Hertfordshire · England
Nettleden External Mastic
Sealing brickwork movement joints, render, cladding and façade joints for householders, landlords and businesses in Nettleden. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Gaps where render, brick and frames meet
- Old sealant gone brittle and cracked
- Sealant pulling away from one side of the joint
FAQs for Nettleden
Do you work for landlords with property near Berkhamsted station?
Yes, landlords and agents are among the people we work for, and several properties can be quoted together. You can call 0345 464 0079 or email us with the details for a clear quote.
Do you cover Nettleden for external mastic?
Yes, Nettleden is within the area we cover. Our work covers London and the South East. You can call 0345 464 0079 or drop us an email and let us know what needs doing, and we will send you a clear quote.
Why is there a gap in my brick wall?
Walls move with heat, cold and moisture, and planned joints take up that movement. The gap is sealed with a flexible sealant over backing rod.
Are you an approved applicator?
Yes. We are approved under the ARBOMaster scheme, which is run for the Arbo sealant brand.
Will the old sealant be removed?
Always. Sealing over old sealant is the main reason resealing fails early, so we never do it.
What is backing rod for?
We fit closed-cell backing rod wherever the joint depth needs controlling. It sets the sealant depth and prevents three-sided bonding.
Is there any odour?
It depends on the product. Some products have a noticeable smell, others very little.
How do I get a quote for external mastic in Nettleden?
Size, access and the old material all affect the cost. Ask us for a quote.
External mastic in Nettleden
Low-level joints can generally be done from the ground. Where joints are higher up, tell us about the building when you get in touch and we will confirm what’s needed to reach them safely. If you have moss and dirt in joints with no sealant left and rigid filler in a joint that should flex, we can put it right.
External sealant needs dry, clean surfaces, so work around Nettleden is planned for dry weather. Tell us about access to all sides of the building, including outbuildings and garages.
You get a one-year guarantee, the same in Nettleden as everywhere else we work.
- Location
- Nettleden (HP1)
- Wider area
- Hertfordshire
- Cover
- One year on every job
- Price
- A clear quote up front
- Call
- 0345 464 0079
- Updated
- 26 October 2026
What we cannot put right
Before you book, it’s worth knowing the limits:
- Loose or hollow render, which needs re-rendering
- Adding movement joints to masonry that has none
- Subsidence or other structural problems
If you are not sure, just phone 0345 464 0079 or send us an email and we will give you a straight answer.
Where we work in Nettleden
- Joints between brick and frames
- Façade panels
- Copings & trims
- Render & cladding joints
- Brickwork movement joints
- Concrete & block
Also near Nettleden
What else we do in Nettleden
DIY sealant or a professional job?
The biggest DIY mistake is sealing over old sealant. New silicone won’t bond to old, so it peels away and traps moisture behind it. Everything old must be removed first.
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and doesn’t move well, and getting the depth right matters as much as the look.
Leave it or put it right?
A low-modulus sealant is chosen because it moves without pulling hard at the edges. That protects surfaces like brick, render and concrete. Too stiff a sealant can pull at the edges and break them. Around Nettleden, older homes often have timber in their floors and frames, where water from a failed joint can cause rot if it’s left.
Homes and businesses are quoted the same way: the amount of work, the access and the products needed, along with when we can work on site. Ask us for a quote and we’ll explain what it covers.
Why Nettleden customers choose us
- Approved under the ARBOMaster scheme
- Experience in homes, commercial sites and hotels
- Colour agreed with you before we start
- Trusted Arbo and Everbuild sealants
Take a look at our cost guide or what customers say.
Nettleden buildings and the weather
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.
For an older house near a landmark such as Church of St Lawrence, an extension built onto an older house moves differently, and the joint between them takes the strain. Rented homes near Berkhamsted station change hands often, and split movement joints are easy to miss on a rental until damp shows inside.
Nettleden is about 3 miles north-east of Berkhamsted, in Hertfordshire. Nettleden gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. Nettleden is one of 381 towns and villages in Hertfordshire we cover. London is on our list too, about 27 miles from Nettleden.
All of HP1 is within our area for external mastic, from the main roads to the quietest streets. Neighbouring places we cover for external mastic include Frithsden (1 mile south-west), Great Gaddesden (1 mile north-east), Potten End (1 mile south), Fields End (2 miles south) and Ashridge (2 miles north-west). Within a short drive, we also cover Watford (10 miles south-east), Hemel Hempstead (3 miles south-east), St Albans (9 miles east), Welwyn Garden City (14 miles east), Harpenden (8 miles east) and Hatfield (12 miles east).
Local landmarks in Nettleden
Typical jobs here are in homes near John F Kennedy Catholic School and the streets around them. Nettleden’s nearest station is Berkhamsted station, about 2.2 miles south-west. A little further out are Hemel Hempstead Hospital (3.1 miles south-east). Green spaces nearby include Long Deans.
When to call us in Nettleden
Sunlight, wet weather and frost wear exterior sealant down. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
Common reasons people contact us are:
- Weathered mastic that no longer stretches
- Cracked joints where brick meets render or frames
- Joints where the bead has come unstuck
- Moss and dirt in joints with no sealant left
Managing a site like Great Gaddesden Church of England Primary School? Then movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.
Questions to ask before you book
- Whether all the old sealant comes out first
- When the joint can take water or movement
- What guarantee comes with the work
- Whether they’re fully insured
How the visit works
A visit follows a simple pattern: we look at the joints together, mask and protect the surrounding surfaces, carry out the job and tidy away. Most jobs take a few hours for a handful of joints, longer for a whole elevation. In a small place like Nettleden, access is normally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- First, the joints are inspected and the access agreed.
- We cut out the old mastic and rake out anything in the joint.
- Joint faces are cleaned back and primed if the sealant needs it.
- We fit closed-cell backing rod to control the depth.
- The exterior sealant is applied, tooled and checked along its length.
How to prepare
- Keep pets and children clear of the area while we work
- Tell us about access, such as stairs, a lift or high-level joints
- Where the joints are inside, avoid wetting them before we arrive
Getting a quote
If you’re in Nettleden and need external mastic, ring 0345 464 0079 or email us. A short description of the job and where it is helps us quote, and you’ll get a clear quote before any work starts.
Read more
For landlords and businesses
In hotels, rooms out of use cost money, so we plan the work room by room. Hotel work is part of what we do, alongside homes and businesses.
Letting agents and landlords in Nettleden can book us as well as householders. Sealant work between tenants is a simple way to keep a property in good order.
What the job involves on each surface
Render joints
The face of render can be soft, so a sealant that stretches easily protects the edges. We prime where the product needs it.
Joints between dissimilar materials
Each side of the joint may need its own preparation. Both surfaces are cleaned and primed as the product requires.