Decks, Patios, Porches and Docks - Log deck and concrete footings (replacement)
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woozoo
05-11-09, 09:19 PM
Hi all,
I am having to rebuild my deck on my log home9 37 years old). I have 10 new 10"X15' logs for my supports. My old concrete footings are only 6"round tube footings above grade and 7"x7" square below those. They seem to be over 4 feet deep(canada). Should I remove each footing and replace with new tube footings or could I just slip a new 8" tube over the existing ones and pour new cement around them. This would save huge time. Old footings are in great shape except for a little leaning.
Please help.
thanks zoo
I am having to rebuild my deck on my log home9 37 years old). I have 10 new 10"X15' logs for my supports. My old concrete footings are only 6"round tube footings above grade and 7"x7" square below those. They seem to be over 4 feet deep(canada). Should I remove each footing and replace with new tube footings or could I just slip a new 8" tube over the existing ones and pour new cement around them. This would save huge time. Old footings are in great shape except for a little leaning.
Please help.
thanks zoo
Pulpo
05-11-09, 09:23 PM
There is no reason to remove them as far as I can see.
woozoo
05-12-09, 08:12 AM
I need to have my new footings 12" above grade and for looks I need them bigger. So you think that yes it would be ok to just drop a larger tube over my existing footings.
please respond as I really need some advise.
thanks in advance.
please respond as I really need some advise.
thanks in advance.
Pulpo
05-12-09, 03:56 PM
Personally, I think it's ok. Just slope the top of the footings in case water hits it, it will run off.
lefty
05-12-09, 10:43 PM
woozoo,
The problem I see with you plan is FROST HEAVE.
You existing footings go down over 4' because of frost. The bottom of the footing has to be below the frost line, or frost will cause them to heave. If they were done properly, you have a LARGER footing at the bottom of the hole (say 15" square and 12" to 15" deep), and that 7" by 7" 'tube' is just an extension on top of that large footing to get it above grade.
If you slip a larger (8") tube around the 7" tube, you need to take it ALL THE WAY below the frost line. If you don't, the freezing is going to expand the soil at the bottom of your 8" tube and heave it.
Soil EXPANDS when it freezes because of the water in it. Water is THE ONLY liquid that EXPANDS when it turns to a solid (freezes). If you give it a lip to grab hold of, it WILL heave your footings.
The problem I see with you plan is FROST HEAVE.
You existing footings go down over 4' because of frost. The bottom of the footing has to be below the frost line, or frost will cause them to heave. If they were done properly, you have a LARGER footing at the bottom of the hole (say 15" square and 12" to 15" deep), and that 7" by 7" 'tube' is just an extension on top of that large footing to get it above grade.
If you slip a larger (8") tube around the 7" tube, you need to take it ALL THE WAY below the frost line. If you don't, the freezing is going to expand the soil at the bottom of your 8" tube and heave it.
Soil EXPANDS when it freezes because of the water in it. Water is THE ONLY liquid that EXPANDS when it turns to a solid (freezes). If you give it a lip to grab hold of, it WILL heave your footings.