Hertfordshire · England
Monkswood External Mastic
Movement joints in Monkswood need attention? We cut out the old, prepare the joints and apply the right sealant, and the work is guaranteed for a year.
- Gaps where render, brick and frames meet
- Movement joints with cracked, split or missing sealant
- Damp patches traced to an open external joint
External mastic for homes and businesses in Monkswood
On houses, flats and commercial buildings across Monkswood, we reseal joints in brickwork, render, cladding and façade panels. The preparation is the same whatever the wall: clean, sound faces and a controlled depth. We work on render & cladding joints, joints between brick and frames and façade panels, and people most often call us about panel joints letting water in and rigid filler in a joint that should flex.
Somewhere as small as Monkswood, homes and farm buildings often face open ground, so walls and rooflines take the full force of wind and rain. Gutter joints and wall joints there need a sealant that can flex and stay put.
A one-year guarantee comes as standard, so you are not left on your own once the job is done.
- Where
- Monkswood (AL8, AL6, AL7)
- Region
- Hertfordshire
- Cover
- 12 months on all our work
- Quotes
- A clear price before work begins
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Monkswood buildings and the weather
Rainfall in the South East is lower than in much of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. Historic houses like Digswell House (about 0.1 miles south-west) are a reminder that the area around Monkswood has older buildings as well as new. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material.
For an older house near a landmark such as The Parish Church of St John, older walls, gutters and the joints where extensions meet them need a flexible sealant. If you let a flat or house near Welwyn North station, outside joints that have cracked can let damp into a rental, so check them between lets. For site and facilities teams at buildings such as Homerswood Primary and Nursery School, its movement joints, gutters and trims need looking after like any other building’s.
Monkswood is about 2 miles north of Welwyn Garden City, in Hertfordshire. We provide external mastic to homes and businesses in Monkswood and the surrounding area. Monkswood is one of 381 towns and villages in Hertfordshire where we work for external mastic. You can also see our page for London, about 23 miles away.
Postcode districts we cover here for external mastic: AL8, AL6 and AL7. Streets in the area include Digswell Park Road, Ingles and Uplands, all of which we cover. Close by, we work in Welwyn (1 mile north-west), Ayot Green (1 mile south-west), Ayot St Peter (2 miles west), Pottersheath (2 miles north) and Rableyheath (2 miles north). Further out, we also cover Watford (14 miles south-west), Hemel Hempstead (12 miles south-west), Stevenage (6 miles north), St Albans (7 miles south-west), Harpenden (6 miles west) and Hitchin (9 miles north).
Around Monkswood
Locally, jobs take us to homes and businesses close to Monk's Walk School, Danesbury Park and Hedgehog pub, among other places. For rail, the closest station is Welwyn North station, about 0.6 miles north-east of the centre. Nearby you’ll also find Queen Elizabeth II Hospital (2.7 miles south) and Howard Centre (1.3 miles south). Green spaces nearby include Tewin Orchard and Hopkyns Wood.
Keeping the joints in good condition
Joint life depends on how it’s used and looked after. We suggest:
- Have failed joints looked at early
- Keep soil, plants and ivy away from the joints
- Make sure movement joints are not pointed over
- Avoid pressure-washing directly into sealant joints
Only paint over the joint if we have confirmed the sealant can take paint. Paint can crack on a flexible joint and spoil the finish.
Act while the splits are small. At that stage it’s a simple cut out and reseal.
Monkswood questions
Is Monkswood in your area for external mastic?
Yes, Monkswood 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 give you a clear price.
Do you work for landlords with property near Welwyn North station?
Yes, we work for landlords and agents. Just ring 0345 464 0079 or drop us an email and tell us about the property, and we will give you a clear price.
Where are you based?
Our base is in Crawley, and we work across South East England, London and Scotland.
What is a movement joint?
Most straight vertical gaps in brickwork are movement joints. It lets the bricks expand without cracking and needs a flexible seal, not mortar.
Can you match the colour of my brickwork?
There’s a good range of exterior colours, including greys, browns, whites and stone tones. We choose the closest to your brick or render so it doesn’t stand out.
How long before the joint can be used?
Many sealants skin over quickly but take longer to cure fully. We’ll tell you how long to leave the joint before we leave.
How much does external mastic cost in Monkswood?
There’s no set price, as it depends on the job: how much there is, what’s there now, how we reach it and what it needs. We agree the price before any work begins.
When will the joints need doing again?
It varies from wall to wall: sunny, exposed elevations and busy joints wear faster. A yearly look will tell you when they need doing. Every job carries our one-year guarantee.
How the job changes by surface
Render joints
Cracks along render joints let water in behind the coat. A sound joint keeps the render dry behind and helps it last.
Brickwork movement joints
People sometimes point up a brick movement joint by mistake. If that’s happened, we rake it out and reseal it properly if the joint can be cleared.
When something else is needed
We’d rather tell you now than do work that will not last, so these are the limits:
- Structural movement, which needs a surveyor or engineer
- Cracked brickwork or render that needs a builder or plasterer
- Damp that is not coming from the joint
If you’re not sure, just phone 0345 464 0079 or send us an email and we’ll give you a straight answer.
Surfaces we seal
- Brickwork movement joints
- Render & cladding joints
- Concrete & block
- Façade panels
- Joints between brick and frames
- Copings & trims
Can I do it myself?
Sealing over old silicone is the commonest DIY error. Silicone does not stick to old silicone, so it lifts and traps water and mould underneath. All the old material has to come out first.
Too much sealant is as bad as too little. A thick, smeared bead looks untidy and does not move well, and the joint depth matters as much as the finish.
What we do, step by step
On the day, there’s very little for you to do. Point us to the joints and we will get on with it. The job generally takes a few hours for a handful of joints, longer for a whole elevation from start to finish. Somewhere as small as Monkswood, access is often the only tricky part. 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.
- 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
- Mention any leaks or damp you’ve noticed
- Let us know about parking restrictions
- Let us know about earlier repairs to the joints
Ask for a quote
The more we know about the job, the more useful the quote. Let us know the location, the problem and roughly how many joints, and email photos if that is easy.
Advice
Work for landlords, hotels and businesses
Mouldy or split sealant often shows up at the end of a tenancy. Several properties can be quoted together.
Businesses can book us for washrooms, kitchens, offices and more. On commercial sites, working times can be discussed when we quote.
Places near Monkswood
Also in Monkswood
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 old material and how stubborn it is
- Working hours on commercial sites
- Whether the work is at height
Every job is a little different, so we quote each one individually. Size, access and the product the joint needs all play a part, and we’ll explain the quote if you ask.
What to tell us for a quote
What to tell us when you ask for a quote:
- What the problem is, such as mould, gaps, leaks or cracking
- Roughly how big the job is
- Any previous sealing or DIY work
- Access, such as stairs, a lift or height
For a quote, call 0345 464 0079 or drop us an email with the location and a short description of the problem. You’ll have a clear quote before work begins.