diff --git a/.github/workflows/generic.yaml b/.github/workflows/generic.yaml
index 0f7f9d2..0898288 100644
--- a/.github/workflows/generic.yaml
+++ b/.github/workflows/generic.yaml
@@ -32,6 +32,10 @@ on:
         description: Continue building from previous debs artifact?
         required: true
         default: false
+      INSTALL_TO_CHROOT:
+        type: boolean
+        description: Incrementally install built packages within the chroot?
+        required: false
       BUILD_TIMEOUT:
         type: number
         description: Cancel build after this time, before github will do (minutes)
@@ -148,6 +152,7 @@ jobs:
           DEB_BUILD_OPTIONS: ${{ inputs.DEB_BUILD_OPTIONS || vars.DEB_BUILD_OPTIONS || 'nocheck' }}
           CONTINUE_ON_ERROR: ${{ inputs.CONTINUE_ON_ERROR || vars.CONTINUE_ON_ERROR || false }}
           SKIP_EXISTING: ${{ inputs.SKIP_EXISTING || vars.SKIP_EXISTING || false }}
+          INSTALL_TO_CHROOT: ${{ inputs.INSTALL_TO_CHROOT || vars.INSTALL_TO_CHROOT || false }}
 
       - name: Store ccache
         uses: actions/cache/save@v3
diff --git a/.github/workflows/interactive.yaml b/.github/workflows/interactive.yaml
index d35d32f..41616f1 100644
--- a/.github/workflows/interactive.yaml
+++ b/.github/workflows/interactive.yaml
@@ -30,6 +30,10 @@ on:
         type: boolean
         description: Skip existing packages?
         required: false
+      INSTALL_TO_CHROOT:
+        type: boolean
+        description: Incrementally fill chroot?
+        required: false
       DEPLOY_MODE:
         type: choice
         description: How to deploy?
@@ -59,6 +63,7 @@ jobs:
       # proceed from existing debs artifact if run_attempt > 1
       DOWNLOAD_DEBS: ${{ github.run_attempt != '1' }}
       SKIP_EXISTING: ${{ inputs.SKIP_EXISTING || vars.SKIP_EXISTING || false}}
+      INSTALL_TO_CHROOT: ${{ inputs.INSTALL_TO_CHROOT || vars.INSTALL_TO_CHROOT || false }}
 
   deploy:
     needs: build
diff --git a/src/build.sh b/src/build.sh
index 601a77b..2458c62 100644
--- a/src/build.sh
+++ b/src/build.sh
@@ -89,6 +89,14 @@ function build_pkg {
   fi
 
   ici_cmd ccache -sv
+
+  if [ "$INSTALL_TO_CHROOT" == "true" ]; then
+    ici_color_output "${ANSI_BOLD}" "Install package within chroot"
+    # shellcheck disable=SC2012
+    cat <<- EOF | ici_pipe_into_schroot sbuild-rw
+      apt install --no-install-recommends -q -y \$(ls -1 -t /build/repo/"$(deb_pkg_name "$pkg_name")"*.deb | head -1)
+EOF
+  fi
 }
 
 function build_source {
diff --git a/src/env.sh b/src/env.sh
index ae0ecc1..b89131d 100644
--- a/src/env.sh
+++ b/src/env.sh
@@ -22,6 +22,7 @@ export EXTRA_SBUILD_OPTS=${EXTRA_SBUILD_OPTS:-}
 export DEB_BUILD_OPTIONS=${DEB_BUILD_OPTIONS:-nocheck}  # don't build/run tests
 
 export SKIP_EXISTING=${SKIP_EXISTING:-false}
+export INSTALL_TO_CHROOT=${INSTALL_TO_CHROOT:-false}
 
 ## deploy paths: 'eval echo ...' expands environment variables
 export DEBS_PATH
diff --git a/src/prepare.sh b/src/prepare.sh
index 811c3c3..c0eaf17 100644
--- a/src/prepare.sh
+++ b/src/prepare.sh
@@ -66,15 +66,6 @@ function create_chroot {
     "deb $DISTRIBUTION_REPO $DEB_DISTRO main universe" \
     "deb [signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu jammy main"
 
-  ici_log
-  ici_color_output "${ANSI_BOLD}" "Add extra debian package sources"
-  while IFS= read -r line; do
-    echo "$line"
-    cat <<- EOF | ici_pipe_into_chroot "$chroot_folder"
-    echo "$line" >> "$REPOS_LIST_FILE"
-EOF
-  done <<< "$EXTRA_DEB_SOURCES"
-
   ici_log
   ici_color_output "${ANSI_BOLD}" "Write schroot config"
   cat <<- EOF | ici_asroot tee /etc/schroot/chroot.d/sbuild
@@ -83,9 +74,12 @@ groups=root,sbuild
 root-groups=root,sbuild
 profile=sbuild
 type=directory
-directory=/var/cache/sbuild-chroot
+directory=$chroot_folder
 union-type=overlay
 EOF
+  # sbuild-rw: writable sbuild
+  sed -e 's#\(union-type\)=overlay#\1=none#' -e 's#\[sbuild\]#[sbuild-rw]#'\
+    /etc/schroot/chroot.d/sbuild | ici_asroot tee /etc/schroot/chroot.d/sbuild-rw
 
   ici_log
   ici_color_output "${ANSI_BOLD}" "Add mount points to sbuild's fstab"
@@ -93,6 +87,19 @@ EOF
 $CCACHE_DIR  /build/ccache   none    rw,bind         0       0
 $DEBS_PATH   /build/repo     none    rw,bind         0       0
 EOF
+
+  ici_log
+  ici_color_output "${ANSI_BOLD}" "Add extra debian package sources"
+  while IFS= read -r line; do
+    echo "$line"
+    cat <<- EOF | ici_pipe_into_schroot sbuild-rw
+    echo "$line" >> "$REPOS_LIST_FILE"
+EOF
+  done <<< "$EXTRA_DEB_SOURCES"
+
+  ici_log
+  ici_color_output "${ANSI_BOLD}" "apt-get update in chroot"
+  echo "apt-get update" | ici_pipe_into_schroot sbuild-rw
 }
 
 function configure_sbuildrc {
diff --git a/src/util.sh b/src/util.sh
index d903eae..08e9c6e 100644
--- a/src/util.sh
+++ b/src/util.sh
@@ -99,10 +99,9 @@ function _sub_shell() (
   eval "$*" || ici_exit
 )
 
-# usage echo "$*" | ici_pipe_into_chroot <chroot folder>
-function ici_pipe_into_chroot {
-  local folder=$1
-  cat -- | ici_asroot chroot "$folder" /bin/bash -- || ici_exit
+# usage echo "$*" | ici_pipe_into_schroot <schroot name>
+function ici_pipe_into_schroot {
+  cat -- | ici_asroot schroot -c "$1" --directory / /bin/bash -- || ici_exit
 }
 
 function _label_hook() {