Hilchos Sukkah: Canvas Walls, Ruach Metzuyah, and Porch Railings

Topics

• The Question of a Canvas Sukkah
• Why the Mechaber Is Concerned About Yeri’os
• Does Modern Heavy Canvas Change the Halachah?
• The First Diyuk: Detachment Is Not the Same as Movement
• A Second Possible Heter: The Porch Railings
• The Mishnah Berurah Makes the Problem Harder
• Is This an Issur—or an Added Chumra?
• How Much Movement Invalidates a Wall?
• Not Every Moving Wall Is the Same
• What If the Wind Cannot Reach the Wall?
• Rav Moshe: Stringent Overall, but a Possible Distinction
• The Porch Railings
• The Final Problem: Are the Porch Railings the Same as the Mechaber’s Canes?

Transcript

## The Question of a Canvas Sukkah

I want to discuss a very practical question: **what is the halachic status of a canvas sukkah?**

For years I had a beautiful wooden sukkah that fit my porch. Then I moved into a much smaller apartment with a small porch, and the old sukkah simply could not fit. I ended up borrowing an older canvas sukkah.

Immediately I began hearing comments.

Everyone else had wood. I had canvas.

So I decided that instead of worrying from comments, we should open the Shulchan Aruch and learn the sugya properly.

The central source is Shulchan Aruch, Orach Chaim 630:10. The Mechaber discusses one who makes a sukkah among trees and uses the trees themselves as walls. If the branches move in an ordinary wind, they must be strengthened and secured **“ad shelo tehei ruach metzuyah menidah osam tamid”**—until a normal wind will not continually move them.

The Mechaber also requires the open spaces to be filled so that the wall is halachically complete.

This gives us our first principle:

A sukkah wall cannot simply be something that the normal wind blows around in a way that destroys its status as a mechitzah.

But before we apply that to canvas, we have to read the next part very carefully.

The issue is not automatically, “Canvas moves, therefore canvas is pasul.”

That is too quick.

We have to ask exactly what the Mechaber is worried about, what the Mishnah Berurah adds, and whether a modern canvas sukkah actually fits the case.

## Why the Mechaber Is Concerned About Yeri’os

The Mechaber continues from the case of the trees and speaks directly about walls made from **yeri’os**—cloth curtains or sheets.

This is the source everyone cites when they say a canvas sukkah is problematic.

The language is important.

Even if the yeri’os are tied, the Mechaber says it is not proper to rely on them alone, because sometimes the ties can become detached—**zimnin d’menatkei**—and the owner may not notice. Then the wall may become a **mechitzah she’einah yecholah la’amod bifnei ruach metzuyah**, a wall unable to withstand an ordinary wind.

The recommended solution is to place **kanim b’pachos mi’gimel**—canes or bars spaced less than three tefachim apart.

Why does that help?

Because through **lavud**, those canes themselves become the wall. Even if the cloth ceases to function properly, the halachic mechitzah still exists.

This is where the entire controversy over canvas sukkahs begins.

The Mechaber does not simply say, “Cloth is invalid.”

He describes a practical concern: the material may come loose and the owner will not realize it.

That distinction is going to become extremely important.

Some contemporary poskim are stringent and advise not using cloth walls at all where one can avoid it. Rav Moshe Sternbuch is cited in that direction.

But before we conclude that every canvas sukkah is a problem, we have to ask:

**What if the canvas is attached in a way that simply cannot become detached?**

And what if there are already railings or bars spaced less than three tefachim apart?

Those questions may change the entire analysis.

## Does Modern Heavy Canvas Change the Halachah?

A common argument is that the yeri’os of the Shulchan Aruch were thin sheets, while today's canvas walls are heavy, reinforced, and attached much more securely.

I once saw a teshuvah from Rav Moshe Feinstein dealing with precisely this argument. I saved a copy from my yeshivah years. I am not certain whether that exact text appears in the standard published volumes, so the source should be verified before publication.

The argument presented to Rav Moshe was essentially this:

Perhaps the Mechaber was speaking about light linen sheets that fluttered and detached easily. Modern canvas walls are much heavier and stronger.

Rav Moshe did not accept that argument so quickly.

His response was very sharp:

Do we really think that in the days of the Mechaber people did not know how to construct a strong tent?

They certainly knew how to make durable walls and coverings.

Yet the Mechaber still wrote that relying on yeri’os alone was not the proper approach.

So the fact that modern canvas is heavier does **not**, by itself, remove the problem.

That is important.

We cannot simply say:

“This is modern technology; therefore the old halachah does not apply.”

But I still want to make a different diyuk in the Mechaber.

The Mechaber’s explicit concern is not merely that the fabric moves.

His stated concern is that it may become **detached** and the owner will not realize it.

If so, perhaps a modern attachment system that cannot reasonably come loose addresses at least that specific concern.

That is the opening I want to examine.

## The First Diyuk: Detachment Is Not the Same as Movement

Read the Mechaber carefully.

When he speaks about the trees, the language is movement: the wall must be strengthened so that a normal wind does not continually move it.

But when he moves to the yeri’os, his concern is stated differently.

He says they may become **menatkei**—detached—and **lav ada’atei**, the owner may not notice.

That sounds like a different problem.

The wall was tied properly.

Then the knot or attachment came loose.

Now the wind can move it to the point that it is no longer a valid wall, and the owner does not realize what happened.

If that is the Mechaber’s concern, then suppose I attach a modern canvas wall in a way that cannot realistically become untied.

For example, the material has loops built around the frame and is secured at the top and bottom with strong fasteners or zip ties.

It may flap.

But it is not going anywhere.

The attachment is not going to open without someone physically cutting it.

If the concern is **“perhaps it will become detached,”** I have eliminated that concern.

That does not yet prove that the sukkah is kosher.

I am only separating the questions.

There are really two possible problems:

1. **The material may become detached.**
2. **Even while securely attached, the material may move too much in the wind.**

The Mechaber’s language gives me reason to say that the first issue may be solved by secure attachment.

Now we have to determine whether the second issue exists independently.

That is where the Mishnah Berurah becomes crucial.

## A Second Possible Heter: The Porch Railings

There is another possible way to look at a canvas sukkah built on a porch.

The Mechaber recommends **kanim b’pachos mi’gimel**—vertical or horizontal members spaced less than three tefachim apart—so that even without the cloth there is a halachic wall through lavud.

Many porches already have exactly that kind of railing.

The bars are spaced much less than three tefachim apart.

If those railings qualify as the necessary kanim, then perhaps the canvas is not carrying the entire halachic burden at all. The porch itself may already provide a mechitzah.

That would be a completely separate basis for heter.

But now we hit the real difficulty.

The Mishnah Berurah, in explaining the earlier case of the trees, says that the problem is not limited to a wall that the wind can knock down entirely. Even if the wall remains standing, if the normal wind moves it back and forth so that the mechitzah itself is unstable, that can destroy its status as a wall.

That is much more serious for canvas.

A securely attached canvas panel may never detach.

It may never fall.

But it can still move.

So we now have to ask a new question:

**How much movement is too much?**

The Mechaber gives us a clear concern about detachment.

The Mishnah Berurah appears to broaden the sugya to **nidnud**, actual movement.

That means zip ties may solve problem number one while leaving problem number two completely intact.

## The Mishnah Berurah Makes the Problem Harder

The Mishnah Berurah makes the analysis more difficult.

When he explains why the canes help, he says that even if the wind moves the yeri’os, the mechitzah still remains because the **kanim** themselves form the wall.

That sounds very significant.

Why does he need the canes to remain a wall if the only concern is that the cloth may become completely untied?

It sounds as though he is concerned with the cloth **moving** even while still attached.

That would mean the problem is not merely:

“Maybe the knot will open.”

The problem may be:

“A wall that moves too much in a normal wind is not a wall.”

If that is correct, my first heter—securing the canvas with permanent ties—does not finish the sugya.

It only eliminates the danger of detachment.

The fabric can still flap badly in the wind.

So I want to be very precise.

I am not claiming yet that a tightly secured canvas sukkah is automatically kosher.

I am saying that the Mechaber's wording gives one line of argument, while the Mishnah Berurah forces us to confront a second line.

That is how a teshuvah has to be built.

First define the exact problem.

Then test each proposed solution against each source.

We are now holding with two distinct questions:

- Does the material stay attached?
- Does the wall move so much that halachically it ceases to function as a mechitzah?

The second question is the harder one.

## Is This an Issur—or an Added Chumra?

There is another diyuk that I think is very important.

The Mechaber does **not** simply write:

“A sukkah with cloth walls is pasul.”

His language is more measured:

**ein nachon**—it is not proper to rely on such walls.

And when he gives the solution of canes, the language is again:

**tov**—it is good to arrange the wall that way.

That is not the language of an absolute pesul.

Now look at the Shaar HaTziyun.

In discussing the canes, the Shaar HaTziyun appears to say that when the yeri’os are tied well, the canes can be regarded as an **additional chumra**, rather than the only thing making the sukkah valid.

That is a very important source.

If the cloth is securely tied, perhaps the basic sukkah wall is fundamentally acceptable, and the canes are an extra safeguard.

But I immediately have to challenge my own raya.

What does **“tied well”** mean?

Maybe it means tied so tightly that the material does not move at all.

If so, the Shaar HaTziyun proves nothing for a canvas wall that is secure from detachment but still flaps in the wind.

This is the problem in the entire sugya.

Every time you think you found the heter, you have to ask:

Exactly what case is the source discussing?

That is why I do not want to give you a slogan like “canvas is kosher” or “canvas is pasul.”

The halachah depends on construction, attachment, movement, and what independent walls may already exist behind the canvas.

## How Much Movement Invalidates a Wall?

Now we reach the central practical question:

**How much may the wall move?**

The Chazon Ish is cited with a very concrete approach.

The mere fact that a wall has some motion is not automatically the problem. The question is whether the movement creates a halachically significant displacement—on the order of three tefachim—at the top, bottom, or through the body of the wall.

In the middle of the wall, this can translate into a substantial amount of total movement because the material can swing in both directions.

According to that approach, a canvas wall that flexes modestly but never creates that kind of gap or displacement may still function as a mechitzah.

Rav Shlomo Zalman Auerbach is quoted much more stringently.

In *Halichos Shlomo*, he challenges that reading and says that the language of the Mishnah Berurah does not sound as though we need a three-tefach threshold. The Mishnah Berurah simply speaks of a wall being moved by the wind.

According to that approach, even relatively slight wind-driven movement can already be problematic.

That is a major machlokes in practical application.

According to the Chazon Ish, we ask:

**How far is the wall actually moving?**

According to Rav Shlomo Zalman’s stricter reading, the very fact that the wall is being shifted by the ordinary wind may itself be the problem.

This is why a canvas sukkah cannot be discussed abstractly.

You have to stand there and look at the actual wall.

How tight is it?

How far does it move?

What happens in the ordinary wind of that location?

And are there independent halachic walls behind it?

Only after answering those questions can you begin to apply the poskim.

## Not Every Moving Wall Is the Same

There is a very useful comparison: a **sliding door**.

A sliding door moves.

Sometimes an entire side of a room is glass and slides open.

Would we automatically say that because the wall can move, it cannot function as a sukkah wall?

Rav Shlomo Zalman Auerbach discusses a similar question regarding a door that opens mechanically or electrically.

His point is that movement caused by a person or by the intended mechanism is not the same as a wall being unstable **because of the wind**.

That distinction has an important proof.

The Shulchan Aruch allows a **person** to function as part of the wall of a sukkah under the relevant conditions.

A person can move.

Obviously the Torah is not demanding absolute immobility from every possible mechitzah.

The question is whether the wall, by its nature, can stand against the **ruach metzuyah** that acts upon it.

That gives us another important category:

- A wall that moves because the wind pushes it.
- A wall that moves because someone deliberately opens or moves it.

Those are not necessarily the same halachic phenomenon.

## What If the Wind Cannot Reach the Wall?

Now take a canvas sukkah in a protected backyard surrounded by buildings.

The fabric itself might be light enough that, if exposed, a normal wind could move it.

But in this actual location, the wind does not reach it and the wall does not move.

Is that enough?

Here too, there is a machlokes.

The Mishnah Berurah is read as requiring the wall itself to possess the ability to withstand an ordinary wind. If the only reason it remains still is because buildings happen to block the wind, that may not solve the inherent defect.

The Chazon Ish is cited more leniently: if in the actual situation the wall does not move, the practical reality matters.

That is highly relevant to porch sukkahs.

A porch may be exposed on one side and protected on another.

So once again, you cannot pasken “canvas sukkah” from the material alone.

You have to evaluate the actual site.

## Rav Moshe: Stringent Overall, but a Possible Distinction

The teshuvah I saw from Rav Moshe Feinstein is fascinating because, overall, he does **not** sound enthusiastic about the standard canvas sukkah.

He says, in substance, that the mere fact that such sukkahs became common in America is no proof that the practice was established through proper hora’ah.

And he appears to conclude that sukkahs of this type run against the concern of the Mechaber and should not be the preferred l’chatchilah construction.

That is a serious consideration.

But inside the same discussion, Rav Moshe raises an important possibility.

If the canvas is tied securely **at the top and at the bottom**, then perhaps movement only in the middle is different.

He writes, as I understood the teshuvah, that slight movement may amount to nothing, and that there is room to consider whether a wall secured above and below remains valid even though the center flexes.

He does not present this as a simple final heter; he leaves the point requiring further analysis.

That is important for us because it shows again that “movement” is not necessarily one undifferentiated category.

## The Porch Railings

Now return to the porch.

If the railings are spaced less than three tefachim apart, we have **lavud**.

That can potentially produce a halachic wall even without relying entirely on the canvas.

But then another question appears:

How high does that independent wall need to be?

A sukkah wall requires ten tefachim.

If the physical railing itself reaches that height, excellent.

If it does not, can we use **gud asik**—treating the halachic wall as extending upward?

And can lavud and gud asik be combined in the same construction?

That opens the famous question of **trei hilchesa**—combining two halachic mechanisms.

The Ran is commonly cited regarding limitations on combining halachic fictions, though the Tur does not necessarily follow the same approach in every case. R. Akiva Eiger also analyzes whether the famous reading of the Ran is correct.

This is already a separate sugya.

But for the porch sukkah it may be critical.

The railings could potentially solve the canvas problem independently—if the measurements and halachic mechanisms actually work.

## The Final Problem: Are the Porch Railings the Same as the Mechaber’s Canes?

At this point, the porch railings look very promising.

They may be less than three tefachim apart.

They may reach ten tefachim, or perhaps there is a further argument through gud asik.

If so, perhaps we already have an independent mechitzah and the canvas becomes secondary.

But I want to be honest about the last problem.

Read the Mechaber carefully.

He does not simply say:

“Have some bars somewhere nearby.”

His language is that it is good to **weave or arrange the canes within the mechitzah**, with spaces of less than three tefachim.

The picture is of the kanim being part of the wall system itself.

On a porch, however, the construction may be different.

The canvas is on one plane.

The metal railing is outside it or behind it.

They are not literally woven together.

Can I automatically say that the railing is the Mechaber’s solution?

I am not certain.

Perhaps the schach, the canvas, and the railing do not combine in the simple way we want them to.

Perhaps they do.

But this requires a real halachic analysis; I do not want to declare them identical merely because both involve bars less than three tefachim apart.

This is exactly how a teshuvah develops.

At the beginning you think the question is simple:

“Is canvas kosher?”

Then you discover that there are multiple independent issues:

- Can the cloth become detached?
- How much does it move?
- Does movement itself invalidate it?
- Is the movement wind-driven or deliberate?
- Is the wall protected from actual wind?
- Are there independent kanim through lavud?
- Are they ten tefachim high?
- Can we use gud asik?
- Can two halachic mechanisms be combined?
- Must the kanim be integrated into the cloth wall itself?

Those are different questions.

And I want to end this part honestly:

**I have not yet resolved every one of them.**

The practical canvas sukkah has to be built in a way that addresses all of these concerns, and the exact construction should be reviewed carefully before relying on it.