Technical
- I. General
- II. Labor/Trainng
- III. Design for VOBB
- IV. Keeping the VOBB wall straight
- V. concrete block expansion
- VI. Insulation
- VII. Electrical and plumbing
- VIII. Strength of block compared to wood
- IX Basements (below grade) & other construction comments
- X. Making VOBB blocks
- XI. "Water penetration tests of masonry walls" by PCA
XII. Moisture manaegment by Masonry Magazine
I. General
VOBB is technically very simple.
VOBB is based on making concrete masonry units ("CMU" or concrete
blocks) based on mathematically correct sizes of 6", 12" and
18" instead of the 'standard' 16" in length. As such, inexpensive
and inexperienced labor can be trained in two hours or less to dry-stack
VOBB. Comparatively, a very skilled and expensive mason will lay from
240 to 360 per day of the 16" long CMU's. We have proven that a DIY
person can dry-stack 90 of the VOBB blocks in one hour, or approximately
700 per day. We expect a "trained and experienced" person to
dry-stack up to 1,000 VOBB per day.
All VOBB blocks are six inches in height
and width. Only the length varies. This correct mathematical size allows
the VOBB blocks to be used for corners, T's (intersecting walls) or just
straight walls with ease.
In summary, VOBB blocks are made
on the same machine with the same concrete mix as regular CMU's. The main
difference is the size so that the block will fit together quickly and
can be dry-stacked much faster with much less expensive labor (which can
be trained in a very short period of time).
side view of 6, 12 and 18 inch VOBB
top view of 6, 12 and 18 inch VOBB
The weight (in pounds) of VOBB blocks is as follows:
|
Size |
Light Weight |
Regular Aggregate |
|
6-inch |
7 |
11 |
|
12-inch |
15 |
21 |
|
18-inch |
22 |
31 |
VOBB block specs:
Length - 6'', or 12" or 18" ; Width - 6"; Height
- 6"
Tested for ASTM-C-90 -
Grooves for VOBB clips are on two, three or four sides of the block-as
desired for VOBB clips. VOBB clips are only to keep the wall straight
on a temporary basis.
For additional detailed block pictures, see http://www.vobb.com/block-pictures.htm
II. Labor/training
Using a low level of skill based on $9 per hour for a laborer who dry-stacks
90 VOBB per hour, labor cost equates to a "raw" cost of 10 cents
per block (before adding in the payroll burden cost, etc.). Based on adding
in the payroll burden and allowing for the time to pump/pour in the concrete
slurry mix (with pea gravel) into the VOBB block cavities, we quote the
labor cost of 30 cents per VOBB block for the labor cost.
For more complex jobs requiring the use of scaffolding, cut-outs for electrical, plumbing, etc., then the cost is higher depending on the job.
III.Design for VOBB
To achieve this significant savings in labor costs, it is most important
that the design for VOBB building/wall is based on a "mathematically"
correct size by using increments of six inches. As such, (for example)
the wall will be 20 feet or 20 feet and six inches long, but not 20 feet
and two inches long. The same will be true for the doors and windows.
For example, the door will be 3 feet or 3 feet and 6 inches, but not 3
feet and two inches wide from outer frame to outer frame. Likewise, the
windows will be 3 feet, or 4 feet or 5 feet wide or 3 feet and six inches,
etc. but not three feet and two inches wide. The most expensive and wasteful
labor is on the job-site. You can either think with your brain or pay
with your wallet. (The same is true from GM, Ford, etc. and all of their
assemblies. All parts are pre-cut to the proper size prior to the assembly
process.) There are times when rounded walls will be used. The VOBB block
will then need to be custom-fitted as desired.
Most major cities have a building code. We strongly urge you to read and follow the local building code. Most building codes are based on el-cheapo wood construction, not quality concrete block. Even if concrete block is 500% stronger than wood, the building plans to use VOBB should be properly approved BEFORE any construction is started.
As California is noted as a state having had many earthquakes
and therefore, they have adjusted their building codes to a "higher"
set of standards, we think it interesting to review such a set of building
code requirements. Here is the link for San Luis Ispo Department of Planning
& Building:
http://www.slonet.org/vv/ipcoplng/resbldgcoderequirements.html
For the International Code Council, please see:
http://www.iccsafe.org/
For the I-Codes, please see:
http://www.ecodes.biz/
IV. Keeping the VOBB wall straight
Stacking the VOBB concrete block quickly with inexpensive labor is important.
But also important is for the wall to be straight when it is completed.
For this purpose, there are VOBB clips to "temporarily" hold
the VOBB blocks straight until the concrete slurry is pumped/poured and
allowed to dry in the cavities.
As such, it is recommended that a chalk line (of the entire project) be drawn prior to dry-stacking any VOBB. The corners with VOBB should be built first. After the corners have had a day for the concrete slurry to hardened, then the blocks in between the corners can be dry-stacked.
V. Concrete block expansion
All concrete expands and contracts with heat and cold. As such, all VOBB
wall construction has a built-in expansion gap. This allows each VOBB
block to expand and contract horizontally based on the temperature. This
is because each VOBB is slightly less than 18" or 12" or 6"
in length which leaves in a built-in expansion gap. This expansion gap
is covered by dry-wall, stucco, insulation, etc.
For a independent measurement test, please
see:
http://www.vobb.com/manufacturers/TX-Davids-Patio/Davids-Patio-measurement-test.pdf
VOBB blocks are made to replace 2" x 4" wood (termite food and firewood) in the structure of the home or building. VOBB blocks are made so that termites will not eat them. VOBB blocks are made so that they will not add to a fire but rather help to stop the fire from spreading. VOBB blocks are made to be much stronger than a wall built out of wood.
VI. Insulation
As the use of VOBB block is the same material
as regular CMU's (Concrete Masonry Unit), it is important to use the proper
insulation to reduce heating and cooling costs for an enclosed building.
Basically, there are two practices for insulation. Many buildings have
the insulation on the interior of the exterior walls. This practice is
done in thousands of homes in Florida, etc. This is so that only the air
on the inside of the building is heated or cooled.
|
Insulation on the exterior - The installation
can be on the exterior or on the interior of the exterior wall.
It makes no difference to the VOBB block. Some engineers think you
should just heat/cool the air space. Some engineers think you take
advantage of the thermal mass. |
Residential VOBB construction:
Interior view with the exterior walls being insulated on the inside
of the VOBB block
http://www.vobb.com/CP-LA-Labauve.htm
Insulation on the exterior of VOBB block
http://www.vobb.com/CP-LA-RCA-1.htm
Commercial VOBB construction:
The insulation is put up. 1" * 4" is nailed on a vertical basis.
(This helps to hang pictures.)
http://www.vobb.com/CP-LA-Westbrook-com.htm
However, there are many other people who say that the insulation should be on the exterior of the exterior walls. Some people believe that it is best to heat and cool the VOBB concrete block. This is suppose to take advantage of the weight mass and allow the temperature to stay more constant in the building.
Insulation being installed on the exterior of the walls
http://www.vobb.com/LA-Complete%20home.htm
VOBB blocks can be used with the insulation
on either the interior or the exterior of the wall. It is estimated that
the R-value of a six-inch wide VOBB block is .95. ( This estimate is based
on the average of a 4" and a 8" as per the ColoraradoEnergy.org
web page.)
In Lafayette, LA where the first VOBB home was built, the owners say several
things about their home. They are as follows:
1. "We love our home."
2. Their VOBB home saves about $100 per month on the utility cost, or
over $1,000 per year. This equates to over $30,000 for a typical 30-year
note period of time.
3. Their VOBB home is so quiet.
In addition, the VOBB home owners have a big smile when a hurricane or other big storm comes to town, as they know they have a quality built home.
Based on the Colorado Department of Energy, it is estimated a six-inch
wide VOBB block has a R-Value of .95. ( Per the CDE,
the R-Value of 4" Concrete Block is 0.80 and for
8" Concrete Block the R-Value is 1.11.)
While there are many good insulating materials, we suggest Polyisocyanurate (foil-faced) which has an R-Value 7.20 per inch.
Below are some table references for the insulating value with various
construction products.
R-Value Table
Insulation Values For Selected Materials
Use the R-value table to help you determine the R-value of your wall or
ceiling assemblies.
Colardo Energy R-Value Table Website
In addition, the following links are for additional detail on energy efficiency
http://www.concreteblockhomes.com/beauty_of_b
lock/energy_efficiency.htm
http://www.concretenetwork.com/concrete/radiant
floorheating/index.html
NOTE: There are a lot of people selling products with insulating materials attached or part of a concrete system (such as ICF - Insulated Concrete Forms). We strongly suggest you look at the cost of using such a product vs. VOBB. We have already had people do this price comparison. When they did their calculations, at first, it looked like ICF was cheaper, but after the total cost of material and labor was calculated, VOBB was proven to be cheaper. (This cost analysis was based on an actual customer's analysis, not our calculation.) In summary, the use of concrete block for structure is great. The use of insulating board, etc. is great. The mixture of the two as one product together is substandard (in our opinion) as compared to the use of VOBB. There are numerous insulating board products, etc. which are very easy to install and to tape so that there is no water or air penetration. This material is light and easy to install. On the other hand, concrete is a much heavier product and absorbs water. Likewise, VOBB can be used for interior walls where insulation is not needed and as such, it would be a waste of money.
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A lot of people want to compare a block-wall
to a poured-concrete-wall. A great article is as per the following by
Tim Carter:
http://www.askthebuilder.com/439_Poured_Concrete_vs_Block
_Walls.shtml
It should be noted that a poured-wall can be very expensive due to the necessity to build forms. As such, a block-wall in many situations is much more cost effective and much simpler to use, especially VOBB.
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VII. Electrical and plumbing
For simple cost effective construction, the electrical, telephone, plumbing, etc. can be installed on a vertical basis in the VOBB block wall. This is because it is recommended that the cavities are filled on an alternating basis. As the VOBB block are made in mathematical correct sizes, a "concrete conduit" is created for the protection of these utilities. (Some large plumbing tubes will need to be placed outside the VOBB block. Likewise, it may better in some cases to run the utilities in the foundation.) In addition, for future wiring for computes, etc., as the cavities are void on an alternating basis, it easy to install the wires, etc. as required.
Putting in an electrical box
VIII. Strength of block compared to wood
It is generally considered by the professionals in the industry, that a block wall is 500% stronger than a wood wall. Likewise, as VOBB block are dry-stacked like bales of hay intersecting the adjoining block with the VOBB on top and on bottom and at the corners, the VOBB block construction is total quality. The government building inspectors who have inspected VOBB construction have approved it 100% and were very impressed with the quality of the construction.
VOBB blocks have been tested in accordance with ASTM-C-90 requirements. It should be noted that ASTM requires CMU to have a wall thickness of at least one inch. The wall thickness on a VOBB block is one and a half inches thick on the exterior to allow for the grooves.
IX. Basements (below-grade) and other construction comments
We believe that VOBB block can be used for building basements and other below grade construction. VOBB blocks are made of the same material, on the same machine and with the same curing process as regular 8" * 16" CMU, except that instead of eight inches wide, VOBB are six inches wide. ASTM requires block to have one-inch thick walls. However, the wall thickness of a VOBB block is one and one-half thick. As such, we believe with the "proper" adjustment in rebar placed inside the cavities with the proper grout and with the "proper" reinforcements (columns) or attached walls, that the VOBB wall is a quality and cost effective method of construction. With basements, the lateral pressure is most important and as such, proper design is required.
A very good article in the Journal of Light Construction by Brent Andersen, P.E. was written. Please see the following (Acrobat PDF file) Designing Concrete Basement Walls
or the the attached link:
Designing
Concrete Basement Walls
As per the article in the JLC "Concrete basement walls are designed to do two main jobs. One job is supporting the house; the other is holding back the pressure of soil against the side of the basement.
Considering the nature of concrete, holding up the weight of the house is the lesser worry. Concrete’s compressive strength is much greater than it needs to be to support a house. As long as the soil under the footing has adequate bearing capacity, the ability of a concrete wall to carry the load is not a question.
Soil pressure against the basement walls, on the other
hand, can sometimes be a problem. A sideways force against a basement
wall puts one face of the wall in tension (see Figure 1, next page), and
concrete’s tensile strength is much lower than its compressive strength.
Designing a wall to prevent failure in bending requires a proper analysis
of the soil loads and an appropriate structural design of the wall. It’s
important to consider not just the wall’s construction, but also
the drainage provided and the way the wall is tied to the house’s
floor frame."
********************************************
As written by Brent Andersen, PE, "Concrete’s compressive strength is much greater than it needs to be to support a house."
As such, for basements, below-grade, retaining walls with constant pressure from soil, lateral strength is most important. Therefore, with the low cost of labor by using VOBB, it is very cost effective to spend money for the grout and rebar inside the cavities to provide the adequate strength required.
Here are some pictures of regular 8" * 16" CMU used to build an approximate three-foot high retaining wall. Due to having insufficient rebar and grout, these regular 8" * 16" failed. The wall was lacking in lateral strength, even though 8" wide CMU were used.
********************************************
As VOBB block are generally placed on
a foundation, it is also very important to properly construct the foundation.
Another good article in the Journal of Light Construction
is about construction of the foundation. Please read Tips
for Crack-Free Concrete Slabs By Gabe Martel
Also, a very good article on ordering concrete in the
Journal of Light Construction is the following:
Ordering
Ready-Mix Concrete By Don Kincaid
********************************************
For a good write-up on testing shear strength of a
dry-stack masonry wall, please see the following by Gero Marzahan:
http://www.vobb.com/technical/shear-strength-dry-stack.pdf
or
http://www.uni-leipzig.de/~massivb/institut/lacer/lacer03/l03_24.pdf
********************************************
CMU is a good material for construction as it does
not feed mold which has been a major problem for the construction industry,
causing millions of dollars of damage or alleged damage. As a result,
contractors, architects, designers, engineers have desired to use a building
material which does not expose them to this damage or alleged damage.
For a good article, by Anthony J. Barron,
Thelen Reid & Priest LLP:
http://www.vobb.com/technical/An
overview on mold.pdf
or
For a technical write-up from the NCMA for TEK 14-22 DESIGN AND CONSTRUCTION OF DRY-STACK MASONRY WALLS, please call to the NCMA, as follows:
X. Making VOBB block
VOBB block have been made on a Besser block machines (V3-12 and a Dynapac). Four VOBB blocks (which are only six inches wide) are made at the same time as compared to only three regular eight-inch wide CMU's. As such, the production of VOBB using the same block machine, forklifts, dryer, personnel, etc. is increased by one-third compared to making regular 8" wide CMU.
VOBB blocks have been produced at 9.5 cycles per minute using 18 1/2" pallets.
VOBB blocks coming out of a Besser block machine
- four-at-a-time
VOBB blocks stacked ready for the dryer
VOBB has designed a unique roller for the purpose of cost efficiently producing the concrete blocks so that the quality control of the six-inch height is maintained. The roller is a heavy piece of of metal which rolls at the same speed as the conveyor line of the blocks being produced from the block machine. The roller is heated by electricity using 230 volts so the concrete will not stick to it at it passes over the CMU. The roller has a motor on top to turn the roller. There is a support for the pallets so that they pass under the roller at the same height on a consistent basis. The footprint of this roller is only 18" wide so that it will easily fit in the conveyor line. The roller is to gently pass over the block and barely touch the block so that any loose or high aggregate is compressed into the CMU without deforming the CMU as it is moving on the conveyor.
overview of the roller
VOBB blocks exiting from under the roller
The VOBB roller has done an excellent job of making sure of a consistent height in the blocks. Having a consistent height allows for dry-stacking and elimination of the weak mortar joint. On a Besser Dynapak block machine, the 18-inch long VOBB had a height as follows (based on a three test blocks):
1. 6.050 inches high
2. 6.056 inches high
3. 6.046 inches high
As such, the height variance from the average was 6/1000ths of an inch. However, most important is to noot change the height of the VOBB roller during production so that the 18-inch, 12-inch and 6-inch long VOBB blocks have the same height. (It has been proven that the use simple wooden wedges can be used on the job site to correct for any height variance in the pallets, etc.)
For a copy of the test company's/engineer's report, click on the following:
LIGHT-WEIGHT AGGREGRATE ON A BESSER DYNAPAK
http://www.vobb.com/technical/Stork-Southwestern-
Laboratories-measurement-Premier-Concrete-2003-May.pdf
REGULAR AGGREGRATE ON A BESSER V3-12
http://www.vobb.com/technical/Stork-Southwestern-
Laboratories-Shaffer-2003-Oct.pdf
VOBB has three patents for the VOBB method of construction and the VOBB blocks. A fourth patent has been applied for just the VOBB roller.
If you have technical questions about the mold or roller to make VOBB
block, please contact Rene Bergeron, General Manager, (with Besser Proneq)
at 1-800-363-2400 or 450-966-3000.
Click
here for the Besser web site.
According to Besser, the 18" VOBB block with two grooves on each end has a concrete volume of 425 cubic inches.
For more detailed pictures of the VOBB
roller and production, see
http://www.vobb.com/roller.htm
This is part of the VOBB mold with the grooves on the side.
The block producing company's crew is changing the VOBB mold parts.
A complete breakdown of the VOBB mold parts to reconfigure the blocks
being made.
A pallet of 18-inch VOBB blocks ready for shipment. See how level the
blocks are.
Thousands and thousands of VOBB blocks ready to be shipped.
XI. "Water penetration tests of masonry walls" by PCA
For an very interesting article on water penetration of regular CMU. For VOBB, which is structural, some form of cating is required to stop water penetration.
http://www.vobb.com/PCA/water-penetration-IS219.pdf
for a link to the source: http://www.cement.org/bookstore/profile.asp?id=240
XII. Moisture Management
For an very interesting article on air barriers, vapor retarders and weather resitive bariers in the Masonry Magazine, see:
http://www.masonrymagazine.com/7-07/moisture.html
From July 2007; volume 46, number 7
