Hampshire · England
Portchester Window Mastic
Mastic around window and door frames, sills and patio doors for homes and businesses in Portchester and across Hampshire. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Gaps left after new windows were fitted
- Cracked or shrunken mastic around the frame
- A bead that doesn’t match the frame
About our window mastic in Portchester
There are two joints on most windows. The external joint is the weather seal; the internal joint closes the gap to the plaster and stops draughts. We seal one or both, depending on what’s needed. If you are dealing with hard, cracked sealant around windows and leaking joints at the ends of sills, we can help.
Homes around Portchester range from older properties to newer houses, and their windows range just as widely. The right sealant depends on the frame and on what it sits in.
All of our work is guaranteed for twelve months, in Portchester and everywhere else we cover.
- Location
- Portchester (PO16, PO6, PO17)
- Region
- Hampshire
- Guarantee
- 12 months on all our work
- Quote
- A clear price before any work starts
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Leave it or put it right?
A quick bead over the top of old mastic looks like an easy fix, but new sealant can’t bond to old, crumbling mastic. It soon lifts and the leak carries on behind it. The old mastic has to come out. In a smaller place like Portchester, wherever a wall is exposed, a failed outside joint is a real source of damp. Indoors, a failed seal lets water into floors and panels as it would anywhere.
Homes and businesses are quoted the same way: how much there is to do, how we reach it and what it needs, along with when we can work on site. Ask us for a quote and we’ll explain what it covers.
Why choose Mr Mastic in Portchester
- Domestic, commercial and hotel work
- A choice of colours where the product allows
- Rated 4.9 stars on Google
- We leave the area clean and tidy
Take a look at how sealant jobs are priced and customer reviews.
When it is not the sealant
We won’t take on work that will not last, so these are the limits:
- Faulty window hardware
- A frame that has rotted at the joint
- A door that needs adjusting, rehanging or new seals
Not sure which it is? You can call 0345 464 0079 or email us and we will tell you honestly.
Joints and surfaces we work on
- Aluminium frames
- Composite doors
- Timber windows & doors
- Patio & French doors
- Window sills
- uPVC windows
For landlords and businesses
In hotels, rooms out of use cost money, so the work can be planned room by room around your bookings where we can. We have worked in hotels as well as homes and businesses.
If you manage several properties in or around Portchester, several properties can go on one quote. Send us the addresses and the work at each, and photos by email help.
Should I try it myself first?
Overfilling a joint is a classic DIY mistake. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
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.
Signs you need window mastic in Portchester
Joint shape matters as much as the product. A thin smear across a wide gap has nothing to it, and a gap filled solid can’t flex. That’s what backing rod is for.
If you can see any of these, it’s time to have the joints looked at:
- Leaking joints at the ends of sills
- Cracked internal joints between frame and plaster
- Old mastic that has gone black or come away
- Gaps left after new windows were fitted
If you look after a building such as Castle Primary School, larger buildings have plenty of frames, and the mastic around each one ages.
Questions to ask before you book
- How the surfaces are prepared before sealing
- What product goes in the joint
- How long the guarantee is
- Who does the work, and how experienced they are
Surface by surface
Composite doors
If the door itself is draughty, the issue may be the door seals or hinges rather than the frame mastic. We’ll tell you if that is what we find.
Timber windows & doors
Older timber windows in stone or brick can suit sand mastic rather than modern sealant. We’ll tell you which suits your home.
What we do, step by step
All our tools and materials come with us in the van, so there’s nothing for you to buy. After a quick look at the joints together, we protect the area and start. Most jobs take most of a day for a typical house, less for a few frames. A visit to Portchester is planned like any other: the time, the access and where to park are agreed in advance. Outdoor jobs depend on a dry day, since sealant needs a dry surface.
- Each frame is looked over and we agree which ones need resealing.
- We remove the old mastic and clean the frame edge and wall.
- Deep gaps get closed-cell backing rod to set the depth.
- A flexible exterior sealant is applied in a colour to suit the frame.
- We tool each bead neatly and check every joint is closed.
Before we arrive
- Mention any parking rules near the property
- Clear items away from the joints we are working on
- Mention any sign-in or site rules at work premises
Get a quote
For a quick quote, get us on the phone, or send an email if you’d rather. Describe what needs sealing and we will explain what’s involved and give you a clear quote.
Related advice
Common questions in Portchester
Do you cover smaller places like Portchester?
Yes, Portchester is covered. Our work covers London and the South East, from towns to the smallest places. Longer journeys are simply planned in advance.
Can you help a landlord with a rental near Portchester station?
Yes, landlords and agents are among the people we work for, and several properties can go on one quote. Just ring 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear price.
Do you hold any approvals?
Yes. We are ARBOMaster approved, the scheme for applicators of Arbo sealants.
Is there any odour?
Sometimes, a little. It fades as the sealant cures, and ventilation helps.
Does the work come with a guarantee?
Yes, for 12 months. Keeping drainage clear and checking the joints yearly helps them last.
How do I get a quote for window mastic in Portchester?
Size, access and the old material all affect the cost. Ask us for a quote and we will talk you through it.
How long does it take to reseal the windows on a house?
It depends on access, the old mastic and the size of the frames. We will tell you how long your job needs when we quote.
Can you do several jobs on one visit?
Yes. More than one area can go on one quote.
Portchester homes and the weather
Portchester is within about 1 mile of the coast, where wind-driven rain is a fact of life and, nearer the shore, so is salt air. That’s hard on the mastic around window and door frames, especially on the side facing the sea. The South East is one of the drier parts of the UK, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
In the older streets around Church of St Mary, frames set in older brick or stone need a sealant that suits the wall as well as the frame. For landlords with property near Portchester station, cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Portchester is about 3 miles north-east of Gosport, in Hampshire. Whether you are in the middle of Portchester or further out, window mastic is available for homes and businesses alike. Our area takes in 683 places across Hampshire, large and small.
Work in PO16, PO6 and PO17 is quoted and booked the same way as anywhere else. Streets in the area include Cow Lane, Hill Road and Ralph Road, and we cover them all. If you are just outside Portchester, we cover Boarhunt (2 miles north-west), Southwick (2 miles north), Elson (2 miles south-west), Wallington (2 miles west) and Priddy's Hard (2 miles south). Larger places within reach include Gosport (3 miles south-west), Havant (6 miles east), Eastleigh (13 miles north-west), Fareham (3 miles west), Horndean (7 miles north-east) and Chandler's Ford (15 miles north-west).
Landmarks near Portchester
We work in homes and buildings around Portchester Community School and The Cormorant pub, among other places. The closest station to Portchester is Portchester station, roughly 0.5 miles north-west of the centre. Other landmarks nearby include Portchester Castle (less than half a mile south-east) and Queen Alexandra Hospital (2.3 miles east). For a walk, there’s West of the River Alver and Portsdown Hill.