Math question for any engineers out here

[trcothorn]

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.

[PastorCharlie]

Divide your 30' TT by 4' Level to get 7.5

Multiply your 9.5" rise in 4' by 7.5 to get 71.25"

Divide 71.25" by 12" to get 5.9375' needed to raise low end to be on level with high end.

5.9375 feet is how much the ground is sloped in 30 feet and needed to be raised on low end to bring to level.

[time2roll]

Is the wall 3' behind the bumper or 1' behind the tires?

[nickthehunter]

Yes you you need about a 6 foot (72 inch) wall to be level if you go the full 30 feet of the trailer. If you let the trailer hang out over the end of the wall you would need less height depending on how far in you move the end of the wall.

[trcothorn]

This is the set up I’m going for. Gravel base for drainage, deadman tee anchors for support. All that.

[TenOC]

Not an answer to your question, but I like for my RV to be parked on a slope like you show so the rain water drains off the roof quickly. The only time it needs to be level is if you run the refrigerator.

[Ivylog]

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.

[Dutch_12078]

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.

[enblethen]

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?

[dedmiston]

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.

[trcothorn]

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 this

Thank you