Opening an umbrella on Shabbat is generally considered to be forbidden because of building. The linked article notes that while the g'mara (not specifically cited) does permit opening a folding chair, even though that creates a "tent" over the ground below, the purpose of opening the chair isn't to create the tent, while the purpose of erecting a structure ...
Yehuda Wiesen wrote a "Guide to Practical Halacha and Home Ritual for Conservative Jews" (available here), from which I quote (from the section concerning Shabbat):
There are many and various so called minor restrictions, some of which the Conservative
movement seems to follow and others that it does not. For example, Orthodox typically avoid
use of ...
The ארחות שבת (by Rav Yosef Gelber and Rav Mordechai Rubin) in Vol. 2 on page 294 in Siman 20:154 discusses this.
They write that one may wear a retainer - פלטה ליישור שינים - on Shabbat.
In the footnotes they explain that since the "medical" action [of moving the teeth] is not apparent, but takes a long time, therefore it's permissible.
Same logic should ...
Shmiras Shabbos Khilchasa (quoted by Rabbi Ribiat in his Sefer 39 Melachos) page 154-155 says it is permitted to add to a Ohel on Shabbos and therefore one may place a plastic covering over a stroller on Shabbos, so long the strollers own canopy is open already. He says the regular canopy can be opened as it is attached and then you place the plastic ...
To answer a mistaken premise of the question -- boneh is possible on the human body.
See Shabbos 107a:
המפיס מורסא בשבת אם לעשות לה פה חייב אם להוציא ממנה לחה פטור
If someone pops a pimple on Shabbos -- if he did so to make an
opening, then he is liable for punishment; if he intended to remove
the pus from inside, he is not liable
Rashi there ...
THIS JUST IN: According to Orchos Shabbos chapter 9 siff 13, one must warn their chinuch aged child not to use building blocks such as Lego or the like to build a house or anything which has an Ohel of a tefach by a tefach if they are going to be using the space inside of it. And if they make this edifice it is not allowed to dismantle it.
This is after ...
For any practical application, you should ask your rav as this is an issue where poskim (halachic decisors) differ. R Eliezer Melamed forbids it
One may not use hair spray or oil to keep one’s hair in place, because
this is similar to Boneh (Rivash as cited in BHL 303:27 s.v. “laĥof”).
Matzav.com brings a more nuanced perspective though
The use of ...
Living as I do on the edge of the Amazon Rainforest, I feel rather well qualified to answer this question.
A coconut shell is indeed חותלות - just as we can't eat an orange without peeling it, we can't drink the coconut water or get at the coconut meat without smashing the coconut shell open.
That said, how are you doing that? In my home, a machete is a ...
It seems from Shulchan Aruch O.C. 315:12 that this is forbidden.
He quotes the Rambam's position (Shabbat 22:32) that when hanging a curtain and the like we must be careful not to make a roof (ohel) while spreading it. Therefore if it is a large curtain, only two people may put it up, but one person may not.
הַנּוֹטֶה פָּרֹכֶת וְכַיּוֹצֵא בָּהּ צָרִיךְ ...
If the Talis would be a very thick material which does not flop over when held up, it would be Ohel. This is the way the Taz (and similarly the Magen Avraham) explain the opinion of the rishonim brought in siman 301 siff 40. They are subsequently brought in later achronim like Mishna Berurah 151.
The Taz 27 specifically mentions Atifa, and the Magen ...
R Jack Abramowitz clarifies (here) the distinction between the permitted and forbiddden part of the melacha of boneh (assembling or building)
While the av melacha (primary labor) involves both assembling separate
pieces into a unified whole and forming a shelter, either activity is
prohibited on Shabbos, even if the other is not accomplished.
I've seen a bunch of people bring umbrellas to shul on Shabbat and leave them open during in the coat room during service. I know you're not supposed to open an umbrella on shabbat but there's a different rule for carrying an already open umbrella. If you open the umbrella before shabbat it's permissible in an erev. The torahmusings link suggests that you ...
The גמרא is referring to an אוהל עראי - a temporary tent - in all the cases on that page, IIRC.
The logic goes, that once you have a Tefach, you have an אוהל עראי -and now you are simply enlarging it.
The Noda BiYehuda and others discuss it; seems like enlarging a tent is D'Rabonon and so is making an אוהל עראי - and 2 D'Rabonons are allowed.
This is actually forbidden.
As background, building new items is forbidden because of the melacha of boneh. Rebuilding is somewhat easier but not that much. As R Daniel Braude (Learn Shabbos, pp. 292ff) explains
fastening tightly (e.g., with screws, nail or glue) is forbidden min haTorah
fastening loosely (e.g., attaching parts of an item in a way ...
Those Halachot are quite famous, this is where you should start looking:
מטה של פרקים, אסור להחזירה ולהדקה, ואם תקע חייב חטאת. ואם היה רפויה
A bed made of "joints" (parts that are made to disassemble and reassemble): It is forbidden to assemble it (on Shabbat), and if he did he needs [to offer] a sacrifice. And if it's ...
The Shulchan Aruch (OC 315:1) writes that Chazal forbade making a temporary ohel on Shabbos. The Gemara (Shabbos 138a) writes that one may unfold a folding chair on Shabbos. While doing so creates a shelter over the space underneath the chair that is not considered making an ...
As explained in the Mishna Berurah siman 303 #82 the reason braiding hair would be Boneh rather than Oreig is specifically because it is attached to and part of the human body. This then would not be a contradiction to the fact that it is an erva, but rather a complimentary idea.