Deck Slowly Moving Down the Hill

[Mo Heat]

Man, I really appreciate all the comments. I'm starting to have a more holistic picture of things in my mind, but let me update you on what I've done, first.

I bought a couple PT 4 x 4's and used the two 2 x 6's I already had to make a fail-safe support so the deck won't fall down (see: photo(s)). Now I feel like I have some breathing room.

I've got a landscaping guy coming tomorrow, but I suspect he will present a limited approach with limited emphasis on drainage and foundation issues. They do have a deck guy on staff, so I thought that was a plus. But since I made that appt, I've found someone else that looks like they might fill the bill better regarding drainage and foundation issues. Here's the web site.

http://www.crowderconstruction.net/home/

I'd appreciate any comments, especially from you, keyman, as to the appropriateness of this contractor for my erosion and soil movement issues. And I suspect I'll either ask them to build a retaining wall, or they will suggest it. Mrs. Mo Heat is now sold on the idea of adding a bit of usable yard space at the back of the house where their is only a "wild" hill area now.

I didn't mention it, but I've got neighbors on both sides whose rain runoff actually comes into my yard. It kind of sucks, but at least one of them, and this was the worst one, put in some irrigation pipes for their downspouts (actually before I moved in). That helps a lot, but his side yard still drains mostly into mine as does the other neighbor. I believe this is probably a lot of my problem, although I have some side yard run-off myself, especially from the side where there is still one downspout that simply dumps onto the side lawn. All my other downspouts are fed into that 6 inch, black, corrugated, irrigation pipe, and dumped on the lower side of my "foundation fill hill". I even have a driveway drain and a couple other yard drains out front that join with several down spouts that dump into a pretty big PVC pipe (about 8 inch diameter) that really dumps some water below the hill when it rains. So there has been some work done here and things could be worse, but some additional work is probably needed.

I've actually got quite a little gully developing on one side where the neighbor simply dumps his down spouts onto his lawn and since I'm somewhat downhill from there, my place takes care of the water course. I'll try to take some photos of that, too, and post them for general interest.

Keyman, my neighbor, who's lived here from the hood's inception, told me my place was NOT built on fill, but I think he may be wrong. At the very least, they moved a bunch of dirt around, which maybe isn't as bad a trucked-in fill? I don't know, but I can tell that my hill has been altered to allow the house to sit flat, that's for sure. The land had no previous uses as far as I know. It was really west of the original developments in St. Louis, and I think they are only building on these ridge lines because they ran out of flatter spaces. I've got 100 year old, 80 or 90 foot tall oaks out back (I counted the rings on one I felled), so this was just unused space prior to the builder buying it about 19 years ago. He left the lots sort of big (2/3 acre average) and left the old trees for the most part.

 

[Mo Heat]

BG, Here's a Dino-Ruler update for you. Looks like my slabs have moved another 1/2 centimeter since the last Dino-ruler photo. That seems like a lot to me.

 

[restorer]

Mo:

I'm certainly not the best at land use and responsibility for drainage, but I think you have some issues with your neighbors. If the run off from a neighbor is causing erosion on your land, they need to correct their drainage problems. Because I am in a commercial zoned area, I am responsible for insuring that all run off ends in the storm drains and not my neighbors property, for the privelege I pay an extra two or three hundred in taxes. Because my parking is adjacent to my neighbors parking and there has been some bad blood with prior owners, I have a speed bump berm around my parking and a 4 X 4 dry well. The roof run off goes to the storm drain.

I think the contractor you show on the last post is a good idea. You should invest a little in exploring why you have so much plumbing in removing rain water. It may be normal in your area, but drainage seems to be an issue. If you have had extra rainfall the last year or so, you may have ground movement. Building on fill should not be a problem if properly done, but you are getting abnormal movement in my opinion. Do you have issues with moisture in the foundation walls, or water in the basement? If you have a sump pump is it running extra lately?

Stabilizing the deck should be the easy part. Stabilizing the ground looks like a problem, but is usually solvable.

My sisters house in Washington years ago was built on a slope over looking the Puget Sound. It had been an orchard, and was a huge blackberry patch. The contractor was anything but a water specialist and had no idea about need for drainage. Their deck started falling away. They first hired a contractor specializing in drainage, who not only solved the water problem, but was able to set up a PUD and the twelve homes put in a master drainage system for pennies. The deck was simply. Another contractor drilled 16 inch piers down 60 inches and hit "bedrock" concrete and rebar with a stainless post anchor. The engineer from the first contractor after the work was done said, "You won't have to worry about the house sliding now!"

 

[begreen]

BG, Here's a Dino-Ruler update for you. Looks like my slabs have moved another 1/2 centimeter since the last Dino-ruler photo. That seems like a lot to me.

If that is the same location, I would agree, it's moving quickly enough to take note. Mark that location permanently by scoring the slab. Document this movement well with date of photo and location. Maybe pick a couple other spots because they might be moving at different rates. Sounds like it's time to get an expert in, but again, ask around and get the best qualified person for the job. Crowder looks like a good start. Best of luck with the neighbors and getting this all resolved.

 

[HarryBack]

Heck, Mo, lemme give ya my 2 cents worth.......currently, I sell stoves, pellets, and lumber. I design decks, and decipher code for the area builders. I do the calcs for lumber sizing and suitability as well. Im a licensed Construction Supervisor. In my earlier days though, surprisingly to many of you, Im sure, I also got a BSc. in....wait for it....Geological Engineering! yup.....and that includes surveying! My senior thesis involved analyses of tailings pond failures in southern Colorado, most of which failed due to inadequate cosntruction and liquefaction of the soils.....yes, the ground moved!

Anyhow....I DO NOT beleive your soil is migrating downhill.....if it were, you would see more evidence of soil movement such as gapping, sloughs, sinkholes, cracked foundations, massive vertical deviation of your deck, and your vertical supports would be far from as plumb as they seem to be in the pictures GVA pointed out..(thanks, GVA). Most likely what you are seeing is effects of water....the patio blocks will move apart with the freeze/thaw of the water in the ground, especially so if there is noting holding the blocks in place and the drainage is poor, the situation can also be exacerbated (sp?) by the type of soils you have. Your rim joists are moving (see pics) because of the water as well, and also very poor construction. When the wood of the deck and rim joists especially get wet, they swell. This pulls the nails out somewhat. When they dry, they tend not to go back together, the nail basically gets pulled away, as seen in the pictures. I hope I dont have to tell you the correct way to carry the joists in this case would have been to use joist hangers, much like the ones used on the ledger. As I see it, most of your issues are due to poor construction.

Ground movement is a funny thing. Its unlikely the ground is moving below the house without the house itself moving.....the foundation and footings would act as a shelter of sorts to stop this. Where you normally see ground movement is when youve a wide expanse of ground on a steep hill that unobstructed by walls, trees, etc.....think of it as a slow-moving avalanche of snow...you see avalanches on steep slopes where nothing holds the snow back.......you almost never see avalanches start below the treeline, where its held in place.

Your slabs could be moving just due to traffic and the fact that they are sitting atop rounded gravel....much like sitting them on marbles.

How to fix it? Well, you could hire a reputable contractor to put a carrying beam UNDER the joists, and use hurricane ties to attach them to the beam, and make sure he/she uses actual footings sized for the soil conditions and set BELOW the frost line. Me, Id rebuild the deck completely.

I wouldnt hire a surveyor. Most likely the only surveying done on your property is a bounds survey, with no real topographical data. If there is some data, and Id be surprised if there were, it would cost ALOT of money to have to surveyor shoot grades and draw up a topo map.

Ditto on the landscaper as well.....you'll get a retaining wall, etc, and maybe with that, better drainage, but possibly not. My money is get a good contractor over there.....talk to the lumberyard, talk to friends who have hired folks. Dont go with the cheapest Billybob you can find, you get what you pay for.

 

[Mo Heat]

Thanks for weighing in HarryBack.

Since April 10 of this year, the slab I measured has moved an additional 0.5 centimeter, or half a centimeter. That seems alarming and there's been no frost in that period. And check out the ornamental gate. See it? It's downhill and to the right of that white trellis. There's a little sapling between the camera and the gate, so it's a bit obscured. It's in the bottom right quarter of the photo.

That gate was pretty much vertical when I moved in 7 years ago. Now look at it! It's leaning at an fairly steep angle. I mean, it looks seriously crooked to me! Isn't that caused by some sort of earth movement. Or maybe erosion? But if it was erosion, wouldn't the post just have the dirt washed away from it? Would erosion lean it over like that? Man, that bothers me! It's only another 15 feet or so to the house! (Take a deep breath Mo... breathe...)

I also notice a lot of dirt "missing" on that hill, pretty much from side to side, the length of the yard, but worse on the side with the gate and trellis. There's a lot of water that runs down there, by that gate, when it rains. And lots of other things that were once buried in that hill, and just below the hill, are starting to pop up out of the ground, like it's being washed away or something. And a big black irrigation pipe from one of my rear down spouts that was once almost completely buried (only about 4 feet of it showed, and only an inch or two at most poked out of the ground) is now almost completely exposed. Where's all the damned dirt going? Why? And how do I stop it?

If I just address the deck (thanks for those suggestions, BTW), it seems like eventually, there won't be enough dirt left out there to hold the house in place.

 

[Mo Heat]

I also notice that if I place a log or something sideways on that hill, or even below the hill, it's not long before dirt starts stacking up on the uphill side. Like I've probably got a lot of dirt washing away with every rain.

Since it rains a lot more in the spring here than most other times of the year, maybe that's what my problem is. Maybe the rain water running down my hillside is just taking all the dirt with it and somehow bending the gate and trellis over and pulling the deck down the hill somehow?

 

[Gooserider]

First off, I would say you have issues with your neighbors property draining onto yours... I know it's a big deal up here from a legal standpoint, and I would imagine it is in your area as well. The law basically states that if you build something, you can't increase the flow of water onto an adjoining property above what would have flowed there "naturally", and you can't concentrate the flow.

While there are laws about this, and proceedings one could take, I would strongly suggest talking to the neighboors first and trying to arrive at a mutually agreeable solution - lawsuits don't improve friendships...

Secondly, while anyone can put up a website that claims anything, that Crowder Const. link looks like it is at least saying the right things - if they can back up their claims, they sound like the sort of folks that can help you out.

Lastly, I think a retaining wall (if properly done) would help you out, both in terms of preventing any earth movement and in giving you more useable space on the lot... Just out of curiosity, where is your property line with respect to that hill? One of the issues you will need to consider, and possibly research, though the contstruction guy should know, is what sorts of setbacks you need from abbutters...


Gooserider

 

[HarryBack]

Goose is correct in this area about increasing water flow onto abutting properties, as well as concentrating the flow. This would cause all sorts of nasty problems with erosion of dirt, etc.......most likely your problem may be due to the erosion and/or inadequate footings. The dirt obviously doesnt go missing, it got carried downhill by water, most likely. Erosion is different from gravity migration of a hillside though. If the hillside is moving due to gravity, its only worsened by the water. More likely water is the transport method of your hillside. You'd need to mitigate the water issue and stabilize the slope by adding things such as landscape fabric, riprap, encouraging the growth of soil-conserving vegetation, re-routing the water (and remember, you cant re-rout it to the neighbors!).....theres quite a few engineering websites which cover slope stabilization.

 

[Mo Heat]

... Just out of curiosity, where is your property line with respect to that hill? One of the issues you will need to consider, and possibly research, though the contstruction guy should know, is what sorts of setbacks you need from abbutters...

Gooserider

The property line is about 150 feet back from the bottom of the hill, so likely there are no issues in that direction. But the sideways direction is another story. The hill starts between 5 and 10 feet from one neighbor and between 15 and 20 feet from the other neighbor, depending upon where on the hill slope you measure (top or bottom) since it tapers.

I don't think my one neighbor is concentrating any water since he installed down spout irrigation tubes to the back of his place that once drenched mine, but the other neighbor is dumping his roof run-off, through the downspouts of his gutters, out into his side yard, and that stuff is definitely coming onto my place. Is this considered concentration? I'd think so.

The good news is that on that side (without the irrigation tubes) the hill is remaining pretty stable, except that there is quite a little gully developing where both his and my side yards and downspouts (my only un-tubed down spout BTW) empty and coalesce into a single rivulet (see: photos).

HarryBack, do you think erosion could cause the tipping of my ornamental gate that appears in the previous post's photo(to the right of the white trellis)?

If you look closely at the first photo (below) you can see my neighbor's down spouts on the right side of the frame. You can also see a gentle sloping of the hillside towards my yard. And his fence base, combined with a gentle slope towards my yard, also insures that pretty much all of his side yard water comes over to my place. It then goes down the hill into the rivulet that is pictured in photo two below. I throw a lot of yard waste, dirt, rocks and stuff in that watercourse to try and slow things down, but to little effect.

 

[HarryBack]

as per the gate, Mo...How is it anchored? Is it cemented in, or are the post just put into holes? See how the top of the gate is going downhill and the bottom is staying in place? Erosion and gravity? If the slope were moving uniformly, you'd see the gate move more or less plumb downslope. It doesnt make sense (to me, anyways), that the soil would slip laterally in layers.....usually the whole mess moves.

 

[Mo Heat]

HB, I pushed on the gate today, and it wobbled easily. I'd say the posts are simply pounded into the dirt, and not very far at that. I think you are right about the gravity, erosion business. And that's good news, for the most part.

Update:

I had the landscape guy out two days ago. This guy's company pretty much does plant sales and installation, retaining walls, and decks. I figured he'd be pushing hard to sell me a retaining wall, but I was pleasantly surprised.

First, he was a really nice guy. About my age. No BS and a regular guy. He wasn't making any commission on a retaining wall and after accessing my situation concluded I didn't have much of a problem with moving earth and such. There's definitely some erosion as indicated by stuff moving around and appearing out of the ground, but that's about it as far as he was concerned.

He liked the plantings I have on the hill for stabilization, even though they aren't stopping all erosion, they are slowing it down, according to him. I even have landscape cloth under the tough monkey grass on the hill.

His conclusion regarding my deck was pretty much an echo of what everyone has been saying here. It is poorly built. But he didn't even try to sell me a new deck. Instead, he recommended several things that I could do to fix it, and maybe improve it if I wanted to replace my flooring boards, which are really starting to show their age.

He told me he'd recently replace his own boards with tongue and groove, PVC planks, and that I might consider doing the same, even though PVC is kind of pricey. He said my joists looked pretty good, and I could probably reuse them all. But the footers need to be dug up and replaced.

He recommended just setting the uprights on top of the footers. On some sort of little pedestal things, and not pour concrete around them. He said I could rent a jack hammer at Home Despot and do it myself, but it wouldn't be easy. He also recommended, as most here did, that I use joist hangers on both ends, and lag bolt the deck to the house somehow. It looked to him like the main 2 x 10 attached to the house had simply been hammered onto my cedar siding, and that's all that holds it to the house.

So basically, he recommended redoing the deck. I don't think he was much interested in his company doing it, or he wouldn't have started right in with the DIY advice. Either that, or he felt like giving free advice that day.

I then asked him for an estimate on replacing my RR tie flower boxes with some sort of stone and $5,000 rolled off his tongue as a ballpark estimate. That was about twice what I had expected, so it was a bit of a shock. Even more so when I attempted to translate in my mind what a retaining wall of much more formidable size and strength would cost. I suspect I'd easily be looking at 4 to 6 times that much, and started to feel nauseas, since Mrs. Mo Heat is really wanting to extend the back yard. Hopefully, those figures will discourage her, as well.

I still plan to get the erosion specialist guys, from the web site I posted earlier, out here and see what they recommend for the erosion. If they don't think a retaining wall is needed, then I'll feel like I'm off the hook. Then I'll just need to consider erosion measures, probably drainage improvements, or something, and redoing the deck, which I might attempt to do myself if I can get some help from hearthnet, my B-N-L, and father-in-law. Elkkimeg has offered to walk me through some of it on the phone if I get into trouble, and I suspect he's pretty good with decks by the suggestions he's made via email.

So that's the update. I thank everyone for their ideas, knowledge, and help. At this point I'm feeling like I'm not going to be subject to the worst case scenario as I was thinking earlier, so I am feeling pretty relieved and grateful.

< pointless whining > Now I've got the driveway repair guy coming tomorrow. The printer and router are finally working again as of today, so now I can mail in the rebate that will never arrive. The father-in-law's printer is still down, even after I sprung for two new ink cartridges. Doh! A couple trees that were damaged in the ice storm still need to come down. The A/C man is coming next Monday, but it will be hot in the house until then, except at nights, when we are getting some relief using a high velocity fan in the window (blowing out) to pull cooler air into the bedrooms. Not too bad at night, really, and the basement area isn't really bad at all during the day, if I can stay holed up here. The little car starting missing really bad my last trip to HD for the deck repair supports, and I barely made it home, but the hole the mechanic described in the oil filter of the family car was detected in time. It was only two and a half quarts low when I noticed the voluminous dripping underneath when the car was out of the garage. The oil is currently being soaked up by kitty litter. And those maple rounds are still out back waiting to be split, along with the Holz Hausen, which is waiting to be repaired.

Got to go, the leaky shower drain is still waiting for me upstairs. I've put that off about as long as Mrs. Mo Heat will tolerate, especially in view of the broken A/C. :red:
< /pointless whining >

 

[HarryBack]

glad things sound like they are getting better..........I detect a hint of optimism in that last post!

 

[Gooserider]

Others might well contradict me, and I will be the first to say I don't have a lot of expertise on the subject, but judging by the photos, I'd be inclined to get a bunch of RR ties or landscape timbers, possibly something longer in the way of preserved logs (Telephone poles?) and build a terrace setup going down the hill. More or less follow the existing slope, but build a 2-3' high retaining wall each time you dropped that much, and flatten the slope out in between each "step". If you had a lot of rock, you could build from stone, but I suspect that wouldn't be as cost effective.

A 2-3' high timber wall doesn't need a great deal of engineering to design or build, and it would mean that no single step is having to restrain all that much in the way of fill. I suspect a terrace system would require far less in the way of permitting / inspecting than a single wall would. A timber wall should have more than enough durability, and would be simpler to build than rock. It wouldn't expand the back yard in terms of 100% flat ground, but it would make the hill into more useable space for things like gardening, etc.

Terracing stops erosion fairly well since the "slope" of any step approaches zero, so the water has a chance to sink into the ground, or filter down through (designed in) gravel beds rather than rushing down over the slope surface.

You could probably even do it slowly over time, building another step every year or so.

The downside might be that it could make it harder to drag stuff up the hill, but I think this could be designed around with an appropriate set of steps or ramps.

Gooserider

 

[Mo Heat]

Goose, You're almost reading my mind. I was thinking the same sort of thing, but hearing it from someone else takes it one step closer to seeming feasible to me.

I was thinking that I'd try and calculate how much of the cheaper 2 foot spec'd retaining wall stones you buy at HD that I need to redo my flower beds, and round up to the nearest pallet. What ever was left over after building the beds, I'd use to start piddling with as a first course, on a proper foundation of compacted gravel intended for such use. And in the mean time, before the lower tier, or terrace, was finished, I'd use the RR ties that I'm taking off the flower beds and lay them on the hill, maybe securing them a bit with 18" or 2 foot stubs of rebar pounded into the ground, to keep them from sliding. Once I finish the bottom 2 foot terrace (could be a couple years), I'd start on a middle one, removing the RR ties as I go. I think I would only need two terraces, each about two feet high to stabilize the hill.

Thanks for the suggestion.

 

[nshif]

Sorry for the late reply, Ive been away. I have a situation similar to yours but its new construction and everything had to be to code. Ive built a house about 18' back from a fairly steep hillside, some of which is fill from cutting the house pad. While the house is not on any fill the deck (12'X4 ) supports are partially in some fill. This required a soils engeneer by the building dept. The situation was made worse by the fact that the 8/12 roof of the house dumped all of the rain and snow melt directly towards the hillside and gutters were notpracticle due to the fact that when heavy snow fall would slide off the roof it would just tear the gutter off.
This is what I was required to do. (keep in mind this is Ca, read earthquakes, and im acout 50 miles from the San Adreas fault.
1) the footings for the deck posts (6x6" ) Had to be 2'x2'x2' or deeper if in 100% fill ( one ended up being 4' deep ) with wet set pier blocks on top.
2) 6' out from the posts a retaing wall 3' tall with the top at grade built from 6x6 pressure treated posts 6' on center with 3 runs of PT 2x12 lag bolted to the posts (on the uphill side of the posts) whith the joints staggered.
3) This was not required but I built a second wall about 14' from the 1st one with the top slightly above the bottom of the 1st one. for a more terraced look.
4 )The ledger for the deck joists is 2x12 PT and lag bolted 16" OC staggered top and bottom into the rim joist of the house. The outer beam is a 6x12 on top of the 6x6 posts mounted with post caps with diagonal braces (also 6x6 )at each post. Joists are 2x8 PT 16" OC with joist hangers at both ends.
So far (2 winters, one heavy, one moderate, and Ive had no ground movement at all. Although I think the design is a bit overkillweve only had one noticable small quake so perhaps for here it may prove to be worth it when really tested.
Hope some of this info may help.

 

[Mo Heat]

nshif, thanks for all the info. i'm new at this construction stuff and feeling my way, but i think i've got a pretty good idea of what your deck and walls look like after looking up some unfamiliar terms.

- outer beam: is horizontal board that's parallel to the house wall plane that the deck is attached to;
- rim joist: I'm thinking this is just the last joist on each side of the deck;
- ledger: couldn't find it, but assuming this might be called an inner rim joist by the uninitiated. If so, then this is the board that all my deck joists are hung from on the house side, and which is simply nailed onto my cedar siding, as far as I can see;
- post cap: are these structural or ornamental? I only found ornamental post caps;
- wet set pier blocks: pier blocks that you stuck on top of the footers while they were wet rather than placing posts directly onto footers (purpose?);

Q's:

How did you attach your posts to the pier blocks? Or did you just set them free floating on top? I suspect they're attached to foil earthquake shear.
I'm thinking of just setting my posts on top of new footers, so they don't get dragged down the hill if it continues to erode. Bad idea?

I'm admittedly ignorant here, but if you attach the deck to a house structural member (rim joist of house) and then lag bolt the retaining wall to the deck posts, and then have an earthquake, isn't all that dirt and timber of the retaining wall (if it moves) going to rip some important part of your house off? Of is the idea that somehow all that inertia is probably going to prevent the retaining wall and the dirt uphill of it from moving at all? I think this (the strength of the house being greater than the strength of the hill movement) might be the part I'm having so much trouble understanding with my deck when some of the suggestions have been to simply fix the deck and "suck" the posts and everything else back into place using lag bolts as a sort of wenching system, without really needing to deal with the small amount of hill movement (assuming it continues to move at the current rate, which is about 3 inches in 19 years).


Also, were those two retaining walls pretty expensive? And is it cheaper to rebuild then in 20 years (when I'd assume the timbers will be pretty much rotten and needing replacements) than to build the thing with stone (or those prefab concrete wall pieces that pass for stone these days)?

Sorry for all the questions. Maybe someone else will chime in, too.

 

[nshif]

nshif, thanks for all the info. i'm new at this construction stuff and feeling my way, but i think i've got a pretty good idea of what your deck and walls look like after looking up some unfamiliar terms.

- outer beam: is horizontal board that's parallel to the house wall plane that the deck is attached to;

outer beam spans the deck posts parallel to the house

- rim joist: I'm thinking this is just the last joist on each side of the deck;

Rim joist is part of the house and is what the house floor joist butt to on 2 sides and is the last floor joist on the other 2 sides. basicly it runs around the perimiter of the house surround the floor joists

- ledger: couldn't find it, but assuming this might be called an inner rim joist by the uninitiated. If
so, then this is the board that all my deck joists are hung from on the house side, and which is simply nailed onto my cedar siding, as far as I can see;

yes but behind that cedar siding is the rim joist and the ledger should be lag bolted ( 3/8 x3 1/2" )
to the rim joist. nails will simply pull out over time.

- post cap: are these structural or ornamental? I only found ornamental post caps;

Simpson strong tie P/N BC6 for 6x lumber or BC4 for 4X http://www.strongtie.com/products/connectors/BC.html

- wet set pier blocks: pier blocks that you stuck on top of the footers while they were wet rather than placing posts directly onto footers (purpose?);

yes just placed on top on the footing while the concrete is still wet and tapped down with a hammer to remove any air pockets underneath. you would think this would not make a very good connection but I misaligned one and had to move it and hade to use the bucket on the tractor to break it loose. The reason for the pier blocks is to raise the post off of grade so they wont be in contact with any surface water and prevent rotting as the posts are not PT. Although if you used PT posts you could set them on top of the footing but PT is pricey (and rather ugly ) and pier blocls are cheap. Pier blocks come with pre cast metal straps to attach the posts, just get the right size for the post, either 4x or 6x.

Q's:

How did you attach your posts to the pier blocks? See Above Or did you just set them free floating on top? I suspect they're attached to foil earthquake shear.
I'm thinking of just setting my posts on top of new footers, so they don't get dragged down the hill if it continues to erode. Bad idea? Yep they wont stay put, just walking around on the deck will cause them to move a little now and then and the deck also wont feel as solid.

I'm admittedly ignorant here, but if you attach the deck to a house structural member (rim joist of house) and then lag bolt the retaining wall to the deck posts, and then have an earthquake, isn't all that dirt and timber of the retaining wall (if it moves) going to rip some important part of your house off? The retaining wall is 6' out from the deck with its own posts. Of is the idea that somehow all that inertia is probably going to prevent the retaining wall and the dirt uphill of it from moving at all? I think this (the strength of the house being greater than the strength of the hill movement) might be the part I'm having so much trouble understanding with my deck when some of the suggestions have been to simply fix the deck and "suck" the posts and everything else back into place using lag bolts as a sort of wenching system, without really needing to deal with the small amount of hill movement (assuming it continues to move at the current rate, which is about 3 inches in 19 years).


Also, were those two retaining walls pretty expensive? The 2 walls cost about 1000$ for materials and took about 4 days for me to install. Keep in mind they are 60' long. And is it cheaper to rebuild then in 20 years (when I'd assume the timbers will be pretty much rotten and needing replacements) than to build the thing with stone (or those prefab concrete wall pieces that pass for stone these days)? Prefab ( I assume you mean fake stone ) wont work for a structural wall, stone wall would work but would require alot of rebar and a footer so I chose Pressure treated lumer which should last a min of 20 years could be even longer, But at my age one doesnt worry to much about 20 years latter LOL

Sorry for all the questions. Maybe someone else will chime in, too.

Ill have to look through my picture arcieve and see if there are any shots that might help as most of this is now covered.
No Prob glad to assist

 

[Mo Heat]

Outstanding. Thanks.

I'm sure I didn't soak all that up on the first read, so I'll study it more, but it sounds like I want to avoid using those fake stone rocks for any retaining wall I might be building. My EE father-in-law told me as much, and also mentioned the need for footers, which I had never heard of, and none of the landscape people mentioned, or install, AFAIK.

You've also pushed me back toward simply replacing my flower box RR tie wall with RR ties (and / or PT lumber) instead of using that fake stone, but I'm not sure how Mrs. Mo Heat is going to feel about such a reversal of plans. She really had her heart set on a stone look, but replacing those wooden boxes with more wood is probably going to be much simpler than using fake stone. Maybe a bit cheaper, too. And I hear you about the 20 years down the road. That's a long, long time and I'll be lucky if I'm still in this place at that point. Unlikely, really. I've never lived anywhere for nearly that long.

Now I need to think about actually doing something about all this. :ahhh: Time for a cold one... :wow:

 

[nshif]

Ill post a few pics that may help
heres the ledger attached to the house wall with joist hangers

 

[nshif]

heres a post cap

 

[nshif]

pier block with straps

 

[nshif]

ledger on house side, Post side is the same only attached to the beam over the posts.

 

[Gooserider]

It is worth keeping in mind that buried PT wood is pretty close to non-biodegradable, it will probably last far longer than 20 years, I'd expect the bolts holding it together to fail first... (PT's long lasting properties is one of the reasons the eco-freaks hate the stuff.)

I've never priced the fake stone, but I'd expect it would be OK for non-structural uses like a flowerbox, but I'd be less inclined towards using it for something structural like a retaining wall unless there was clear documentation saying it was suitable, and giving instructions on how to do it. The ancients Mediterranians used stones for terracing, and it worked, but they had a different ground structure to deal with, and mostly did fairly short walls, made with LOTS of rock. The other alternative to timbers that I'd consider might be poured concrete with a good footing. It's ugly but lasts and could be covered by a stone facing later.

If I was putting your used timbers on the hill I'd want to dig them into the hill a bit, not just lay them on the surface - you need to slow the water flow down, and if you just put them on the surface you will get the water washing under them at the inevitable low spot, and making a gully. If you dig them in a bit, and put the removed dirt on the hight side it will act as a better barrier to water flow.

I would absolutely attach the porch posts to the footer in some way, probably with a strap or post anchor in the footers. The footers should be dug down to undisturbed solid dirt, below whatever passes for a frost line in your area.

Gooserider

 

[begreen]

It may be my soil, but the underground portion of the PT 4 x 4 posts I put in around the garden were rotten clear through in 7 years. I had expected 20 years as well, but they didn't deliver. There's a new set of round treated posts in there now. Hope they fair a bit better.