Wet Foundation
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At our 30 year old family cabin in Northern
Canada, we are having problems the timber piers settling. Unfortunately, the
piers are sitting directly on the saturated ground, no concrete footings
were ever placed at the time of construction because to get below the frost
line would have meant extensive manual excavation. At the back of the cabin,
due to settlement over the years, there is only about 8" of clearance from
the bottom of the joists to the ground, making any retrofitting of any
footings difficult. We continually jack the cabin and keep placing varying
sizes of timber plates under the piers as the old ones sink out of site. My
question is, would shallow excavation below the piers (while the pier is
supported by jacks/temporary posts) followed by the introduction of 3-4"
cobbles assist in increasing the bearing capacity of the soil? Or should I
try something else? Last year I installed a perimeter drainage system (4"
Big O Pipe surrounded by drain rock and enclosed in filter cloth) which
assisted in drying the soils out a bit, however, excessive moisture still
exists. Thanks for any assistance you can provide me!
Vancouver, Canada |
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This question is a little more
complicated than what I can handle here. In general, such a situation calls
for either support on bedrock, or using deepened foundations that reach
below the frost level. I would have expected the settlement to stop after so
many years, which indicates that there is more than simple settlement going
on. I am sorry, but you should discuss it with a local engineer who is
familiar with the soils and possible solutions. |
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Thanks Doc, As you stated, this is a complicated problem and as a Civil Technologist I could solve it as you suggested by placing deep foundations, however, the expense is prohibited! Would the cobbles assist in increasing the bearing capacity? Water, nice to drink but a pain in the ass when it comes to foundations! Thanks again, xxxxx ps. A series of springs in the area are providing the water to some degree. I hoped that the perimeter drain would have captured most of the water! |