Adding a second story to a garage
I would like to add a second story to a garage and convert the entire structure to living space. The garage is in zone 6 and currently has no insulation. It’s on a 4″ slab with a thickened edge of 8″ for a total of 12″. In a brief conversation with an engineer, he stated I have to go down to 42″, frost line, to be able to do so. I feel very confident that I can negate any potential frost heave. On two sides of the structure there are 40″ retaining walls holding back the earth that are not in the best of shape, they lean slightly towards the structure. There is a clear walkway around these two walls. My son recently purchased the property and I think the retaining walls are something we’ll have to deal with at some point in time. The garage has 8′ walls, the bottom half is made of block and the top half is framed. Because it would be very difficult to get large quantities of backfill in the walk way, I looked into using geofoam to fill the void and was pleasingly surprised that I could use 2′ thick pieces of the foam and cover the entire bottom half of the wall at a reasonable cost. So the foam blocks would be 2′ thick and 4′ tall. I would then back fill with gravel between the block and earth the remaining small voids. So that would be more than adequate for frost protection. On the two other remaining walls I would be adding on more structures using a FPSF, so the all four walls would have excellent frost protection. The remaining walls would become interior walls. So since I have eliminated the frost heave potential, my question is. Will the modest thickened edge of the slab support a second story? The soil conditions seem very good there. The garage slab has a few hairline cracks but it is 35 years old. There are also a few hairline cracks in the mortar of the blocks, but one really has to be looking for them to find them. I will add that the garage floor of my house has more cracks, it was built to code and half the age.
This potential house is for my son and we are trying to build it as inexpensively as possible, but will be using very green materials with insulation values and windows being beyond code. The price of Zip System has more than doubled in our area, so we are working hard so we don’t have to compromise on building materials.., insulation and windows.
Your input would be greatly appreciated. Thank you.
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