Portsmouth · England
Portsmouth External Mastic
Our applicators work in Portsmouth on sealing brickwork movement joints, render, cladding and façade joints. Old sealant removed completely, joints prepared properly and every job guaranteed for a year.
- Sealant that has lost its bond to the brick or render
- Old sealant gone brittle and cracked
- Movement joints with cracked, split or missing sealant
About our external mastic in Portsmouth
Ground-floor and low-level joints are straightforward to reach. Where joints are higher up, tell us about the building when you get in touch and we will confirm what access is needed. We work on joints between brick and frames, render & cladding joints and copings & trims, and the jobs we see most are sealant that has lost its bond to the brick or render and movement joints filled with mortar instead of sealant.
In a large town like Portsmouth, plenty of buildings are rented or managed, and outside joints are easy to forget. A failed joint above a door or a dripping gutter end is normally the first sign.
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.
- Where
- Portsmouth (PO6, PO4, PO1, PO2)
- Region
- Portsmouth
- Guarantee
- One year on every job
- Quotes
- Quoted before any work starts
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
Keeping the joints in good condition
After the cure time, these simple habits help:
- Fix overflowing gutters above sealed joints
- Keep movement joints as flexible joints, not mortar
- Tell anyone working on the walls about the movement joints
- Clear growth from the base of walls and joints
Keep the joints clear of soil, plants and climbing growth. Anything that holds water against the joint wears it out sooner.
Once a joint can’t move, the wall finds another way, normally as cracking in the brickwork or render nearby. Catch it early and you reduce the risk.
What else we do in Portsmouth
When it isn’t the sealant
Honest advice matters more to us than a booking, so here’s what sealant cannot fix:
- Subsidence or other structural problems
- Damp from another source, such as a leaking gutter or a bridged damp-proof course
- Failed render or damaged cladding panels
If in doubt, call 0345 464 0079 or send us an email and we’ll say what we think.
Surfaces we seal
- Concrete & block
- Render & cladding joints
- Brickwork movement joints
- Joints between brick and frames
- Façade panels
- Copings & trims
FAQs for Portsmouth
Does the coastal weather in Portsmouth affect outside sealant?
Near the coast, wind-driven rain and, nearer the shore, salt air make outside sealant work harder. The right product, a clean joint and the right depth all help it cope.
Do you cover Portsmouth for external mastic?
Yes, Portsmouth is within the area we cover. We work across London and the South East. Just call 0345 464 0079 or email us with a few details of the job.
Are you an approved applicator?
Yes. Mr Mastic is an ARBOMaster approved applicator, and we are fully insured.
Do you guarantee your work?
Yes. Every job comes with a 12-month guarantee.
Do you work for hotels and businesses?
Yes. We can plan bigger jobs in stages to suit the site.
Why do you put foam in the joint first?
Backing rod controls the sealant depth and keeps it off the back of the joint. That way it bonds to the two sides only and can stretch.
How long before the joint can be used?
Cure times vary by product and the temperature. Before we leave, we will tell you the cure time.
What’s an expansion joint in brickwork?
Most straight vertical gaps in brickwork are movement joints. It gives the wall room to move, and it should be sealed with a flexible sealant.
Why it’s worth doing now in Portsmouth
Resealing a run of joints in one go is normally better than patching one at a time. They’ve weathered the same way, and access only has to be arranged once. For landlords in Portsmouth, failed sealant soon turns into tenant complaints about mould, damp or draughts. It’s simpler to sort between tenants than in the middle of a let.
Some things make a job bigger or smaller: the old material and how easily it comes out, whether mould needs treating, and whether the work is at height. Your quote takes all of that into account.
Why us?
- We never seal over old sealant
- Rated 4.9 stars on Google
- Neat joints and a tidy finish
- Homes, businesses and hotels
Take a look at our cost guide and what customers say.
How the visit works
Every visit runs the same way: we look at the joints together, mask and protect the surrounding surfaces, carry out the job and tidy away. It normally takes a few hours for a handful of joints, longer for a whole elevation. Where a business in Portsmouth needs to stay open, out-of-hours working can be arranged, while home visits are arranged within our normal working hours, Monday to Saturday.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- Joint faces are cleaned back and primed if the sealant needs it.
- Backing rod sized to the joint goes in to set the depth.
- The exterior sealant is applied, tooled and checked along its length.
Getting ready for the visit
- Move anything stored near the joints
- Mention any tricky access
- Tell us about any water getting in
Get a quote
There’s no standard price list, because every job is different. Instead, your job gets its own clear quote. To get started, phone 0345 464 0079 or drop us an email.
Read more
Do you need external mastic in Portsmouth?
Sometimes a movement joint was filled with mortar or a rigid filler. With the joint locked solid, the movement turns into cracks elsewhere in the wall.
The most common problems we see are:
- Hard, crazed mastic that has stopped moving
- Plants rooting in failed movement joints
- Movement joints filled with mortar instead of sealant
- Panel joints letting water in
In the older streets around St Wilfrid, older walls, gutters and the joints where extensions meet them need a flexible sealant.
What to look for in a quote
- What the cure time is
- Are they insured?
- The length of the guarantee
- What preparation is included
External mastic in Portsmouth: local notes
Portsmouth is close to the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. Both are hard on movement joints and outside wall joints, which can dry out and crack sooner where a building faces the weather. Rainfall in the South East is lower than in much of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
Rented homes near Fratton station change hands often, and split movement joints are easy to miss on a rental until damp shows inside. If you look after a building such as Manor Infant School, larger buildings have long runs of movement joint that eventually need resealing.
Portsmouth is in England. Portsmouth gets the same service as everywhere we cover: old sealant removed completely, careful preparation and a 12-month guarantee. We cover 19 towns and villages across Portsmouth.
Here we cover the PO6, PO4, PO1 and PO2 postcode area for external mastic. That includes homes and businesses on Church Road, April Square and Rudmore Square. You will find Portsmouth on the A3 and A27, which makes it straightforward to reach. We also cover Rudmore (1 mile north-west), Landport (1 mile south-west), North End (1 mile north), Fratton (1 mile south-east) and Kingston (1 mile south-east). Larger places within reach include Wymering (3 miles north), Paulsgrove (3 miles north), Drayton (3 miles north-east) and Farlington (3 miles north-east).
Landmarks near Portsmouth
We work in homes and buildings around The Portsmouth Academy, Alexandra Park and St Edmund's Catholic School. The nearest railway station is Fratton station, about 0.9 miles south of the centre. Other landmarks nearby include Royal Portsmouth Hospital (0.7 miles south-west) and Charles Dickens Birthplace Museum (less than half a mile west). For a walk, there’s Milton Locks and Portsdown Hill.
Surface by surface
Render joints
Render has movement joints and stop beads that need sealing. We reseal them with a flexible exterior sealant that suits the render colour.
Brickwork movement joints
Brick movement joints are often mistaken for a missing mortar line. If that is happened, we rake it out and reseal it properly.
Landlord and commercial work in Portsmouth
Water getting past a failed joint can damage the building, which matters even more when someone else lives there. Keeping joints in good order is simple maintenance.
Hotels need rooms back in use, so the work can be planned room by room around your bookings where we can. Hotel work is part of what we do, alongside homes and businesses.