Written by Mark Reid,
Trades Editor ·Verified 23 September 2026
Portsmouth's housing stock throws up a fair range of window jobs, from Victorian terraces in Southsea and Fratton with their original sash windows, to 1930s semis around Copnor and Baffins, plus the newer builds out towards Port Solent and the harbour developments. Salt air off the Solent doesn't do timber frames any favours either, so a lot of local installers spend as much time dealing with weathered wooden frames and swollen sashes as they do fitting modern uPVC or aluminium units. Flats and terraces close to the city centre often mean tighter access and scaffolding considerations too, which is worth bearing in mind when you're comparing quotes.
The businesses listed here are pulled from public business listings and ranked by their review rating and how many reviews they've built up, with a small lift given to those showing a working website and phone number. We then check each business's homepage to confirm window installation is actually what they primarily do, which stops general builders or unrelated tradespeople slipping onto this page. Listings flagged as permanently closed are stripped out automatically as part of that process. Where you spot a Trust Verified badge, that business has gone through our fuller verification, covering trade qualifications and accreditations, public liability insurance, trading history, customer review history and registered company information. Our How We Verify page sets out exactly what that involves. For any business without the badge, those checks haven't been done by us, so it's on you to look into them before booking.
Before signing anything, ask for a written quote that breaks down the frame material, glazing type and installation cost separately, and get confirmation of FENSA or CERTASS certification, since that's what covers the building regulations side of window replacement. Check whether the guarantee covers the frames, the glass and the workmanship, and for how long, because these can differ. It's worth getting two or three quotes for anything beyond a single window, as prices for the same spec can vary quite a bit between installers in Portsmouth. Ask previous customers or check reviews for how tidy the fitting was, since window installation creates a lot of dust and rubble, particularly on older properties where the reveals need building up.
How We Select & Rate The Best Window Installers in Portsmouth
Rankings are driven primarily by review rating and review count from public business listings, with a small lift given to businesses showing a working website and phone number. We check each business's homepage to confirm window installation is what they primarily offer, which keeps unrelated trades off this page. Listings flagged as permanently closed are removed automatically. Businesses marked Trust Verified have additionally passed our full verification, covering trade qualifications and accreditations, public liability insurance, trading history, customer review history and registered company information; see our How We Verify page for the full list. Other businesses haven't been independently verified by us, and being listed isn't an endorsement. Always do your own checks before hiring.
Recommended and Featured listings are paid placements, so a business's fee affects whether and where it appears. Every other listing is ranked on rating and review count from third-party business listings. How we rank & verify →
BJH Windows is a Portsmouth-based window installation company serving residential customers across the area. Rated 4.9 from 77 Google reviews, the business has built a consistent local reputation for quality fitting work. Its postcode coverage centres on PO6, making it a practical choice for homeowners in the north of the city.
Sussex Sash is a window installation company serving Portsmouth and the surrounding area, with a focus on sash window replacement and restoration. The postcode PO36 8EG places the business within the Isle of Wight corridor, suggesting coverage across a distinct coastal patch. Householders in period properties are the natural audience, given the specialism implied by the name.
Covering Portsmouth and the surrounding coastal area, Crest Windows & Conservatories Ltd installs windows, doors, and conservatories for residential properties. The PO11 postcode base places the company well for serving Hayling Island and its neighbours. Enquiries and further details are available through crestwindows.com.
Historical window repair and secondary glazing sit alongside replacement windows, roof lights, and UPVC doors in the service range offered by Days Window & Door Services, based in Portsmouth. The company also fits insect screens and skylights, covering a broad spread of domestic glazing work. A Google rating of 4.5 from 15 reviews reflects broadly positive feedback from local customers.
Transparency notice: Recommended and Featured listings are paid placements, so a business's fee affects whether and where it appears. All other listings are ranked by a combined score drawn from ratings and review counts published on third-party business listings, plus basic completeness signals such as a working website and phone. A Trust Verified badge means we have independently checked that business's documents; businesses without it have not been independently verified by us. How we verify →
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How much does a window installers cost in Portsmouth?
A single uPVC casement window, supplied and fitted, typically runs from around £400 to £700 depending on size and glazing spec. A full house re-fit for a three-bedroom semi in areas like Cosham or Drayton can land anywhere from £4,000 to £9,000 depending on how many openings you've got and whether you go for uPVC, aluminium or timber. Sash window renovation or replacement in the older Southsea terraces tends to cost more, often £700 to £1,200 per window, because of the mechanism and the trickier fit. Getting two or three quotes is standard practice and helps you spot anyone pricing well outside the local range.
How long does a window installation job take in Portsmouth?
A handful of windows can usually be done in a day or two once the frames arrive, which is typically three to six weeks after you place the order for made-to-measure units. A full house re-fit, say eight to twelve windows, often takes two to four days on site. Older properties with rotten timber frames or brickwork that needs making good around the reveals can add extra time, so ask your installer for a realistic estimate based on your specific property.
Do I need planning permission to replace windows in Portsmouth?
Most window replacements fall under permitted development and don't need planning permission, but there are exceptions. If your property is listed or sits within a conservation area, which covers parts of Old Portsmouth and areas around Southsea's seafront, you may need consent, particularly for changes to style or materials on street-facing elevations. Check with Portsmouth City Council's planning department if you're unsure, and ask your installer whether they've dealt with conservation area rules before.
What's the difference between FENSA and CERTASS certification?
Both are competent person schemes that let installers self-certify compliance with building regulations without needing separate council sign-off. FENSA is the more widely known and covers the vast majority of window and door installers in the UK. CERTASS offers similar coverage. Either is acceptable, but make sure your installer is actually registered with one of them and ask for the certificate once the job's finished, as you'll need it if you ever sell the property.
Should I choose uPVC, aluminium or timber windows for my Portsmouth property?
uPVC is the most common choice locally because it's low maintenance and handles the salty coastal air well without rotting or corroding. Aluminium suits modern extensions and larger glazed areas, and copes well with the exposure you get near the water, though it costs more upfront. Timber gives period properties in areas like Old Portsmouth or Southsea the right look, but needs regular repainting or staining to hold up against the weather, so factor that ongoing cost in before deciding.
How do I check a window installer in Portsmouth is worth hiring?
Ask to see their FENSA or CERTASS registration number and check it against the official register online, don't just take their word for it. Request proof of public liability insurance and ask how long they've been trading locally. Look through recent reviews for comments on tidiness, timekeeping and how they handled any snags after the fit. If a business on this page carries our Trust Verified badge, those checks have already been done as part of our full verification. If it doesn't carry the badge, treat it as unverified and do the legwork yourself before you book.
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