* However, the [http://www.hebrewbooks.org/pdfpager.aspx?req=37191&pgnum=18 Mikdash Me'at 287:1:5] suggests that perhaps a roof can function as a lintel. Also, the Chovat Hadar 7:5 fnt. 8 equates the issue with that of having the edge of a roof function as a lintel to the opinion of the Rosh who holds that the edge of a wall can function as a doorpost. The Netivot in [http://www.hebrewbooks.org/pdfpager.aspx?req=31812&st=&pgnum=49 Derech Hachaim Siddur 239:1] also holds that a roof can serve as a lintel. Minchat Yitzchak 10:91 explains that a roof doesn't function as a lintel but if the roof has an edge where the door is according to some opinions it functions as a lintel. Yet, if the roof extends beyond the door in both directions it doesn't function as a lintel. He compares it to the Machloket Rama 630:2 and Magen Avraham 630:2 if there's doorposts and no lintel if that can serve as a tzurat hapetach. He admits that it seems not to be a proof though from further analysis.
* Adoney Paz 2:121:1 sides with the Chazon Ish though he recommends being strict for all opinions to put up a mezuzah without a bracha. Mezuzah Vehilchoteha 10:3 concurs.</ref>