Almost Finished

[cbrian]

After a lot of debate a year or so ago, I decided on a pier foundation. A dozen big storms and one tornado later she is holding steady. Lost some nice trees though  Here are some pictures, in no particular order.





















Will get some more updated pictures soon!

[cbrian]

Here are some more up to date photos including bracing and split level detail....even after the split level my post where to high for my liking on the front. I drilled holes in my pier footings and added some rebar, then poured concrete up the post to shorten the post height.









I know that pier foundations are not ideal, but I have a ton of water coming off the hill behind me and I was scared of a concrete wall trying to hold it all back. Any ideas on what else I can do to strengthen my foundation? I have had some crazy high winds and if I didn't have a metal roof I would not have even known it. The structure doesn't move, but you guys had me so scared of pier foundations before I started this, and I was hard headed enough to do it anyway, just want to make sure I am still on the right track.

[cbrian]

If I was to go back and retro fit this structure with a step down footing, with block wall or block and stem wall, what would I need to do in regards to water? The only reason I built this using a pier system is my neighbor had a block curtain wall blow out due to water coming off the hill during heavy rain. Now the water just goes under and around, so if I block its path what are my options?

[old_guy]

Holding it back is a losing proposition.  Why not divert it?  Some effort in changing the shape of the hillside above the cabin should be able to divert most of the runoff around the sides of the structure.  That hill is tall, so perhaps a series of structures further up would be more reliable than just one.

If you must resort to a wall, incluide a good french drain to carry off the water, so the wall need not pretend to be a dam.

It would help if you could add some pictures and/or descriptions of the terrain uphill of the cabin.

Your build site is similar to some of those on our Tennessee property, so I am very interested in learning from others who chime in here.

[cbrian]

The house itself is on a natural saddle back, and I have put a large retaining wall to help some, and also give me a driveway. But I still get a lot of water, not sure a french drain would keep up, and I am in solid rock. Water just really comes down that hill, even with the retainer.





My piers go down 4 foot into solid rock. I wish I had just listened and waited until I could afford to do more. I don't have any immediate problems, everything is holding steady, and we have actually been living in the house for a year now. I just rather make any changes now, while I am still working on it, than later. I mean if I have to add a perimeter step footing and then add some block and build a stem wall, I rather do it before it's completed. My wife isn't sure why I am freaking out, but my father in law wants to build one like mine, and I am telling him not to cut corners, but he says mine is fine. Well, maybe, but for how long?



I have a lot of rock outcroppings, and the guy that drilled my footings had a hell of a time. I am just worried that if I do need a perimeter footing and stem wall, how will I dig it? I just hope someone will take a look and see if there is room for improvement or anything I should do that I haven't. Or if I should try to do a perimeter footing or wait until failure?

[cbrian]

The front of this building is higher than I wanted, even with the step down. I think I will pour a continuous step footing under the first half of the house (the tall part) above grade and then build a stem wall. That will give me an area for storage, or maybe even finish it out and make a man cave. I can then divert water from behind that with a drainage system and maybe place some shear panels on the remaining piers in the back. After that my tallest pier would only be 4 ft above grade and the entire downhill side of the structure will have a proper foundation. Just to tall for my liking, even with bracing.

Any thoughts? Opinions? Can't believe I didn't get any comments either way. Not even a "oh man that house is cool" or "oh man that house is scary as hell" 

[Patrick]

That's what I was thinking also, that's a lot of unbraced concrete out the ground and they look small in diameter for that much building above them otherwise I like the landscape was wondering where and how did you get the massive retaining blocks around the driveway? Those are pretty cool.

[John Raabe]

You've done a great deal of work and the site is both awesome and frightening.

I would suggest talking to a geotech or soils engineer about abating or diverting the potential for water damage. You should also have the foundation looked at by someone with structural design experience on hillside pier foundations.

I'm not qualified to give advice on this project, but the house below is an example of an engineered pier and beam foundation. It uses metal plates and bolts to reinforced the connections and joints where bracing and support members connect. You can see how that adds a great deal to the stiffness.

[cbrian]

Thank you John for the input. I still have a lot of retro fitting to do. That is what happens when you get in a hurry.  I am hoping a perimeter step footing with stem walls will be enough to remove any risk associated with the house being that high above grade. I like the metal bracing, shouldn't be to hard to have some fabricated.

[cbrian]

Thanks Patrick. The blocks are precast concrete 2' x 2' x 4.5' and weigh roughly 3000 lbs. They are about 90$ a piece here in Central Texas and work based on a level footing and gravity. They are cheap and effective, and unless you mortar the joints, they do not require a drainage mechanism. The only down side is they are heavy requiring special delivery and heavy machinery to handle them, unless you want to make a ton of trips back and forth. The concrete plant here makes them with left over concrete from their jobs, that is why they are so cheap.

The front of my house is the high spot that worries me, the post are 8-9' above grade under the deck portion, and 5-7' above grade under the bearing wall of the house. I used 6 x 6 posts attached to grade level 18" piers poured at different depths according to soil condition, some as deep as 8' some in solid rock at 3'. The post is attached with a 3/8" metal bracket embedded 2' into the concrete. After construction the height scared me, so I retroactively drilled into my piers to add re-bar, poured concrete up the post to shorten their length between concrete contact. Still scares me, I don't feel the house move, and haven't had any problems, but knowing the height on paper and seeing it in person, two different things.

The 6 x 6 post at 8' has an allowable compression load of 25,000 lbs, at 12' it is only 17,400 lbs. It's amazing how strong the post are. But that does not take in affect, water, wind shear, soil shifting/heaving. That is why even though I am well within the limits for my post, the height worries me. The higher you go the more those variables come into play, especially wind shear.

My wife says I am being a worry wart, since we rarely have high winds, and are no where near earthquake country. But man that dang thing is just tall, even with a solid concrete slab under it, it would make me nervous, from ground level to tip of roof is 38'.

[cbrian]

It really sticks out above the trees.

[glenn kangiser]

I agree with old guy and John touched on it a bit ... Try diverting the water uphill before it ever gets to be a problem.  I read a story of an old Chinese guy reclaiming land that was dry but had runoff issues during rains. He said, if you take care of the water at the top of the hill, it will not be a problem at the bottom of the hill.

[dablack]

How is that beam attached to the top of that 6x6 post?

I don't think compression is the problem here.  I'm much more worried about a side load.  Is there anyway a car or truck could roll down the hill and take out a concrete column?  What about a rock?  Like you said, that house makes one impressive lever arm working on those concrete columns. 

Besides that, I think it is a great house in a great location.  We love living in east TX but we also love to visit the hill country. 

Austin

[pmichelsen]

I have a love hate relationship with those concrete blocks, when we built my buddies house we raised the lot six feet due to the high water table and we must have placed a few hundred of those blocks. But by the end of the job we got really good at setting those things.

[UK4X4]

list me down in the scared camp !...thats dam tall !

the triangulation looks like 1x material, but hope its 2x

are the blocks blocking the flow or diverting it ?

it looks like their just blocking...

in this picture
https://s1375.photobucket.com/user/christopher_gilbert2/media/20131109_100357_zpsb96f5021.jpg.html#/user/christopher_gilbert2/media/20131109_100357_zpsb96f5021.jpg.html?&_suid=14131984541190801419327170817

It looks to be water errosion between the foundation and the scafold, I think that need diverting further away from the foundation..

Same picture looking from down hill it looks like the left hand side of the building has the lowest side and drops both down and away from the property. to the left.

In the pic of the limestone shelf and the gas cans how easy would it be to build a cemented wall of blocks a foot down hill from the ledge making a large gutter and diverting the water to the left where the natural drainage is

[cbrian]

UK4x4...it is all 2x material
The blocks are just holding back the road material...the placement of the structure on a saddle back (high spot on the side of the hill) naturally diverts the majority of the water before it ever reaches my house, but if I place a cross footing under the house I am worried about blocking the water that falls directly around the back of the house. I don't have much water coming from uphill hill, but even the direct rainfall around my house is a lot of water, so it is not as much as uphill water problem but direct water coming off the roof of the house and porches that adds up fast.
The erosion you are seeing between the scaffolding and the house is because I dug a trench for a sewer/power and the water seems to find it and eat it out...in the process of filling with rocks/gravel.
I like your idea of a retaining wall below the rock wall. Should be able to drill into the rock and put up a block retaining wall. It is only 30 feet between my block wall and the rock wall and then 14 feet between my rock wall and house, but man does the water come down. The wall should help divert that area. If a 40 foot area behind my house can create that much water would hate to have the whole hillside water coming down on me, thank God we choose a natural saddle back to build on.

[cbrian]

dablack..the post where just toe nailed and 2x6 side blocked until my brackets came in. Had some 1/2" plates fabricated. I know the Simpson strong tie stuff is rated for this, but I just don't trust that thin stuff for some things.

[GSPDOG]

Holding it back is a losing proposition.  Why not divert it?  Some effort in changing the shape of the hillside above the cabin should be able to divert most of the runoff around the sides of the structure.  That hill is tall, so perhaps a series of structures further up would be more reliable than just one.

If you must resort to a wall, incluide a good french drain to carry off the water, so the wall need not pretend to be a dam.

It would help if you could add some pictures and/or descriptions of the terrain uphill of the cabin.

Your build site is similar to some of those on our Tennessee property, so I am very interested in learning from others who chime in here.

IMHO I have to agree with old guy and a couple of other post,  You need if you have not already done so have an engineer look at this.  Diverting the water is the better option.  I did not see how the piers were poured but I would hope they have plenty of rebar tied together and even then depending on how cold it get and the moisture I would be concerned about freeze sheer.  Freeze sheer occurs at the point where concrete is at two temperatures and the expansion or contraction vary enough to cause a shift or crack once this occurs water penetration over time will do the rest of the damage, as an example rusting rebar expands and cracks the concrete even further. 

Not meant to scare you as this is something that happens over time not necessarily quickly unless there are specific extremes.  In addition there is a lot of weight sitting on those piers.

Not knowing how these were piers were built how deep or the kind of stone.  These are variables the engineer is going to need to know.  Remember heat rises when I was stationed in North Dakota and being a Missouri farm boy I was surprise my first spring to see 1,000 lb boulders in the middle of a field where there were no rocks or boulders the previous year.  This occurs there due to something known as frost heave and it happens every where to some degree in colder climates.

In Missouri anything below 36" inches is protected to some extent from frost heave.  However the granite here is known to cause rock slides and driving through Missouri you will see warning signs where they have dug in the side of a hill.  Water infiltration into this exposed rock over time causes it to break free and in some cases in rather spectacular fashion.

Water off the roof open end gutter (down hill side open uphill side is closed, no downspouts) if you have a leaf problem with a splash pan we use them for barns to keep water away from the piers in pole barns.

Hope that helps.