“Best mud-set mortar system” is a red herring because you don’t "mud set" or grout pavers unless it is for looks – like a pedestrian path you want to look like a brick wall laying on the ground. For heavy traffic applications you place the pavers on a sand bed over a concrete or compacted road rock base. Then you fill the cracks between the pavers with sand. The shape of the pavers and the sand cause them to interlock (which is where the name “interlocking pavers” comes from).
Grouts used in heavy traffic application are subject to crushing and subsequent failure so are avoided.

If you put the pavers over a solid concrete base you have to include weep holes to drain away the water.

For circular patterns where you encounter radial forces you want good "in plain" interlocking to prevent shifting and a herring bone pattern is usually recommended.

The simple answer is that unless the specifications specifically call out for a special criteria for workmanship the codes contain one universally accepted criteria – view at 20 ft under diffused lightning. Period. This is in section 7.2 of ASTM C90-14. The current version of C90 referenced in the 7th Edition Florida Building Code is 2014.

It is understood that full head joints and bed joints are called out in the TMS 602 Code (current referenced edition is 2016) but there is no further guidance given. A mock up panel, if built and agreed on prior to construction, would govern for workmanship. In the absence of a mock up panel you are left with that most rare of commodities – common sense.

So, on the basis of common sense lets think about where our only code based criteria, 20’ in diffused lighting, might or might not apply.

It probably wouldn’t apply for the installation of a glazed block in an 8’x10’ bathroom. In that case your mortar joints are going to be expected to approach perfection. Any imperfections are going to be visible. Since the joint is tooled the mason at least has a fighting chance of striking the joints with a high degree of care.

Our 20’ criteria is regularly used for architectural block in an exterior wall. Cracks and holes that are not visible at 20’ under diffused lighting are considered acceptable.

In the case of block substrate to receive a direct applied stucco coating the 20’ criterial would be considered adequate for several reasons. The first is that the joints are not tooled. The joints must be cut flush so that they do not reflect through the finished stucco. Without tooling complete densification of a mortar joint is not possible. The second reason is that the direct applied stucco is the exterior weather barrier. There should absolutely be a solid block and filled mortar joint behind the stucco but the stucco itself is your primary protection. The third reason is that there are no esthetics issues.
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My view is that without a mock up panel and without job specifications specific to the appearance of the mortar joints, the 20’ diffused lighting rule would govern as the only applicable code guidance.

The fill material could be a variety of material, The key is what the CMU is manufactured with. If the 6" CMU is manufactured using sand and/or limestone aggregate you cannot reach a 4 hr equivalent rating. What you fill the cores with takes on the rating as the CMU. Full lightweight CMU with cores filled will meet a 4 hr requirement. A proper blend of sand and lightweight with filled cores may meet 4 hrs. The blend will have to be verified by an independent lab. Fill material can be practically anything that is fireproof itself. Perlite, sand, expanded clay aggregate and masonry cell fill (course or fine grout) are possibilities.  

The Masonry Society has an excellent book on Fire Resistance of Masonry. Chapter 7 Section 722 covers calculated fire resistance in the IBC. I am attaching a link to the NCMA TEK that covers the same subject. 

FIRE RESISTANCE RATINGS OF CONCRETE MASONRY ASSEMBLIES - NCMA 

Thank you for contacting the MAF.  Our goal is to make sure that when masonry is designed and installed correctly the public has the best wall system available.
Be safe,
Jerry M Painter, FASTM
352-494-8955

​Thank you for contacting us with your question. TMS 402/602-16 (Building Code Requirements and Specification for Masonry Structures) does not address locating control joints (CJ) in concrete masonry walls. In the Commentary for TMS 602  in Figure SC-7 on page S-51 samples of constructed joint types are shown. The figure for a Fire-Rated Control Joint is the one to be used. I would highly recommend placing rebar and grout in the cells on either side of the CJ. In TMS 602 Part 2 the commentary for sections 2.5 A&B it is recommended to use NCMA TEK 10-02D. This is the Empirical Method for determining the location of CJ in concrete masonry walls. It gives a ratio formula of 1.5:1 or not to exceed 25lf maximum. In your case that is a 12'-0" high x 38"-0" long wall. Using the ratio the spacing would be 18'-0". One CJ would not be enough and 2 would be required. They could be placed as the architect decides or if he does not locate them you could decide the location based on panels not to exceed 18'-0". I would personally put a 17'-4" panel centered and a 5'-4" panel on either side because that would be modular blockwork. There are two additional TEKs that could be reviewed by the architect. They are TEK 10-01A which is a general discussion of control joints in concrete masonry and TEK 10-03which is the Engineered Method. A quick rule of thumb is locate a CJ at any change of the mass of the wall and/or not to exceed 25'-0".
I hope this is helpful. Thank you for contacting us and using one of the many services available. You can call me at 352-494-8955 if necessary.
Be Safe.
 

All COLORED block made in Florida Contains integral waterproofing.   The assumption you MUST make is that if the block is not colored it will not contain integral waterproofing.   EVERY block that is used in a single wythe installation SHOULD contain integral waterproofing --- even if it is going to be painted or sealed.   So…. If you are designing a single wythe wall that does not contain integral color be sure to request integral waterproofing!!   ONE more thing --- EVERY single wythe wall SHOULD be painted or sealed.

Remember – Single Wythe  --  Integral Waterproofing   --- Painted and Sealed   -- ALWAYS.

​I am looking for guidance and I am hoping your organization can point me in the right direction.

I had a home originally built in 1972 extensively remodeled (90%+) in 2012 and brought up to what I believe were 2007 Florida Building Codes. Recently the home has experienced catastrophic failure of the stone facade. I am in the process of exploring my options as it relates to construction defect and I have had several masons come asses the damage. The mason who originally did the work is no longer in business, but the GC who re-built the home is. I am trying to identify in code where the missteps were in the installation. It appears that a scratch coat was applied directly over an unclean and painted stucco (original to the 1972 home) surface (see photos). In time, this has resulted in a de-bonding of the scratch coat and the stone facade and mortar falling off the home, exposing the original painted stucco. My limited understanding is that this would have been a violation of ASTM C 926 reference 5.2 “...and shall be free of form oil or other elements, which would interfere with bonding.”. I have had masons who have inspected the damage who also bring up that it does not appear a bonding agent was used. At this point the GC is wanting to simply remedy the failed area with new stone and admit no fault. However if the entire stone facade was installed using the same incorrect methods (see pictures) it is just a matter of time before the bond fails. Furthermore, I think it is unlikely that the GC will be able to match the stone as it was manufactured stone with pigmentation that has been baking in the FL sun for nearly 8 years. My ask is, if you could advise on what codes may have been violated with this installation and / or if you have a recommendation of an engineer / GC (based in N C FL) that I could hire to document said violations? I appreciate your time in reading my story, reviewing photos, and consideration of a response.

Thank you for contacting the Masonry Association of Florida with your concerns. You are correct that it appears that the Scratch coat of mortar has de-bonded or delaminated from the original painted stucco. While paint is good weather proofing it will also prevent cementitious material from bonding. Here are some considerations that need to be included in any repair discussion.

1. Simply replacing the fallen stone with the existing stone will not work. Cleaning the mortar from the existing stone could result in much damage to the stone and loss of a considerable amount of stone. 
2. Replacing the fallen stone with new stone will not work even if the original producer is still manufacturing the same stone. There is an 8 - 9 years difference in age and there will be a color difference.
3. Since it appears that the manufacturer's installation guide was not followed a shear bond strength test would have to be performed to determine the strength of the bonding of the mortar to the substrate.
4. It appears not to meet the current building code and standard practice for adhered thin veneer. That would probably have to be remedied.

I wish you the best of luck in resolving this issue. If we can be of further assistance please contact MAF. Be safe.
Jerry Painter, FASTM

​In the case of directly applied (called “direct applied”) stucco the bond between the stucco and the solid substrate (in this case concrete block) is the most important thing.    With good bond the thin layer of stucco will crack in any place the solid substrate cracks.  Thus, there should be a control joint in the stucco at any location that you find a control joint in the block.   There are no other control joints required in direct applied stucco.

In stucco on lath, the ASTM 1063 code requires a control joint at a maximum spacing in walls of 18 ft o/c both horizontally and vertically enclosing an area no more than 144 sf.  The area enclosed by the control joints cannot have a length to width ratio greater than 2 ½ :1 .  The control joints in the lath are not require to line up with the control joints in the block because in this case the stucco layer is independent of the wall to which it is attached."

​There is no specific “up” or “down” direction that block have to be laid in.   You may hear a masonry say that block are manufactured “upside-down”.   This means that the block molds are slightly wider on the bottom than the top.   The reason is common sense – so you can lift the mold off of the freshly compacted block.   The mason will usually turn the block over before he picks it up so he is holding the thicker portion of the web.   It is simply easier to grip and hold the thicker end.   Structurally, it makes no difference.