Introduction

The 57 acres that comprise Cedar Ridge Farm are located in the beautiful rolling hills of South Central Kentucky. My wife, our four children, and I are on a homesteading adventure as we work toward increased self-sufficiency. We grow much of our own food and enjoy being in touch with the agrarian roots of our lives.

One of the major projects we have undertaken is the building of our own home. The house we're building has three major distinguishing features: 1. we're building it without incurring any debt; 2. it is a timber frame structure; and 3. the exterior walls will be plastered straw bales. We live debt and mortgage free, and building our house with that approach makes perfect sense. Large timbers in a home possess a beauty and project a sense of strength, stability, and warmth that we want in our home. Straw bale walls provide insulation and make ecological sense. This blog is a record of our home-building project.

Wednesday, April 29, 2009

Dry stack concrete block construction

While doing some research about laying blocks in anticipation of building our root cellar, I came across drystacked.com and thenatualhome.com. I also found a U.S. Dept. of Agriculture bulletin entitled Construction with Surface Bonding. This information convinced me to use this method.

Today, I had opportunity to actually experience dry stacking concrete blocks. Having set the first course in mortar on the foundation yesterday, making sure it was level, allowed me to get a lot of blocks put into place. As I stacked each block today, I checked it for level along and across the wall. corners stackedOften, when it was out of level across the block, just turning the block around brought it back in the bubble.

I started on the corners, stacking the four corners to five blocks. Then, I set blocks belunch timetween the corners until I had the walls built up to five courses by lunch time. Some of the last blocks on a side took a little persuasion to get to slide in, but they all went.

I’m building my root cellar walls ten courses high. By the time I stopped today, I had two walls at ten courses, one long wall at seven courses, and the other short wall ten courses at one corner and eight at the other corner.

quitting time

Along the wall near the house, I applied the surface bonding cement (Quikrete Quikwall) on the outside of the blocks. I won’t be able to get behind this wall to do surface bonding cementit later. So, after laying the first four courses, I leaned over and troweled it on. After laying three courses, I added more above what I’d put on before lunch. Based upon how this bit went on, I think surfacing the rest of the walls shouldn’t be too difficult.

Dry stacking the blocks was simple enough that even Jessica helped. She came to see what I was doing this afternoon and wanted to help. I showed her how to check level on each block and how to put them on the wall. She worked for a while and set several blocks.

12 comments:

Anonymous said...

Hey Darryl,

Great job as always however are you concerned at all about the backfilling on the dry stacked walls? From the pictures I can't tell if they will be holding back any hills or significant weight.

Wade
Ontario, Canada

dp said...

Thanks, Wade! I've had my concerns about the pressures of backfilling -- the rear wall is against the hill. However, the reading I've done claims that once the walls are surface bonded, they will be stronger than mortared walls. Mortar is not good in tension, but the surface bonding cement which has lots of fibers in it is good in tension, resulting in a wall that is up to six times stronger (according to some studies). I'm also filling cavities in the blocks with rebar and concrete every 32 inches along the back wall and the side walls. This method has worked well for others, and from what I've done so far, it's quite doable for the novice. I hope it lives up to what I've read.

lynn said...

My name is Lynn and I run the www.drystacked.com website. You don't state that you have rebar embedded into the slab/footer.

The strongest wall for earth pressure has embedded rebar in the footer that overlaps the rebar in the wall cell. (it sticks up out of the footer where the rebar cells fall.

I don't know what the top of your walls will attach to, but a bond beam is normally specified. That consists of a set of lintel blocks on the top row, with rebar going around the perimeter of the walls (laying inside the lintel blocks) and that top lintel block row is then filled with rebar and concrete. This adds great strength to the wall against lateral forces.

Good Luck

dp said...

Lynn, thanks for the comment and information. I appreciate it. In an earlier post to my blog (Root cellar: the floor is poured) I detailed the rebar embedded in the footer which extends into the block wall cavities. These cavities were filled with concrete and rebar from the footer to the top of the block wall. The filled cavities are closer on center than what info I found specified for my application.

I'm planning on a wooden beam (4.5" x 4.5") as a sill around the top of the wall, bolted to the wall with embedded j-bolts where the concrete and rebar filled cavities are. There will be eight foot strawbale walls directly above the block walls. The block walls are almost 7 feet high and the back fill level on the outside is about 6 feet high on the wall. If necessary, I can form and construct a concrete bond beam along the top of the wall.

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Patricia said...

Thanks So much for your information - I am planning to build a dry stack concrete home next year and I really appreciate you sharing your experience. It doesn't look too difficult- I am going the simple mortgage free route too and am hoping to do most of it myself - congrats to you and your family for leading the way!

Anonymous said...

Hello Darryl,

I really like what you did with your cellar, and I'm contemplating do the same with a building project of my own. I have looked over a lot of material on the internet and I see you are using 8 inch blocks, and I'm wondering if that proved to be sufficient, or if wider blocks would be better? Also, did you only use the Quickrete QuickWall surface bonding material to waterproof on the outside? If so, how has that held up for you? Just curious to know how you did things with your below ground structure. Thanks for your time and help! :)

dp said...

So far, the 8" blocks have been sufficient. The walls haven't moved at all. On the back side which is against the hill and is the longest wall, I did fill every 3rd void and ran 1/2" rebar from footer to top of the wall. My only recommendation is to do a proper bond beam at the top of the wall. I cheated and bolted a cedar beam to the top of the block wall, but a concrete bond beam with rebar embedded in it would be better. I used only Quickwall on the inside and outside of the walls, and it seems to keep water/moisture out just fine. In fact, before I got the cellar covered, there were times the floor drain got clogged and the structure held water like a swimming pool.

toom smith said...

I read your blog. Thanks for sharing such good information about concrete block construction...
Concrete blocks

Lightweight Concrete Blocks said...

Thank you so much for your information.

Tim milldoz said...

Hi years have passed how well has the bonding coating held up to freeze and thaw cycles? Thanks for sharing your pursuits. Tim

dp said...

Tim, I have noticed no problem with the bonding coat -- no evidence of it being negatively affected by freezing-thawing.