Hertfordshire · England
External Mastic in Marshalswick
Our applicators work in Marshalswick on sealing brickwork movement joints, render, cladding and façade joints. Old material cut out, joints cleaned and sealed neatly.
- Cracked joints where brick meets render or frames
- Joints where the bead has come unstuck
- Moss and dirt in joints with no sealant left
Common questions in Marshalswick
I let a flat near St Albans station. Can you help?
Yes, landlords and agents are among the people we work for. You can call 0345 464 0079 or drop us an email with the details for a clear quote.
Do you cover Marshalswick for external mastic?
Yes, Marshalswick is within the area we cover. We work across London and the South East. Just phone 0345 464 0079 or send us an email with a few details of the job, and we will give you a clear quote.
How long will you be here?
That depends on the amount of work, but most jobs take anything from a few hours to several days, depending on the building. We will give you a better idea when we quote.
Can you quote for more than one area?
Yes, and it often makes sense. Combining jobs makes good use of the visit.
What do you put in the joint?
The product depends on the job: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. Brands we use include Arbo and Everbuild.
Can you work on commercial sites?
Yes. Hotels, offices and other businesses use us.
Do you guarantee your work?
Yes. Every job comes with our 12-month guarantee.
Do I have to be there?
That depends on where the joints are. Inside work needs someone to give us access.
External mastic in Marshalswick
Joints between dissimilar materials, like brick against render or concrete against a steel frame, see movement from both sides. A flexible exterior sealant takes up that movement where a rigid filler would soon crack. We work on copings & trims, façade panels and concrete & block, and people most often call us about brick movement joints where the sealant has split and panel joints letting water in.
Around Marshalswick, garages, outbuildings and extensions all add to the joints on the outside of a home. Leaks generally start at a gutter end, a garage door frame or where an extension meets the house.
The work is guaranteed for twelve months. If something isn’t right with it in that time, tell us and we will put it right.
- Location
- Marshalswick (AL4, AL1, AL3)
- Wider area
- Hertfordshire
- Guarantee
- 12 months on all our work
- Quote
- A clear price before work begins
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
How it works
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. For most jobs that takes a few hours for a handful of joints, longer for a whole elevation and we leave things clean and tidy. For a job in Marshalswick, we agree the time, the access and parking before the day. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- We look at every joint and agree a colour to suit the wall.
- We take out the old sealant until the faces are sound.
- Backing rod goes in so the sealant can stretch between the two faces.
- Primer is applied wherever the sealant needs it.
- A low-modulus exterior sealant is gunned in and tooled to a neat finish.
Getting ready for the visit
- Try not to wet indoor joints just before the visit
- Tell us about access, such as stairs, a lift or high-level joints
- Tell us if parking is tricky
Get a quote
A good description makes for an accurate quote. Tell us where the job is, what’s wrong and how much there is, and add photos by email if you can.
Advice
What the job involves on each surface
Render joints
Rendered walls have joints at beads, openings and changes of material. We reseal them with a flexible exterior sealant that suits the render colour.
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. That movement goes into the joint, so the sealant in it must stay soft and stretchy.
When something else is needed
We will not take on work that will not last, so here’s what sealant can’t put right:
- Failed render or damaged cladding panels
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Cracks in the bricks or render themselves, away from the joints
If you’re not sure, just ring 0345 464 0079 or send us an email and we’ll give you a straight answer.
Where we work in Marshalswick
- Copings & trims
- Façade panels
- Render & cladding joints
- Brickwork movement joints
- Concrete & block
- Joints between brick and frames
How to look after the new joints
How long the joints last depends on use and care. We suggest:
- Point out the joints to other trades
- Keep high-pressure jets off the joints
- Deal with leaking gutters that soak the joints below
- Check the sealant is paintable before painting near it
If you have more work done on the wall, such as new render, cladding or an opening, show the contractor the movement joints. They must stay as flexible joints, never rendered or pointed over.
Small splits are the time to act. At that stage it’s a simple cut out and reseal.
Common problems we fix in Marshalswick
Using the wrong sealant is another common reason. A high-modulus or general-purpose sealant can be too rigid for a busy joint, and it tears off the sides.
These are the problems we are asked about most:
- Movement joints filled with mortar instead of sealant
- Damp patches traced to an open external joint
- Leaking joints around cladding and façade panels
- Joints with sealant missing in places
Letting a property close to St Albans station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What to look for in a quote
- What the quote includes, VAT included or not
- How long to leave it before use
- What insurance they hold
- What preparation is included
Also near Marshalswick
Also in Marshalswick
Work for landlords, hotels and businesses
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. We can quote for more than one property at once.
Housing providers, facilities teams and property managers book us too in Marshalswick and across Hertfordshire. Several sites can go on one quote, and we are fully insured for the work.
What happens if it’s left?
Pointing a movement joint with mortar might seem a neat fix, but it locks the joint solid. The wall then cracks somewhere else. The correct repair is a flexible sealant with the right backing. In a smaller place like Marshalswick, wherever a wall is exposed, a failed outside joint is a real source of damp. Indoors, a failed seal lets water into floors and panels as it would anywhere.
Every job is a little different, so we quote each one individually. Size, access and the product the joint needs all make a difference, and we will explain the quote if you ask.
Why choose Mr Mastic in Marshalswick
- Any old sealant cut out fully, not covered over
- Full insurance on every job
- An ARBOMaster approved applicator
- Sealant colour chosen to suit
Walls and rooflines in Marshalswick
The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast. Historic houses like Batchwood Hall (about 2 miles west) are a reminder that the area around Marshalswick has older buildings as well as new. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
Managing a site like St John Fisher Roman Catholic Primary School? Then its movement joints, gutters and trims need looking after like any other building’s. If you live in an older home near Saint Mary's, an extension built onto an older house moves differently, and the joint between them takes the strain.
Marshalswick is about 1 mile north-east of St Albans, in Hertfordshire. Jobs in Marshalswick get the same care as everywhere else we work: the old material taken out, joints prepared properly and a 12-month guarantee. Marshalswick is one of 381 towns and villages in Hertfordshire we cover. For nearby work, see our London page.
We work across AL4, AL1 and AL3 for external mastic. Whether your property is on Milvus Road, Jersey Lane and Sandpit Lane or a nearby road, our applicators can take on the job. We also cover Sandridge (1 mile north), Bernards Heath (1 mile west), St Albans (1 mile south-west), Childwick Green (2 miles north-west) and Sopwell (2 miles south-west). Larger places within reach include Watford (8 miles south-west), Hemel Hempstead (7 miles west), Stevenage (11 miles north-east), Welwyn Garden City (5 miles north-east), Harpenden (4 miles north-west) and Hitchin (13 miles north).
Around Marshalswick
In Marshalswick, that means homes and buildings near The Baton pub, Sandringham School and Clarence Park, among other places. The nearest railway station is St Albans station, about 1.3 miles south-west. A little further out are St Albans Musical Museum (0.8 miles south-west) and The Maltings (1.6 miles south-west). Open spaces near Marshalswick include The Wick Local Nature Reserve and Verulamium Lake.