant can stretch between the two faces.
- We prime the faces where required.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
How to prepare
- Try not to wet indoor joints just before the visit
- Tell us about any previous sealing or DIY attempts
- Tell us about any water getting in
Getting a quote
Want a quote for external mastic? Please ring 0345 464 0079 or send us an email with a few details. You’ll know what we plan to do, and what it will cost, before any work begins.
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Quotes for external mastic in Letty Green
Every job gets its own quote. These are the things that affect it:
- The size of the job
- Which sealant suits the joint
- When we can work, for business premises
- How many areas need sealing
The cost depends on how much there is to do, how hard the old material is to remove and how easy the joints are to reach. We give a clear quote before any work starts, so you know where you stand.
What we need to know
To help us quote quickly, let us know:
- What the problem is, such as mould, gaps, leaks or cracking
- The type of property
- Roughly how big the job is
- Where the property is
Every job is quoted individually, so start by telling us what you need. Simply ring 0345 464 0079 or send us an email and describe the job and send photos if you have them.
Should I try it myself first?
If you’re set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it does not work out, we can still put it right.
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
Work for landlords, hotels and businesses
Water getting past a failed joint can damage the building, which is a bigger problem in a rented property. Resealing at the right time is simple maintenance that we can handle for you.
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Honest limits
To be straight with you, some problems need a different trade:
- Damp that isn’t coming from the joint
- Cracked brickwork or render that needs a builder or plasterer
- Loose or hollow render, which needs re-rendering
If in doubt, call 0345 464 0079 or send us an email and we’ll say what we think.
Joints and surfaces we work on
- Render & cladding joints
- Joints between brick and frames
- Brickwork movement joints
- Façade panels
- Copings & trims
- Concrete & block
Places near Letty Green
More services for Letty Green
Outside joints around Letty Green
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. Historic houses like Hatfield House (about 3.4 miles south-west) are a reminder that the area around Letty Green has older buildings as well as new. In older buildings, older brick and stone need a sealant that suits them, at the right joint depth.
If you let a flat or house near Hertford North station, outside joints that have cracked can let damp into a rental, so check them between lets. If you look after a building such as Hertingfordbury Cowper Primary School, larger buildings have long runs of movement joint that eventually need resealing.
Letty Green is about 3 miles south-east of Welwyn Garden City, in Hertfordshire. For external mastic in and around Letty Green, please ring 0345 464 0079 or send us an email for a quick quote. We cover Hertfordshire from our Crawley base, Letty Green included. Across Hertfordshire, we cover 381 places, and Letty Green is one of them. You can also see our page for London, about 20 miles away.
Postcode districts we cover here for external mastic: SG14. Whether your property is on Station Road, Woolmers Lane and Chapel Lane or anywhere close by, we can help. We also cover the places around Letty Green: East End Green (1 mile east), Staines Green (1 mile north-east), Hertingfordbury (1 mile north-east), Essendon (2 miles south-west) and Little Berkhamsted (2 miles south). We also work in nearby towns such as Watford (14 miles south-west), Hemel Hempstead (14 miles west), Stevenage (9 miles north), St Albans (8 miles west), Bishop's Stortford (14 miles north-east) and Welwyn Garden City (3 miles north-west).
Near you in Letty Green
Around Letty Green, our work takes us to homes and buildings near The Sele School and Panshanger Park, among other places. For rail, the closest station is Hertford North station, roughly 2.2 miles north-east. Well-known places in the area include Howard Centre (3.2 miles north-west) and Mcmullen & Sons Brewery Museum (2.6 miles north-east). Open spaces near Letty Green include Willowmead.
How the job changes by surface
Copings and trims
Joints in copings, parapets and trims are exposed to the worst of the weather. We reseal them with an exterior sealant suited to the material.
Cladding and façade panels
Cladding and façade panels are usually separated by sealed joints. Each joint gets a sealant that suits the panel and its movement.
When to call us in Letty Green
A lot of failed joints come down to preparation: dusty or wet faces, no primer where one was needed, or old sealant left in. The sealant never bonds properly.
If you can see any of these, it’s time to have the joints looked at:
- Hard, crazed mastic that has stopped moving
- Joints with sealant missing in places
- Damp patches traced to an open external joint
- Plants rooting in failed movement joints
For an older house near a landmark such as St John's Church, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Comparing quotes
- Are they insured?
- What the cure time is
- Which sealant they’ll use, and why
- How much experience the applicator has