Errata and Changes to the DryStacked Construction Handbook...
Although the eBook has been published, improvements in the dry stacked block building process continue. We have added this errata page to keep our readers informed of the latest changes.
in the Book
Most block houses use trusses as the roof structure. These trusses are normally engineered and built by a company that specializes in trusses. You provide your foundation and wall plans to them and they design and build your required trusses. After the trusses are designed and accepted, a copy of the truss plans are provided before the actual trusses are built. You will need your truss plans to mark where the tie-down straps are placed within the bond beam before the bond beam is poured.
Transpose your truss plan tie-down strap locations onto the wall. When using the outside edge of the truss width to place the truss mark, use a convention such as the mark will always be on the clockwise side of the truss all around the bond beam. Then when you place the truss upon the wall you will know upon which side of the tie-down strap to place the truss (the counter-clockwise side in this example).
In my design, I had two rebar in the bond beam. I installed the tie-down straps in place at the marked locations and then wire-tied each strap to the bond beam rebar. While pouring the bond beam, ensure the straps are mostly vertical and not leaning.
Your local building code will specify the size of tie-downs required. Consult with your local building inspector. Most tie-down straps have a mark which indicates how deep the tie-down must be inserted into the concrete bond beam. Be sure to use the proper nails when fastening the truss to the tie-down straps. The wrong nails will fail inspection.
b. Installed block dimensions. (7/24/10) Although this is not an error, we reference it here to reduce possible confusion. In the "Dry stacked Wall Dimensions Chapter", we point out that the corner- block is 8.0625-inches wide. We also point out that the installed half-block linear length is about 7.9-inches and the installed full-block length is about 15.7-inches. These estimates were provided as guidelines for planning walls. These estimates do not consider wall growth, but instead are the real installed block lengths including 1/16" gap to compensate for slight misalignments.
Later in the same Chapter, we discuss wall growth in greater detail and next we describe the spreadsheet solution. The spreadsheet solution eliminates the estimates described in the previous paragraph of this text. The spreadsheet block unit length is defined as 15-6/8" which equals 15.75". This dimension precisely includes wall growth and installed length. A linear half-block is defined as 15.75"/2 = 7.875". The difference between a linear half-block length (7.875") and a corner block width (8.0625") is rounded off to (0.25") when in reality, this difference is (0.1875") which is actually (3/16"). This add-on for a corner-block was rounded up to (0.25") simply for the ease of doing the math during manual wall dimensioning. This slight excess doesn't hurt and it also ensures that short two-block out-croppings wont have a problem.
Now that we have completed the CAD training course, we now explain in detail how to draw the house plans using QCad. Since CAD is a very precise drawing method, we decided to teach the add-on as (3/16") instead of teaching the add-on as (1/4") for corner-blocks as described in the book.
During the first 30 Lessons of TheCadTrain-CD, we didn't get into this topic, and we specified the architectual dimensions for the QCad to be (feet - inches - 1/8-inches) for the rounding-off accuracy. When we developed the Bonus-CD (Lessons 31,32,33) for accurately placing corner blocks, we discovered that the architectual dimensions rounded off to (1/8") was inadequate. We now recommend that the architectual dimensions be rounded-off to (1/16"). This allows the add-on of (3/16") for corner blocks without misleading rounding-off of CAD dimensions to the nearest (1/8").
In conclusion, the wall stretch required for each corner-block (8.0625") increases the spreadsheet wall segment length by (3/16") in reality and not (1/4") as estimated in the Book. Hopefully, this will explain why we changed from (1/4") add-on as defined by the spreadsheet tables, to the (3/16") add-on as described in the Bonus-CD (Lessons 31,32,33).
a. Changes in the "Draw Your Own Plans" Chapter. (7/24/10) This Chapter has been changed at our Website to reflect our new belief that QCad is now the better CAD program to use with dry stacked block house plans. This change is because we have completed a QCad Training Video CD. With this 6-hour video training course, the power of QCad can be easily realized by most users within a very short time frame. CadStd simply has too many limitations to be considered now that QCad training is available. It took 6-months effort to learn QCad and then develope the required training course; but that effort is now completed and can be found at www.LearnQcad.com. You will also find a Bonus-CD on the order page.
b. Bonus-CD Updates. (7/24/10) The Bonus-CD is specific to dry stacked block plans only. We expect to add additonal information to the Bonus-CD as time passes, and those additions will be listed here so that previous Bonus-CD owners can order a new Bonus-CD ($3.00 First Class domestic shipping and handling fee) (price may vary over time) at www.LearnQcad.com/order.htm. Each update will have a release date, and if your Bonus-CD was received prior to the release date, then you should update.
c. Changes in the "Draw Your Own Plans" Chapter. (7/31/10) As we gain more experience using QCad, important new knowledge will be added here. This particular change has to do with paper size and Current Drawing Preferences Options for QCad. Refer to the Draw Your Own Plans web page for details.
d. Setting window/door openings (03/10/11) for drystacked blocks. We would suggest that you build a jig which exactly represents the installed window/door rough opening width and height. We also now recommend that you pour the window sill before pouring the window header. By pouring the window sill first (and making sure it is level), then you can prop the window header form boards on the window sill, and the window opening will be square. Refer to the Wall Openings web page for details.
Monolithic Slab Regrets I used a monolithic slab for my home because of it's inherent strength. What I missed is that this is a bad choice when the walls are insulated on the inside. I insulated on the inside because I planned to leave the home closed for months at a time. I was concerned that bringing the home back up to temperature when returning would take a long time, so I insulated on the inside of the walls.
These drystacked walls remain at the average daily temperature averaged over several days. Because of this, the inside insulation never sees the peak outside temperature changes. So my heating and cooling only deals with the average daily temperatures and this saves a lot of energy. In the summer the walls ignore the peak high temperatures and in the winter the walls ignore the lowest temperatures. For the reasons listed in the next paragraph, five days of extreme low temperatures will cost more energy to heat the home..
In the winter, the walls suck heat from the footer which also sucks heat from the floor because of the monolithic slab. This causes heat loss which isn't to bad in Florida but would be unacceptable in northern climates. The good news here in Florida is that this same heat transfer also keeps the home cooler early into summer. The best solution would be to insulate on both inside and outside of the walls.
If I would have used a typical footer with slab poured inside the footer (and with insulation between the footer and the slab) then this winter heat loss would not be an issue. Here in Northeast Florida (2500 sq ft home) my highest summer monthly electric bill (heat pump) is $95. My highest winter monthly electric bill (heat pump) is $160 and this was after 30 days of unseasonable cold weather, when the temperature never got above 40 degrees (F). Typically most winter days reach high 60's which warms the walls each day to compensate for the night low temperature swings. My average electric bill for the last five years is $82.