About Pesach cleaning… It seems humanly impossible to find every single crumb that may be around the house – so to what extent is a person expected to clean? Most of us come to the seder totally exhausted!
There is a difference between Pesach cleaning and the obligation of cleaning for Pesach. Although many clean houses thoroughly before Pesach, including much that is not obligatory, the basic obligation is to ensure that there should be no pieces of chametz larger than a kezayit in places where the chametz is liable to arrive at. Some maintain that one should search even after smaller crumbs, but not in places where the crumbs would have certainly become sullied.
Therefore, it is important to check couches, schoolbags, beds, and so on — places where chametz might be found. But, there is no obligation to check closets (that children don’t reach), bookcases (again, depends on children), and there is no need to clean between the tiles, and so on.
The secret of efficient cleaning for Pesach is organization. Make a “cleaning-plan,” start early enough, and if you are under pressure don’t go overboard on cleaning that is not required (windows, and so on).
The basic obligation of bedikas chametz is to ensure that there are no sizeable pieces or items of chametz in places where there is such a possibility. For those with children, one cannot tell where a cookie or a wafer have ended up, and such items must be searched for. Even for adults, we may put a bottle of beer somewhere and forget about it, and so on.
Concerning pieces of chametz smaller than a kezayis, according to Shulchan Aruch (442:11) there is no obligation to check for crumbs that are smaller than a kezayis (see Gra 442:11; Peri Megadim, Eshel Avraham 12 in the name of Kesef Mishnah). Mishnah Berurah (442:33), however, cites the opinion of poskim who are stringent in this regard, and obligate checking for pieces even smaller than a kezayis. Moreover, according to Chazon Ish (116:13) even Shulchan Aruch agrees to this, and is only lenient concerning crumbs that are stuck to the sides of a vessel.
For crumbs of bread, rather than dough, most poskim agree that there is no obligation to check for crumbs (see Shaar Hatzion 433:33; see also Iggros Moshe, Orach Chaim Vol. 1, no. 145, who distinguishes between smaller crumbs and larger crumbs). Even those who are stringent concerning breadcrumbs (see Chayei Adam 119:6 and Chazon Ish 116:13) agree that where the crumbs become dirty, are stepped on, and so on, and such crumbs do not need to be searched for.