South East England and London

External Mastic in Hertfordshire

We cover 381 towns and villages across Hertfordshire for external mastic, with old sealant always removed and a one-year guarantee on every job., with every joint properly prepared, with a clear quote before we start and a one-year guarantee.

External Mastic across Hertfordshire

Call 0345 464 0079

Get a quick quote

Where we work in Hertfordshire

Sealing brickwork movement joints, render, cladding and façade joints. Pick your town below to see the details for your area, and get in touch for a quick quote.

Main towns

Other services in Hertfordshire

Postcode areas we cover

External mastic in Hertfordshire: how it works

A movement joint is a deliberate break that lets a wall expand and contract. The sealant in it has to stretch and squeeze for years, and when it fails, the wall takes the strain and water finds a way in. We work on render & cladding joints, concrete & block and copings & trims, and people most often call us about movement joints with cracked, split or missing sealant and sealant pulling away from one side of the joint.

Every visit runs the same way: we check the joints, protect the area around them, do the work and tidy away. It generally takes anything from a few hours to several days, depending on the building.

We start by walking round the building and agreeing the joints and the access.
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.
Backing rod sized to the joint goes in to set the depth.
We apply the sealant, tool it and check the whole run.

How we quote

What it costs depends on the size of the job, how much old material has to come out and how easy the joints are to reach. We give a clear quote before we start.

Why choose Mr Mastic

Colour agreed with you before work begins
Colour picked to suit the job
Tidy, careful work
Every job guaranteed for a year

Get a quote

Every job is quoted individually, so the first step is telling us about yours. Just call 0345 464 0079 or drop us an email with the details, and pictures are welcome.

Landmarks near Watford

In Watford, that means homes and buildings near The Estcourt Arms, Watford St John's Church of England Primary School and Church of St Andrew and the streets around them. Nearby too are Cassiobury Park (0.8 miles west) and The Watford UTC (0.5 miles east). Watford has its own railway station: Watford Junction station. A little further out are Hilfield Castle (2.8 miles east) and Charter Place (0.5 miles south). The countryside around Watford includes Harrow Weald Common.

External mastic across Hertfordshire: local notes

Across Hertfordshire, from Watford, Hemel Hempstead and Stevenage outwards, outside joints range from old gutters to modern movement joints. Each needs a sealant that can move, laid at the right depth.

Most of the South East has hard water, so limescale builds up on sealant, grout and fittings. For any job in Hertfordshire, joints are cleaned back properly before anything new goes in.

Watford: For landlords with property near Watford Junction 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 Watford St John's Church of England Primary School, movement joints, cladding joints and gutters on larger buildings need the same care as a house’s.

Different surfaces, different methods

Copings and trims

Coping joints that leak let water straight down into the wall. Sealing them early saves the wall below.

Brickwork movement joints

Vertical joints in long brick walls let the brickwork expand without cracking. We reseal them with a low-modulus sealant over backing rod.

Why deal with it now?

A failed movement joint lets water into the wall, behind render and cladding. Dealing with it early keeps the repair to the joint, rather than the wall around it.

Comparing quotes

What happens if the job turns out different
How long to leave it before use
Are they insured?
What guarantee comes with the work

Signs you need external mastic

Many joints fail because they were sealed too deep or with nothing behind them. Sealant bonded to three sides has nowhere to go and rips as the joint opens.

The problems people generally mention when they call are:

Rigid filler in a joint that should flex
Plants rooting in failed movement joints
Old sealant gone brittle and cracked
Joints where the bead has come unstuck

Landlords, agents and businesses in Hertfordshire

Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements and we will give you a quote.

Letting agents and landlords in Hertfordshire can book us as well as householders. Resealing between tenancies is a simple way to keep a property in good order before the next move-in.

Should I try it myself first?

A DIY attempt does not rule out a professional job. We cut it out and start again, so tell us about it when you ask for a quote.

Not every job suits DIY: high-level joints, fire-rated gaps, external movement joints and big jobs call for the right materials, safe access and experience.

Hertfordshire questions

Do you hold any approvals?

Yes. We are an ARBOMaster approved applicator, which is run for the Arbo sealant brand.

Do you use backing rod?

Backing rod goes into deeper joints as a matter of course. It controls the depth and stops the sealant bonding to the back.

I rent my home. Can I book you?

Yes. Ask your landlord first, and we can send them the quote if that helps.

Can you seal over the old sealant?

No. New silicone won’t bond to old silicone, and anything trapped underneath, including mould and water, stays there. It all has to come out first.

Can you match the colour of my brickwork?

We aim for a joint that suits the wall rather than one that jumps out. We will talk through colour options before we start from the range available.

Is there any odour?

There can be a smell while the sealant cures, which fades as it sets. Ventilation helps.

How do you reach high-level joints?

It depends on the building. We work on joints that can be reached safely. Tell us about the building and we’ll confirm what access is needed.