# Building Pad creating TypeError: expected IList\[CurveLoop\], got CurveLoop

**URL:** <https://forum.dynamobim.com/t/building-pad-creating-typeerror-expected-ilist-curveloop-got-curveloop/18623>\
**Category:** Developers\
**Tags:** python\
**Created:** [January 30, 2018, 11:28am UTC](https://forum.dynamobim.com/t/building-pad-creating-typeerror-expected-ilist-curveloop-got-curveloop/18623 "2018-01-30T11:28:25Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![Tomasz](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.dynamobim.com/tomasz/32/66785_2.png) [@Tomasz](https://forum.dynamobim.com/u/Tomasz)\
**Post date:** [January 30, 2018, 11:48am UTC](https://forum.dynamobim.com/t/building-pad-creating-typeerror-expected-ilist-curveloop-got-curveloop/18623/2 "2018-01-30T11:48:47Z")

</div>

```
import clr
#Import Revit Services
clr.AddReference ("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager
#Import Revit API
clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *
from Autodesk.Revit.DB.Architecture import *
clr.AddReference('RevitAPIUI')
from Autodesk.Revit.UI import *
#Import Revit Node
clr.AddReference('RevitNodes')
import Revit
clr.ImportExtensions(Revit.GeometryConversion)
clr.ImportExtensions(Revit.Elements)
#Import Proto Geometry
clr.AddReference('ProtoGeometry')
from Autodesk.DesignScript.Geometry import *

import System
from System.Collections.Generic import *

#inputs
level = UnwrapElement(IN[0])
padType = UnwrapElement(IN[1])
curves = IN[2]

#necessary ID's
levelId = level.Id
typeId = padType.Id

#creating CurveLoop
loop = CurveLoop()
for c in curves:
	loop.Append(c.ToRevitType())

#get the document
doc = DocumentManager.Instance.CurrentDBDocument

#use safe transaction with Revit
TransactionManager.Instance.EnsureInTransaction(doc)

#creating pad
loops = [loop]
pad = BuildingPad.Create(doc,typeId,levelId,loops)

#Finish transaction with task done
TransactionManager.Instance.TransactionTaskDone()

OUT = pad
```

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