Wednesday, March 21, 2012

[papercreters] Re: First Time PC Wall: Block or Slip?

Thanks for re-asking your question. (I've decided to quote the original post so everyone can remember what you said.)

It is an unwritten rule on Papercreters that we shouldn't let a question go unresponded to.


My initial response is to ask whether papercrete is the proper material to be using in this application in the first place?

I strongly encourage you to read up and view the many online videos from Brad Lancaster about "Rainwater Harvesting."
http://www.youtube.com/watch?v=2iQ-FBAmvBw
(be certain to look over the many related videos to that one, and also search YouTube for "Brad Lancaster" or "Rainwater Harvesting.)
http://www.harvestingrainwater.com/

You are wise to want to retain your topsoil, but the method you may be attempting might not be the best way to go about it. Brad has some amazing insights about how to create simple swales and fill them with large amounts of mulch (hopefully free material you can obtain locally) to slow down the runoff of water and capture it for dryer seasons. Rain is not your enemy. It is a resource that you should want to keep on your property and infiltrate it into the soil where your plants can thrive on it.


So, my first advice is to make certain that you really want to build a wall in the first place. Nothing wrong with a wall, but it sounds from your description like you are looking for the functionality of a swale.

Having said that, building a short wall can be a nice addition to a landscape. Again, is Papercrete the best material to use in your situation? Consider all the materials that are available to you on or near your site. Rock? Urbanite? Earthbag? Adobe? Cob? Any of these, or a combination might be a possibility, and may last a lot longer than a papercrete wall depending upon how each is built.

No matter what you choose to build your landscape wall out of, BUILD A FOUNDATION. Dig a trench, ideally one deep enough to be below the frost line in your climate. (Don't forget to call to have buried utilities marked before you dig.) Have the trench be able to drain itself out to daylight (hopefully a planting bed downhill where you can take advantage of that water. Backfill with gravel, rubble, broken concrete, etc. Tamp it down in shallow layers solidly. That will prevent your wall from frost heaving and breaking apart or falling over in the future. Digging can be a lot of work, but it is worth it in the long run. This probably sounds like overkill, but believe me. This foundation is WORTH the extra effort. If you're not willing to invest the time and effort to build a foundation for your wall, think about a fence and maybe a bench instead. The foundation will be the key to everything about your wall.

Finally, build your wall on top of this LEVEL foundation of gravel or rubble you have built. Make certain that the ground near the base of your wall slopes away from the base of the wall on both sides. This will prevent water from wanting to pool at the base of the wall and erode it.


If you choose to use papercrete for your wall, make certain to keep the papercrete up off the ground. Possibilities for this "stem wall" on top of the rubble foundation include, a layer or two of gravel filled earthbags (double bagged), urbanite, bricks, large stones, or something similar that you can get free or cheap locally. Then build your papercrete wall on top of that.

As far as whether to use blocks or slipforming, that is mostly a matter of personal preference. My personal preference would be to use some old wooden pallets to make some freebie formwork and slipform. Why fiddle around with the extra labor of making blocks when you can simply pour the papercrete in place?

Of course, you will also want to plaster your papercrete wall (and the stemwall) to protect it from the elements. There are many plasters that can do this, from lime plasters, to earthen plasters.

Finally, to finish your wall... GIVE IT A CAP!!!

Put something on the very top of the wall that will shed water well. Ideally this cap can even have a bit of overhang of each face of the wall. That way water will drip off the cap to the ground without trickling along the face of the wall. You might pour a concrete cap. Mortar on some flagstones? Tiles? Whatever you want to do that you think looks nice, but protect the papercrete wall (or wall built from any other material) from direct exposure to water from above.

Following these guidelines should result in a very attractive wall that will last indefinitely.

Just make sure that you really want a wall in the first place.

Really.

I cannot recommend learning from Brad Lancaster enough. You'll be glad you did.

Thanks again for re-asking your question.

Be sure to post photos of your progress.

--- In papercreters@yahoogroups.com, "trendawareness" <trendlinesystems@...> wrote:
>
> Spring has sprung in the Midwest and I'm installing a French drain on the upslope side of my 50' x 16' garden.
>
> My garden sits at the low-end of my downsloping backyard, terraced on 3-sides 6" landscape timbers. But anytime we get a decent rain, water flows down the yard, over the edging, and through my garden and out the other side, often taking my topsoil and mulch with it.
>
> Since I'm going to be laying down a bed of gravel anyway, I was thinking of adding a small retaining / decorative wall as well. Such would be my very first PC project. I've been saving paper all winter.
>
> My question for those more experienced than I is, given a wall 50' long, 8" wide, 2' high, would it be better for me to build the wall with PC block or PC slip-form techniques? Again, the wall is mostly for decoration and perhaps some water diversion in a heavy rain, but it won't be a retaining or load-bearing wall.
>
> Thanks!
>
> Dan
>


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