Berniebeee
03-21-2014, 06:41 PM
Hi all,
My mom's 30 year old log house up here in the frozen north is supported by vertical wood posts as a foundation. The posts are located every 6 feet around the perimeter of the house and additionally there are a couple of posts supporting the main beam in the center of the house. The posts were driven directly into the ground. (About three feet down, according to a neighbor.)
The posts are now rotting where they contact the surface of the soil.
There are sections of wall under the perimeter of the house, in between the vertical support posts, which enclose the crawl space under the house . These wall sections are constructed of 2"x4"s, with fibreglass batt insulation, clear plastic vapor barrier on the inside and panelling on the exterior. These wall sections do not support the house at all, they just keep the crawlspace warm in the winter.
My mom had four contractors look at the foundation. They all suggest basically the same thing; Replace the wood posts by vertical steel posts. The top of the steel post would be bolted to the bottom of the house. The bottom of the steel post would be either embedded in or attached to a concrete pad, 2 feet square by 10" thick. The concrete pad would either rest directly on the ground or be dug in a few inches. (Yes, inches.)
I have two concerns here. First, the concrete pads at the perimeter of the house would be half inside on warm ground, half outside on the frozen ground. They could be tilted by frost heave. (The frost line here is five feet down. It gets cold!)
Secondly, if a small earthquake or even a strong wind should occur, I think that the steel pole/ concrete pads could all just topple over like dominoes.
The ground appears to be pretty loose sandy soil.
Am I way off base here? My experience is with poured concrete foundations and stick built houses, not logs. These contractors all seem to propose pretty similar solutions, but it just doesn't smell right to me. I'm thinking of convincing my mom to call in a building or civil engineer, but that is going to cost a fair amount, in part because her house three hours out of town.
I would really appreciate your thoughts.
My mom's 30 year old log house up here in the frozen north is supported by vertical wood posts as a foundation. The posts are located every 6 feet around the perimeter of the house and additionally there are a couple of posts supporting the main beam in the center of the house. The posts were driven directly into the ground. (About three feet down, according to a neighbor.)
The posts are now rotting where they contact the surface of the soil.
There are sections of wall under the perimeter of the house, in between the vertical support posts, which enclose the crawl space under the house . These wall sections are constructed of 2"x4"s, with fibreglass batt insulation, clear plastic vapor barrier on the inside and panelling on the exterior. These wall sections do not support the house at all, they just keep the crawlspace warm in the winter.
My mom had four contractors look at the foundation. They all suggest basically the same thing; Replace the wood posts by vertical steel posts. The top of the steel post would be bolted to the bottom of the house. The bottom of the steel post would be either embedded in or attached to a concrete pad, 2 feet square by 10" thick. The concrete pad would either rest directly on the ground or be dug in a few inches. (Yes, inches.)
I have two concerns here. First, the concrete pads at the perimeter of the house would be half inside on warm ground, half outside on the frozen ground. They could be tilted by frost heave. (The frost line here is five feet down. It gets cold!)
Secondly, if a small earthquake or even a strong wind should occur, I think that the steel pole/ concrete pads could all just topple over like dominoes.
The ground appears to be pretty loose sandy soil.
Am I way off base here? My experience is with poured concrete foundations and stick built houses, not logs. These contractors all seem to propose pretty similar solutions, but it just doesn't smell right to me. I'm thinking of convincing my mom to call in a building or civil engineer, but that is going to cost a fair amount, in part because her house three hours out of town.
I would really appreciate your thoughts.