This structure was completely below ground with raised entrances level with the surface and was roughly aligned north to south. The northern entrance was 46cm above the roof of the chamber and measured 5.45m long by 1m wide and was capped by concrete-covered corrugated iron. This sat on a lip in the entrance walls that was 5cm deep at the sides and entrance. The southern entrance was 52cm above the chamber roof and measured 5.3m long by 1m wide. The concrete covered-corrugated iron cap sat on a 5cm-deep lip that extended around the entire interior of this entrance. Both entrances descended eleven steps into a corridor (70cm wide) that terminated in a recess (87cm deep), with a centrally-positioned 10cm-diameter exhaust vent. The floor of the north corridor was of poured concrete with five 60cm by 46 cm slabs set into it. In contrast to this shelter and the others on Area J1, the south corridor had only four slabs.
The central chamber was identical to shelters F1-F7 and F9-F10 in terms of measurements and fittings. <1>