12-08-2009, 05:50 AM
Dennis - You should have no issues with a post and beam atop a rafting pad system. I would at the same time also point out that an alternative turn down footing pad foundation will save you much money as well provide you with a naturally cooler floor surface and that’s something to consider also. Just for G.P. In lava, the rip occurs when a dozers single claw is forced deep into the lava by wobbling the tractors load with the claw deployed against the lava surface and then when driven down below the surface it's used to rip through it by advancing forward and or tilting the claw forward and backwards. Rolling is when the larger lava fragments are driven over by the heavy dozers steel tracks crushing it into smaller lava rubble making it more gravel like in nature. Hence ripping and rolling, this also serves to collapse and crush any subterranean voids that may otherwise succumb to a house load atop them inducing foundation failure. A D-9 or like type Dozer has the weight to flesh out these problematic voids and crush them, essentially removing them from the sites equation. Sometimes in Aa a lighter dozer may be used and the area simply rolled to save $ on the dozer and its time. In the end, your Engineer or Architect should call the shot.
Mr. Bill - Ultimately your foundation will rest in the hands of a licensed Engineer regarding the matter but I would say if it's your desire to build in that manner, than your engineer can make it happen and all should be fine. Sounds to me when you span a crack you're citing a grade beam type foundation also perhaps serving as a drag strut across the cracks? On pahoehoe lava, I personally like less ground coverage by concrete and dislike disturbing the natural grade in an area depending on the subterranean conditions, though it's not always practical - it's my preference for aesthetic purposes. I would caution that a 30" concrete wall/beam will interfere with natural air flow under your house if it becomes a full perimeter type. I would not advocate the use of any sort of full perimeter stem wall foundation in the Puna region, it's just asking for floor system issues regarding fungi and pest issues.
If you're just putting in a single grade beam/wall, ventilation should be fine.
E ho'a'o no i pau kuhihewa.
Mr. Bill - Ultimately your foundation will rest in the hands of a licensed Engineer regarding the matter but I would say if it's your desire to build in that manner, than your engineer can make it happen and all should be fine. Sounds to me when you span a crack you're citing a grade beam type foundation also perhaps serving as a drag strut across the cracks? On pahoehoe lava, I personally like less ground coverage by concrete and dislike disturbing the natural grade in an area depending on the subterranean conditions, though it's not always practical - it's my preference for aesthetic purposes. I would caution that a 30" concrete wall/beam will interfere with natural air flow under your house if it becomes a full perimeter type. I would not advocate the use of any sort of full perimeter stem wall foundation in the Puna region, it's just asking for floor system issues regarding fungi and pest issues.
If you're just putting in a single grade beam/wall, ventilation should be fine.
E ho'a'o no i pau kuhihewa.