Sourdough Spreading Flat in the Oven: Hydration and Shape

Short answer: if your sourdough spreads into a pancake instead of springing up, the dough was either too wet for your flour or shaped too loosely. Lower hydration by 5% and shape tighter.

What "spreading" looks like

You drop a beautifully proofed boule onto parchment and slide it into a 500°F oven. Twenty minutes later, the loaf is:

• Wider than it was tall
• Flat on top
• A score that opened sideways instead of up
• Very little oven spring

The dough relaxed before it could rise.

The 5 causes ranked

1. Hydration too high

The most common cause. A 9% protein flour can't hold 80% water; the dough is just water bound by weak gluten. When the support of the basket disappears, it spreads.

Test: take 100g of the same flour, mix with 75g water, knead 5 minutes. Can you stretch it into a window without tearing? If no, your flour can't handle 75% hydration.

Match flour to hydration:

2. Weak shaping

If the dough doesn't have surface tension, it can't hold its shape on the parchment. It just collapses outward.

Build tension:

• Pre-shape tight
• Rest 30 min
• Final shape: drag across bench
• Cold retard to firm up
• Bake straight from fridge

3. Over-proofed

Over-proof = weak gluten. The structure can't push up; it spreads sideways.

Catch the proof window:

• Finger dent springs back slowly
• Dough has risen 50–75% from shape
• Surface still has some tension

4. Weak gluten development

If you didn't fold enough during bulk, the gluten network is sparse. Spreading happens because there's no scaffolding.

Fix:

• Do 4 sets of folds at 30, 60, 90, 120 min into bulk
• Add a lamination mid-bulk for high-hydration dough
• Don't skip folds because "the dough looks fine"

5. Wrong flour

All-purpose flour and pastry flour spread because they don't have enough gluten to support a free-standing loaf. Switch to bread flour for sourdough.

The basket test

If your dough holds its shape in the basket but spreads on the parchment:

• The basket was supporting it artificially
• Real structural integrity is missing
• Lower hydration or shape tighter

If it spreads in the basket too:

• Severe over-fermentation or very low gluten
• Reset with a bread flour bake at 70%

Cold retard for shape retention

Cold retard firms up the dough. A cold loaf holds its shape better in the oven than a room-temperature one.

For high-hydration doughs that tend to spread:

• Cold retard 12–18 hours
• Bake straight from fridge
• Don't let it warm up first

A flat-loaf fix bake

Recipe:

• 500g bread flour (12% protein)
• 350g water (70%)
• 100g starter, peaked
• 10g salt

Method:

• Mix, bulk 5h at 75°F, 4 folds
• Pre-shape, rest 30 min
• Final shape with tension
• Cold retard 12 hours
• Bake at 475°F

This bake almost never spreads. If it does, the issue is severely upstream (dead starter, soft flour).

Oven loading and spread

A loaf that's already starting to spread when loaded will spread more in the oven. To minimize:

• Load fast (don't fuss)
• Score quickly
• Close the oven immediately
• Don't peek for 20 minutes

The first 5 minutes set the crust. If the dough spreads in those minutes, it's locked in.

When to lower hydration vs. shape tighter

If your dough is also wet and hard to handle: lower hydration. If your dough is normal-feeling but the loaves spread: shape tighter.

Both fixes apply, but pick the dominant symptom.

A flour-specific approach

If you've been baking with one flour and getting flat loaves:

• Test: weigh the same recipe with 5% less water (335g instead of 350g)
• Bake the same way
• If the loaf is no longer flat: hydration was too high for that flour

This bracket method finds your flour's true hydration ceiling in one bake.

A note on rye

Rye spreads more than wheat at the same hydration. For rye-blend doughs, drop hydration 5% and bake in a tight tin or basket.

Standing tall

A well-shaped, well-fermented sourdough sits tall on the parchment, doesn't spread when scored, and springs visibly in the oven.

If you've never had this experience, work through the 5 fixes above. Most home bakers solve flat loaves on the first or second attempt.