it is a double skinned timber built lean too built on a suspended timber frame. I have used the space to make a Hobbit/Lord of the Rings themed cinema room to seat 3 people. It has a pitched tiled roof ... oak floor built in rear cinema seats that used to be the seats in an 1989 XJS jaquar... everything in there is themed towards the films/books Lord Of The RIngs and the Hobbit.
It took us a year to do it working on and off evenings and weekends outside of any lockdowns... i had a budget of ﾣ4k which we just about hit ... the stove was a rusty heap in a friends garden which i up cycled and is used purely for show and to house tea lights/candles. The tiles on the roof we got for free from someone redoing the roof on his extension and the solid oak floor we got for ﾣ90 again 2nd hand. it has insulation in between a double skinned timer frame including insulation under the oak floor ... the base frame is attached to the wall of the house and then the rear boundary wall keeping the whole build approx 5 inches off the ground...the exterior is clad in log effect tongue and groove... it has a 65inch tv with surround sound system all installed and the blu ray player is a ps3 allowing me to use it as a games room also.