The term tignum includes every kind of material employed in building, and the object of this provision is to avoid the necessity of having buildings pulled down; but if through some cause or other they should be destroyed, the owner of the materials, unless he has already sued for double value, may bring a real action for recovery, or a personal action for production.    From Wordnik.com.  [The Institutes of Justinian] Reference

And yet he who was owner of the materials does not cease to own them, but he cannot bring a real action for their recovery, or sue for their production, by reason of a clause in the Twelve Tables providing that no one shall be compelled to take out of his house materials (tignum), even though they belong to another, which have once been built into it, but that double their value may be recovered by the action called 'de tigno iniuncto.'.    From Wordnik.com.  [The Institutes of Justinian] Reference