Low retaining wall

Reply

  #1  
Old 09-29-12, 07:58 PM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
Low retaining wall

I've started a couple threads already about this project, but I recently had a new idea that seems like it might be ideal, but I need some confirmation and details resolved.

Our house is near the top of a hill with only one of the houses behind us being about 12" higher than us and the ground sloping down beyond them. I have 1200 bricks I was going to use to build an 80' long wall 12" high. But the proposition of the footing has been daunting especially because I also want to add small walls in our front yard for more gardening room. The area is inaccessible to a concrete truck.

Rather than pour these huge long footings, it occurred to me that I could build brick pillars every 4-8' and put a combination of 4x4 and 2x6 redwood boards between them. 1) I think it would look cool and maybe a little more casual/natural than just the brick. 2) It would also be way cheaper and 3) take me way, way, way less time.

So my question is, since this will be a retaining wall but it won't be retaining much, should I go with 4' or 8' or maybe 6' spacing between the pillars? And what would be the best way to attach the wood boards? I'd like something permanent so that if the boards ever break down, I can replace them easily. I thought about putting a 1/4" thick metal bracket through the middle of the brick pillar to which I could bold the boards. I don't know if that would ruin the integrity of the mortar bond. Would I be better off just drilling and bolting to the brick directly or is there something else I could do?
 
  #2  
Old 09-29-12, 08:37 PM
Join Date: Mar 2005
Location: USA
Posts: 6,130
Received 0 Votes on 0 Posts
You are going to need wider concrete footings for the piers than for a wall since they take the concentrated load from the 4' to 8' between the piers. - Not a huge high-tech engineering problem, but ultimately the load (which is not great) must the resisted somehow. In the 80' length, you can expect some tipping and differential movement of the individual piers that may or may not be acceptable,

Segmental retailing wall units (SRWs) can easily handle wall heights of 5' with no engineering and NO concrete footings, but they are designed to be exposed (colored/split/textured) when installed.

The different materials (wood and concrete) in your latest idea, exposed to moisture and the soil can make a difference depending on your climate and location.

Dick
 
  #3  
Old 09-29-12, 11:26 PM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
Thanks. Ya, I figured I'd have to go a little thicker. The SRW is out because my wife and I really dislike the look of it and I already have the bricks. It's also a much more expensive proposition when I look at terracing the front yard.

I'm just east of Sacramento.

So I'm trying to figure out how much distance between the piers and how best to attach the wood.
 
  #4  
Old 09-30-12, 06:08 AM
S
Member
Join Date: Dec 2011
Location: england
Posts: 28
Received 0 Votes on 0 Posts
A lot of people are using old timber railway sleepers for retaining walls.

[ATTACH=CONFIG]3855[/ATTACH]
 
Attached Images  
  #5  
Old 10-01-12, 11:39 AM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
I'm still going to need posts. Also, because this will be retaining a vegetable garden as well, I'm not going to use treated lumber. So that also means it will rot at some point, but I'm fine with that and will do everything I can to extend the life of the wood mostly by using good drainage. Which is why the brick pillars are important because if I can find an effective and durable way to attach the wood to them and they are strong enough, replacing the wood down the line should be easy.
 
  #6  
Old 10-01-12, 05:47 PM
D
Member
Join Date: Aug 2009
Location: USA
Posts: 4,946
Received 0 Votes on 0 Posts
Good drainage is not going to do very much in extending the life of this retaining wall.
 
  #7  
Old 10-01-12, 06:19 PM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
The wood is going to do what it's going to do. If I need to replace the boards in 10 years, that will be acceptable. What I don't want to have to replace are the brick pillars. That's why I'm here trying to see if anybody has some guidance for how to give them enough strength and durability and how best to attach the wood boards.
 
  #8  
Old 10-03-12, 02:34 AM
BridgeMan45's Avatar
Member
Join Date: Oct 2011
Location: USA
Posts: 3,194
Received 1 Vote on 1 Post
Using untreated wood as part of any retaining wall is not a good idea (unless you really enjoy ripping out the rotted stuff every few years and replacing it, along with dealing with the dirt that will have to be retained while you re-work the wood). Think about the big, long-term picture--would it be better to build a wall with proper materials just one time, and forget about it, or do you want to be slave for the rest of your life to a wall that you initially built incorrectly?

Availability of materials should not a significant, deciding factor for long-term, satisfactory wall performance.
 
  #9  
Old 10-04-12, 11:35 PM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
I can appreciate that you guys are trying to save me from a bad decision. But there are a lot of factors involved here.

The design is basically the same as a wood retaining wall. There are tons and tons of those all over the place and they are very solid. The treated wood is primarily for the posts because it will always be in the ground. Rather than use treated wood posts, I'm going to use brick pillars. These are not holding back terribly much soil. Again, there's no way a 2x let alone a 4x redwood board won't last 10 years.

I just need to figure out a strong and durable and re-usable way of connecting the boards to the brick pillars. And I need to figure out if I can get away with spacing them 8' apart.
 
  #10  
Old 10-05-12, 01:47 PM
S
Member
Join Date: Jan 2012
Location: USA
Posts: 147
Received 0 Votes on 0 Posts
I appreciate your situation but you must also appreciate ours. What you are proposing is potentially a unsuccessful wall. This risk may be acceptable to you and if so great. however you need to understand that you are still suggesting methods which are not typically considered advisable.

That being said I would think that your original idea of metal brackets set into the brick piers would work. The brackets should however be exposed on the finish side of the wood boards to put less pressure on the actual fastener (thru-bolt?).

You will also need a good concrete footing under the brick piers so you are back to concrete work again which I know you are trying to avoid. (as Concretemasonry mentioned previously) The piers will have more of a tendancy to 'roll' forward compared to the simple wall because of the amount of load that will be transfered to the piers by the wood boards. I realize that this is a very low height retaining wall and I realize that it might very well hold up well without all of the extra measures that are being suggested. however I would wager that all of the "doom & gloom" you are hearing will prove to be true if you chose to risk a less expansive project. Good Luck.
 
  #11  
Old 10-05-12, 05:15 PM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
I don't mind concrete work. But since I'm doing this myself, I can't figure out a way I could put down a 80' long footing for a retaining wall all at once.

Wood retaining walls are done the same way, correct? A 4x4 or 6x6 post every so often bearing the load? How would brick pillars not be at least as strong?
 
  #12  
Old 10-05-12, 06:27 PM
D
Member
Join Date: Aug 2009
Location: USA
Posts: 4,946
Received 0 Votes on 0 Posts
Again, there's no way a 2x let alone a 4x redwood board won't last 10 years.
I use 2x red cedar to build a raised garden for myself. After 2 years, it is already rotting on the side that is in constant contact with the soil. Wood of any kind doesn't last long when in continual contact with wet soil. Even treated lumber doesn't last forever when it is in the dirt.
 
  #13  
Old 10-05-12, 10:19 PM
A
Member
Thread Starter
Join Date: Aug 2009
Location: Fair Oaks, CA
Posts: 36
Received 0 Votes on 0 Posts
That's hillarious. I built 16 raised beds out of cedar fence panels less than half an inch thick and they look new on the inside one year later.

I also just watched a video of a guy excavating his two foot tall raised beds two years after he built them using similar cedar fence panels and his look new on the inside as well. I can post it if you like.

And here's a scientific study by Oregon State University that puts the durability of red cedar posts at 24 years when fully submerged.
Service life of treated and untreated fence posts

If you need advice on how to build and maintain garden beds, I'm sure there's a forum on this site somewhere. I can only hope you'll receive as much useful advice as I have.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: