Master Crumb

Why Did My Sourdough Spread Flat?

You shaped a beautiful round loaf and put it in the oven—only to watch it spread sideways into a flat disc. This frustrating problem usually comes down to over-proofing or weak structure, both of which are fixable.

The Main Causes

Bread spreads flat when it can't hold its shape. This happens because:

  1. Over-proofing – Gluten has weakened from too much fermentation
  2. Weak gluten development – Structure wasn't strong enough
  3. Poor shaping – No surface tension
  4. High hydration – Very wet doughs spread more
  5. Oven not hot enough – No initial set

Cause #1: Over-Proofing (Most Common)

When dough ferments too long, the gluten network breaks down. It can no longer hold the gas or maintain structure.

Signs of Over-Proofing

  • Dough more than doubled during bulk
  • Dough felt very slack when shaping
  • Poke test: dough didn't spring back at all
  • Strong, alcoholic or very sour smell
  • Large bubbles breaking on surface
  • Loaf spread immediately after turning out of banneton

The Fix

  • Reduce bulk fermentation time
  • Reduce final proof time
  • Use cooler environment or refrigerate sooner
  • Use less starter (10-15% instead of 20%)
  • Watch the dough, not the clock

Cause #2: Weak Gluten Development

Without a strong gluten network, the dough can't support its own weight.

Signs of Weak Gluten

  • Dough never became smooth and elastic
  • Dough tore easily when stretched
  • Couldn't create surface tension during shaping
  • Shape collapsed immediately after shaping

The Fix

  • Perform more stretch and folds (4-6 sets)
  • Ensure adequate autolyse (30-60 minutes)
  • Use bread flour (higher protein)
  • Don't overwork late in bulk (deflates dough)
  • Handle gently during shaping to preserve structure

Cause #3: Poor Shaping Technique

Shaping creates the surface tension that holds the loaf together. Without proper tension, even well-fermented dough will spread.

Signs of Poor Shaping

  • Loaf looked loose and shapeless even before proofing
  • No visible smooth "skin" on the surface
  • Seam came apart during proofing
  • Dough spread in the banneton

The Fix

  • Create more surface tension by dragging dough against counter
  • Use minimal flour during shaping (some stickiness helps create tension)
  • Do a proper pre-shape with bench rest before final shaping
  • Practice the cupping/dragging motion

Cause #4: High Hydration

Very wet doughs (78%+ hydration) naturally spread more. This isn't necessarily a problem—many artisan loaves are flat and wide.

The Fix

  • Reduce hydration to 70-75% for a taller loaf
  • Develop extra gluten strength (more folds)
  • Use a well-floured banneton to prevent sticking
  • Bake in a loaf pan to contain the spread
  • Accept that some spread is normal for wet doughs

Cause #5: Oven Temperature Issues

If the oven isn't hot enough, the crust doesn't set quickly enough to contain the loaf.

The Fix

  • Preheat for at least 45-60 minutes
  • Use an oven thermometer to verify temperature
  • Preheat Dutch oven inside the main oven
  • Start at maximum temperature, reduce after loading

The Diagnostic Test

When your loaf spreads, ask yourself:

Did it spread when you turned it out of the banneton?

  • Yes, immediately → Over-proofed or weak structure
  • No, only in the oven → Oven not hot enough or under-scored

How did the dough feel when shaping?

  • Slack and sloppy → Over-proofed
  • Sticky and wet → High hydration + needs more gluten development
  • Tore when stretched → Insufficient gluten development
  • Normal → Shaping technique issue

Prevention Checklist

  • ☐ Bulk fermentation stopped at 50-75% rise (not doubled)
  • ☐ Dough still had some strength when shaping
  • ☐ Surface tension was visible after shaping
  • ☐ Final proof done in a supportive container (banneton)
  • ☐ Poke test showed slow spring-back before baking
  • ☐ Oven fully preheated (45+ minutes)
  • ☐ Dutch oven preheated with the oven

When Flat is Fine

Some breads are meant to be flat:

  • High-hydration artisan loaves (French-style)
  • Focaccia
  • Ciabatta
  • Fougasse

If you want a taller loaf, focus on structure and fermentation control. If you like the flavor but want to avoid the spread, bake in a loaf pan.

Recovery Options

Flat bread is still bread! It's perfect for:

  • Sandwiches (the wide shape is actually convenient)
  • Toast
  • Bruschetta or crostini
  • Dipping in soups

For Next Time

The most likely fix: ferment less. Over-proofing is the cause in most cases. If you're confident fermentation was correct, focus on building more gluten strength through additional folds.