I’m in the process of building a parking pad in this spot. I ran a string line to measure my retaining wall height. If I have the line 3 feet above the ground and check the line for level, it is still just barely sloped back. I do not want to build a wall taller than 3 ft due to increase chance of the wall leaning or giving way. So I went inside the trailer with my 4ft bubble level and measured, if I rise the back of the bubble level 9.5 inches it shows level. So my question is, for every 4ft there is a 9.5 inch drop. My trailer is 30ft. So do I divide 30 by 4, and times that by 9.5 to figure how to get level? Doing that tells me I need a 71 inch wall to get level. Am I doing this all wrong or over thinking it? Really would appreciate input on this my brain is hurting.

And in anyone’s opinion, even with a 3ft wall having a little slope, could I get the trailer level enough to run slides and fridge? I am buying a bunch of railroad ties this weekend and am going to start the wall. The plan is to pack in some fill as I’m building wall to make sure it’s packed nice and tight. I guess I could just test out how much higher the wall needs to be as I’m building by parking the trailer there. This is the first time doing something like thisThank you

I'm no engineer, but I assume you're going to trench down and pour footings for the retaining wall?As for the final slope, it's good to have some pitch to it for drainage, and then you can use blocks for final leveling if you need to.

Roughly 3 inch drop per foot times length. Equals 90 inches divided by 12. is closer to 7.5 feet roughly.You would need to put tie backs using a normal construction. What happens during heavy water situation?

I suggest looking into retaining wall anchor systems so you can go high enough for a fully level pad. No front to back slope is needed for drainage if the pad is crowned side to side.

Your math is correct assuming the trailer is parallel with the ground... looks like it’s close. You could hang 10’ of the trailer off the pad getting it down to a 4’ wall.You’ll be replacing the crossties in 20 years as they finish rotting.

Math question for any engineers out here | Good Sam Community

DrewE
Explorer II
Mar 15, 2021
It might be worth looking at building a strong deck/platform rather than putting in enough fill and retaining wall to make a level spot.
schlep1967
Nomad
Mar 15, 2021
d3500ram wrote:
Thought experiment #3 with tongue dropped such that trailer is level.
All dimension are approximate:

Using this diagram, Back where the post is at the rear of the trailer build your 3 foot wall.
Then fill in to level.
Then put another wall behind the axles.
After the second wall is built you could fill in behind that wall at a moderate slope down to the first wall so you have something to put stabilizers down on.
blt2ski
Moderator
Mar 15, 2021
I built my last RR/Treat lumber wall over 20 years ago. SInce then I have installed 1000's of sq ft of concrete walls. Including for a Class A RV parked closer to the walls you are doing.
As mentioned, even for that 4' wall, I used geo grid, every two layers of Allan Block wall in that case. #0K lbs Type A went thru the Nisqually quake here locally a year or two later.
There are lots of ways to do what you are trying to do. Even a 3 or 4' wall frankly needs some engineering help other than tire backs etc.

Marty
coolmom42
Explorer II
Mar 15, 2021
trcothorn wrote:
This is the set up I’m going for. Gravel base for drainage, deadman tee anchors for support. All that.

Not to be discouraging.... But in TN, those crossties will be termite homes pretty quickly.
JaxDad
Explorer III
Mar 10, 2021
wapiticountry wrote:
Harbor Freight will sell you a laser level for less than $30.00. Set the level at the front of the rig and using a two by four set perpendicular to the ground behind the rear tires measure how high the rear of the pad needs to be, skip the math.

Easier still. Take length of garden hose and fill it with water, holding one end of the hose a couple feet up against a board (the base end) at a known height (2 feet, 3 feet, etc) walk around with a tape measure and the other end of the hose (the roving end). Lower the roving end until the water is up to the open end of the hose. Measure from the end of the hose down to the ground. That length minus the height of the base end is the difference in elevation.

Water will always find its own level.

BTW, terracing the wall, go up 3’ feet, go in 3’, go up another 3’, etc, etc, and leaning the wall back into the slope will allow you to go up a lot more than a single height wall will.
fred42
Explorer
Mar 10, 2021
This somewhat obvious suggestion may not be an option in your case. Can you rotate the pad 90 degrees to have its length across the slope instead of falling with the slope? This would turn a 72" problem into a 20" problem.
time2roll
Nomad
Mar 10, 2021
Consider paving two strips for the tires down to some wheel stops and leave it on a slope. This will give traction for the tow vehicle and a positive stop for the trailer. +1 for doing this with some type of stone vs wood.
d3500ram
Explorer III
Mar 10, 2021
Thought experiment #3 with tongue dropped such that trailer is level.
All dimension are approximate:
wr1032
Explorer
Mar 10, 2021
If I was doing this I would put two strings of perforated plastic tile up grade from parking area. dry ground will not move as fast as saturated ground. My two cents.
wapiticountry
Explorer
Mar 10, 2021
Harbor Freight will sell you a laser level for less than $30.00. Set the level at the front of the rig and using a two by four set perpendicular to the ground behind the rear tires measure how high the rear of the pad needs to be, skip the math. Your photo seems to indicate about a two to three foot rise, not seven. That would make a pad easy to construct. Just use concrete "Windsor Wall" type blocks and fill in the space with road base.