diff --git a/docs/modules/Conch::Controller::Rack.md b/docs/modules/Conch::Controller::Rack.md
index a8e0c2ba6..e8dd5cae7 100644
--- a/docs/modules/Conch::Controller::Rack.md
+++ b/docs/modules/Conch::Controller::Rack.md
@@ -24,12 +24,17 @@ Get all racks
 
 Response uses the Racks json schema.
 
-## layouts
+## get\_layouts
 
 Gets all the layouts for the specified rack.
 
 Response uses the RackLayouts json schema.
 
+## overwrite\_layouts
+
+Given the layout definitions for an entire rack, removes all existing layouts that are not in
+the new definition, as well as removing any device\_location assignments in those layouts.
+
 ## update
 
 Update an existing rack.
diff --git a/docs/modules/Conch::Route::Rack.md b/docs/modules/Conch::Route::Rack.md
index fb5ed223b..fdf809b5b 100644
--- a/docs/modules/Conch::Route::Rack.md
+++ b/docs/modules/Conch::Route::Rack.md
@@ -42,6 +42,12 @@ Unless otherwise noted, all routes require authentication.
 - User requires the read-only role on a workspace that contains the rack
 - Response: response.yaml#/RackLayouts
 
+### `POST /rack/:rack_id/layouts`
+
+- User requires the read/write role on a workspace that contains the rack
+- Request: request.yaml#/RackLayouts
+- Response: Redirect to the rack's layouts
+
 ### `GET /rack/:rack_id/assignment`
 
 - User requires the read-only role on a workspace that contains the rack
diff --git a/json-schema/request.yaml b/json-schema/request.yaml
index ade6975be..77a7a43e6 100644
--- a/json-schema/request.yaml
+++ b/json-schema/request.yaml
@@ -188,6 +188,20 @@ definitions:
         $ref: common.yaml#/definitions/uuid
       rack_unit_start:
         $ref: common.yaml#/definitions/positive_integer
+  RackLayouts:
+    type: array
+    uniqueItems: true
+    items:
+      type: object
+      additionalProperties: false
+      required:
+        - hardware_product_id
+        - rack_unit_start
+      properties:
+        hardware_product_id:
+          $ref: common.yaml#/definitions/uuid
+        rack_unit_start:
+          $ref: common.yaml#/definitions/positive_integer
   RackLayoutUpdate:
     type: object
     additionalProperties: false
diff --git a/lib/Conch/Controller/Rack.pm b/lib/Conch/Controller/Rack.pm
index d5f3c8b88..086e78a9a 100644
--- a/lib/Conch/Controller/Rack.pm
+++ b/lib/Conch/Controller/Rack.pm
@@ -2,7 +2,7 @@ package Conch::Controller::Rack;
 
 use Mojo::Base 'Mojolicious::Controller', -signatures;
 
-use List::Util qw(any none first uniq);
+use List::Util qw(any none first uniq max);
 
 =pod
 
@@ -97,7 +97,7 @@ sub get_all ($c) {
     $c->status(200, \@racks);
 }
 
-=head2 layouts
+=head2 get_layouts
 
 Gets all the layouts for the specified rack.
 
@@ -105,7 +105,7 @@ Response uses the RackLayouts json schema.
 
 =cut
 
-sub layouts ($c) {
+sub get_layouts ($c) {
     my @layouts = $c->stash('rack_rs')
         ->related_resultset('rack_layouts')
         ->with_rack_unit_size
@@ -116,6 +116,87 @@ sub layouts ($c) {
     $c->status(200, \@layouts);
 }
 
+=head2 overwrite_layouts
+
+Given the layout definitions for an entire rack, removes all existing layouts that are not in
+the new definition, as well as removing any device_location assignments in those layouts.
+
+=cut
+
+sub overwrite_layouts ($c) {
+    my $input = $c->validate_request('RackLayouts');
+    return if not $input;
+
+    my %layout_sizes = map +($_->{id} => $_->{rack_unit_size}),
+        $c->db_hardware_products->active->search({ id => { -in => [ map $_->{hardware_product_id}, $input->@* ] } })
+            ->columns([qw(id rack_unit_size)])
+            ->hri->all;
+
+    my %desired_slots; # map of all slots that will be occupied (slot => rack_unit_start)
+    foreach my $layout ($input->@*) {
+        my $size = $layout_sizes{$layout->{hardware_product_id}};
+        return $c->status(409, { error => 'hardware_product_id '.$layout->{hardware_product_id}.' does not exist' }) if not $size;
+        my @slots = $layout->{rack_unit_start} .. $layout->{rack_unit_start} + $size - 1;
+        my @overlaps = grep defined, map $desired_slots{$_}, @slots;
+        return $c->status(409, { error => 'layouts starting at rack_units '.$overlaps[0].' and '.$layout->{rack_unit_start}.' overlap' }) if @overlaps;
+        $desired_slots{$_} = $layout->{rack_unit_start} foreach @slots;
+    }
+
+    if (my $last_slot = max(keys %desired_slots)) {
+        return $c->status(409, { error => 'layout starting at rack_unit '.$desired_slots{$last_slot}.' will extend beyond the end of the rack' })
+            if $last_slot > $c->stash('rack_rs')->related_resultset('rack_role')->get_column('rack_size')->single;
+    }
+
+    my @existing_layouts = $c->stash('rack_rs')
+        ->related_resultset('rack_layouts')
+        ->columns([qw(hardware_product_id rack_unit_start)])
+        ->hri->all;
+
+    my @layouts_to_delete = grep {
+        my $existing_layout = $_;
+        none {
+            $existing_layout->{hardware_product_id} eq $_->{hardware_product_id}
+                and $existing_layout->{rack_unit_start} eq $_->{rack_unit_start}
+        } $input->@*;
+    }
+    @existing_layouts;
+
+    my @layouts_to_create = grep {
+        my $new_layout = $_;
+        none {
+            $new_layout->{hardware_product_id} eq $_->{hardware_product_id}
+                and $new_layout->{rack_unit_start} eq $_->{rack_unit_start}
+        } @existing_layouts;
+    }
+    $input->@*;
+
+    $c->txn_wrapper(sub ($c) {
+        my $layouts_rs = $c->stash('rack_rs')
+            ->search_related('rack_layouts', [ map +( +{
+                    'rack_layouts.hardware_product_id' => $_->{hardware_product_id},
+                    'rack_layouts.rack_unit_start' => $_->{rack_unit_start},
+                } ), @layouts_to_delete ] );
+
+        my $device_locations_rs = $layouts_rs->related_resultset('device_location');
+
+        my $deleted_device_locations = 0+$device_locations_rs->delete;
+        my $deleted_layouts = 0+$layouts_rs->delete;
+        $c->db_rack_layouts->populate([ map +{ rack_id => $c->stash('rack_id'), $_->%*, }, @layouts_to_create ]);
+
+        $c->log->debug(
+            join(', ',
+                ($deleted_device_locations ? ('unlocated '.$deleted_device_locations.' devices') : ()),
+                ($deleted_layouts ? ('deleted '.$deleted_layouts.' rack layouts') : ()),
+                (@layouts_to_create ? ('created '.scalar(@layouts_to_create).' rack layouts') : ()),
+            ).' for rack '.$c->stash('rack_id'));
+    });
+
+    # if the result code was already set, we errored and rolled back the db...
+    return if $c->res->code;
+
+    $c->status(303, '/rack/'.$c->stash('rack_id').'/layouts');
+}
+
 =head2 update
 
 Update an existing rack.
diff --git a/lib/Conch/Route/Rack.pm b/lib/Conch/Route/Rack.pm
index c6f7d731e..9f7229c5e 100644
--- a/lib/Conch/Route/Rack.pm
+++ b/lib/Conch/Route/Rack.pm
@@ -37,7 +37,9 @@ sub routes {
     $with_rack->require_system_admin->delete('/')->to('#delete');
 
     # GET /rack/:rack_id/layouts
-    $with_rack->get('/layouts')->to('#layouts');
+    $with_rack->get('/layouts')->to('#get_layouts');
+    # POST /rack/:rack_id/layouts
+    $with_rack->post('/layouts')->to('#overwrite_layouts');
 
     # GET /rack/:rack_id/assignment
     $with_rack->get('/assignment')->to('#get_assignment');
@@ -121,6 +123,18 @@ Unless otherwise noted, all routes require authentication.
 
 =back
 
+=head3 C<POST /rack/:rack_id/layouts>
+
+=over 4
+
+=item * User requires the read/write role on a workspace that contains the rack
+
+=item * Request: request.yaml#/RackLayouts
+
+=item * Response: Redirect to the rack's layouts
+
+=back
+
 =head3 C<GET /rack/:rack_id/assignment>
 
 =over 4
diff --git a/t/integration/crud/rack-layouts.t b/t/integration/crud/rack-layouts.t
index 1d1901342..7f3ea7478 100644
--- a/t/integration/crud/rack-layouts.t
+++ b/t/integration/crud/rack-layouts.t
@@ -321,5 +321,97 @@ $t->delete_ok('/layout/'.$layout_3_6->id)
 $t->get_ok('/layout/'.$layout_3_6->id)
     ->status_is(404);
 
+# now we have these assigned slots:
+# start 1, width 2
+# start 11, width 4
+# start 20, width 4     # occupied by 'my device'
+# start 42, width 1
+
+$t->post_ok('/rack/'.$rack_id.'/layouts',
+        json => [{ rack_unit_start => 1, hardware_product_id => create_uuid_str }])
+    ->status_is(409)
+    ->json_cmp_deeply({ error => re(qr/^hardware_product_id ${\Conch::UUID::UUID_FORMAT} does not exist$/) });
+
+$t->post_ok('/rack/'.$rack_id.'/layouts',
+        json => [{ rack_unit_start => 42, hardware_product_id => $hw_product_compute->id }])
+    ->status_is(409)
+    ->json_is({ error => 'layout starting at rack_unit 42 will extend beyond the end of the rack' });
+
+$t->post_ok('/rack/'.$rack_id.'/layouts',
+        json => [
+            { rack_unit_start => 1, hardware_product_id => $hw_product_compute->id },
+            { rack_unit_start => 2, hardware_product_id => $hw_product_compute->id },
+        ])
+    ->status_is(409)
+    ->json_is({ error => 'layouts starting at rack_units 1 and 2 overlap' });
+
+$t->post_ok('/rack/'.$rack_id.'/layouts',
+        json => [
+            # unchanged
+            { rack_unit_start => 1, hardware_product_id => $hw_product_compute->id },
+            # unchanged, and has a located device
+            { rack_unit_start => 20, hardware_product_id => $hw_product_storage->id },
+            # new layout
+            { rack_unit_start => 26, hardware_product_id => $hw_product_compute->id },
+        ])
+    ->status_is(303)
+    ->location_is('/rack/'.$rack_id.'/layouts')
+    ->log_debug_is('deleted 2 rack layouts, created 1 rack layouts for rack '.$rack_id);
+
+$t->get_ok('/rack/'.$rack_id.'/layouts')
+    ->status_is(200)
+    ->json_schema_is('RackLayouts')
+    ->json_cmp_deeply([
+        superhashof({ rack_unit_start => 1, hardware_product_id => $hw_product_compute->id }),
+        superhashof({ rack_unit_start => 20, hardware_product_id => $hw_product_storage->id }),
+        superhashof({ rack_unit_start => 26, hardware_product_id => $hw_product_compute->id }),
+    ]);
+
+$t->get_ok('/rack/'.$rack_id.'/assignment')
+    ->status_is(200)
+    ->json_schema_is('RackAssignments')
+    ->json_cmp_deeply([
+        { rack_unit_start => 1, rack_unit_size => 2, hardware_product_name => $hw_product_compute->name, device_id => undef, device_asset_tag => undef },
+        { rack_unit_start => 20, rack_unit_size => 4, hardware_product_name => $hw_product_storage->name, device_id => $device->id, device_asset_tag => undef },
+        { rack_unit_start => 26, rack_unit_size => 2, hardware_product_name => $hw_product_compute->name, device_id => undef, device_asset_tag => undef },
+    ]);
+
+$t->post_ok('/rack/'.$rack_id.'/layouts',
+        json => [
+            { rack_unit_start => 3, hardware_product_id => $hw_product_compute->id },
+        ])
+    ->status_is(303)
+    ->location_is('/rack/'.$rack_id.'/layouts')
+    ->log_debug_is('unlocated 1 devices, deleted 3 rack layouts, created 1 rack layouts for rack '.$rack_id);
+
+$t->get_ok('/rack/'.$rack_id.'/layouts')
+    ->status_is(200)
+    ->json_schema_is('RackLayouts')
+    ->json_cmp_deeply([
+        superhashof({ rack_unit_start => 3, hardware_product_id => $hw_product_compute->id }),
+    ]);
+
+$t->get_ok('/rack/'.$rack_id.'/assignment')
+    ->status_is(200)
+    ->json_schema_is('RackAssignments')
+    ->json_cmp_deeply([
+        { rack_unit_start => 3, rack_unit_size => 2, hardware_product_name => $hw_product_compute->name, device_id => undef, device_asset_tag => undef },
+    ]);
+
+$t->post_ok('/rack/'.$rack_id.'/layouts', json => [])
+    ->status_is(303)
+    ->location_is('/rack/'.$rack_id.'/layouts')
+    ->log_debug_is('deleted 1 rack layouts for rack '.$rack_id);
+
+$t->get_ok('/rack/'.$rack_id.'/layouts')
+    ->status_is(200)
+    ->json_schema_is('RackLayouts')
+    ->json_is([]);
+
+$t->get_ok('/rack/'.$rack_id.'/assignment')
+    ->status_is(200)
+    ->json_schema_is('RackAssignments')
+    ->json_is([]);
+
 done_testing;
 # vim: set ts=4 sts=4 sw=4 et :