Hampshire · England
Sand mastic for sash & case windows in Portchester, Hampshire
Window and door surrounds in Portchester need attention? We remove the old material, prepare the joints and seal them properly.
- Weathered mastic on the most exposed windows
- Tired mastic found when preparing windows for paint
- Open joints round the window box
Sand mastic in Portchester
A silicone bead around a sash window can look out of place and does not suit the building. Sand mastic gives a finish that matches the age of the house and we can swap the silicone for it. If you’re dealing with open joints round the window box and crumbling sand mastic round a window, we can put it right, whatever the surface.
In smaller places like Portchester, homes range from older cottages to newer houses, with windows to match: timber, uPVC and aluminium. The right sealant depends on the frame and on what it sits in.
There’s a 12-month guarantee on every job, whatever its size.
- Location
- Portchester (PO16, PO6, PO17)
- Region
- Hampshire
- Guarantee
- A year, on every job
- Price
- A clear price before work begins
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
Signs you need sand mastic in Portchester
Shallow joints are a common cause. Mastic that is too thin cracks and drops out, which is why we pack deep voids first and get the depth right.
The most common problems we see are:
- Cement or filler used on old window joints that has cracked
- Draughty sash windows at the surround
- Weathered mastic on the most exposed windows
- Cracked mastic round a front door frame
Homes close to Church of St Mary include some older properties, and the windows may be timber, sash or later replacements, and each needs the right sealant against the wall.
Before booking anyone
- Whether all the old sealant comes out first
- Is VAT in the price?
- What preparation is included
- How hidden problems are handled
Frames and glazing around Portchester
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 is hard on the mastic around older windows and doors, especially on the side facing the sea. 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.
Rented homes near Portchester station change hands often, and any sash windows need sound mastic to keep draughts and rain out. If you look after a building such as Castle Primary School, its window and door frames need their mastic kept sound, just like a home’s.
Portchester is about 3 miles north-east of Gosport, in Hampshire. Every kind of property in Portchester can book us for sand mastic, old or new, large or small. The work is guaranteed for a year. 683 places in Hampshire are on our list, from the larger towns to small villages.
We work across PO16, PO6 and PO17 for sand mastic and the streets around it. Local streets include Cow Lane, Hill Road and Ralph Road, all of which we cover. Close by, we work in 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). Further out, we also cover 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).
Around Portchester
We work in homes and buildings around Portchester Community School and The Cormorant pub and the streets around them. Portchester’s nearest station is Portchester station, roughly 0.5 miles north-west of the centre. A little further out are Portchester Castle (less than half a mile south-east) and Queen Alexandra Hospital (2.3 miles east). Not far away are West of the River Alver and Portsdown Hill.
How to look after the new joints
Joint life depends on how it’s used and looked after. We suggest:
- Check the mastic when you check the paintwork
- Go gently near the mastic when preparing windows
- Check with your local planning authority if your home is listed
- Get any rot dealt with first
Avoid sealing over the mastic with silicone. If anything cracks, get it looked at rather than patching it.
Gaps round a sash box let in draughts and rain. The longer it’s left, the more the joint opens.
DIY sealant or a professional job?
A DIY attempt doesn’t rule out a professional job. We cut it out and start again, so tell us about it when you ask for a quote.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
Why act early in Portchester
Not every draught comes from the sashes themselves. Open mastic joints round the box can let air in and new mastic seals them. Homes in smaller places like Portchester can face more weather, and failed outside joints let damp into walls. Inside, a split seal lets water into floors and panels just as it would anywhere.
Leaving a failed joint generally makes the job bigger, not smaller, because water and mould keep working on it. If you are not sure whether it needs doing, ring 0345 464 0079 or send us an email and we’ll give you an honest view and a quote.
Why choose Mr Mastic in Portchester
- A 12-month guarantee on all work
- Experience in homes, commercial sites and hotels
- Approved under the ARBOMaster scheme
- Neat joints and a tidy finish
See our cost guide and what customers say.
Nearby places to Portchester
Also in Portchester
Portchester questions
Does living near the coast affect sand mastic in Portchester?
Near the coast, wind-driven rain and, nearer the shore, salt air make outside sealant work harder. Choosing the right sealant for the frame and wall, laid at the right depth, helps it last.
Do you cover smaller places like Portchester?
Yes, smaller places are covered as well as towns. We work across London and the South East. Just mention lanes, gates or anything else about the route when you book.
Do you do commercial work?
Yes. Commercial and hotel work is a large part of what we do. We can talk about working times when we quote.
Is there any odour?
There can be a smell while the sealant cures, but it fades. Opening a window helps.
Can you quote for more than one area?
Yes. Just list everything you need and we will quote it together.
Can I do it myself?
It depends on the job. Work at height, movement joints, fire-rated gaps and large areas are best left to a professional.
Will the old sealant be removed?
Always. Sealing over old sealant is the main reason resealing fails early, and it’s something we never do.
Can old silicone round a sash window be swapped for sand mastic?
Yes. The silicone is cut out and the joint cleaned before the sand mastic goes in.
The process
Every visit runs the same way: we check the joints, mask and protect the surrounding surfaces, do the work and tidy away. It normally takes a few hours for a single window, longer for several. For a job in Portchester, we agree the time, the access and parking before the day. If the work is outside, the weather plays a part, as sealant needs a dry surface.
- We start by checking each surround and agreeing the joints to renew.
- We rake out the old mastic and clean the joint.
- We pack any deep gaps so the mastic sits at the right depth.
- We mix the sand mastic and apply it by hand, shaping it to the joint.
- The mastic is finished to sit tidily against the stone or brick.
Before we arrive
- Where the joints are inside, avoid wetting them before we arrive
- Let us know about stairs, lifts or work at height
- Mention any leaks or damp you’ve noticed
Getting a quote
Getting a quote is simple: tell us what needs doing and where, and roughly how big it is. Photos by email help us understand the job.
Related advice
What we cannot put right
Before you book, it’s worth knowing the limits:
- Planning or listed building consent (your local planning authority decides)
- Timber that has rotted
- Putty and glazing repairs
If in doubt, ring 0345 464 0079 or send us an email and we’ll say what we think.
Where we work in Portchester
- Brick reveals
- Sash and case windows
- Period & listed homes
- Stone surrounds
- Timber door frames
- Tenement windows
What affects the cost of sand mastic
Some jobs are bigger than they look, and some smaller. What affects the quote:
- Which sealant suits the joint
- How many areas need sealing
- How easy the joints are to reach
- When we can work, for business premises
Every job is a little different, so each one gets its own quote. The number of joints, how easy they are to reach and the sealant needed all make a difference, and we will explain the quote if you ask.
Helping us quote
When you contact us, it’s useful to know:
- Any access issues, like height or stairs
- Whether it has been sealed before
- Photos by email, if that’s easy
- The problem you’ve noticed
For a quote, phone 0345 464 0079 or drop us an email and tell us where the job is and what the problem looks like. We will give you a clear quote before any work starts.