Hole at the Bottom of Sourdough Loaf — Causes & Fixes

Your loaf has a large hole or tunnel at the bottom after baking. Identify the likely causes and practical fixes you can apply immediately and for future bakes.

Quick Diagnosis

WHAT exactly happened to the crumb/bottom?

Large single pocket under the crust Multiple small tunnels near bottom Collapsed area at the base after baking Loaf split at the seam and left a cavity

Causes & Solutions

Trapped gas from poor degassing before shaping

very common

Symptoms:

  • • Single large pocket directly under the bottom crust
  • • Surface looks smooth but interior has a cavern

Why does this happen?

If big bubbles created during bulk fermentation aren't gently released before final shaping, they can migrate to the loaf's underside and expand in the oven, leaving a cavity. Proper coil folds or gentle degassing redistribute gas and strengthen the crumb structure [1].

🚨 Immediate Fix:

When shaping next time, do one careful degassing step: press dough gently with fingertips to release very large bubbles, then reshape with tension. Use a dough scraper to support the dough while moving it.

📅 Long-term Fix:

Refine your shaping sequence so gas is evenly distributed and the final seam is sealed. Practice tension building during pre-shape and final shape [1][2].

🧪 Test:

After pre-shape, look for large visible bubbles. If present, gently deflate them before bench rest.

Poor seam seal / seam ends up on bottom

common

Symptoms:

  • • Large hole near an obvious seam line
  • • Loaf splits along an off-centre seam

Why does this happen?

If the final seam isn't sealed or ends up on the loaf's underside, steam and expanding gas exploit that weakness and create a cavity. Proper sealing prevents gas escape paths and uneven expansion [1].

🚨 Immediate Fix:

When shaping, roll the seam tightly and press the seam into the bench to lock it. Place the seam up in the banneton so the loaf sits seam-side up until scoring. Use a banneton proofing basket for consistent support.

📅 Long-term Fix:

Adopt a shaping routine where the seam is pinched and tucked under the loaf; practice tension creation so the seam doesn't open in the oven [2].

🧪 Test:

After shaping, invert the loaf: a well-sealed base looks smooth and taut, not loose.

Gassing late in oven (overly active starter or under-proofing)

common

Symptoms:

  • • Large pockets concentrated in lower half
  • • Good oven spring elsewhere but hole remains

Why does this happen?

Under-proofed dough still has a lot of fermentable sugars and active yeast; when the oven heat kicks in they produce a rapid gas surge that can create lower cavities as steam/CO2 accumulate before the crust sets [1][2].

🚨 Immediate Fix:

Allow a slightly longer final proof at cooler temperature next bake, or retard in the fridge to slow yeast so gases mature evenly. Check dough maturity with the poke test.

📅 Long-term Fix:

Tune proof times for your starter strength and room temp; consider a longer bulk and gentler final proof to avoid late gassing [1].

🧪 Test:

Poke test: under-proofed dough springs back quickly; properly proofed dough springs back slowly and leaves a slight indent.

Shaping method creates a hollow under the loaf

medium

Symptoms:

  • • Bottom cavity mirrors the shape of a handling pocket
  • • Loaf feels light and hollow when tapped

Why does this happen?

Some shaping techniques (too aggressive cupping, trapping air under the loaf when tightening) can leave an internal void. The cavity then expands in the oven [2].

🚨 Immediate Fix:

When final shaping, avoid lifting the loaf too often which can trap air pockets; use a dough scraper to rotate and build tension without creating pockets.

📅 Long-term Fix:

Adopt a consistent shaping workflow: pre-shape, bench rest, final shape with progressive tension and minimal lifting [2].

🧪 Test:

Place shaped dough seam-up in the banneton; invert carefully before scoring — a hollow sound or visible separation suggests trapped air.

Excessive steam or oven setup that lifts bottom

medium

Symptoms:

  • • Loaf base detached from baking surface or parchment
  • • Bottom blistering with a central void

Why does this happen?

Too much initial steam or a very slick surface (oiled parchment or silicone sling) can allow the loaf to lift slightly and form a cavity underneath as gases expand. Alternatively, if the loaf shifts in the oven, the bottom can separate and trap air [1].

🚨 Immediate Fix:

Use a slightly less slippery surface: bake on uncoated parchment (for first mention use link) or a lightly floured couche. Place the loaf on a preheated Dutch oven or baking stone to anchor the base.

📅 Long-term Fix:

Develop a consistent transfer method to the oven: use a floured peel or a silicone bread sling for wet doughs so the loaf doesn't shift or lift mid-oven spring.

🧪 Test:

If loaf moves when you open the oven in the first 5 minutes, anchoring was insufficient.

Overly high hydration combined with weak shaping

rare

Symptoms:

  • • Very open crumb with isolated large voids near bottom
  • • Dough difficult to handle and spreads in basket

Why does this happen?

High-hydration doughs produce big bubbles that need strong gluten structure and very careful shaping to hold them. If structure is marginal, bubbles can migrate downward and collapse into a large bottom pocket during baking [1][2].

🚨 Immediate Fix:

For this bake, bake in a Dutch oven to support sides and reduce bubble migration. Score to control expansion.

📅 Long-term Fix:

Improve gluten development via longer autolyse, additional stretch-and-folds in bulk, or slightly reduce hydration until you master shaping at that hydration [1].

🧪 Test:

During pre-shape, dough should show windowpane strength; weak windowpane indicates insufficient gluten.

🆘 Can I save this loaf?

You see a hole after cutting

Solution: No structural fix for the baked loaf. Use the bread for sandwiches, toast, or hollow out to make stuffed bread. Learn the shaping/degassing fixes for next bake.

Success chance: good for salvage, irreversible for structure

You notice large bubbles before scoring

Solution: Gently dock the surface with a tool to deflate the biggest pockets, then reseal and score. This risks losing some oven spring but can prevent a large bottom cavity.

Success chance: medium

Loaf shifted in oven and formed cavity

Solution: Next time: bake on a preheated surface or inside a [Dutch oven](https://amzn.to/4sVhKhN) and use a floured peel to transfer. For this bake, accept and repurpose.

Success chance: prevention-only

Prevention

  • ☐ Degas large bubbles gently before final shaping
  • ☐ Seal the final seam tightly and proof seam-up in a banneton proofing basket
  • ☐ Check proof maturity with the poke test rather than time alone [1]
  • ☐ Develop shaping that builds surface tension without trapping air
  • ☐ Use a Dutch oven or preheated baking surface to anchor the base during oven spring
  • ☐ If using very high hydration, strengthen gluten with extra folds or lower hydration until shaping is consistent

Sources

  1. [1]
    The Perfect Loaf – The Perfect Loaf – Link
  2. [2]
    Plötzblog – Plötzblog – Link