Different levels of financial loss
In the first paragraph of this siman, the Shulchan Aruch states: “If one’s garden wall became broken, he may build it up in an unskilled manner” – e.g. using stones to temporarily patch the breach. Further it states: “However, if the wall separating between his courtyard and the public domain broke, he may build it up in the normal manner” – i.e. even in a skilled manner. Mishnah Berura explains that in the first case, the loss factor is small, with the fear being only that a few animals may enter and forage in his garden, whereas in the second case, the concern is that thieves may enter his property and steal everything – which is a bona fide DHA! See the difference?
Another new point is the element of danger to people. If the falling wall presents a safety risk, one may even demolish the entire wall and then re-build it from scratch, if necessary! Here an additional rationale is introduced: If we do not permit him to build a proper wall after he demolishes the broken one, he is likely to refrain from demolishing it altogether, causing the danger to remain unchecked!
Hiring a non-Jew
(Excerpted from MBY 537:1-16, 538:1-6)
“In general, one may not instruct a non-Jew to do any melacha for a Jew on Ch”H (with or without pay) which the Jew himself is forbidden to do…”
Hilchos Chol Hamoed Zichron Shlomo, by Rabbis Zucker and Francis, pp. 111-114:
Construction on Real Property
“One who is having a house built by a non-Jewish builder may not allow this work to continue during Ch”H. Construction must be halted even if it will result in additional costs. It is prohibited even when done under a job-contracting agreement and even if the builder was not instructed to work on Ch”H… (Ed. Contracting is generally treated more leniently than a “per diem worker” since the contractor is essentially working “for himself” and being paid only for the completed job, not for his labor day-by-day. However, there is the halachic issue of ‘maris ayin’ – semblance of wrongdoing, i.e. a suspicion by onlookers that the builder was hired on a per diem basis.) There is a view which permits construction work on Ch”H under a job-contracting agreement, if this is the customary arrangement in the city for this type of work. However, one should not conduct himself according to this view without consulting a competent Rabbinic authority.”
Gardening“Gardening is another example of work done on real property and is subject to the same laws as construction work…”
Repairs (Ibid. p. 36-37)
“Complex home repairs which normally require the services of an electrician, carpenter or plumber may not be made on Ch”H by either a skilled professional or a capable homeowner. Since such repairs entail a ‘maaseh uman’, they are prohibited even when needed on the festival, unless a halachically valid ‘shinui’ (deviation) is employed.” (Note: If the repairs were necessary for basic physical needs – plumbing, hot water, heating or air conditioning etc. - a Rabbinic authority should be consulted for possible leniency. Generally speaking, physical needs are treated the same as ‘tzorech ochel nefesh’ / work needed to prepare food - ! - which is not restricted by ‘maaseh uman’, ‘tircha’/exertion or even pre-scheduling for repair on Ch”H! Also, in the event of a DHA, there may be grounds for leniency as well.)
Summary: In considering a possible heter for building or heavy repairs, one must begin by determining whether the need falls into the category of tzorech hamoed, DHA or tzorech ochel nefesh. Always consult a Rav when in doubt!