Fencing an area with partitions to make carrying in it permissible, will serve that purpose only when the area was fenced around for dwelling purposes. What is meant by "fenced around for dwelling purposes" ? If you built a house to live in, or you opened a door from your house, and fenced the area with partitions, the way courtyards are built for houses, then, even if the [enclosed area] is very large, it is an absolute private domain. But areas that have been fenced around for other than dwelling purposes, such as gardens or orchards,¹ 358: 1 on whether animal dwellings are considered dwellings. whose fences are made only to guard their contents, these are graded by their size. If the area would not require more than two seahs² [of seed], you may carry things in it, but if it would require more than two seahs [of seed], it is considered a karmelis.³ it is a private domain [Shulchan Aruch Harav 358]

footnotes: ¹ See Biur Halachah ² See paragraph 2. ³ Rabbinically. But mide’oraisa

What is the size of an area requiring two seahs [of seed] ? It is the area of the courtyard of the Tabernacle, [which was] one hundred amos long by fifty amos wide. If the space is a square, it would measure seventy amos and four tefachim by seventy amos and four tefachim. (In our amos it measures fifty three by fifty three and a little more).⁴ If the area is circular or in any other shape, it should also be calculated to measure 5, 000 square amos. (In our amos it is 3, 750.)⁵ However, if the length of the area is more than twice its width even if only by one amah,⁶ longer it is valid. [Magein Avraham, Mishnah Berurah] then it is considered as requiring more than two seahs [of seed],⁷. If it is less, you may carry there regardless of its length. [Peri Megadim, Rabbi Akiva Eiger—Rambam 16: 4, Mishnah Berurah 358: 12] since it does not resemble the courtyard of the Tabernacle.

footnotes: ⁴ The author’s intent here is unclear. ⁵ See preceeding note. ⁶ If it is less than one amah ⁷ This is true only if the area is a beis sa’asayim

A space which has been fenced around for other than dwelling purposes, and which is not larger than "two seahs" so that you are allowed to carry in it, if there is a courtyard next to it, you are also permitted to carry from there into the courtyard and from the courtyard into the enclosed space, because [the enclosure] and the court are considered as one domain. However, it is not considered the same domain as the house, and therefore the vessels in such an enclosed space are forbidden to be carried into the house, and vessels that are in the house are forbidden to be carried into the enclosed space.

If you fenced around a space with partions⁸ it seems that this holds true even if you fenced the area with the intention to build or open up the house. The Peri Megadim and Shulchan Aruch Harav support this view, but the Mishnah Berurah 358: 19 tends to be meikil. Sha’ar Hatziyun 358: 21 quotes Rishonim and Acharonim to that effect. for other than dwelling purposes, and afterwards built a dwelling on it, or you made a door in the house leading to it; what can legally be done to change it into an enclosure for dwelling purposes? You should make a break in the partition of more than ten amos; because an opening of ten amos is considered a door; but if it is more than that, it is considered a break, whereby the partitions will be nullified.⁹ 358: 12. See Rema for other methods. After that if you repair the fence,¹⁰ (doorway). [Peri Megadim 358: 5] it will be considered as fenced around for dwelling purposes.

footnotes: ⁸ From the Kitzur Shulchan Aruch ⁹ Mishnah Berurah ¹⁰ Or you can make a tzuras hapesach

[If you have] a courtyard that is larger than two seahs, and you planted trees in it,¹¹ 6, Resp. 48] even in the greater part of it, the status of dwelling is thereby not nullified, and it is still considered as fenced around for dwelling purposes, because people usually spend time in the shade of trees. However, if you planted¹² say that gardens planted for beauty and relaxation are like trees. [Maharyo Halevi 2, Resp. 101, Maharsham 6, Resp. 48 Imrei Yosher 1, Resp. 109. The Divrei Chaim 2, Orach Chaim Resp. 25 disagrees.] seeds that cover the greater part of the yard (even if it is not in one area, but scattered) the status of dwellings has been nullified¹³ say that planting nullifies the status of dwellings only when the planting was done after the walls were put up, but if you put up a wall around an existing garden for dwelling purposes, the garden does not affect the status of the dwelling. [Divrei Malkiel 4 Resp. 3; Dovev Meisharim 1 Resp. 2] and the entire [yard] is considered as a garden. If [the planted area] covers less than half of the courtyard; and this area is less than two seahs, it is of no consequence compared to the courtyard and the whole area is regarded as a courtyard.¹⁴ 358: 83] But if [the planted area] covers more than two seahs (in one place), then the planted area is regarded as a karmelis, and the rest of the courtyard is completely open to a place which is forbidden (to carry into), and thus it is forbidden to carry anything in it except within four amos.

footnotes: ¹¹ Including non-fruit bearing trees. [Maharsham ¹² Vegetable seeds. Most poskim ¹³ Most poskim ¹⁴ Except that you may not carry vessels from the house to the garden. [Mishnah Berurah

Likewise, a courtyard measuring only two seahs or less, part of which has been planted, should also be judged by the greater part of it. If the greater part has been planted, although you are permitted to carry there, since it is not larger than two seahs, nevertheless, vessels that are in your house are forbidden to be carried into it. Therefore, it is necessary to make a partition in front of the garden in order that you may carry things from the house into the courtyard.¹⁵ 358: 10, Mishnah Berurah.

footnotes: ¹⁵ Shulchan Aruch