Wall creation on Room Boundries by wall finish type

Hi all,
I am a beginner user in Dynamo so forgive me if my question is so silly.

I have formulated a dynamo script which creates walls on room boundries. Scripts checks wall finish parameters in room elements, creates walls (plasters) on room boundries based on these corresponding parameters. Untill here, there is no problem, script works fine.

Problem starts whenever i re-execute the script. Everytime when i execute, it keep continues to create walls inside of room boundries and rooms are getting smaller by size (which i dont want)
Somehow need a method that checks whether if there is plaster wall at the location of room boundry or not. If none, script will create a plaster wall and do its job. But if there is a plaster wall, then no need to recreate another walls. (because it makes my room smaller than before)

Hope i could describe the issue.

@greendogsky Can you share your script? Also Please check out element binding issue.