Assembling and building a permanent structure is forbidden on Shabbat, and is the av melachah of Boneh.1 This includes adding to an existing structure as well as leveling the ground to make it more usable.2 This melachah encompasses a wide range of forbidden activities and proper study of the subject will ensure that one observes its laws properly. Here, we will explore some of the basic principles.

Boneh in the Mishkan

The walls of the Mishkan were made from specially designed planks of wood that were inserted into sockets on the ground and connected to each other. The construction of these walls and the roof that was stretched over them are the source for the melachah of Boneh.

Creating a Land-Based Structure

The Mishkan, whose construction serves as the source for all forbidden activity on Shabbat, was a land-based structure. Therefore, the melachah of Boneh forbids creating any land-based, permanent structures. This includes fences, posts, houses and shelters. Paving a path with tiles3 or digging a hole in the ground to store things4 is also considered Boneh, as one is making the space suitable for a constructive purpose.

Home Improvements

Adding something to an existing structure in a permanent way is considered building, and doing so would transgress the melachah of Boneh.5 This includes many typical fixes done around the house, such as attaching a door knob, knocking a nail into the wall, or putting a door back on its hinges. For the purposes of our discussion, large appliances such as refrigerators are considered full fledged structures,6 and anything that is forbidden to be done with a structure would be forbidden to be done with them as well.

Assembling an Appliance

We will now turn our attention to binyan b’keilim - assembling movable items or utensils, which includes things like putting together a new baby stroller or assembling a piece of furniture. The Talmud7 clearly states that there is no prohibition against building (Boneh) or destroying (Soter) movable items. Nevertheless, throughout the Talmud we do find prohibitions against assembling or fixing such items.8 Various explanations are offered as to how to resolve this apparent contradiction. Some authorities9 say that fixing or building moveable items is not included in the Biblical prohibition of Boneh at all, and the issues surrounding them involve other Biblical prohibitions (like Makeh Bepatish - striking a final blow) or rabbinic safeguards. The accepted halachah does not follow this opinion, and in many cases assembling a moveable item will be considered full-fledged Boneh.10 Similarly, screwing back together something that came apart, is considered Boneh. The Sages forbade one to even loosely reattach loose parts, out of concern that one will do so tightly and transgress the melachah.11

When something is assembled to use for a short period of time and will be taken apart before Shabbat ends, there is room to say that Boneh is not transgressed at all.12 This is a useful argument to allow children to play with lego and building sets that are usually taken apart soon after they are built.13 Another reason to permit them is the fact that their regular mode of use is to be built and then undone. Whenever something functions in such a way, it is not considered a melachah. For example, closing or opening a door on Shabbat is not considered a transgression of Boneh and Soter (building and demolishing), even though closing the door effectively closes an opening (which would generally be a Boneh-like activity), because the way a door functions is that it closes and opens regularly. The same is true with children's toys.14 Folding chairs and the like are permitted on Shabbat being that no assembling of parts is involved; the chair is fully built and just needs to be folded into shape.15

Temporary Structures

As mentioned, the melacha of Boneh involves assembling and building a permanent structure. The Sages extended the prohibition to include the creation of temporary structures out of concern that it may lead to making a permanent structure.16 While it is beyond the scope of this article to delve into the intricacies of when something is considered a temporary shelter and when not, suffice it to say that creating any sizable sheltered space, especially if it is created to protect from the elements, is forbidden on Shabbat.17 Adding to a cover (that shelters the width of one handbreadth) already in place before Shabbat, is permitted.18 Therefore, if a tarp was set up before Shabbat (and is sheltering over one handbreadth), it may be extended on Shabbat to provide more shade.19 Extending the canopy of a baby stroller is also permitted on Shabbat,20 because that is its regular mode of use and can be compared to opening and closing a door as discussed earlier. Arguably, the same logic should apply to an umbrella, but many great halachic authorities21 strongly caution against the use of an umbrella on Shabbat, and such has become the accepted practice.22

Common Activities to Avoid:

  • Reattaching a broomstick to a broom.
  • Assembling a baby crib by connecting different parts.
  • Opening an umbrella.