grouted/reinforced block wall penetration

[rchrd]

Hello,

I work for a GC and am not looking for a professional statement of opinion (just trying to learn and get professional's opinions).

Please look at the photos which may explain better.

http://www.dmrnetworks.com/mazzei/P7090079.JPG

http://www.dmrnetworks.com/mazzei/P7090080.JPG

http://www.dmrnetworks.com/mazzei/P7090081.JPG

http://www.dmrnetworks.com/mazzei/P7090082.JPG

http://www.dmrnetworks.com/mazzei/P7090083.JPG

http://www.dmrnetworks.com/mazzei/P7090084.JPG

I have 12" thick, grouted (very) reinforced block wall (vertically and horizontally). The penetration in the pics is 5' wide x 16 inches high. This wall was not "designed" to support itself over the penetration (which was an afterthought ((now THAT'S a story), but does it "need" an LLV or other support mechanism? Equating it to lego's with some blocks missing may be simplistic, but doesn't it apply?

The split-faced veneer is supported, but the owners waiting until the last minute to spring the support issue on us.

This penetration has been in place for two month with no visible cracks, and I don't understand why there is concern.

My thought would be that the higher you go, the more the load is distributed horizontally, so really the part that may be ion question is right above the penetration. I understand the concern, but won't the rebar take care of that?

P.S. P7090082.JPG and P7090081.JPG show the horizontal and vertical rebar.

Thank You,

Rich

 

[JAE]

Well, the wall was probably designed for a number of forces...

1. Component lateral wind perpendicular to the wall where the wall spans vertically and/or horizontally.

2. Component lateral seismic - similar to 1. above.

3. Longitudinal shearwall perhaps? Wind or seismic forces in the plane of the wall.

4. Axial loads from roof or floors above.

In any of the above cases, the loss of a 5 ft. wide section certainly has diminished the wall capacity. Has this been checked by the Engineer of Record?

Also curious is the fact that the exposed rebar that I see was located offset from the center of the block - towards the inside face. This is strange. Most times you set the rebar in the center, or have rebar in both sides....but rarely one side only.

Has the EOR seen this?

 

[msucog]

shouldn't there be a bond beam above the opening? if it was an after thought, i doubt there was a bond beam(s) and the necessary vertical grout support constructed with the appropriate rebar during the original construction. also, i would expect there to be a rather significant amount of rebar both horizontal and vertical (and appropriately placed within the cells).

 

[hokie66]

msucog,

From the photos it is a fully grouted wall with both horizontal and vertical bars. The opening was sawn, and very neatly at that. Only the design engineer can make the determination if the wall has been unduly compromised. Like JAE, I wonder at the position of the bars within the wall.

 

[msucog]

the blocks above the opening appear to be normal blocks (since the opening was cut in to the existing wall), not U-shaped or lintels so i wonder how/where the horizontal bars are located above the opening. it seems to me that the course or two above the opening should've been removed and replaced with a more appropriate bond beam with horizontal reinforcing extending to outside the width of the opening. that is my main point.

i see no where that says the wall is fully grouted. and i also see no specifics on where the horizontal and vertical bars are located. i try not assume a wall is fully reinforced horizontally and vertically or fully grouted based on what is visible at one opening.

 

[Tomfh]

I assumed the bars are on the inside because the wall holds back soil and spans top to bottom.

 

[hokie66]

msucog,

Just based on what I think I see, but looks to me like there is a horizontal bar in each course. You don't need a U-shaped block in order to build in horizontal bars. And again based only on what I see, looks like the wall is fully grouted. All the cores which are in the photos are grouted. Where I come from, we grout them all as a matter of course, although I know in some areas they waste time by trying to just grout the ones with bars.

Tomfh,

Think you are right, looks like the wall is designed as a basement wall, with the external grade about 8 courses above the internal. So there would be a concern as to whether the wall at the jambs can pick up the extra bending.

 

[JAE]

Folks, I don't think this is a basement wall at all (rchrd can verify this) because you have a very decorative veneer block on the exterior side with rebar on the interior side. I don't see this as being set up to receive dirt. Why use the special color/texture block with a nice color band and then bury it?

 

[hokie66]

JAE,

I trust the decorative veneer would stop just below the external slab. If you look at the photos taken inside, the floor is quite a few courses, maybe 8, further below the sill than the slab outside. You would have to think that the cavity is grouted below the outside slab. The veneer that we can see from the photos was built with the opening, with only the reinforced backup hole sawn out. A bit of a worry with the veneer is that there do not appear to be any weepholes or any sign of flashing.

 

[msucog]

hokie66, how would you install horizontal bar through normal block? by saw cutting and knocking out the cavity? would you normally do that if the opening wasn't going to be there when you did the construction? and typically when i see contractors cut in normal block for horizontal reinforcement in a bond beam, they rarely provide the appropriate dimensions...they will usually put just enough room to get the rebar in. as far as the horizontal bars i can see at the edge of the opening, it appears to me to only be 1-#4 or #5 which seems a little "thin on reinforcement" for 12" cmu or bond beam. instead of guessing, rchrd, please explain the horizontal/vertical reinforcement and spacing you have in the two courses above the opening and to each side of the opening.

either way, it does appear that the block only has two courses before it reaches the above deck/beam, so there should be a bond beam there anyway since it's an exterior wall. i would expect the opening to be ok if there is only two courses with one of the courses being a bond beam. i'm not so sure the opening would satisfy code if there is not a bond beam immediately above the opening (there again, i don't have x-ray vision to see what's not visible in the picture).

 

[msucog]

i guess one important question would be to ask whether there were special inspections performed during the initial wall construction. this might help firm up whether the masonry, grout spaces and reinforcement satified code requirements more appropriately than from what i see out of many masonry contractors that simply throw the wall up however they feel that day.

just to clarify, my comments and questions in this thread are geared more toward satisfying code requirements rather than evaluating the structural integrity of the scenario put forth.

 

[lkjh345]

While I definately think the EOR should be consulted to make a final determination, my 2 cents worth is:

Looking at the first photo, there appears to be plenty of wall above and to the sides of the opening for arching action to develop.

Looking at the 3rd photo does seem to indicate that there may be a horizontal bar (though fairly small, #4? ) in each course.

The last photo's show that there is a floor level a few course above the opening. I would think there 'should' be a bond beam at this level.

My guess would be that arching action is taking place over the opening, with either the walls to the side, or the bars in each course, or the bond beam bars at the floor level, taking the horizontal thrust.

My guess is that the opening is probably fine.

 

[concretemasonry]

Regarding the steel placement without knowing about the building layout and details of the structural design -

The steel is consistantly near the inside face. The horizontal steel is lighter. It appears the horizontal steel is place in special web recesses of an open bond beam. The steel can correctly locate the heavier vertical steel where the engineer determined it should be. The horizontal steel in every block looks a little excessive if it is only for minimum/placement.

It is surprising that a two core block were used instead of a single core or "H" block, but that is probably why the entire wall was grouted. Could be a local practice.

The grouting looks great with no voids, so the grout must have been very fuid and consolidated well. Despite the high water content, the blocks absorbed the water well and created a good tigh bond between the block and grout. The beautiful sawing makes everything look better.

 

[csd72]

As stated previously, you need to get the engineer of record to look at this one.

csd

 

[hokie66]

msucog,

Just to answer your question about installing horizontal bars, I think in many locations the blocks are made with the horizontal bars in mind. Admittedly I am in Australia, but I don't think our block manufacturers are smarter than yours. We use "knockout blocks", in which the top part of the web can easily be removed, or blocks with the top 50 mm of the web left out in the manufacturing process.

 

[rchrd]

First, WOW and thank you all. I'll do my best to explain some things. The goal was to see if this penetration would not need any additional support (my boss thinks it will never go anywhere). Although the wall wasn't necessarily designed for this load, I don't think that it necessarily can't handle the load. If it's so solid like a bond beam, is more support needed? I think it might be easier if I address the comments/questions as a whole rather than individually....

The HVAC penetration was "somewhat" of an afterthought. It was known that is was going to be, though how big and where was the question. That was the problem with all of this.. we were pressured into keeping a schedule when the hole size/location/construction method should have been known but wasn't. So knowing that the other side of the coin would have said "why did you put a hole in the wall if you didn't know where and how big etc., etc.

***(just as a sidenote, I would wonder if you would agree with this statement from the architect, keeping in mind that Change Orders are VERY hard to come by....**

"My stance is and has always been that an opening should have been "planned" for in the field..... either for the inside unit or the outside unit. That is purely my opinion. I am entitled to an opinion, just as you are.

In my opinion, it would have been far more cost effective, for the client AND for X Contracting to have a larger opening in the reinforced foundation wall(say 5' x 8'). That enlarged opening could have been infilled to the correct size once the HVAC details(size, elevation & location) were worked out. X could have and should have provided that information. It would have been easier than cutting out both re-inforced foundation wall AND masonry veneer."

** End of architect's comments **

The rebar is set toward the inside of the building. The

http://ivanyblock.com/

has two "channels and the drawings specified only the inside channel. So those are in every coarse (8" centers horizontally). There are two pieces (as you can see in the pic that looks down onto the cut) every 16")

The EOR has seen this (the arch only waited a month to disuss with him, and of course we're trying to install HVAC ductwork so now that's being delayed) and the architect's suggestion is using a 7x4 LLV (the EOR ok'd 6" of bearing each side - just more work for us).

The wall IS fully reinforced horizontally and vertically as described, and fully grouted as well.

The split-faced veneer does only go to just below grade externally, and sits on wider block - and internally, it is a basement.

I'm in Western Pennsylvania.

 

[hokie66]

rchrd,

I sympathise. If the EOR has seen it, what did he do about it? Would have only taken me 2 minutes, then on to the next problem. I think your boss is right. And it is usually hard to get me to agree with the GC. Have you done something to aggravate these guys?

 

[structengineer]

Does the floor above bear on this wall? There is a concern that the wall above the opening is not engaging arching action due to the location of the opening below the floor. When the floor sees the live load that is was designed for that there could be issues with the opening/wall etc.