# Engine error when placing roof with stand alone structures

**URL:** <https://discourse.stonehearth.net/t/engine-error-when-placing-roof-with-stand-alone-structures/23627>\
**Category:** Previous Build Reports\
**Created:** [July 2, 2016, 7:03pm UTC](https://discourse.stonehearth.net/t/engine-error-when-placing-roof-with-stand-alone-structures/23627 "2016-07-02T19:03:13Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Karthick](https://avatars.discourse-cdn.com/v4/letter/k/dbc845/32.png) [@Karthick](https://discourse.stonehearth.net/u/Karthick)\
**Post date:** [July 2, 2016, 7:03pm UTC](https://discourse.stonehearth.net/t/engine-error-when-placing-roof-with-stand-alone-structures/23627/1 "2016-07-02T19:03:13Z")

</div>

release-559 (x64)  
stonehearth/lib/build\_util.lua:739: assertion failed!  
stack traceback:  
[C]: ?  
[C]: in function 'assert’  
stonehearth/lib/build\_util.lua:739: in function 'create\_edge\_loop\_for\_wall’  
stonehearth/lib/build\_util.lua:747: in function 'create\_edge\_loop\_for\_wall’  
stonehearth/lib/build\_util.lua:747: in function 'create\_edge\_loop\_for\_wall’  
stonehearth/lib/build\_util.lua:747: in function 'create\_edge\_loop\_for\_wall’  
stonehearth/lib/build\_util.lua:826: in function ‘calculate\_roof\_shape\_around\_walls’  
…th/services/client/build\_editor/grow\_roof\_editor.lua:116: in function ‘\_compute\_roof\_region’  
…th/services/client/build\_editor/grow\_roof\_editor.lua:78: in function ‘fn’  
…ces/client/selection/entity\_or\_location\_selector.lua:233: in function ‘\_get\_selected\_entity’  
…ces/client/selection/entity\_or\_location\_selector.lua:269: in function ‘\_on\_mouse\_event’  
…nehearth/services/client/selection/selector\_base.lua:115: in function '\_mouse\_cb’  
stonehearth/services/client/input/input\_capture.lua:49: in function '\_dispatch’  
stonehearth/services/client/input/input\_service.lua:55: in function '\_dispatch\_input’  
stonehearth/services/client/input/input\_service.lua:12: in function \<stonehearth/services/client/input/input\_service.lua:11\>