Fence/Retaining wall combo question

[84Aquarius]

Hey guys and gals,

I built a fence/retaining wall combo in the yard and wondered what you all thought of the design.

I have 4x4 posts set 8 feet apart and 3 feet below ground. For the back quarter of the fence I have a "retaining wall" built under the fence sections. I have secured the 2x12 to the bottom of the posts with metal brackets, and to cover any bulging in the 8 foot span driven a 2x4 2 feet into the ground and screwed it to the 2x12. There is about 12 inches of dirt coming almost to the top of the 2x12.

I have included a picture for hopefully an easier reference. The 2x4 is on my side of the fence and the dirt is on the foreground side of the picture when complete.

Do you think the wall is strong enough to hold back 4ft wide by 12 inches deep of dirt?

[AndyL]

That's not adequate for a fence in alberta, let alone retaining wall....

[84Aquarius]

I didn't include the fence boards in the drawing so I could fit more text in, the fence is built directly on top of the 2x12

[ExtraSlow]

I think AndyL is saying that your 4x4 posts are too far apart., isn't a six foot or four foot span more common?

As for "holding back" 12" of soil, that's not a tough job for any brick system. If you haven't built this yet, consider doing two rows of brick. Bunco has lots of vareity . . .Bunco - Retaining Wall systems

This wood setup might work, depending on a bunch of factors that are hard to assess over the internet like drainage, slope near the wall etc. If the yards on both sides of this are flat, and you don't have any natural drainage across that new barrier, you will probably be OK.
Good luck.

[project240]

We're currently fixing a fence/retaining wall that is leaning due to improper/insufficient installation. It's going to cost her approx the same cost to fix as it would have to do it right the first time.

Your design doesn't look terrible, but I also wouldn't have much confidence in it.

[bwling]

I don't think that 2x12 will not hold the soil in the long run. As others have said, your fence will likely start to lean after a few years. I would suggest using Allan Block or other similar-type product for your retaining wall.

[AndyL]

Maybe I should have been more specific as to my concerns... You say 3' down into dirt... Now normally i'd expect someone to say 3' down into CONCRETE. About the only time you can really get away with that kind of construction - is on a ranch style fence where you have 3-400' linear feet - even then we'd usually pound those fence posts down at least 4'

Here in alberta - call me nutty - but me and my friends when we do a fence usually go at least 5' down into concrete to get down at least close to the frost line... If the owners feeling rich - 6' is gooder.

Add that your retaining soil along the lower edge- that frost is going heave that section of fence in no time. No you at least 5' concrete footings, the 8' span isn't a big issue but I wouldn't run a 2x12 physically connected to those - I'd want something independant of the fence (ie one of the block systems)

[84Aquarius]

Oops, I forgot to include that the 4x4's are set in concrete 3 feet below ground. Sorry for the confusion.

The amount of rocks in the holes and the services that run parallel made it impossible to use any mechanical means to dig these holes. I had to dig them all by hand and 3ft is as deep as they were going.

The retaining wall is along side the garage, where there will be little to no water flowing, and with the new dirt up to the height of the 2x12 my yard on that corner is now 12 inches higher than my neighbors.

[Masked Bandit]

The only problem with using wood as your retaining material is that IT WILL ROT, at some point. It might be five years, it might be ten, it might be 15, but it will rot. If you go with a stone block you'll never touch it again. With that said, depending on how many lineal feet you need to run, stone block will be more expensive and it takes a lot of work to run it straight & level. If you can get at this 2 x 12 later for replacement then I think this is a reasonable design.

3' holes with concrete is PLENTY deep. Anything more is overkill.

[ddduke]

AndyL is talking out of his ass again.

First off your fence posts are fine if they're at 3 feet, his whole speal about frost lines/5-6 feet is bullshit too.

I own 2 cats, both with auger bits used for fences, both of which are 4.5 ft long and in 11 years have NEVER had a problem. Most people go anywhere from 3-4 feet deep. This is why every wholesaler/chain store carries TONS of 9 and 10 ft 4x4 posts and many places don't even have 4x4x12s. Think back to the last time you saw a fence package with 12 ft posts, I see packages every day and can't.

As for the frost line that he speaks of. We start drilling in feb usually, and the DEEPEST frost I have found in calgary was 2.5 ft and that was crazy. This year our winter was very mild, and frost went anywhere from 8-10 inches.


Buttttt.......

To answer your question if that would support your wall. I'd say completely change your plans, there's a few key things I see that will make it fail. One being the bracket idea instead of putting the 2x12 off the face of the post, second being the 2x4 spiked in the ground instead of having proper posts every 4 feet.

If you want then shoot me a pm and I can tell you how exactly to build it to make it perfect.

[freshprince1]

I built my fence with 12' 4x6's burried 4' deep with 3' of concrete. The beast will never tilt.

It think you're biggest problem is using the 2x12 undergroug to reatin the soil. If you're planning on long term usage of this, the frost heaving and moisture will noticably affect the structural intregrity within a few years...maybe sooner, IMO.

I would suggest using som cheap brick to retain the soil and build the fence around it. It's better to err on the safe side and build something too strong instead of doing a whole project only to have to go back and fix it a couple years later.

I think both AndyL and dduke raise good points, and either of their suggestions would work fine. I tend to overbuild on the strong side and am no contractor.

[AndyL]

I tend to follow typical commercial practices - 3' would never fly in the commercial world - why do we accept it in residential? Sorry, I work commercial construction - it's a radically different world.

I can take you on a tour of fences I've built with friends using what we typically think is appropriate - you wont find one that's in anything less than as-built condition. One even had a car hit it - took about 20 minutes to repair - as the posts were completely unfazed - that wouldn't happen with a 3' deep footing. Then you can look at adjacent fences with the typical 3' footings - many are leaning / falling over - I expect a fence to last 20+ years, not <10.

[Bisklimpkit]

Originally posted by AndyL
Here in alberta - call me nutty - but me and my friends when we do a fence usually go at least 5' down into concrete to get down at least close to the frost line... If the owners feeling rich - 6' is gooder.

Just wanted to comment about the frost line thing. Code is 4' for frost line in Calgary. Here in Saskatoon it's 6'. It changes depending on where you live.