Rav Yosef Kushner
Answer: Building has its own set of halachos regarding working on Shabbos. Since construction is done in public, there is a problem of maris ayin. People who see the building being done will know that the house being worked on belongs to a Jew; therefore, they may assume that he is allowing sechirai yom to do forbidden work for him on Shabbos. For this reason, the halacha is that one may not even allow a kablan to work on his house on Shabbos.
Since the problem is based on maras ayin, one might think that in a situation where everyone knows that the worker is a kablan it would be permitted; however, the Biur Halacha says that even if the worker is doing the type of job that is always done by a kablan, such as building a house, it still should not be done for a job performed in public. While it is not clear why that would be, the Poskim accept this as the practical halacha. Accordingly, it is forbidden to allow a kablan to do any work in public for a Jew in a place where Jews live nearby and will see it.
Even if one lives "off the grid", on a property that is not visible from the street, he still would not be allowed to have a kablan do work on his home. Chazal say that this is prohibited because the homeowner may have guests who will see the ongoing work.
Even if one has a contractor doing work inside his home, such as fixing tiles, it is seemingly forbidden, as we do not see the Poskim making any exceptions in such cases. Apparently, this is also prohibited as passersby will see the worker going back and forth to his truck and will realize he is working on Shabbos. | 
