From: Rabbi Moshe Sofer
To: Rabbi Zelig Leib
A synagogue owner whose roof needs repair wishes to build a grain storage loft above the synagogue. The Chasam Sofer rules this is forbidden, as a grain storehouse constitutes fixed degrading use above a space with full synagogue sanctity. The nobleman's theoretical right to redeem the land does not diminish the owner's current ownership and cannot serve as grounds for leniency.
Source: Shu"t Chasam Sofer OC §30