Concrete slab issues? Need opinions

[DavesGarage]

Hello fellas! This is going to be a long winded post but Ill trim the fat the best I can. I am in the process of building a detached 40' wide by 56' deep garage in my side yard and the concrete was poured about 3 weeks ago by a reputable licensed and bonded company specializing in concrete work. They set the forms and dug the footings in mid to late December and then this area (Phoenix) had a lot of rain on and off for a couple weeks. After new years they decided it was time to pour while there was a window of clear skies for a few days but it was known that 2/3 days after the concrete pour it was going to rain again. I emphasized to these guys that the concrete pad quality was my biggest concern so we agreed on 3500 psi mix, 6" min thickness, #4 rebar at 2' centers, 1 lb of stealth fiber per yard. I do mechanic work and one of my biggest peaves is a crappy shop floor. I intend to have a 12,000 lb car lift in the building and the heaviest vehicle that I will probably ever have in the building is a diesel Excursion, so the floor may be a tad overkill for what Im doing.

Fast forward to last friday, I have a friend that owns a Bobcat doing some dirt work around the site to get ready for a patio pour on Saturday. I opened my side gate and noticed that the south door opening of the garage pad has a decent void of dirt or concrete under it and there is a hairline crack starting to form right over the void. I took a tree branch and stuck it in the hole and it went almost 2 feet under the pad without hitting anything but loose dirt or ABC. I havent parked or driven anything on this concrete yet, nothing but humans walking on it so far. I immediately took some photos and sent them to the owner of the concrete company and told him that I am concerned and he responded that he would send the foreman out. When he arrived several hours later he played it off as "No big deal dude" but when I told him that it wasn't acceptable to leave it that way so what do I do? He said there should have been a footing under the garage door opening but I specifically remember asking him why there wasn't one when they were installing rebar and he said it didn't need one. Now hes throwing words around like "its a design flaw".He said his boss wants more pictures so he took some Friday, I haven't heard back yet. I did have a structural engineer review the plans before submitting them to the City for a permit and I have not yet heard back from him regarding this issue.

I do recall that when their backhoe operator was digging the footings, he did dig the footings under the garage door openings but the foreman told him to fill them back in since the plans didn't call for a footing. I am assuming that they did not pack that soil back down and it has settled after the rain we had. I was told by one of their employees (who was pouring my patio last saturday) that if I was to try to repair that issue myself, I would lose any structural warranty they offer on the pad. If thats the case then I feel like they are going to try to slam me with a repair bill. Going through my photos tonight, I have pictures that show the footings under the garage door openings and also photos that show they were back filled.

What do you guys suggest? I have attached some photos and have plenty more. Thanks in advance and sorry to write a book about this, just concerned for the long term quality of this expensive garage floor.

 

[DavesGarage]

More photos. I have photos that they removed that soil and then put it back, should they be held responsible for correcting this issue?

This one clearly shows that they dug the footing out across the garage door opening and then filled it back in.


Filled in footer. This red square is where the 20' wide 10' tall garage door opening will be. On both sides of the door opening the structural engineer called for steel Simpson Strong walls and the footings for them are tremendous.

 

[matt_i]

I think you have a rock solid piece of evidence that shows they screwed up and attempted to cut a corner rather than repairing the screw-up correctly (via compaction and or flooding).

So what to do now...

....professionally saw out the square in question, dowel the edges, and repour that square
....expend money on lawyers to try to get them to tear out the entire thing and start over
....live with it and ask for a discount to cover "future possibility of repairs"

Based on the rebar used, I think I'd go for the latter. Another question is regarding the "structural warranty"...what are the specifics of this?

 

[GMCGarage]

Looks like a shrinkage crack, it cracked there instead of the saw cuts. The saw cuts should have been deeper, at least 25% of thickness.

That slab would span 8' easily over the voids.

I would ask them to fill the void under the slab, epoxy the crack, and move on. trying to cut it out and repour might make it look even worse.

Not sure what the the engineer says. Why did they dig out the footings if the plans didnt show any?

#4 @ 2'-0" o.c. really doesnt do much for a slab on grade. If you wanted crack control reinforcing, then the bars should be closer to the top of the slab.

 

[pstnbly]

looks like a shrinkage crack, it cracked there instead of the saw cuts. The saw cuts should have been deeper, at least 25% of thickness.

^^^^^this +1

 

[rburke65]

No "concrete guy" here but from all that I have read, saw cuts are figured at 1/4 the slab thickness. Look a little shallow to me. Is the floor 6" there at the void?

 

[chaosracing]

#1 thing to do is nothing until you hear back from the contractor.
#2 Listen to what they say. They poured it, they have the warranty for it.
#3 I agree the cuts should have been deeper.
#4 Since they dug it out for a footer, it should have been compacted rather than just filled in. Really, they should have left it open and poured more concrete in it or compacted stone.

I think your best option at this time is to wait till you hear back from them. But at the very least, they should offer to grout the void and recut the joints.

 

[DavesGarage]

I completely agree with the cut depth but for some reason he didnt run the saw to the edges with a deep cut, the rest of the pad has cuts that are maybe 1.5-2" deep. Is that good enough? Ive also been told that there should always be a saw cut coming from the corners (door openings), is this true as well because they didnt do that.

The floor thickness is between 6-7" thick throughout and that edge has a turn down on it that is supposed to be 8" thick (horizontally). I dont want to disturb anything right there to have a look so they can hand the blame off to me.

I just spoke with the structural engineer and he is baffled why they didnt just leave the dirt out of the footing and order more cement. He said it does need to be fixed by either packing soil under there or setting a form and filling it with a slurry mix. I havent heard anything today but I have a feeling that I know whats going to happen, I owe them their amount due on the 13th and I may not hear a resolution before that date.

 

[n20junkie]

They make void filling foam that works well.

My bigger concern is that there are more voids your not seeing. The site prep seems less that optimal. Lots of disturbed material there.

 

[chaosracing]

I completely agree with the cut depth but for some reason he didnt run the saw to the edges with a deep cut, the rest of the pad has cuts that are maybe 1.5-2" deep. Is that good enough? Ive also been told that there should always be a saw cut coming from the corners (door openings), is this true as well because they didnt do that.

The floor thickness is between 6-7" thick throughout and that edge has a turn down on it that is supposed to be 8" thick (horizontally). I dont want to disturb anything right there to have a look so they can hand the blame off to me.

I just spoke with the structural engineer and he is baffled why they didnt just leave the dirt out of the footing and order more cement. He said it does need to be fixed by either packing soil under there or setting a form and filling it with a slurry mix. I havent heard anything today but I have a feeling that I know whats going to happen, I owe them their amount due on the 13th and I may not hear a resolution before that date.

Don't have them fill with soil, have them use flowable grout (slurry mix as the engineer put it) No matter how tight they pack the soil, it will still settle since they cannot put downward pressure on it. With the grout, it will just flow thru all the holes and gaps. The foam as mentioned above is another option, but the grout is easier to come by and would be done sooner.

As for the saw cuts, they probably used a wheeled saw then and just didnt run it to the edge all the way for some reason since you say its deeper in the pad. As for cuts at doors, unless spec'd out by an engineer, I have never seen cuts specifically for doors. I have been inside hundreds of commercial spaces and warehouses and they just follow a set pattern. Now usually when you have a inside corner on a slab, then there is a cut parallel to one of the sides, usually on the larger part.

 

[DavesGarage]

Chaos, you are correct it was a wheeled saw and he was having issues with the saw handle that locks and unlocks the blade from lifting and dropping. I noticed with that saw he wasn't able to get very close to the curbing so he also had a skil saw and a hand grinder both with diamond bits.
I have tried to reach both the foreman and owner of the company today with no luck. I hope to hear something tomorrow, their pay day is right around the corner and I don't want to pay up before this is repaired.

 

[machsnell]

It is unfortunate that they excavated and the foreman told him to fill it back in. They probably didn't have a jumping Jack or roller and couldn't and didn't compact it back and now that is why you have a void.

I would demand that they use a large air compressor (100 or 185) powered hand tamper like this

https://www.google.com/imgres?imgur...f7RAhXG6yYKHWbKDqkQMwgwKAswCw&iact=mrc&uact=8

I am not sure how far to the interior from the edge you need to compact. It seems like about a foot and a half or so. You could use one of these to compact underneath the slab. I would definitely have this done and possibly want to pour a pier in the center of the area that was backfield improperly. This would act as a caisson if it worked dug down to undisturbed ground.

It is a simple as concrete needs to be resting on solid well compacted subgrade or stone. It was not. There is a void under the slab and this is not acceptable.

There are two options one is to excavate out the loose ground to get to solid undisturbed or compacted soil or stone. Then slappa form up on the outside and pour concrete in to support the slab down to Solid Ground. Or do as I previously mentioned and compact the soil under the slab where you have a void. I would probably for a pier in the middle that's two feet deeper so 12 inch square 18 inch square to feel better about having some support under the entrances to the garage.

Other than redoing the slab these are the only two acceptable fixes. Your contractor knows this and if he tells you otherwise he's lying

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[LXCam]

That void makes no sense. You can see they did a very good job of consolidating the pour as every area you can see in the pictures is very tight with no pocket issues. The only way I could imagine the void occurring would be it was all fluff (no compaction) and somehow it was washed out by the rains. I'd try and bury a shovel in that area and if you can easily dig the soil from under the slab, well it isn't compacted. As for a fix your best bet is to just grout it, packing soil under it will do nothing.

Also why are the footings so washed out, did you have some heavy rains after they dug them? And what kind of soul do you have, sandy or loose and rocky? Did they do any kind of over excavation then compact or just dump base over the natural and compact that? And last but probably not least was a compaction test performed on the natural before they dumped the base.

Good luck

 

[henrysgarage]

If I understand right the drawings did not show any footing at that location? If the contractor did not follow the drawing it is up to him to fix it, however if it was not on the drawings then it is up to the engineer to rectify the situation. In all the garages I have built we always form footings all around the floor.
Ii should be excavated then formed and pined under the area to restore integrity to the area. You would want to fill the void under the floor with a concrete mix to replace the missing fill and then complete the foundation work.

 

[APEowner]

If I understand right the drawings did not show any footing at that location? If the contractor did not follow the drawing it is up to him to fix it, however if it was not on the drawings then it is up to the engineer to rectify the situation.

This. I don't know enough about concrete to comment on the correct fix but if the contractor built to the plans then its not his responsibility to fix it.

 

[Todd.Brock]

This. I don't know enough about concrete to comment on the correct fix but if the contractor built to the plans then its not his responsibility to fix it.

Technically, he may have built to the plans, but if he dug out the footing and just tossed the soil back in with no prep, he is liable, imo.

 

[GMCGarage]

More photos. I have photos that they removed that soil and then put it back, should they be held responsible for correcting this issue?

This one clearly shows that they dug the footing out across the garage door opening and then filled it back in.

Filled in footer. This red square is where the 20' wide 10' tall garage door opening will be. On both sides of the door opening the structural engineer called for steel Simpson Strong walls and the footings for them are tremendous.

So there were some footings called for? Can you upload the engineers plans? Make sure you take his name off though.

 

[APEowner]

Technically, he may have built to the plans, but if he dug out the footing and just tossed the soil back in with no prep, he is liable, imo.

That does muddy the picture a bit. There shouldn't be loose soil under there and there clearly is.

 

[wssix99]

Looks like a shrinkage crack, it cracked there instead of the saw cuts. The saw cuts should have been deeper, at least 25% of thickness.

This is what the crack appears to be. You can find many references to prove that this is the commonly accepted practice for saw cuts.

Here is what I see from the pictures:

First issue: From a placement perspective, it looks like the cut is too shallow. I would also measure the cuts in the field of the slab. I doubt they are the 1.5-2" you mention. (That is not easy to do!) Lot's of people cut corners here and this is an area where having a thicker slab works against you. (You have to go deeper with the cuts.)

Second issue: From a placement perspective, it looks like they didn't use proper rebar chairs and set the bar on top of cut pieces of block. This creates large weak points in the slab which could promote shrinkage cracking.

Third issue: From an engineering perspective, skipping the thickened edge/footer is OK for carrying the load of the building (there are no loads coming down in the door opening) but it interrupts the band of reinforcing steel wraps around the slab. (Think a band wrapping a wine barrel.) This creates a weak point right in the middle of the door opening where a shrinkage crack would be likely to form - just like you are seeing.

Fourth issue: From an engineering perspective, increasing the slab thickness increases the shrinkage tension in the slab. In order to manage the process of specifying a thicker slab, the cross sectional area of the reinforcing steel in the slab needs to increase by a proportional amount. (Either by having the rebar spaced more frequently or by using larger bar.) For example: If you want "up" to a 6" slab from a typical slab/rebar design for a 4" slab, you'd need to increase the rebar by 50% to have the same control over this type of cracking. #4 rebar spaced every 2' is not very much for a 6" slab. This is another area where the thicker slab works against you. (Not only do you need more concrete, but you also need proportionally more steel.)

From what you describe, #1-3 are all decisions/actions made by the contractor. It would be interesting to know more about the design and #4.

I would not worry about the void with regard to the crack. This is a common construction issue around slabs and as long as you grout or compact fill underneath it before you drive over the lip it should be fine. The crack will still be there, though and it will likely increase in length/size as the slab continues to cure and shrink.

I owe them their amount due on the 13th and I may not hear a resolution before that date.

You don't owe them squat until the job is finished according to the drawings and specifications. From the sounds of things, the job isn't there yet...

 

[Musicinabottle]

Enough folks have weighed in and I'm not sure where you're located as that has an effect on this as well, but no matter what, that's a no go under any circumstances. I've done a lot of concrete work in my construction business and some needs a good old fashioned Malaysian style caning in America for that ****.

 

[ssdave]

I wouldn't worry about the crack, that is the nature of concrete. If it really bothers you, epoxy fill it later.

What I would be worried about, and your cause for action in this case is the uncompacted fill where they erroneously excavated for the footing, and subsequently failed to adequately fill and compact it. If it has settled a couple of inches in a few weeks, it is likely to continue to settle more and more for years.

You need a designed fix, and excellent execution on that fix. Being that you have a somewhat substantial slab with rebar to work from, I'd excavate out the old footing area in small sections, and then fill the resulting void with concrete. After one section is done, do another, until all of it is replaced. I would then drill through the slab over the void area, and do a small amount of pressure grouiting to make sure the void space is entirely filled. By doing all this, you're removing the soil that has the potential to settle, and making sure the void is filled fully to the bottom of the slab so no settlement can occur.

If your contractor just wants to tamp some concrete or grout or fill dirt or gravel under the slab, or use expanding foam under it to fill the void that you can see, I'd take the photo's and narrative you presented above to a reputable engineer, and get his recommendations. Take that to your contractor, and ask for that repair. If he refuses, file a small claims court case to get the remedy that your engineer recommends. I think with the evidence you have, you'd win without any question. What I would not do is let the contractor talk you into trying a lesser remedy, with the thought that he warranties his work, so you have nothing to worry about. What you will have to worry about is getting him to honor the warranty, hoping he is still in business, identifying an adequate fix once you get him to warranty it, proving that future problems are related to his work, and all the hassle of a failure in the first place. If he can kick the problem down the road a few months or years, your chances of getting him to do anything become vanishingly small. Much better to fix it correctly now, and avoid any problem.

For those saying that with #4 bar 24" o.c. you don't have to worry about settlement; not true at all. Any void under concrete equals failure. It's just a matter of time. You will have to worry about settlement, and deal with the consequences in the future if you don't fix it right now. Not only do you have to deal with the void you see now, but also the future voids that will develop as the fill continues to settle if you don't replace it with something that will not settle.

Adding a postscript to my post: I looked at your pictures closer and read that you have large, correctly designed footing pads on each side of the void. I think you can reasonably excavate all the loose soil from between the pillars, and do the repair all at once. Time is of essence in this; the sooner you repair the support under the slab, the less sagging and damage will occur to it.

 

[joes169]

Just curious, but WHEN did they cut the control joints in relation to finishing the slab. Personally, I think they're joint spacing and depth are adequate from the pictures and your explanation. I have a feeling they didn't cut them soon enough or the rate that the slab was curing. I think the shrinkage crack is independent of the settling.

As for the void, as others have stated, the loose fill needs ot be taken out and replaced. My choice would be flowable fill/lean concrete, with a form built at an angle to the side of the slab and as high as the slab, to promote head pressure. A small concrete ******** would help fill the area.

Best of luck, it's unfortunate they had to skip such a simple step to cause this, as the rest of the slab looks relatively well done.

 

[dadsEH]

There are only 2 types of concrete slab........

 

[wssix99]

Ive also been told that there should always be a saw cut coming from the corners (door openings), is this true as well because they didnt do that.

This would be a method for dealing with "reentrant corners", which would only happen when the slab is poured after the footings and foundation walls:

Since you have a monolithic pour, you don't have this problem or the associated diagonal cracking. (As chaosracing pointed out, there are also better ways of addressing this problem when it does come up.)

 

[joes169]

Second issue: From a placement perspective, it looks like they didn't use proper rebar chairs and set the bar on top of cut pieces of block. This creates large weak points in the slab which could promote shrinkage cracking.

Not trying to start a war, but ACI allows for pre-cast concrete chairs as far as I remember.

 

[ConcreteAce]

@ssdave about your comment "Any void under concrete equals failure. It's just a matter of time."
Concrete void forming is a common practice. You actually pour on top of cardboard. It rots away leaving a void under the slab.

 

[wssix99]

Not trying to start a war, but ACI allows for pre-cast concrete chairs as far as I remember.

Thanks. I didn't mean to imply that the chairs would need to be made out of any particular material but that using blocks or bricks would not allow the concrete to "flow through" like a purpose-built chair. This could create a slight weakness with regard to shrinkage cracking.

If the crack is not lined up with a piece of rebar (and hence these blocks/bricks) then this item can be discounted. It's probably the least impactful factor here but it's another thing to pile on if this gets to the point of calling out the contractor.

(I'll let lakeroadster elaborate on the consequences of taking contractors to the mat in threads...)

 

[ssdave]

@ssdave about your comment "Any void under concrete equals failure. It's just a matter of time."
Concrete void forming is a common practice. You actually pour on top of cardboard. It rots away leaving a void under the slab.

I am very familiar with the design of free spanning concrete slabs using cardboard void forms. However, they are not your typical garage floor slab like the OP pictured. They are grade beam designs, carefully designed with specific reinforcement. I use them for special situations, like a slab on grade ramp or sidewalk built on a site with freeze/thaw and drainage problems or expansive soils, where I don't want anything under the slab to heave it.

Don't use that type of design to justify poor practice in a standard slab; it is just confusing what is a very clear quality of construction issue.

 

[DavesGarage]

Thanks for all the great info guys! I'll try to answer all the questions:
-we did get a TON of rain here in Phoenix in December and early January. A day or two before the pour they brought in two truck loads of ABC, smoothed it over with a gannon to get to to 4" and then ran a plate compactor for the better part of a day. No soil compaction testing was done and I am aware that is my baby if it becomes an issue. The soil in my yard was really rich dirt with minimal clay, not a lot of granite as I thought it would be since I'm not far from some mountains.
-pad was cut about 26/28 hours after the pour
-the chairs they used came on a pallet and they were small solid blocks of cinder block with a tie wire molded into them
-I will take some measurements in the center of the pad for the saw cut depth but I believe it is 1.5-2" deep
-I spoke with the engineer about this and sent him photos. He said the turn down he had specified in the plans was plenty good for this building. I believe him since he went with Simpson steel strong walls on both sides of the garage door and 2x6 studs 12" on center. He went overkill on most everything. His suggestion was that they need to fix it with slurry or flow able cement with a form to hold it up high under the pad.

I've been trying to reach the concrete guys since Friday afternoon and they just responded tonight and said they will be over tomorrow afternoon to fix it. I immediately texted back "what are your plans for the repair?"....no response. This company has been around for several years and apparently do a lot of work around town. The owner used to own a much larger concrete company but he was diagnosed with cancer (not sure what kind) and then I believe he sold the business. A few years later he was cancer free and started this current concrete company, so I believe he will be around for a while and looking to keep a good name. Now it's just me and the foreman who I will have to hash this out with over how cheap he can try to do the repairs.

 

[ms fowler]

I would tend to listen to ssdave's advice. There is no load (other than the weight of the concrete) in the door openings. The crack is likely due to shrinkage and not associated with the void. The Contractor screwed up by not compacting the soil after he excavated for a non-existent footing. He also screwed up by the lack of sufficient depth in the saw cuts and the delay before he cut them. Typically they are cut as soon as the finishers have finished troweling and the surface can be walked on without marking it up.

 

[wssix99]

Don't use that type of design to justify poor practice in a standard slab; it is just confusing what is a very clear quality of construction issue.

I believe this method is called #AltConstruction

 

[wssix99]

I immediately texted back "what are your plans for the repair?"....no response.

The only thing they can do is sweep dust in the crack, hope you can't see the crack afterwards, and hope that they get your check before you get really mad.

Don't give them your final payment, whatever you do. That is your only leverage to get something to happen.

Having them rip up the slab and do it right will cause them to loose money and will result in unhappy discussions. I think you have a strong case to request that and someone told me these types of places are fine spots to start in negotiations...

Repairing what you have can be done, but you'll see that repair unless you put a finish on top of the floor. Such a repair should not be done until the floor is fully cured - and the concrete stops shrinking/the crack stops growing.

 

[DavesGarage]

Update,
Foreman showed up today around 10am and I had some remodel buddies here to ask questions in case I overlooked a detail. The foreman asked me who they were and I said they were going to be working on the structure. Without any questions asked, he said his guys were going to dig out the loose soil under the pad, pin the existing pad, set forms, fill with cement and then use the ******** to work out any air pockets. He said he was also planning to do the other narrow garage door right next to it which has a hairline crack same as this opening. They didnt remove that soil for the footing under the narrow door before the pour but I dont think I should stop them from doing it. Im afraid to ask him but he didnt mention a cost.

In case its not clear, the face of my garage is 40 foot wide. Left to right there is a 2.5' wall (Simpson steel strong wall inside), 10' tall x 20' wide garage door, 3 foot wall (with another Simpson steel strong wall inside), 14' tall x 12' wide garage door, 2.5' wall (without a Simpson steel strong wall). The footings for the steel walls were big enough to park a Volkswagen inside them and they continue several feet past each side of the steel walls.

 

[chaosracing]

I would let them do this repair as stated. They are going above and beyond to cover their butts later on down the road.

 

[ssdave]

Good response from them. I'd drill a hole through the slab to release air, otherwise it will be really hard to get the cavity totally filled. I'd also form the front up higher than the bottom of the slab, and pool up the concrete there to put some pressure on it. Vibrate it well to allow the concrete to move under the slab and fill all the air space, displacing air out the hole in the slab as it goes. Then, grout the hole full after all the air is out.

 

[wssix99]

I'm afraid to ask him but he didnt mention a cost.

It should cost you $0 and if you withhold your final payment until the fix is completed to your satisfaction, (and make them sign a lien waiver when you pay them!!!) you can make sure things stay that way.

Did you check the depth of your saw cuts? It isn't too late for shallow cuts to still cause you problems, nor is it too late to go back and re-cut ones that are too shallow.

 

[DavesGarage]

I did check, they are about 1.5". I have a friend with the same saw they used and he said he would let me use it for the day. Should I take them deeper? Pad is a month old in a couple days.

 

[machsnell]

1.5 on 6 inch slab is fine. What is spacing in control joints?

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[DavesGarage]

Funny you ask, they put in the spec that it would be 10'x10' squares and I knew that was a tad larger than I wanted to do so when the day came to cut I told him that you quoted 10x10 squares but since there's an 8" curb and you aren't cutting at the base of the curb I want to make the squares smaller. It turned into a big debate and he finally realized I was right. He counted how many NS cuts and then EW passes were in the scope rather than 10x10 squares so I did the math and it came out to 7'9" squares. I helped him mark the lines and then chalk line it so there weren't any misunderstandings.

I emailed the structural engineer tonight with the photos and also asked him if there was anything I should require them to do while they dig out the loose soil, pin the pad, set forms up higher than the base of the pad and then fill with cement. I don't know if they are pinning the bottom of the pad or the face but I'll find out later today. Should they use the same concrete mix as the pad (3500 psi, stealth fiber)? Should they come out a certain distance from the pad with the concrete?

 

[wssix99]

With 8' control joint spacing, you shouldn't need any reinforcement in the slab to control cracks at all. Given the consistency of these two cracks and their placement in the middle of the door openings, it looks like the likely cause is the missing footer (and band of rebar that would be inside) under the doorways.

^ Pinning the slabs should take care of those cracks spreading. Hopefully, this will move the stresses to the adjacent control joints so any continued cracking will happen there. You might also make those adjacent cuts just a tad bit deeper near the cracks to encourage this. (So cracks don't form between the pins and the control joints.)

I would expect they would use some sort of epoxy or synthetic product to set the pins. (Definitely not regular concrete or mortar.)