The Walloon Roof Material spectral library (WaRM) was created in the framework of the CASMATTELE project to reflect regional peculiarities of roof materials employed in Wallonia, Belgium. This library accounts for 26 roof material spectra in the spectral range 350–2,500 nm. Spectra were acquired using an ASD FieldSpec3 Hi-Res spectrometer in laboratory and in situ conditions with a spectral sampling interval of 1 nm. Although building materials can vary regionally due to different available construction materials, the WaRM spectral library can certainly be used for wider applications.