A loaf that spreads out instead of holding its shape is one of the most common sourdough frustrations.
It often looks fine going into the oven, but then it relaxes outward, loses height, and bakes up flatter than expected.
The key point: spreading is almost always a loss of structure before baking, not something that happens in the oven itself.
Let’s break it down.
The short answer
Your loaf usually spreads because:
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the dough was overproofed
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the gluten structure was too weak
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hydration was too high for your flour
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or fermentation happened too fast in a warm environment
In most cases, the dough simply didn’t have enough strength at bake time to hold its shape.
First: what “spreading” actually is
Spreading happens when the dough can no longer maintain tension.
Instead of holding a tall, structured shape, it:
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relaxes outward after shaping
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loses height during proofing or transfer
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spreads in the oven instead of lifting
This tells us the internal structure has weakened or never fully developed.
The most common reasons your loaf spreads
1. Overproofing
This is the most common cause.
When dough is left too long:
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gluten starts to break down
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structure becomes weak and fragile
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gas escapes instead of supporting lift
Even if the dough looks airy, it no longer has the strength to hold shape.
2. Weak gluten development
If the dough hasn’t built enough structure during bulk fermentation:
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it may shape initially but cannot hold tension
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it slowly relaxes and spreads out
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it feels soft and slack rather than strong
This often comes back to insufficient folds or development time.
3. Hydration too high for the flour
Different flours absorb water differently.
If hydration is too high:
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dough feels loose from the start
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shaping tension is difficult to build
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structure doesn’t hold after shaping
The loaf spreads because the dough is too weak for its water content.
4. Warm fermentation environment
Warm dough ferments faster.
If fermentation moves too quickly:
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dough can overproof before structure fully develops
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gluten weakens faster than expected
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dough becomes slack and unstable
This often leads to spreading even when timing seems “normal.”
5. Weak or inconsistent starter
If your starter is not strong:
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fermentation is uneven
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structure development is limited
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dough lacks stability at bake time
Even perfect shaping cannot compensate for weak fermentation.
What you should do next time
Instead of changing everything, focus on one or two adjustments:
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shorten fermentation slightly if dough feels weak or collapses
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build more strength during bulk fermentation (extra folds if needed)
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reduce hydration slightly if dough is consistently slack
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ensure your starter doubles reliably before baking
Small changes create noticeable improvements.
Quick checks before baking
Ask yourself:
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Did my dough feel strong and slightly elastic before shaping?
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Did it hold tension briefly after shaping?
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Was fermentation too long for my environment?
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Was the dough already soft or weakening before baking?
These usually point directly to the cause.
When spreading is expected
Some spreading can be normal with:
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high hydration artisan doughs
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beginner starter stages
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warm kitchens with fast fermentation
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early learning shaping technique
The goal is controlled shape—not rigid perfection.
Nikki’s note
A spreading loaf is rarely a shaping failure.
It’s usually the result of timing and strength not lining up properly before baking.
Once you start recognising when dough is at peak strength, shaping becomes much more predictable—and spreading becomes far easier to control.
Related guides
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Why Didn’t I Get Oven Spring?
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Why Is My Sourdough Dense?
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My Dough Won’t Hold Its Shape
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Overproofed vs Underproofed Dough
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Why Is My Dough Sticky?