Most flat loaves aren’t the result of bad shaping or a “weak” starter. They flatten because something earlier in the process quietly failed.

If you’ve ever baked a loaf that spread instead of standing tall, this post will help you understand why it happens and how to avoid it next time.

Flat loaves are almost always a process issue, not a single mistake. Let’s walk through the most common causes in plain language.

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1. Over-fermentation (the most common cause)

Dough needs fermentation to build gas and structure, but too much fermentation weakens gluten.

When bulk fermentation goes too far:

• acids build up

• gluten starts breaking down

• dough becomes soft and fragile

• shaping tension won’t hold

The dough may look airy and feel light, but it won’t support itself in the oven, so it spreads.

How to avoid it:

Stop bulk based on dough behavior, not time. Look for moderate volume increase, smoother surface, elasticity, and strength during folds. Warmer dough needs *less* rise than cooler dough.

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2. Underdeveloped gluten

If gluten hasn’t been properly developed, the dough simply has no backbone.

This often happens when:

• mixing is too short

• folds are stopped too early

• hydration is too high for the flour

• the dough wasn’t given enough rest

Underdeveloped dough feels stretchy but not elastic and relaxes immediately after shaping.

How to avoid it:

Build strength early through proper mixing, adequate rest, and well-timed folds. Dough should resist stretching slightly and hold shape between folds.

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3. Hydration that exceeds your flour’s capacity

High hydration is popular, but not all flours can support it.

When hydration is too high:

• gluten forms slowly

• structure stays weak

• dough spreads after shaping

This is common with low-protein flours, soft wheat, or locally milled flour.

How to avoid it:

Match hydration to your flour, not the recipe. Lowering hydration by even 2–5% can dramatically improve loaf height.

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4. Shaping without enough internal strength

Shaping doesn’t create strength.

It only organizes strength that already exists.

If the dough spreads immediately after shaping, the issue isn’t your hands, it’s what happened earlier.

How to avoid it:

Make sure the dough already feels strong before shaping. Shaping should feel like tightening, not rescuing.

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5. Temperature and support issues

Warm dough spreads faster. High temperatures soften gluten and accelerate fermentation.

Also, a banneton that’s too wide offers little side support while the dough sets.

How to avoid it:

Cool the dough before final shaping if needed, and use a properly sized basket to support vertical structure.

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The takeaway

Flat loaves are rarely fixed at the shaping stage.

When a loaf spreads, always look earlier:

• fermentation level

• gluten development

• hydration

• temperature

Once those are right, shaping becomes easy and loaves naturally hold their form.

If you’re learning sourdough and dealing with flat loaves, you’re not failing. You’re just still learning how dough behaves.