The GRIDON Extension Calculator gives you a quick and easy ballpark figure of the costs for your extension. The costs calculated here offer a general idea, but cannot completely replace a formal price estimate. Still, the cost calculator offers a decent indication of the approximate costs. Specific technical considerations sometimes play a major role in the final costs, such as vibration-free pile driving. The price can also be affected by the quality and/or luxury of the various elements, such as the façade and skylights.

Roughly speaking, an extension costs about €3500 – €4500 per m2 . However, there are quite a few factors that impact the price. A smaller extension (under 10m2) is usually much more expensive per m2 because the basic costs are still considerable. If there is enough room to do so, it is usually more cost-effective to build a somewhat larger extension. On average, extensions are around 15m2 (usually between 12m2 and 20m2). From 15m2 and up, the benefits of scaling up no longer apply; from that point, the cost per m2 largely determines the price. In the end, it is the extra details and luxury elements that have the greatest impact on price.

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