Home / Woodworking / How to build a wood retaining wall that will not lean! video Part 1. A Wood Deadman Design.

How to build a wood retaining wall that will not lean! video Part 1. A Wood Deadman Design.

We cover the basic concepts of creating a retaining wall that will not lean or collapse over time using a wood dead-man system. Also we talk about some of the trade offs and options concerning the use of ground contact wood.

Basically a dead-man transfers the load from the wall to a flat surface under the dirt. We use bolts to hold together a triangle shaped form that we built. The 1/2 inch bolts are structural. They are deigned to take the load.
Also it is critical to treat the base of your posts from below ground to at least 2 inches above ground.

Transcibed audio from the Video

hi Im Mike Stokes with lush planet

design/build and today were going to be

showing you how to build a Deadman on

retaining wall so if you look right here

we have the beginnings of a retaining

wall that were building and if you come

on a little closer I will show you what

a Deadman is and how to design one that

is hidden behind the wall and serves the

function of making sure that the

retaining wall doesnt kick out so Im

sure all of you have seen a retaining

wall where this post is leaning out and

what happens is basically you know the

dirt comes hits the retaining wall and

pushes the wall out so you can see these

two by twelves theyll be stacked up

three high and then behind here we have

a dead man so before we get to the dead

man lets cover a couple of important

principles about setting posts one thing

is you want to have in the hole around

your post you want to have at least two

inches of concrete on all sides and when

you have your when you run your post

line the strings to set your posts in a

parallel line sometimes its difficult

to get those posts perfectly in line on

that line and have that two inches so

its good to have your pole your hole be

eight to ten inches a little more

concrete is better than not enough if

you have less than an inch and a half of

concrete theres just not enough

structural integrity in the post in

order to make sure that its not going

to break the concrete so we have twenty

inches of concrete down some people like

to go but was enough for this

design with this Deadman and at least

two inches around all the sides and

another important thing about posts is a

lot your most of your rot happens if

youve ever seen a retaining wall thats

falling down the rot usually happens

right here at this line where the

concrete faces and theres most the rot

happens for microbes in the soil so you

want to always build up your concrete so

you have less soil around the post

ideally you have no soil around the post

we like to make these nice little round

bases and then try to make sure that the

concrete stays really flush here because

sometimes a ten

the cavity tends to open up and you have

a little pit where water can gather and

you dont want that either so thats the

basics about the post so onto the dead

man so the dead man is as you can see

its a triangle so in the way some

people design dead mans is with a big

concrete piece and in this case we

didnt want to do a big concrete one so

were doing a wood dead man so how the

dead man works is all this soil right

here is going to be on top of this

footing and so when this footing tries

to lift up like this the load is

transferred through these joints where

we put bolts in an order for it to push

up in order for this post to move its

got to lift all of this weight so thats

what the purpose of the dead man is so

weve made small dead mans around each

post so that this retaining wall doesnt

kick over so a couple of other important

things to do when youre building with

wood in retaining walls is get come

closer and well do a close-up just on

this painted edge right here so if you

see this this is a painted edge and then

you can back up that painted edge every

time you cut thats an exposed wood so

this is pressure treated wood and right

here you see the raw edge of the wood

you always have to treat that every time

you make a cut and its underground or

touching ground you want to treat the

edge so one of the things that we did

was on this one was we put a coat of

pressure treating on the edge and then

we put a coat of paint so your rot is

going to happen anywhere you have

exposed wood pressure treated wood is

treated in it the treatment goes in a

few about a quarter of an inch so all of

these exposed parts are vulnerable to

rock so I want to say a couple things

about sustainability because we are a

sustainable construction company and you

may be wondering why were using

pressure-treated wood even though this

is pressure treated we bought this wood

from Mendocino Forest Products Company

which is a local company and they only

CEL fsc-certified lumber which stands

for Forest Stewardship Council