We have recently purchased a small apartment in the historic

Construction costs throughout Europe have gone up significantly since the start of Putins "liberation' of Ukraine  so a rise is expected.

However, it does depend on several factors. 

   1.  When was the original estimate given?

   2.  What works have been carried out?  Different material costs have risen differently.  Materials shortages have had major effects

   3.  Labour costs have risen.

However, did your builder keep you on formed of price increases as the works progressed?

....and were there any unforeseen changes since the preventivo? Working on existing buildings usually results in extras which couldn't be foreseen. As you'll know a preventivo is just an estimate.  

Some costs went up due to Putin,  Most went up because with the introduction of the 110% incentives, the demand was high, and since ' the state was paying'  the retailers decided to make a killing.  Some prices are now coming back down, but yes, you will find that costs have nearly doubled, and more than doubled in some cases, over the least 2 years.   Similarly labour costs have gone up as companies looked for extra hands.  This is now going into reverse.  This has been also impacted with high electricity costs which means that tiles, sanitary ware, glass,  anything that requires kilns and heat, have gone up hugely, as well as being much more difficult to find, as many companies just shut up shop over the winter.    If you wait another 3 or 4 months before getting another computometrico you should notice a difference in your favour. 

Certain things they could not have known.  Most builders are covered by increases in costs of materials etc.  It depends what you mean by preventivo.  Was it a full computometrico prepared by a professional or was it 'back of an envelope' from a local builder? 

But  I doubt you have recourse.  Have you a geometra/architect on board? 

You obviously don't have to pay whatever they ask for so you should tell them that before you pay for the extras they have to fully justify it. That doesn't mean wooley words but proper analysis of each increase. How easy that will be will depend, as Modicasa alludes to, on what detail was provided in the preventivo. There should have been a computo metrico - an itemised list of works with quantities and unit prices

my thought is that if you trust your designer, project manager, you must study with him all the possible alternatives, of reducing the price - And in any case, absolutely do not resort to lawyers and courts, these procedures, in Italy, last years , and finally, the value of the house, and all your savings, will not be enough to pay all the expenses - Know however, that you can make a contract, with some supplier companies to have a VAT reduced to 10% - and also , if you have at least your elective residence in Italy (like some of my clients) obtain some concessions, both from Enel Energia - or simply with the discount on the invoice - follow these links - I RECOMMEND, in this period DO NOT be in a hurry to start the work, but analyze, analyze, analyze.. material prices are going down

https://www.fiscoetasse.com/normativa-prassi/13221-cessione-crediti-edi…

https://www.myaedes.com/blog/cessione-del-credito-e-superbonus-aprile-2…

I so appreciate everyone's comments and suggestions.  At this point, the work is nearly finished.  As I analyze the expenses it is becoming clear that the price of the renovation is not elevated.  It has come in fairly on budget; however it is costing me twice as much.  I will need to analyze the other payments that have not been paid to other entities connected with the reno.  There  seem to be hidden costs that we were not made aware of.  Plus, as I speak only English and just enough Italian to get into trouble, it was difficult because the contract was in Italian.  When I asked to have them translate it into English I was told it would cost 500 euro.  Something is wrong...

Lisa

try asking - in uk - an English restoration company, for a small apartment, to sign a contract written in Italian ...