Portsmouth · England
Window & door mastic in Portsmouth
Window mastic in Portsmouth from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- White mastic on grey or black frames
- Rain getting in at the frame or under the sill
- Mastic that has split away from the wall
Portsmouth homes and the weather
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 is hard on the mastic around window and door frames, especially on the side facing the sea. London and the South East are among the drier parts of the UK, though outdoor sealant still has to go onto a dry joint, so the forecast decides the day.
If you live in an older home near St Wilfrid, frames set in older brick or stone need a sealant that suits the wall as well as the frame. Letting a property close to Fratton station? Then cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Portsmouth is in England. Wherever you are in the PO6 postcode area, we cover window mastic for homes and businesses. We cover 19 towns and villages across Portsmouth.
Work in PO6, PO4, PO1 and PO2 works the same way as everywhere else we cover. That includes homes and businesses on Church Road, April Square and Rudmore Square. Being close to the A3 and A27, Portsmouth is easy for our applicators to reach for window mastic. 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). Within a short drive, we also cover Wymering (3 miles north), Paulsgrove (3 miles north), Drayton (3 miles north-east) and Farlington (3 miles north-east).
Near you in Portsmouth
Typical jobs here are in homes near The Portsmouth Academy, Alexandra Park and St Edmund's Catholic School. Portsmouth’s nearest station is Fratton station, roughly 0.9 miles south of the centre. Nearby you will also find Royal Portsmouth Hospital (0.7 miles south-west) and Charles Dickens Birthplace Museum (less than half a mile west). Green spaces nearby include Milton Locks and Portsdown Hill.
About our window mastic in Portsmouth
A window frame and the wall around it expand and shrink at different rates. Plastic and aluminium frames move with the temperature, while masonry stays fairly still. So the sealant has to stretch and recover, which is why we use a low-modulus product. We work on aluminium frames, composite doors and timber windows & doors, and the jobs we see most are cracked sealant at the sill ends and rain getting in at the frame or under the sill.
In Portsmouth, windows range from older timber frames to modern uPVC and aluminium. The mastic around all of them ages, and it’s normally the first thing to let the weather in.
Big or small, you get the same 12-month guarantee.
- Place
- Portsmouth (PO6, PO4, PO1, PO2)
- Region
- Portsmouth
- Guarantee
- 12 months on all our work
- Quote
- A clear price before any work starts
- Call
- 0345 464 0079
- Updated
- 26 October 2026
Leave it or put it right?
Failed mastic is not a reason to replace sound windows. If the frames and glass are in good order, resealing the joints is often all that is needed. Problems with the glass or gaskets are for a window company, and we’ll say so. Busy buildings in Portsmouth, from hotels to offices, can’t afford rooms out of use for leaks or mould, so it pays to replace failing joints before they get that far.
A failed joint rarely gets cheaper to fix by waiting. If you’re not sure whether it needs doing, phone 0345 464 0079 or drop us an email and we’ll give you an honest view and a quote.
Why Portsmouth customers choose us
- Neat joints and a tidy finish
- Arbo and Everbuild products
- A choice of colours where the product allows
- A sealant colour to suit the surroundings
Read what affects the cost or our reviews.
FAQs for Portsmouth
Is Portsmouth in your area for window mastic?
Yes. Our work covers London and the South East, and Portsmouth is part of that. You can ring 0345 464 0079 or drop us an email and let us know what needs doing, and we will give you a clear price.
Do you work for landlords with property near Fratton station?
Yes, we work for landlords and letting agents. Just call 0345 464 0079 or email us and tell us about the property, and we’ll give you a clear price.
Is the new sealant paintable?
Most silicone can’t be painted. Let us know beforehand, and we will use a paintable product where it suits.
Do you have sealant for grey or black windows?
Yes, in most cases. Tell us the frame colour when you get in touch and we will match it as closely as we can.
Can resealing stop a draught around my window?
Often, yes. Air often gets in between the frame and the wall, and sealing the inside and outside joints closes that path.
Will you leave a mess?
Very little: the area around the joints is protected first, and we tidy up before we go.
Do you seal inside as well as outside?
Yes. Outside is the weather seal; inside closes the gap to the plaster. We can do either or both.
Do you work on first-floor windows?
Yes, in most cases. We plan safe access before the job, so mention the height and anything in the way.
Landlord and commercial work in Portsmouth
From a single let to a portfolio, the work is the same standard: the old material taken out, careful preparation and a 12-month guarantee.
A neglected joint can let water reach the structure, which is a bigger problem in a rented property. Keeping joints in good order is simple maintenance that we can handle for you.
When to call us in Portsmouth
Joints that are too thin or too deep fail early. A thin smear across a wide gap has nothing to it, and a gap filled solid cannot flex. Backing rod sets the right depth.
Signs it’s time to call us include:
- Cold air getting in at the frame edge
- Cracked or shrunken mastic around the frame
- Rain getting in at the frame or under the sill
- White mastic on grey or black frames
For site and facilities teams at buildings such as Manor Infant School, larger buildings have plenty of frames, and the mastic around each one ages.
What to look for in a quote
- When the joint can take water or movement
- Are they insured?
- Is VAT in the price?
- How the colour is chosen
Other services in Portsmouth
Should I try it myself first?
What a professional job adds is preparation and the right product. Joints are cleaned back to sound surfaces and dried, and the sealant is matched to the joint and its conditions, and the work is guaranteed for a year.
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and the joint depth matters as much as the finish.
Looking after it afterwards
To keep the joints looking good and working properly:
- Keep paint and stain on wooden frames in good order
- Wash the frames with mild soapy water
- Ventilate rooms so frames don’t stay wet inside
- Paint up to the joint, not over it
Wipe the frames with soapy water when you clean the windows, and avoid solvent cleaners on the sealant.
Leaks normally show up in wet, windy weather, but resealing works best in dry conditions. Sorting cracked mastic early means the joint is sound before the bad weather.
Different surfaces, different methods
Composite doors
A composite door normally sits in a plastic outer frame, so its perimeter joint is sealed much like a window. We match the colour to the frame.
Aluminium frames
Large aluminium doors have long joints down each side and across the head, and the threshold joint takes a lot of water. Each is cleaned, backed where deep and resealed.
What we do, step by step
There is not much for you to do on the day. Show us the job and we will take it from there. The work itself takes a few hours for a handful of frames, longer for a whole house. Where a business in Portsmouth needs to stay open, out-of-hours working can be arranged, and homes are booked within our usual hours, Monday to Saturday.
- We check how each frame can be reached safely.
- Old, cracked mastic is removed completely.
- The surfaces are cleaned and left dry, and primed where the sealant calls for it.
- Backing rod fills deep voids and the sealant goes in on top.
- The joint is shaped to shed water and the area tidied.
Before we arrive
- Where the joints are inside, avoid wetting them before we arrive
- For business premises, tell us about site rules or sign-in
- Mention any parking rules near the property
Getting 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 talk you through the work before giving you a price.