SeaFury - they are known as Tempest 1 and 2 and are of a modular design. The internal units are akin to portakabins and a brick skin is then applied to the outer and then a normal pitched roof added -this type of construction is quite common but you are correct that they do not meet 'Z type' standards and everyone at Odiham knew this; the 20 extra rooms they afforded are currently a god send despite the slightly deficient standard! As they are of a 'modular' design, the theory is that they can be moved should future infra plans at Odiham dictate. In fact, Tempest 1 was taken from another RAF Station and re-erected at Odius!
As Odiham had suffered a planning blight under Project Belvedere (now cancelled) for the past 15 years it was all the unit could afford to solve a long standing dearth of SLA. We are hoping, depending on forthcoming Defence Review, to be allocated funding to address these issues as soon as possible.