Hampshire · England
Thedden External Mastic
We cover Thedden for sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly and a 12-month guarantee.
- Water getting into walls through failed joints
- Plants rooting in failed movement joints
- Sealant that has lost its bond to the brick or render
External mastic for homes and businesses in Thedden
Failed sealant is cut out, the depth set with closed-cell backing rod, and the joint resealed with a low-modulus sealant made for outside. We pick a colour that sits well with the wall. We’re often asked to deal with sealant pulling away from one side of the joint and movement joints filled with mortar instead of sealant, on render & cladding joints, concrete & block and joints between brick and frames.
Around Thedden, older buildings can be stone, brick or timber-framed, many with extensions added later. The joints where those materials meet are the weak points.
We guarantee the work for a year. If there’s a problem with our work within the year, let us know and we will sort it.
- Location
- Thedden (GU34)
- Region
- Hampshire
- Cover
- 12 months on all our work
- Quotes
- A clear price before we start
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
What happens if it’s left?
It often makes sense to reseal all the failing joints on an elevation together. Joints of the same age tend to fail together. Where a wall is exposed, as many are in small places like Thedden, wind-driven rain gets into any failed joint, and older walls, once damp, take a long time to dry.
Combining jobs into one visit is generally more efficient than separate visits, so it’s worth mentioning everything you’d like done. We will give you a clear quote for the lot.
Why choose Mr Mastic in Thedden
- Arbo and Everbuild products
- Colour picked to suit the job
- More than 20 years in sealant work
- We are fully insured
See our cost guide and customer reviews.
Thedden questions
Can you help a landlord with a rental near Alton station?
Yes. We work for landlords and agents as well as homeowners. Just ring 0345 464 0079 or email us with the address and what needs doing, and we’ll give you a clear quote.
Do you cover smaller places like Thedden?
Yes. Thedden is within the area we cover, which takes in towns, villages and rural addresses. Our work covers London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
Do you use backing rod?
We fit closed-cell backing rod wherever the joint depth needs controlling. It controls the depth and stops the sealant bonding to the back.
How long does external mastic last?
It varies with how exposed the wall is and how much the joint moves. Signs to watch for are cracking, hardening and gaps at the edges.
Do you take out the old sealant first?
Yes, every time. New sealant won’t bond properly to old, so any old material comes out before anything new goes in.
What colours does the sealant come in?
Exterior sealants are made in a range of colours, from greys and browns to whites and stone shades. We choose the closest to your brick or render so it does not stand out.
Do I have to be there?
Access is agreed with you when the job is booked. Indoors, that usually means someone at home.
How long does the job take?
A typical job takes a few hours for a handful of joints, longer for a whole elevation, including the preparation. We’ll confirm how long when we quote.
How it works
There is not much for you to do on the day. Point us to the joints and we will get on with it. The job generally takes anything from a few hours to several days, depending on the building. Somewhere as small as Thedden, access is often the only tricky part. For outside work, also let us know about exposed walls and any outbuildings involved.
- 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.
Preparing for the visit
- Keep children and pets away from the work area
- Let us know about earlier repairs to the joints
- Clear the area around the work
Getting a quote
For external mastic in Thedden, ring 0345 464 0079 or send us an email. A short description of the job and where it is helps us quote, and we’ll agree the price before any work begins.
Read more
Walls and rooflines in Thedden
With historic houses such as Bentworth Hall (about 1 mile west) nearby, there’s older building stock in the area around Thedden as well as newer homes. Where a home is older, older walls and rooflines need a sealant that moves with them and suits the material. 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.
Managing a site like Amery Hill School? Then larger buildings have long runs of movement joint that eventually need resealing. For an older house near a landmark such as St Peter's, an extension built onto an older house moves differently, and the joint between them takes the strain. Letting a property close to Alton station? Then outside joints that have cracked can let damp into a rental, so check them between lets.
Thedden is about 2 miles west of Alton, in Hampshire. If you need external mastic in Thedden, please call 0345 464 0079 or send us an email for a quick quote. We are based in Crawley and cover Hampshire. Our area takes in 683 places across Hampshire, from the larger towns to small villages. There’s also a page for Reading, about 21 miles away.
Work in GU34 works the same way as everywhere else we cover. Neighbouring places we cover for external mastic include Beech (1 mile south-east), Wivelrod (1 mile south-west), Bentworth (1 mile north-west), Holt End (1 mile west) and New Copse (2 miles west). Within a short drive, we also cover Basingstoke (9 miles north), Winchester (14 miles south-west), Farnborough (15 miles north-east), Fleet (12 miles north-east), Aldershot (13 miles north-east) and Petersfield (10 miles south).
Near you in Thedden
The closest station to Thedden is Alton station, about 2.6 miles east. Nearby you will also find Alton Community Hospital (1.6 miles east) and Barton Castle (3.9 miles west). Green spaces nearby include King's Hill.
Can I do it myself?
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.
If you do try it yourself, take your time over the preparation: remove every trace of old sealant, clean and dry the joint, and follow the product’s cure time. If it fails, we can still redo it.
Aftercare tips
After the cure time, these simple habits help:
- Point out the joints to other trades
- Avoid pressure-washing directly into sealant joints
- Keep movement joints as flexible joints, not mortar
- Look over the joints every year, ideally after winter
Give the sealant the cure time we tell you before anything rubs against it. The surface skins over quickly, but full cure takes longer.
Small splits are the time to act. Then it’s a straightforward cut-out and reseal.
When it isn’t the sealant
It helps to know what we can’t do too:
- Subsidence or other structural problems
- Adding movement joints to masonry that has none
- Render that is blown, hollow or coming away
Not sure which it is? You can call 0345 464 0079 or send us an email and we’ll tell you honestly before you book.
What we seal
- Brickwork movement joints
- Concrete & block
- Façade panels
- Render & cladding joints
- Copings & trims
- Joints between brick and frames
Landlords, agents and businesses in Thedden
In hotels, rooms out of use cost money, so we plan the work room by room around your bookings where we can. We’ve worked in hotels as well as homes and businesses.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
What else we do in Thedden
What the job involves on each surface
Brickwork movement joints
Brick moves with heat and moisture, and grows a little over time. The movement joint takes that up, so the sealant in it must stay soft and stretchy.
Render joints
Rendered walls have joints at beads, openings and changes of material. They’re resealed in a sealant that suits the render.