The Billy Oh Popular Tongue & Groove Apex is a truly wonderful building made from the more aesthetically pleasing tongue & groove cladding. This design also offers a more secure construction method over the overlap type of building.. Easy Assembly. To aid in the assembly some of the work has already been carried out for you. Each building comes with fully assembled panels & we supply a fixing kit with sufficient nails & felt to complete the roof assembly.. Construction. The walls on the building are made from strong & secure 11mm thick tongue & groove cladding so that the overall construction of the building blends naturally into your garden environment. The building is provided with pre-assembled side panels Excluding roof & floor panels. The robust framing of the building is 28mm x 28mm.. The door gable can be fitted on either of the end of the building. The window panels can also be placed on either side of the building meaning you can build this shed to how it bes