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Need Input And Advice On Building A Pressure Treated Retaining Wall

Need Input And Advice On Building A Pressure Treated Retaining Wall


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Old 08-15-13, 08:57 AM
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Need Input And Advice On Building A Pressure Treated Retaining Wall

First, if this isn't the right forum to raise my questions about retaining walls please let me know.

This DIY web site has always been my go-to place to get good advice and help so hopefully some folks here can help with my retaining wall project.

I have a area on my side yard where I want to build a retaining wall. I've attached a couple of pictures but here are some details about the wall:

- the portion that runs parallel with the house is about 70' long

- tallest portion that is perpendicular to the basement wall juts out about 12'

- the grass area on the top of is about 10' wide

- the old wall was made from irregular shaped large rocks that come out of the ground when we installed our pool a number of years ago but it was settling and housed rodents and just started to look bad

I've priced hiring out to have a wall built using Versa-Lok blocks with a few Landscape professionals however the price is just way too high at $6,000 - $7,000. So I'm considering building one myself using pressure treated wood.

90% of the area has a average height of about 2 1/2' - 3'. Only the very end closest to the house foundation rises to 4 1/2' above grade so here's what I'm thinking of doing:

- install 4x4 pressure treated posts every 4' installed 4' below grade since I live in the Northeast. Would use fast setting concrete mix to set each post

- build the wall using pressure treated 2x lumber (2x6 or 2x8) attached to the outside of the posts

- put a stone base down with perforated 4" drain pipe on top of it along the entire length behind the first row of face boards and would follow the downward ground and drain out at the end

- put landscape cloth on top of the drain pipe to filter out any dirt then fill the rest of the cavity between the dirt wall and top of the wood wall with stone

- would also install T shaped deadmen out of 4x4's attached to the back of the posts every 8' or so


My biggest concern is probably the tallest section of the wall and whether my approach will adequately work there.

So I'm asking this forum whether my approach makes sense and will work or what specific changes do I need to make.

I would appreciate any help, advice and suggestions.

Thank you.
 
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Last edited by targa; 08-15-13 at 09:52 AM. Reason: add pictures
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Old 08-15-13, 10:07 AM
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It sounds like you are considering a serious amount of work installing a wooden wall. Have you considered installing the modular block wall yourself? It's heavy work but not rocket science and you would have something with an almost unlimited life span where with wood you'll probably get 20 years.

If you do end up building the wall out of pressure treated I would not use the normally treated wood you get from a home center. The 2" lumber is only rated for above ground use only and even at that I've been disappointed in how well it stands up. I would special order the lumber used in coastal areas which has a much higher preservative content. I would also install dead men at every vertical 4 x 4 since the 2" lumber will not have sufficient strength to span 8' if you only install dead men every other vertical.
 
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Old 08-15-13, 11:04 AM
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Have you considered installing the modular block wall yourself? It's heavy work but not rocket science
Pilot Dane, I considered it briefly but my back said no. The Versa-Loc blocks (and probably all others) weigh about 85 lbs each. The wall would take a lot of blocks. I do realize that properly establishing the base and first course is the hardest part of a modular wall other than lifting all the heavy blocks.

I felt the wood approach would be a more manageable DIY project. I have someone who would dig all of the post holes I need ( 10" diameter by 4' deep) for $250 which I thought was a bargain.

I will look into whether any of the local suppliers have access to the pressure treated wood with a higher preservative content.

And thanks for suggesting I would need more dead men.

At this point I'm trying to gather as many facts from knowledgeable people like yourself to determine if my approach makes sense and is affordable enough to proceed.

Keep the input and comments coming
 
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Old 08-15-13, 12:16 PM
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One other thought I had that I should have mentioned in my first thread was whether its possible to use some type of landscaping alternative by creating a more slanted area instead of the wall like area I now have and incorporate planting of some type along with ground cover and large rocks?

The end that's the highest would still be a challenge but I wondered whether some type of tiered design could be used at that end?

If this approach was possible, it would be the least expensive and least labor intensive.

Btw, I have a John Deere 4WD compact utility tractor with a loader and backhoe attachment so moving dirt around would not be a problem. I just do not know how to approach this idea.

Thank you
 
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Old 08-15-13, 05:31 PM
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If you have a tractor with loader and hoe I'd be leaning towards the masonry block wall especially if you have a helper since the worst part of that type construction is the excavation and moving the gravel. With a helper, chain & clamp you could use your backhoe to lift and do the crude positioning of the heavy blocks.

If you go with the wood wall I'd consider that a 4x4 is only so strong. Buried about 30" you'd probably break the wood before it's buried depth becomes an issue from a lateral strength issue. You could go up to 4x6 or 6x6 to take advantage of your deep holes.

As you mentioned, regrading the area is an option. Remove the big rocks. Then taper the bank so you are able to mow it. You might need to bring in dirt for the end at the house or if you don't want to remove the rocks just bring in dirt and create a mowable or landscapable bank without disturbing what's there.
 
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Old 08-15-13, 08:53 PM
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You could do a rip rap look using 12" and smaller boulders and just use the slope you have. This will clean it up, boy would not be easier to mow around undlee you also put in a some kicd of edge on the bottom.

Here is a good video for a wood wall: How to Build a Timber Retaining Wall | Video | This Old House I suggest 6x6s.
 
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Old 08-16-13, 08:17 AM
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Thanks for the comments.

I just called the local manufacturer and distributor for Versa-Loc in my area to price the items I would need to do it myself.

When you consider the blocks, caps, pins, adhesive for the caps, stone for the base, stone for the backfill for drainage and delivery the cost would be just about $3000 which sounds about right. The contractors I spoke with said the cost if they do it at $6000-$7,000 breaks down to about half for materials and half for labor. I am just not sure I want to spend $3,000 for materials and do all the labor myself. Plus, my house is in a country setting surrounded by 2 acres of pine trees not in a suburban neighborhood so the more natural look would probably make more sense.

I'm starting to lean more toward the idea of tapering the hill and incorporating some planting, large rocks that I have and perhaps some low maintenance product for covering the open areas like mulch or small gravel.

If I go with this approach I would want some type of border to not only set it off but keep the area separate from the lawn on the top and bottom of the slope.

Any thoughts on what to use for a simple border?

Please keep the comments and ideas coming.

Thank you
 
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Old 08-16-13, 08:34 PM
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Black plastic edging is a low cost, easy edge. I suggest getting the 20' straight pieces from a landscape supplier rather then rolls from the big box.

Otherwise a brick edgers are easy to work with and you can set them low so all you need to do is run a mower over them. (same with the plastic edging)

This is more of a rip rap like I was referring to earlier. Just envision more mulch and less rock: http://www.thequercusgroup.com/Image...gRockSlope.jpg
I had a picture of a place with what I think you're talking about but is can't seem to find it.

I think what your planning is a good idea. Please post a picture what you get it done!
 
 

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