Is a shingle, gravel or timber base okay for these sheds?

We would not recommend any shingle or gravel bases. You need to ensure the base is completely solid and level, as an unsuitable base will affect the life of the building. For instance, an uneven surface could cause the building to twist over time. A timber base can be suitable as long as it is designed to support the building fully and the ground beneath is both solid and level. We recommend concrete, slabs or our plastic Pro Shed Base Kits (with suitable level ground preparation).