Reading · England
Sonning External Mastic
We cover Sonning for sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly and every job guaranteed for a year.
- Movement joints with cracked, split or missing sealant
- Damp patches traced to an open external joint
- Leaking joints around cladding and façade panels
About our external mastic in Sonning
Many failed façade joints only get noticed once there’s a stain or a damp patch inside. We inspect them, agree which need doing and reseal with a weatherproof, flexible sealant in a matching colour. Common call-outs are for old sealant gone brittle and cracked and joints with sealant missing in places, across brickwork movement joints, joints between brick and frames and façade panels.
Older homes in small places like Sonning may be stone, brick or timber-framed, often with later extensions. Where one material meets another is where water normally gets in.
You are covered for a year from the day we finish. If anything is not right with it, ring 0345 464 0079 or email us.
- Place
- Sonning (RG4)
- Region
- Reading
- Guarantee
- One year on every job
- Price
- A clear price before work begins
- Call
- 0345 464 0079
- Page updated
- 26 October 2026
Surface by surface
Cladding and façade panels
Metal and composite panels move a lot with temperature, so the joint sealant has to cope with frequent movement. The sealant is chosen with that in mind.
Concrete and blockwork
Big joints in concrete need careful depth control. Backing rod sized to the joint sets it so the sealant is not too deep.
When it isn’t the sealant
A few problems are outside what sealant work can do:
- Cracks in the bricks or render themselves, away from the joints
- Movement that’s more than a sealant joint can take
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
If you’re not sure, just call 0345 464 0079 or email us and we’ll give you a straight answer before booking.
Surfaces we seal
- Joints between brick and frames
- Render & cladding joints
- Brickwork movement joints
- Copings & trims
- Façade panels
- Concrete & block
How it works
On the day, we look over the joints with you first, so there are no surprises. Surfaces next to the work are protected before any work begins. The work normally takes a few hours for a handful of joints, longer for a whole elevation. Somewhere like Sonning needs a little journey planning: tell us about narrow lanes, gates, long drives and where we can park. We bring what the job needs, so it can be finished in one trip where possible.
- 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.
Getting ready for the visit
- Tell us about any previous sealing or DIY attempts
- Mention any leaks or damp you’ve noticed
- Mention any tricky access
How to get a quote
A good description makes for an accurate quote. Let us know the location, the problem and roughly how many joints, and email pictures if that is easy.
Advice
What we are called out for in Sonning
UV, rain and frost all age exterior sealant. Over the years it hardens, cracks on the surface and loses its give, so the joint eventually tears or comes away from one side.
The most common problems we see are:
- Cracked joints where brick meets render or frames
- Panel joints letting water in
- Rigid filler in a joint that should flex
- Water getting into walls through failed joints
Letting a property close to Twyford station? Then failed wall and movement joints let damp in, so they’re worth checking between tenancies.
What to look for in a quote
- How hidden problems are handled
- When the joint can take water or movement
- Whether you can choose the colour
- Whether all the old sealant comes out first
Questions from Sonning
Do you cover smaller places like Sonning?
Yes. Sonning is within the area we cover, which takes in towns, villages and rural addresses. We work across London and the South East. Let us know about access, parking and anything unusual about getting there when you book.
I let a flat near Twyford station. Can you help?
Yes. We work for letting agents and landlords as well as householders. You can ring 0345 464 0079 or drop us an email with the details for a clear quote.
When will the joints need doing again?
It varies from wall to wall: joints on exposed walls or with a lot of movement age sooner. A yearly look will tell you when they need doing. Our work comes with a one-year guarantee.
Are you an approved applicator?
Yes. ARBOMaster is the approved applicator scheme for Arbo sealants, and we’re part of it.
Should I try DIY first?
Some simple jobs can be done by a careful DIYer. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
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 so the bead can stretch.
What does external mastic cost?
There’s no set price, as it depends on the job: its size, the old material, access and the product needed. We agree the price before any work begins.
Can you seal over the old sealant?
No. New silicone will not bond to old silicone, and it traps any mould or water underneath. We remove it all first.
Work for landlords, hotels and businesses
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Hotels need rooms back in use, so we plan the work room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
Why act early in Sonning
A failed movement joint lets water into the wall and can run behind render or cladding. Dealing with it early keeps the repair to the joint, instead of the wall and finishes around it. Around Sonning, older homes often have timber in their floors and frames, and water through a failed joint can rot timber if it’s left.
A few things move the cost up or down: how much old sealant there is and how stubborn it is, whether mould needs treating, and whether the work is at height. Your quote takes all of that into account.
Why choose Mr Mastic in Sonning
- 20+ years of sealant experience
- ARBOMaster approved applicator
- You choose the colour before work begins
- Neat joints and a tidy finish
See what affects the cost and what customers say.
DIY versus a professional finish
A careful DIYer can reseal a simple joint, such as a straightforward joint indoors. The common mistakes are sealing over old sealant, sealing a damp joint and using far too much.
If you’re set on DIY, put the effort into preparation: take out all the old sealant, make sure the joint is clean and dry, and give it the full cure time. If it does not work out, we can still put it right.
Also near Sonning
Other services in Sonning
What external mastic looks like in Sonning
The South East is one of the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
For site and facilities teams at buildings such as Sonning Church of England Primary School, larger buildings have long runs of movement joint that eventually need resealing. If you live in an older home near St Andrew's Church, the joints between older walls, newer extensions and the roofline need a sealant that can move.
Sonning is about 1 mile north-west of Woodley, in Reading. Sonning gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. Sonning is one of 34 towns and villages in Reading we cover.
We cover every part of RG4 for external mastic and the streets around it. Streets in the area include High Street, Parkway Drive and Pound Lane, all of which we cover. With the B478 and B4446 close by, Sonning is simple for us to get to. Neighbouring places we cover for external mastic include Play Hatch (1 mile north-west), Dunsden Green (2 miles north-west), Newtown (2 miles south-west), Caversham Park Village (2 miles north-west) and Littlestead Green (2 miles north-west). Within a short drive, we also cover Caversham (3 miles west), Norcot (5 miles west), West Reading (4 miles west), Tilehurst Within (5 miles west), Shinfield (5 miles south-west) and Arborfield Garrison (6 miles south).
Near you in Sonning
We work in homes and buildings around Ali's Pond Local Nature Reserve, Bull Inn and Waingels College and the streets around them. Sonning’s nearest station is Twyford station, roughly 1.9 miles east. Well-known places in the area include Berkshire Medical Heritage Centre Museum (2.5 miles south-west) and Royal Berkshire Hospital (2.6 miles south-west). Open spaces near Sonning include Sonning Hill and South Lake.