Clay masonry house walls

[scottiesei]

I am looking into designing a very small single family residence with clay masonry. The builder is wanting to use 4" brick. Right now I am just brain storming the problems that may come up and would like to have others input as well. So far one of the biggest things that is jumping out at me is the tie beam design. Doubt I could get a 4" to work. This house would be in Florida so no snow, but plenty of wind.

 

[csd72]

What about brick veneer?

Otherwise, with double brick, rods can be cast into the cavities to form tie downs, walls can be stiffened up with tube posts.

 

[scottiesei]

The idea is to use the brick to replace the typical 8" cmu, not just for asthetics. Double wythe walls are going to be too expensive.

 

[csd72]

Then you will struggle. Where would you put your tie downs?

Or provide pilasters to take the wind (and embed the uplift rods).

But I would also be concerned about the condensation, water ingress e.t.c. Does the building code even allow single wythe walls for dwellings?

 

[UcfSE]

Look into structural brick. These brick have cells like regular cmu's and get reinforced as such. You get the look of veneer in a structural wall. I have designed a small commercial building in central Florida with these. Looks good, similar engineering to cmu, not really a big deal.

 

[scottiesei]

UcfSE,
Did you use 6" brick or 4" brick? Also, what did you do about the tie beam? CIP?

 

[UcfSE]

8" brick. I believe I required the top courses of brick to be cut to make lintel units for the bond beam. You could use cmu lintel units if the architect wants a smooth band at the top. I wouldn't go cip because of the potential for spilling and messing up the brick. You have the same issue with lintel over openings. The architect may want a smooth band at the top of openings in which case you could use a precast lintel. Otherwise you have a brick beam. I can't go look up what we did because this was at another company and it was a few years ago (memory isn't working today).

 

[JKW05]

So the wall will just be 4" of brick? How is the interior finished? Any insulation? Surface mount conduits? By tie beam, do you mean the roof tie-downs csd72 is referring to?

 

[concretemasonry]

The 4" clay brick probably will not fly because of constructubilty problems (cannot reinforce) and structural (height to thickness, wind and bearing).

You could go with a 6" or 8" "engineered" brick that can be reinforced and grouted as required. The beam could be a problem since the availablity of the units required to poor and sawing could be required. A cast in place beam is possible if it is archecturally accepable. Material cost will be high because of number of the small size(height, length) units and the amount for mortar (twice) required. The labor cost will be correspondinly higher due to the number of units that must be mortared and laid.

There are many 8" CMU homes (minimal reinfrocement) built in Florida. At one time a cast-in-place beam was used, but now a top beam made using filled, reinforced bond beam block is more compatible the the rest of the wall. The same units can be used over windows for lintels. Individual block cells may be reinforced and grouted as required (usually at opening and intermitantly where required to provide a maximum 4' spacing).

You could also look ar 6" CMUs, either reinforced or prestressed. The details at doors and windows look more conventional from an aesthetic standpoint. You can also obtain 4" high x 6" thick colored, split architectural CMUs, but the freight would be as much as for the brick. Block with conventional faces would be local.

Make sure you check the local Florida requirements for "projectile protection", etc that are enforced in many coastal counties. They closely follow the FEMA "safe cell" suggestion which generally come down to either reinforced block or concrete (wood doesn't fly or maybe it does LOL). I don't know if any clay brick assemblies are approved. The Florida codes are quite specific about what is permitted for their conditions.

 

[scottiesei]

The proposed design was to use 4" brick with post tension all threads as reinforcement. Insulation, weather proofing and wiring was delegated to someone else, but they intended on using 2x bucks on the inside. The bond beam would be 2 fold, #1 for the truss anchors to be emebeded and directed to the all threads, and #2 for the diaphragm chord. I think the #2 is where I am going to have problems. The bond beam would be hidden by the truss overhang so CIP would be acceptable. The challenege of having a 4" overall depth tie beam would still remain an issue. I supposed interior walls could be shear walls, but then I would be getting into addition footings on the inside.

 

[JKW05]

So it sounds like you have just been assigned to do the structural. But I'm curious as to how all of the other issues will be resolved (insulation, electrical, etc.). Is this project under a state or municipal building code where these items will need to be approved for a permit? I guess my point is, if they need to do something to get the insulation, finish, etc., and they end up furring out the inside, then it seems like a conventional wood fame may be appropriate.

This is probably just regional terminology, but is a "tie beam" and "bond beam" the same thing here?

 

[scottiesei]

tie beam=bond beam
The plans will need to be permitted and with the way everyone is slow around here I am sure they will go through them with a fine tooth comb. From what I understood, the 2x furring would allow the wiring and shallow boxes to be concealed. This would also allow room for insulation.

 

[JKW05]

I'm certainly not an HVAC guru, but it doesn't seem to me that this will meet the International Energy Conservation Code, if that is applicable in your area. It would just be unfortunate for you to jump through these hoops to make it work, and then find out that they end up sticking 2x4 or 2x6 walls around the inside of envelope.

Regards,

JKW

 

[UcfSE]

Let us know how you did when you decide what to do with it.

 

[hokie66]

4" brick should not be considered a structural material unless for support of gravity loads only with only limited lateral loading transverse to the wall. People have tried to posttension it, but it really doesn't stand up to common sense. You need more depth, say 6" or 8" to allow cores for reinforcing.

 

[concretemasonry]

Make sure you check for the special coastal requirements. Wood frame may not be permitted. It is not strictly a structural question but a question of holding up to the hurricane conditions. - Not as bad as tornados (ptojectiles, etc.), but required in some areas.

 

[JKW05]

Wood frame not permitted in coastal areas? Really? That surprises me, because most of the residential constuction I've seen in southern New Jersey the past 3 years has been wood studs w/wood sheathing; wood I joists; and wood trusses (including small condos). These have been within 4 blocks of the ocean. Is there some restriction in Florida (or other states) beyond the impact resistance requirements?

 

[scottiesei]

Well for a moment, let's assume that the local municipality will accept it, and we are not violating any codes. Let's also assume that the spans and loads are low enough that even with the large l/r every thing works. How could I handle the diaphragm boundary?

 

[UcfSE]

Where are you going to put reinforcing in a 4" brick? What size do you plan to use?

 

[scottiesei]

1/2" all threads in the cores. The thought was that they could be shafted some how through a CIP tie beam and then tensioned.