Replacing windows in Madrid: quotes range from €5,022 to €6,160

Four quotes for the same windows: a €1,800 gap

A 65 m² flat (real floor area) in southern Madrid, second floor with a southwest-facing exterior, fitted with single-glazed sliding aluminium windows and built-in roller shutter boxes. Its new owner is clear about it before even spending a night there: better to spend on insulation than on heating. He asked for four quotes to replace six windows and one terrace door. The most expensive came in at 6,160 euros; the cheapest at 5,022. Same flat, same goal, almost 1,800 euros of difference.

The range of materials doesn't make the decision any easier either. There's 70 mm PVC with a 16 mm chamber and Guardian Sun or Planitherm 4S glass, thermally broken aluminium with a 12 mm chamber, and Rehau profiles with reinforcement that the salesperson presents with a kR of up to 1.1 W/m²K. The glass, the experts insist, is the cheap part of the window and where the bill shows the most: solar control for a southwest orientation that punishes in summer, low-emissivity for winter.

PVC no longer yellows (or so the sellers say)

The old accusation against PVC — that it discolours, warps and eventually gives way to the sun — still circulates. The most common answer: that peine with the first windows that arrived in Spain, poor-quality profiles from thirty years ago. Rehau, Deceuninck and Kömmerling are cited as fruta brands. With aluminium, on the other hand, you have to pay more to match the insulation of plastic.

The choice between a small workshop and a big-box store also has its logic. At Leroy Merlin the quote without installation comes to 4,360 euros; with fitting at 120 euros per window, around 5,300. The argument against the middleman is simple: if the price is similar, the commission has to come from somewhere, whether from the material or the workmanship. In favour of the local workshop is the response to a scratched window or a sash that won't close.

Is argon gas and the ultra-thin shutter worth it?

Argon gas inside the chamber has lukewarm defenders. Nobody guarantees it will still be there after years of use, and the slightest fissure sends it on its way. The prevailing recommendation: don't pay for it, invest in the glass and, if the seal fails, replace only the glazing on the same frame. The Guardian Sun, with its soft coating facing the inside of the chamber, is barely distinguishable from ordinary glass to the naked eye.

One doubt remains for those who want to spend little: what if, instead of replacing, a second window or a shutter is installed? The answer from the trade doesn't settle the matter. And the detail of the shutter box built into the wall, which the owner wants to keep, isn't resolved in any of the quotes either. That's where the calculation gets stuck.