Portsmouth · England
Sand Mastic in Portsmouth
We cover Portsmouth for traditional burnt sand mastic around sash and case windows and doors in stone and brick. Old material cut out, joints cleaned and sealed neatly and every job guaranteed for a year.
- Gaps where the frame meets the masonry
- Silicone on a period window that looks wrong
- Old sand mastic that has cracked, crumbled or fallen out
What affects the cost of sand mastic
Jobs vary more than people expect. The main factors:
- Which sealant suits the joint
- The size of the job
- Whether old sealant or filler has to be cut out
- Whether the work is at height
Commercial jobs are quoted on the same basis as homes: the amount of work, the access and the products needed. Ask us for a quote and we’ll explain what it covers.
Helping us quote
You don’t need to know the technical terms. It helps if you can tell us:
- A few photos by email, if you can
- Roughly how big the job is
- Where the property is
- The problem you’ve noticed
Asking for a quote is easy: let us know the job and the location, and roughly how big it is. A few photos by email make the job easier to understand, and we’ll take it from there.
How we handle sand mastic in Portsmouth
We renew sand mastic around sash windows and doors set in stone or brick. The old mastic is raked out, and new mastic is applied and shaped by hand. We’re often asked to deal with silicone on a period window that looks wrong and failed mastic on an exposed elevation, on brick reveals, tenement windows and sash and case windows.
Beyond its homes, Portsmouth has shopfronts, offices and flats with plenty of frames and glazing, often on upper floors. A cracked joint on an upper floor can let water in long before anyone spots it.
We stand behind the work with a one-year guarantee.
- Place
- Portsmouth (PO6, PO4, PO1, PO2)
- Region
- Portsmouth
- Guarantee
- 12 months on all our work
- Price
- A clear price before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Can I do it myself?
A DIY attempt doesn’t rule out a professional job. We remove it and do the joint properly, so just mention it when you contact us.
The biggest DIY mistake is sealing over old sealant. New silicone will not bond to old, so it lifts and traps water and mould underneath. All the old material has to come out first.
When it is not the sealant
Sealant is not the answer to every problem, and we will tell you before any work starts. Sealant won’t put right:
- Sashes that rattle, stick or will not open
- Broken panes
- Decisions on consent for listed homes
If you’re not sure, just call 0345 464 0079 or drop us an email and we’ll give you a straight answer.
Surfaces we seal
- Period & listed homes
- Stone surrounds
- Tenement windows
- Sash and case windows
- Timber door frames
- Brick reveals
Questions from Portsmouth
Can you help a landlord with a rental near Fratton station?
Yes, rental work is part of what we do. You can call 0345 464 0079 or send us an email with the address and a few details, and we’ll give you a fixed price before work begins.
Is Portsmouth in your area for sand 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.
Should I try DIY first?
Some simple jobs can be done by a careful DIYer. Most DIY failures come from sealing over old material, wet joints or too much sealant.
What do you need from me for a quote?
Let us know what needs doing and where, with photos by email if possible. We’ll ask anything else we need to know.
Are you ARBOMaster approved?
Yes. Mr Mastic is an ARBOMaster approved applicator and we’re fully insured too.
Will there be a smell?
Sometimes, a little. Any smell clears as the sealant cures, and ventilation helps.
Can you do several jobs on one visit?
Yes, and it often makes sense. Doing several areas at once is usually more efficient, so mention them when you ask for a quote.
Can new sealant go over the old?
No. Fresh sealant does not stick to old sealant, and it traps any mould or water underneath. It all has to come out first.
Other services in Portsmouth
Aftercare tips
To keep the joints looking good and working properly:
- Ask the planning authority about consent for listed or conservation-area homes
- Ask us before painting near the mastic
- Renew mastic before redecorating the windows
- Check the mastic when you check the paintwork
Leave the new mastic alone while it firms up. It skins over quickly but needs longer to fully harden.
It’s best to renew mastic before painting the windows. Paint over cracked mastic only covers it up.
Sand mastic in Portsmouth: local notes
Portsmouth is within about 1 mile of the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. That’s hard on the mastic around older windows and doors, especially on the side facing the sea. 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.
Homes close to St Wilfrid include some older properties, and the joint between an old wall and a newer frame is usually the first place rain gets in. Rented homes near Fratton station change hands often, and cracked sand mastic around sash windows lets in the draughts tenants complain about. If you look after a building such as Manor Infant School, the mastic around its windows and doors needs looking after like any other building’s.
Portsmouth is in England. Every kind of property in Portsmouth is covered for sand mastic, old or new, large or small. The work is guaranteed for a year. We cover 19 towns and villages across Portsmouth, large and small.
All of PO6, PO4, PO1 and PO2 is covered for sand mastic, from the main roads to the quietest streets. If you need sand mastic at a property on Church Road, April Square and Rudmore Square or anywhere close by, our applicators can take on the job. You will find Portsmouth on the A3 and A27, so it’s easy for us to get to. We also cover the places around Portsmouth: 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). We also work in nearby towns such as Wymering (3 miles north), Paulsgrove (3 miles north), Drayton (3 miles north-east) and Farlington (3 miles north-east).
Local landmarks in Portsmouth
In Portsmouth, that means homes and buildings near The Portsmouth Academy, Alexandra Park and St Edmund's Catholic School, among other places. For rail, the closest station is Fratton station, roughly 0.9 miles south. Well-known places in the area include Royal Portsmouth Hospital (0.7 miles south-west) and Charles Dickens Birthplace Museum (under half a mile west). Not far away are Milton Locks and Portsdown Hill.
Why act early in Portsmouth
If you are redecorating, renew the mastic first. Painting over failed mastic doesn’t seal it and traditional guidance is to leave the new mastic unpainted. In a busy place like Portsmouth, a failed joint in a flat or office can send water into the space below, where it’s often found late and is bigger to put right.
A few things move the cost up or down: the old material and how easily it comes out, any mould to treat, and whether the work is at height. We take all of that into account in your quote.
Why choose Mr Mastic in Portsmouth
- 4.9 on Google from 180+ five-star reviews
- Every job guaranteed for a year
- An ARBOMaster approved applicator
- 20+ years of sealant experience
Take a look at what affects the cost or what customers say.
Work for landlords, hotels and businesses
Letting agents often deal with us directly. Send the address, what’s needed and the access arrangements and we will give you a quote.
Landlords and letting agents in Portsmouth can book us as well as householders. Resealing between tenancies is a simple way to keep a property in good order.
The process
You don’t need to clear the whole room or building before we come, just the space around the work. Everything nearby is protected, and the work takes a few hours for a single window, longer for several in most cases. In central Portsmouth, parking can be tight, so tell us about driveways, permits or nearby car parks. For flats, mention stairs, lifts and shared entrances as well.
- We look at the surrounds with you and agree the joints to renew.
- Old mastic and any loose material are raked out.
- We pack any deep voids first.
- The sand mastic is mixed and pressed into the joint by hand.
- The surface is finished to suit the stone or brick.
Before we arrive
- Mention any tricky access
- Tell us about any water getting in
- Plan for the work area to be out of bounds to pets and children
Ask for a quote
It all starts with a short chat. Describe the problem, the location and the size of the job. Whenever you’re ready, phone 0345 464 0079 or drop us an email.