Hertfordshire · England
External & façade joints in Whempstead, Hertfordshire
External mastic for Whempstead, by sealant specialists with 20+ years’ experience. Rated 4.9 on Google from 180+ five-star reviews.
- Panel joints letting water in
- Joints where the bead has come unstuck
- Moss and dirt in joints with no sealant left
External mastic in Whempstead
As ARBOMaster approved applicators, we choose exterior sealants to suit the joint and the surfaces. Porous or awkward surfaces are primed where the sealant needs it and we use one wherever it does. We work on brickwork movement joints, concrete & block and joints between brick and frames, and people most often call us about failed seals between different materials and water getting into walls through failed joints.
Outside joints can only be sealed when they’re dry, so work in Whempstead is booked around the forecast. Let us know about access to every wall, plus any garages or outbuildings.
Big or small, it’s backed by our one-year guarantee in Whempstead and across Hertfordshire.
- Where
- Whempstead (SG12)
- Wider area
- Hertfordshire
- Cover
- 12 months on all our work
- Quote
- A clear price before we start
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Surface by surface
Joints between dissimilar materials
Where a frame or panel meets masonry, water often finds a way in. The old joint is removed and a sealant that bonds to both sides goes in.
Concrete and blockwork
Concrete and block walls shrink as they dry and move with temperature. We reseal their joints with backing rod and a flexible product.
Common problems we fix in Whempstead
If plants are growing out of a joint, the sealant has generally failed or was never there. Dirt and roots then trap moisture in the joint and speed up the damage.
Common reasons people contact us are:
- Rigid filler in a joint that should flex
- Leaking joints around cladding and façade panels
- Brick movement joints where the sealant has split
- Water getting into walls through failed joints
Letting a property close to Watton-At-Stone station? Then split movement joints are easy to miss on a rental until damp shows inside.
What your quote should include
- What product goes in the joint
- The length of the guarantee
- Which colour the sealant will be
- How much experience the applicator has
DIY versus a professional finish
Some sealant jobs are within reach of a careful DIYer, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
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.
Whempstead questions
Will you come out to Whempstead?
Yes, Whempstead is covered. We work across London and the South East, and smaller places are part of that. The journey is planned ahead, so it helps to know about access.
I let a flat near Watton-At-Stone station. Can you help?
Yes, we work for landlords and letting agents. You can call 0345 464 0079 or drop us an email with the address and a few details, and we will give you a fixed price before any work starts.
Are you insured?
Yes. Mr Mastic is fully insured, with over 20 years’ experience in sealant work.
Where is Mr Mastic based?
Our base is Crawley, with over 20 years’ experience. Our area covers South East England, London and Scotland.
How long does the job take?
That depends on the amount of work, but most jobs take anything from a few hours to several days, depending on the building. We’ll give you a better idea when we quote.
Will there be a smell?
Possibly a little. Any smell clears as the sealant cures, and ventilation helps.
What sealant do you use?
It depends on the joint: anti-fungal sanitary silicone in wet areas, and other sealants where joints move or face the weather. We use products from Arbo and Everbuild.
Can you match the colour of my brickwork?
The sealant colour is picked to suit the wall, so the joint sits quietly in the wall. Exterior sealants come in a good range of colours.
Honest limits
In fairness, there are a few things sealant will not fix:
- Cracking across the wall rather than at a joint
- Subsidence or other structural problems
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
If you are not sure, just phone 0345 464 0079 or send us an email and we will give you a straight answer.
Joints and surfaces we work on
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Façade panels
- Joints between brick and frames
- Copings & trims
Places near Whempstead
Also in Whempstead
For landlords and businesses
Whether it’s one flat or a portfolio, the work is the same standard: old sealant fully removed, joints prepared properly and a 12-month guarantee.
We regularly work with letting and managing agents. Send the address, what’s needed and the access arrangements.
External mastic in Whempstead: local notes
London and the South East are among the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. With historic houses such as Aston Bury (about 2.6 miles west) nearby, there’s older building stock in the area around Whempstead as well as newer homes. In older buildings, older walls and rooflines need a sealant that moves with them and suits the material.
Homes close to Parish Church of All Saints include some older properties, and the joints between older walls, newer extensions and the roofline need a sealant that can move. For site and facilities teams at buildings such as Munden Church of England Voluntary Controlled Primary School, larger buildings have long runs of movement joint that eventually need resealing.
Whempstead is about 5 miles south-east of Stevenage, in Hertfordshire. Anywhere in SG12, our applicators can take on external mastic. Whempstead is one of 381 places in Hertfordshire where we work. Our London page covers work nearby.
Every address in SG12 is covered for external mastic, from the main roads to the quietest streets. Local streets include Whempstead Road and Mill Lane, and we cover them all. If you are just outside Whempstead, we cover Dane End (1 mile east), Burn's Green (1 mile north-west), Sacombe (1 mile south-east), Haultwick (2 miles north-east) and Sacombe Green (2 miles south-east). Further out, we also cover Stevenage (5 miles north-west), St Albans (13 miles south-west), Bishop's Stortford (10 miles east), Welwyn Garden City (7 miles south-west), Harpenden (12 miles west) and Hitchin (9 miles north-west).
Landmarks near Whempstead
The nearest railway station is Watton-At-Stone station, about 1.8 miles south-west of the centre. Well-known places in the area include Hertford County Hospital (5.4 miles south) and Benington Castle (2 miles north-west). Green spaces nearby include Astonbury Wood.
What affects the quote in Whempstead
We quote each job individually. This is what makes a difference:
- Any mould that needs treating
- When we can work, for business premises
- The old material and how stubborn it is
- How many rooms, windows or areas are involved
No two jobs are quite the same, so we quote each one individually. The number of joints, how easy they are to reach and the sealant needed all play a part.
Asking for a quote
What to tell us when you ask for a quote:
- Whether it has been sealed before
- The type of property
- What the problem is, such as mould, gaps, leaks or cracking
- Access, such as stairs, a lift or height
Getting a quote is simple: let us know the job and the location, and roughly how big it is. A few pictures by email make the job easier to understand, and we’ll come back to you with a quote.
How the visit works
Once we’re on site, we compare the joints with what we discussed. If anything is different, we explain it before carrying on. Most jobs then take a few hours for a handful of joints, longer for a whole elevation. In a small place like Whempstead, access is generally the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We look at every joint and agree a colour to suit the wall.
- We take out the old sealant until the faces are sound.
- Closed-cell backing rod is pushed in so the sealant bonds to two sides only.
- We prime the faces where required.
- We gun in low-modulus sealant and tool it neatly.
Before we arrive
- For indoor joints, keep the area dry beforehand if you can
- Keep pets and children clear of the area while we work
- Let us know if you’ve seen damp or leaks
Ask for a quote
Want a quote for external mastic? Please call 0345 464 0079 or drop us an email with a few details. We’ll explain what we’d do and give you a clear price before work begins.