The need for more storage...we had two options available, either extend on the front of the cave which we didnt realy want to do or extend back by digging. Digging it was, with it being too risky to extend sideways (neighbours) and with 3 of our ceilings in different rooms being supported with rsj's the only option we had was to dig back from the deepest part of the cave.
Tools for the job, picks, wheelbarrow, SDS hammer drill and a mattock.
The wooden beam and doorway were dug out last year, now it was time to extend the room. Carefull measurments were taken both inside and on the roof - its very easy to lose your bearings once you get up top so its essential to spend some time estimating and measuring wall thickness and angles. Angles can be tricky... its also good to get inside the neighbours caves to make sure they havnt had the same idea and they are closer than you think!
Keeping the arch is essential for the general strength in the roof, every 6-8 inches we dig back we finish up the session shaping the ceiling and corners. The room at the moment is only six feet high but will eventualy be seven feet high once the floor is lowered. This we plan to do by digging around eighteen inches down, a foot for extra height, a few inches for beer bottles (see post) and few more for levelled concrete.
The rock.... a big difference the further we go back, the top half of the rock is very soft and crumbles away. In contrast the lower half of the rock is very very hard - the hammer drill is essential for this part, instead of crumbling away the rock breaks off in large shards and chunks. This is just our area and the rock will vary from cave to cave and village to village.
Safety tip - to test for movement yeso the roof as you go, any hairline cracks suggests the cave is saying hello and RSJ's may be an option.