Windows come up on nearly every report we write on an older house in Portugal. Either it’s the original single glazing in timber that has gone soft at the bottom rail, or it’s replacement aluminium or PVC that someone foamed into the hole and rendered over. Below are the window figures from our 2025 and 2026 reports, from a two-bedroom flat in Porto to a manor house, so you can see roughly where your own house will land.
Pricing this on a property you’re about to buy? Our pre-purchase inspection puts a cost range on every finding, from €490 + IVA. Already own it and holding a quote? Quote Check, €220 + IVA. Not here to run the job? Project management, priced per project.
What we actually priced
- Two-bedroom apartment, Porto, economy PVC double glazing throughout: €7,500–8,500.
- Whole apartment, premium thermally broken frames: €12,000–22,000.
- Farmhouse, 12 windows: €8,400–14,400 with a standard double-glazed unit, or €12,000–20,000 for windows rated Uw 1.4. That’s about €700–1,200 a window for the first and €1,000–1,700 for the second.
- Manor house, every window replaced: €53,000–86,000. Secondary glazing behind the original windows came to €450–750 a window instead.
- One badly fitted window, stripped out and re-bedded: €700–1,100 per opening.
- Security front door: €1,800–3,800.
What the spec gets you
Uw is the heat lost through the whole window, frame and glass together. The lower the number, the better the window. On the farmhouse, going to Uw 1.4 cost another €3,600–5,600 across the twelve windows. In a house you’re going to live in through a Minho or Porto winter, we’d usually spend it.
With aluminium the thing to ask for is a thermal break, an insulating strip between the inside and outside of the frame. Without it the frame carries the cold straight through and you get condensation running down the inside of the frame every cold morning. Economy PVC does a reasonable job in a flat and is the cheapest way to get rid of single glazing. Premium frames cost more for slimmer profiles, better seals and hardware that lasts.
Looking at a property with this kind of problem? Our pre-purchase inspection finds it and prices it before you sign. From €490 + IVA.
The fitting matters as much as the window
A good window fitted badly will perform worse than an old one fitted well. What we find most often is a new frame foamed into the opening with no proper seal to the wall, then plastered or rendered over. Water gets in round the sill, the reveal stays cold, and the mould starts there. Putting that right means taking the window out and bedding it again properly, which is the €700–1,100 per opening above, on top of what was paid for the window the first time.
The other thing new windows do is stop the draughts that were drying the house out. We see it again and again: a house renovated, sealed up with new glazing, no extraction, and black mould by the second winter. A bathroom extract fan is €350–600. Budget for ventilation in the same job. More on that in mould in renovated homes.
Old houses, historic centres and flats
Swapping windows for equivalent or better ones in the same openings doesn’t normally need a licence. Inside a historic centre or a protection zone the Câmara can dictate the window type, the material and the colour. In a flat, the street-side windows are part of the look of the building, so changing them needs the condominium. Check both before you order anything. The detail is in do I need a licence to renovate.
On the manor, replacing every window was a big number for windows that were part of what made the house worth buying. Secondary glazing at €450–750 a window kept the originals and dealt with most of the heat loss. On a house with good timber windows that’s often the better spend.
IVA
All the figures here are ex IVA. Under DL 97/2026, construction and renovation works on a permanent home can be charged at 6% IVA instead of 23% (verba 2.42), from 1 July 2026 to the end of 2032, on properties up to a value cap of €660,982. Whether your window job qualifies depends on the property and how the contract is written, so get your accountant to confirm it before you sign. More in what it costs to renovate in Portugal.
Before you buy
On an inspection we open and close every window we can get to, check the frames, sills and reveals for water and mould, and look at how the newer ones were fitted. If they need replacing, the report puts a cost range on it so you can take it into the negotiation. For the wider picture on cold houses, read why Portuguese houses are cold and damp. If you already have a window quote, Quote Check will tell you whether the spec and the fitting are in it.
Figures are from our own inspection reports in 2025 and 2026, ex IVA, with names and addresses left out. Every house is different, so treat them as a guide to scale, not a quote.
Planning the work?
If you’re buying, we inspect first and cost the work in the report. If you already own it, we check the builder’s quote before you sign it. And for owners who live abroad, we manage the job on your side of the table: vet and tender the builders, check the work and the invoices, deal with the Câmara.
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