concrete or wood piers? (house, new construction, live in)

[namder1]

I recently posted a similar post but have this question. Had a guy come estimate replacing the posts under my house. he said he uses hemlock posts because they last the longest. I asked an old friend and he agreed....any thoughts on this brfore I commit to it?

[kellysmith]

Originally Posted by namder1

I recently posted a similar post but have this question. Had a guy come estimate replacing the posts under my house. he said he uses hemlock posts because they last the longest. I asked an old friend and he agreed....any thoughts on this brfore I commit to it?

Hemlock will last longer than spruce, probably not as long as pressure treated, but if I was doing it, I'd use concrete in footing tubes. (not sauna tubes) Even if the post goes below the frost, it will still move because the frost will grab the sides of it and literally pull it up or push it sideways some over time. The concept of the footing tube is the bell housing is well below frost line and provides too much resistance to frost pulling at it at the frost line. Why use 1800's technology in today's world? These tubes are used extensively in Canada and hold up well in that environment. Biggest problem would be excavating a large enough hole to drop the footing tube in.
Here's their website...
Concrete Pier Forms | Suitable for Decks, Fences, Additions, Docks | The Footing Tube

[retiredtinbender]

Originally Posted by kellysmith

Hemlock will last longer than spruce, probably not as long as pressure treated, but if I was doing it, I'd use concrete in footing tubes. (not sauna tubes) Even if the post goes below the frost, it will still move because the frost will grab the sides of it and literally pull it up or push it sideways some over time. The concept of the footing tube is the bell housing is well below frost line and provides too much resistance to frost pulling at it at the frost line. Why use 1800's technology in today's world? These tubes are used extensively in Canada and hold up well in that environment. Biggest problem would be excavating a large enough hole to drop the footing tube in.
Here's their website...
Concrete Pier Forms | Suitable for Decks, Fences, Additions, Docks | The Footing Tube

I've seen these used quite often lately. Good idea IMO.

[kellysmith]

Originally Posted by retiredtinbender

I've seen these used quite often lately. Good idea IMO.

I've used them on a couple projects and they will not be moved by frost, and will last a lot longer than any of us! It does take a big hole to get them in place however....wouldn't want to try to put them under an existing structure without a machine to excavate.

[Nor'Eastah]

These are the neatest thing I have ever seen, called Dek-Blocks:

How to build - Shed Floor Decks - Deckplans.com - deck building made easy using our custom decks setup.

We have used them for both an outdoor deck and for some toolshed-type buildings at our home. We live in Rhode Island, where the winter temps go as low as -10F, and neither the deck nor the sheds have in-ground foundations. These concrete blocks 'float' on top of the grass or dirt, and the structure above it holds them in place. Works like magic. No wobbling, no frost heave.

[Northern Maine Land Man]

If you have old posts now the first task is to find out what the existing posts sit on. If they are directly on the ground and you have limited access to the area the best way to proceed is to lift the building beside each post about 3/8 inch one at a time. While lifted, make a level spot and spread a couple of inches of pea stone about 2 feet square. Place a round concrete pad on the pea stone. These are called "elephant feet" in Maine. Measure the distance from the pad to the top of the old post. Cut a utility pole to that length. Place the new pole in place and lower the building 3/8 inch onto the pole.

Do this one post at a time til done. It's a lot of work, but those utility poles will outlast any of us. How do you lift the building? Use 4x4 wood cribbing and hydraulic jacks. The heavier capacity jack capacity the easier is is to lift the building. I use 12,000 pound jacks.

This is for buildings in place. For new construction, the blocks in the post above look good, but compare the cost with the elephant pad system. Remember to put crushed stone under the pad. Your building will move less.

[namder1]

I have done it that way before NMLM and it works well. My problem here is when they moved this building here, they dragged it onto the lot using a skidder and rolling it on logs. When they got it where they wanted it, they simply unhooked the skidder and left the logs underneath the house, then put posts around the perimeter. So basically the logs under the house are all the supports the middle of the place. So, one guy proposed lifting the place using steel girders about 2 feet in the air so he can get access to the middle to dig for posts....at a cost of $8000. probably not a bad price if ya have an extra 8k rolling around but more than I planned on spending for sure....

[dmyankee]

Go with NMLM's plan. By far the simplest and easy on the budget. We are getting ready to replace an entire sill this summer with 20 ton jacks and 6 or 8" PT.

[Submariner]

Originally Posted by Nor'Eastah

These are the neatest thing I have ever seen, called Dek-Blocks:

How to build - Shed Floor Decks - Deckplans.com - deck building made easy using our custom decks setup.

We have used them for both an outdoor deck and for some toolshed-type buildings at our home. We live in Rhode Island, where the winter temps go as low as -10F, and neither the deck nor the sheds have in-ground foundations. These concrete blocks 'float' on top of the grass or dirt, and the structure above it holds them in place. Works like magic. No wobbling, no frost heave.

I have seen those but I do not see why they wouldn't heave.

[Zymer]

Originally Posted by kellysmith

Hemlock will last longer than spruce, probably not as long as pressure treated, but if I was doing it, I'd use concrete in footing tubes. (not sauna tubes) Even if the post goes below the frost, it will still move because the frost will grab the sides of it and literally pull it up or push it sideways some over time. The concept of the footing tube is the bell housing is well below frost line and provides too much resistance to frost pulling at it at the frost line. Why use 1800's technology in today's world? These tubes are used extensively in Canada and hold up well in that environment. Biggest problem would be excavating a large enough hole to drop the footing tube in.
Here's their website...
Concrete Pier Forms | Suitable for Decks, Fences, Additions, Docks | The Footing Tube

I have heard that wrapping the posts with several layers of polyethylene is supposed to prevent them from being 'pulled' up in this manner. The layers of plastic 'slide' so that the post isn't pulled.

YMMV, I don't know for a fact if it works but is *sounds* plausible.