Hampshire · England
Portmore External Mastic
Problem with your movement joints in Portmore? We remove the old material, prepare the joints and seal them properly, with a 12-month guarantee.
- Hard, crazed mastic that has stopped moving
- Gaps where render, brick and frames meet
- Weeds or debris growing in open joints
External mastic in Portmore
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. If you have weeds or debris growing in open joints and leaking joints around cladding and façade panels, we can help, on joints between brick and frames, façade panels and concrete & block alike.
In a village or hamlet like Portmore, older cottages and farm buildings often stand in the open, so walls and rooflines take the full force of wind and rain. Gutter joints and wall joints there need a sealant that can flex and stay put.
We guarantee the work for a year. If something isn’t right with it in that time, tell us and we will put it right.
- Where
- Portmore (SO41)
- Region
- Hampshire
- Guarantee
- 12 months on all our work
- Quote
- A clear quote up front
- Telephone
- 0345 464 0079
- Updated
- 26 October 2026
Aftercare tips
Aftercare is simple, and it makes a real difference:
- Make sure movement joints are not pointed over
- Look over the joints every year, ideally after winter
- Have failed joints looked at early
- Ask before painting over external sealant
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.
Act while the splits are small. At that stage it’s a simple cut out and reseal before water has had years to get in.
Walls and rooflines in Portmore
Portmore is close to the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. Both are hard on movement joints and outside wall joints, which can dry out and crack sooner where a building faces the weather. With historic houses such as Beaulieu Palace House (about 4.5 miles north-east) nearby, there’s older building stock in the area around Portmore 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.
Rented homes near Lymington Town station change hands often, and split movement joints are easy to miss on a rental until damp shows inside. Managing a site like Southlands School? Then its movement joints, gutters and trims need looking after like any other building’s.
Portmore is about 2 miles north-east of Lymington, in Hampshire. For external mastic in and around Portmore, it’s easy to get a quote: please ring 0345 464 0079 or email us. We are based in Crawley and cover Hampshire, Portmore included. Across Hampshire, we cover 683 places, and Portmore is one of them. Our Southampton page covers work nearby, about 11 miles away.
Work in SO41 works the same way as everywhere else we cover. Whether your property is on Warborne Lane, Jordans Lane and Main Road or a nearby road, we can help. If you’re just outside Portmore, we cover Warborne (1 mile west), Pilley (1 mile north-west), Bull Hill (1 mile north), Pilley Bailey (1 mile north) and Walhampton (1 mile south). Within a short drive, we also cover Eastleigh (15 miles north-east), Fareham (15 miles east), Totton (10 miles north), Hedge End (14 miles north-east), Romsey (15 miles north) and Hythe (8 miles north-east).
What’s near Portmore
In Portmore, that means homes and buildings near William Gilpin Church of England Primary School, Priestlands School and Walhampton Arms. The closest station to Portmore is Lymington Town station, about 1.1 miles south-west. Nearby you will also find Lymington New Forest Hospital (1 mile south-west) and Yarmouth Castle (4.8 miles south). Not far away are Boldre Foreshore.
What happens on the day
On the day, there’s very little for you to do. Show us the job and we’ll take it from there. The work itself takes anything from a few hours to several days, depending on the building from start to finish. Somewhere as small as Portmore, access is often the only tricky part. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- First, the joints are inspected and the access agreed.
- Every bit of old sealant and any mortar or debris is cut out.
- The faces are brushed clean and primed where the product requires it.
- Backing rod sized to the joint goes in to set the depth.
- We apply the sealant, tool it and check the whole run.
How to prepare
- Keep pets and children clear of the area while we work
- Tell us about access, such as stairs, a lift or high-level joints
- Tell us about any previous sealing or DIY attempts
Getting a quote
For a quote, call 0345 464 0079 or email us and tell us where the job is and what the problem looks like. We’ll give you a clear quote before any work starts.
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What affects the cost of external mastic
Some jobs are bigger than they look, and some smaller. What affects the quote:
- The size of the job
- Whether there’s mould to deal with
- Any working-time requirements on site
- The type of sealant required
Homes and businesses are quoted the same way: the amount of work, the access and the products needed, along with when we can work on site. Ask us for a quote and we’ll go through it with you.
What to tell us for a quote
There’s no need for technical detail. Just tell us:
- The type of property
- Any previous sealing or DIY work
- Any access issues, like height or stairs
- Pictures of the joints, sent by email
It all starts with a short chat. Tell us what’s wrong, where it is and how much there is. When it suits you, call 0345 464 0079 or email us.
What sealant work cannot fix
Before booking, it’s worth knowing the limits:
- Cracking across the wall rather than at a joint
- Render that is blown, hollow or coming away
- Adding movement joints to masonry that has none
Not sure which it is? You can ring 0345 464 0079 or email us and we will tell you honestly.
Joints and surfaces we work on
- Façade panels
- Joints between brick and frames
- Concrete & block
- Render & cladding joints
- Copings & trims
- Brickwork movement joints
Portmore: your questions answered
Is external mastic in a coastal place like Portmore any different?
Coastal homes put outside sealant through more weather than inland ones, so the choice of sealant and the preparation matter even more. Walls facing the sea are generally the first to need attention.
Can you help a landlord with a rental near Lymington Town station?
Yes. We work for landlords and agents as well as homeowners. You can ring 0345 464 0079 or send us an email with the details for a clear quote.
What do you put in the joint?
It depends on the joint: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. We use products from Arbo and Everbuild.
Is it OK to fill a movement joint with cement?
No. A mortar-filled joint cannot move, so the movement cracks the wall elsewhere. It needs a flexible sealant over backing rod.
When is the sealant fully cured?
It depends on the product and the temperature. Before we leave, we will tell you the cure time.
Where is Mr Mastic based?
Our base is Crawley, with over 20 years’ experience. We work across South East England, London and Scotland.
Will there be a smell?
Sometimes, a little. Any smell clears as the sealant cures.
Will the old sealant be removed?
Yes. All of the old material is cut out and the joint cleaned before applying anything new.
When to call us in Portmore
Weeds, moss and debris in a joint are a sign the sealant has gone. Roots and dirt hold water against the wall and speed up the damage.
People generally contact us when they notice one of these:
- Joints with sealant missing in places
- Sealant that has lost its bond to the brick or render
- Movement joints filled with mortar instead of sealant
- Plants rooting in failed movement joints
For an older house near a landmark such as Saint Nicholas Chapel, older walls, gutters and the joints where extensions meet them need a flexible sealant.
What your quote should include
- When the joint can take water or movement
- How the surfaces are prepared before sealing
- What happens if they find a problem under the old sealant
- Who turns up on the day
Landlord and commercial work in Portmore
Landlords and agents in Portmore can book us as well as householders. Sealant work between tenants keeps a property looking cared for before the next move-in.
For anyone letting property in or around Portmore, several properties can be quoted together. Just tell us the addresses and what each one needs, and photos by email help.
Why act early in Portmore
It often makes sense to reseal all the failing joints on an elevation together. They’ve weathered the same way. In a small place like Portmore, homes can be exposed to wind and rain, which finds any gap, and damp in older walls is slow to dry out.
What it costs depends on the size of the job, how hard the old material is to remove and access to the work. We give a clear quote before we start.
Why Portmore customers choose us
- Homes, businesses and hotels
- Arbo and Everbuild products
- We are fully insured
- A 12-month guarantee on all work
Take a look at how sealant jobs are priced or customer reviews.