if the house floats, should we anchor it
Our cottage in Northern Michigan sits on cement piers and cinderblocks, and has done so for eighty years. In the fifties it was remodeled and a large fieldstone fireplace was added. There has been next to no shifting of the house or fireplace.
We are adding a ten foot porch on the front of the house and a smaller one on the back. The front porch will be two stories high and the roof will be extended from the original existing roof line.
There has been some discussion about the four foundation piers that will hold up the porch. My question is, if the house has been “floating” for this long, will anchoring the porches be a good idea?
The house is a seasonal one, and is unheated and unoccupied for nine months each year.
Replies
if it is on piers that extend below the froct line and are ideally tapered small end up then it is not floating as normally defined
floating around here normally refers to sitting on the ground and not bellow the frost line
Wisconsin and eastern Ontario are about the same for frost depth
Normally around here we either float a structure completely or support it below the frost line completely and do not mix them if we dont want structural cracks
On piers normally gives you a colder floor but this isent your concern as you are not there in winter
I would be surprised if your cottage was not floating. It is not common to find footings on an old place that are dug below frost. Usually the piers go below grade about as much as they stick out of the ground. You can determine this easily enough by digging down the side of the footing and seeing how deep it is.
You should match the existing footings with your porch footings in any case. If the house footings are not deep, dig to undisturbed earth and make sure your base is big enough to support the load.
It shouldn't be a problem for you but it wouldn't hurt to take precautions. If you feel that there could be risk of movement in the new footings try boring a 16" diameter hole well below the frost line in your area. pour a 6" bed of concrete and allow it to set. Then using a 12" "sonotube" concrete form and fill with concrete and reinforce with rebar. fill untill the concrete is above grade. Before the concrete sets insert an adjustable carport bracket. This will allow you to re-adjust the height if any settling does occur.