They call it a loft.
Other posts of interest
https://www.vintageandchicblog.com/201...
https://www.eleconomista.es/empresas-finanzas/noticias/11006721/01/21/Openbank-calienta-el-mercado-de-las-hipotecas-con-rebajas-de-precio-a-tipo-fijo-y-mixto.html