I am have just finished your book Earth Sheltered houses in preperation to start on our own earth bermed/ cordwood house this coming summer. You talked in your book about using concrete blocks for the wall that will be bermed and using a surface bond rather than mortar between the blocks. To me this sounded like a great idea and simplier to do. However, upon having a brief conversation with someone who tried to set up the blocks for a surface bond I am now hesitant to try it. She said the issues she ran into was the blocks were rarely exactly the same size so heights would be uneven and over several courses was really a problem, if any of the blocks had even a little burr on them then they wouldnt set flat, the burr had to be found and removed. It ended up with way more handling of the blocks then if one just used mortar as buffer zone to absorb the slight differences in sizes of blocks. Did you run into either of these problems and how did you resolve them? Thanks for your input.
Great question, Tracy, and one that I deal with in Earth Sheltered House. Maybe not well enough!
Laying blocks with a 3/8" mortar joint is a very skilled job, and labor intensive. Surface bonding, I find is much easier, and several times stronger against lateral pressure.
We discovered - after four courses of dry laying - that our corner blocks had a one-sixteenth inch bias, one end of the block to the other. So after four courses, we were one-quarter inch out of level (because we laid them all in the same direction. Once we discovered this, we simply laid the blocks the other way for four courses and - presto -we were back on track.
The best way to take out burrs and irregularities in blocks to put on a pair of rubber masonry gloves and slide or scrape the block over the pallet of blocks, both sides. This will usually make them fit upon one another without a wobble. If a slight wobble is perceived, put a thin metal shim under the appropriate corner to take the wobble out. Use your level to find out which corner to put the shim under.
Thanks Rob for taking the time to give your input. We are going to do our unbermed walls in 16" cordwood so I like the idea of using 16" blocks for the bermed area, except for the fact that you mentioned how heavy they are, so I am visualizing trying to scrape a 70lb block free of burrs. As a woman that would be a handful for me. May have to rethink which size blocks to use. Thanks again
posted 6 years ago
Tracy: Use 8" by 8" by 16" corner blocks. They should weigh about 45 pounds each. See Earth Sheltered Houses. Rob