The Billy Oh Park Tongue & Groove Stable Door 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 & comes complete with a stable door.. 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 buildin