Who did the design work? I keep asking, because if the contractor built ''as designed'', you have no recourse against him either. And if the site conditions demanded alterations, you don't have a lot of recourse then either. It was inspected and approved.

Sophie and renovator 8, in his drawings, he has the footing and 3 CMU blocks, then whatever else goes under floors and in walls (has some writing I can't read, but assuming the inspectors know what it means.) But instead, he left out the blocks and put the sill plate directly on the footing. I was thinking that he just made the wall really tall, but are you saying maybe the sill plate is directly on the footing and then there's the floor joists and the subfloor and that's it? And that's why he left out the blocks??? If so, oh crap! We were thinking he left them out just because and that there was room in between for him to still put something... Ugh!!!

The inspector should have nothing to do with your contract with the builder but if he disapproves the work it will help you enforce your contract with the builder so get whatever he says in writing.

You have to understand that what was poured is a foundation and a footer. With a required foundation depth of only 12"below grade there would be no need for a separate footing and stem wall foundation. What is apparently missing is an "upturn" that would raise the exterior wall higher than the bottom of the joists in order to protect the framing from a high finish grade (i.e. the house is build to low for the site). This is often seen at garage foundations but not a house. If that upturn or curb was shown in the permit drawing you can probably make the builder correct the mistake. What is required is supporting the wall, cutting some of the bottom off and pouring a concrete curb or installing CMU (concrete block) whatever is easier. It might be done in short sections. Ask the builder what he proposes before telling him what to do. You can always do that after getting his written proposal. Do everything in writing even if it is by email.

Raise the addition or lower the soil in the yard. One or the other. Adding block on top of what's ther raises the addition. Doing the dirtwork fixes what sounds like is an existing problem that already needs to be addressed anyway. You are required to have the first 10' of soil around any foundation graded to 1/4" per foot away from the home. Put your level on it. If it doesn't comply, it will need to be addressed regardless of any other issue.

A project must comply with the building code regardless of what was passed earlier in error. Inspectors are essentially faultless.

If there are AC ducts in the crawl space, the cooling and air leakage should be adequate ventilation to meet modern code standards so its probably not a major concern.

The concrete slab in the crawl space will probably be enough of a vapor barrier and its probably too late to worry about it anyhow. Ventilation is more important.

I keep thinking it needs a foundation wall, but it is the "upturn wall" that I know it needs and that he didn't include. I'm going to attach a pic of the drawings (it's a very bad pic, the blurriest part of all of his drawings... but it shows the footer and 3 CMU blocks...) shouldn't the inspector have at least questioned him on it? I'm thinking the inspector is going to talk to him about the project now.

Our contractor has said he can cut off the side of the concrete so that the water slides straight down, but honestly I don't trust that it will even be straight (based on the 1st pic in my 1st post, he did some cutting there b/c he said the footing was too big... it's too jagged...) I want to get advice from other contractors. I have one contractor coming this week, will have others. Want to at least have advice from other contractors about what to do. I'm still not sure I want him to do the correction... renovator8, do you happen to have a pic of what you're talking about with " supporting the wall, cutting some of the bottom off and pouring a concrete curb or installing CMU (concrete block) whatever is easier. It might be done in short sections."?

So... in order to keep the addition at the same level, should we have excavated from the beginning and either done a slap or crawl space? He said he had an engineer and architect on staff that he consulted (all lies, I'm assuming now) and since there is an existing stone patio on top of a cement patio that they could just cut out part of the stone/cement and put down the footer and blocks and have the crawl space. Initially it was going to be a space with ventilation and a door, but he decided to go ahead and encapsulate it, which the inspector and supervisor approved. He told me that instead of doing the block he was just going to do all cement (I was assuming this meant in place of the block, more sturdy, not that it meant he was totally getting rid of it...) I'm assuming he's the professional and of course the city inspectors will make sure it's safe... Ugh! Now that I have questioned where the water is going to run, I figure out that he totally got rid of the blocks b/c I guess he figured out they wouldn't fit! (He didn't mention that part!)

There is nothing essentially wrong with the foundation as it exists. It matches the level of the existing space and seems to be properly constructed and inspected per your comments. Given the other shortcuts that were done on the job, such as leaving all of that mess in place to build on top of, Raising the addition should probably be avoided as it requires a higher skill level and more effort that has been exhibited so far.

I'm curious as to the before and after pictures that you may have of the space before the addition was placed on it.

live wire oak, here are some before pics (not great, but the first one is at thanksgiving showing the concrete and the house, only about 21" from the inside floor to the ground level... now that I'm doing all this research, I realize that we should have dug it out, but I was leaving it up to the "professionals" (I now use this term loosely...) The only thing I see wrong with the foundation is that the wood part of the sole/frame/wall/plywood is sitting directly on the footer... seems like there needs to be at least a little bit of upturn or there will be water rot? These are some before pics and pics as the footer is being poured and some after pics are above...

I'm curious as to whether or not he used pressure treated lumber to frame from the footing. If so, this could be a perfectly acceptable installation with the right details.

You keep saying that the foundation is wrong, but it's really not ''wrong'' as if it were built to plan,you'd have steps into the addition because of that slope that you see so clearly in the photo with the fence. The problem is the overall design did not take into account the hill behind the house, and the fact that water runs downhill. Which goes back to the designer of the project.

Here's one more after...

99% sure he did not use pressure treated lumber, though I will ask. His plans showed him putting 3 CMU blocks on top of the footer, which would have made me feel better about the water not sitting on the wood for the frame... he said we didn't need to hire a separate engineer or architect, he would consult with their "in house" one (total lie I'm sure), at first said would do a crawl space with footer and blocks with door into crawl, then said was changing it to all cement (thought it meant changing to all cement in place of the blocks, not just getting rid of the blocks...he must have realized that the height was lower than he thought...) Didn't explain any of that to us. And it slipped by the city inspectors as well... He should have said "I thought we could do it this way, but we need to change it..." We thought we needed to dig out the stone patio, but he was the one saying we don't need to do that...

A footer + 3 CMU blocks sounds like a crawl space design. That would have entailed digging down the entire space by about 2' (i.e., removing the patio), then footers around the perimeter below that. Pour the footers, add 3 blocks, then frame from there. Then presumably you'd put access to the addition crawlspace from the basement. At least then you'd have access to the mechanicals from below.

But you'd still have the top of the CMU crawlspace at the level where the top of the footer is now. To have the siding farther away, you'd need to lower the level of the soil all around it.

You've got two issues/problems here.

Green Designs, what do you mean by we'd "have steps into the addition because of that slope that you see so clearly in the photo with the fence."? It might be hard to see in the picture, but the hill doesn't even start for at least 15 feet from the far side of the addition and it goes down about 8 feet... I didn't think that was an issue. Definitely a design issue...

So, regrade the lot so that the soil is lower at the addition. Simple,really.

Green Designs and Sophie, we will regrade the lot so that all around it has 6 inches of concrete showing, but still has 12 inches underground (assuming he really did pour 18 inches...will verify...) and slope down correctly.

But the other issue we're trying to fix is that the frame/plywood is sitting flat on the footer, so any rain will just sit there and probably at some point rot the wood? (at least that's my worry...) Would be interested renovator8, to hear more about what you were talking about with " supporting the wall, cutting some of the bottom off and pouring a concrete curb or installing CMU (concrete block) whatever is easier. It might be done in short sections."? Originally I was thinking we could "just" go in and add some block or concrete, but I think the floor joists are pretty close to the bottom, maybe a couple inches from the ground? (I've emailed the contractor asking how much space is between the joists and the stone below...he knows we're contacting someone to find out what we want done about the foundation.) Had someone look at it today (grandfather of a neighbor, contractor for 40+ years),he thought we might be able to cut into the concrete footer to make it smooth to look like the foundation on the rest of our house, so the rain would run down the siding and right onto the ground, like the rest of the house...

Slab on grade homes are ALL built with the sill sitting on the footer. It's not an issue. Not if the proper building practices were followed with the sill seal and housewrap.

I don't think that the sill sitting on the footer is the problem the OP is trying to convey. It is that the footer extends past the wall and creates a ledge. You essentially have a brick ledge there, which will hold water and let it into the house unless you flash it somehow. I would think there are many easy ways to deal with that. I wouldn't cut into the footer unless that was the only way.

I think I understand this GreenDesigns. For slab on grade, the sill is sitting directly on the footer, but the siding is flush or really in front of the concrete, right? So the water will run down the siding and drop on the ground?

For you experts Green Designs, renovator8, sophie, live wire, Joseph and WeedyAcres, Our siding is sitting in the middle of the footer. Can you look at the middle picture in my first post? When he takes out the wood forms, there will still be about 3 inches of cement in front of the siding, which has the framing/plywood/foam/wrap behind it. Should he have placed it on the edge of the concrete so that rain would roll right off the siding? And can this still be done by "sawing off" the right amount of concrete?

Yes, that is what I mean bry911! Sorry I was having trouble conveying that :) I'm definitely not a builder, though I feel like I'm getting schooled in it pretty quickly! In our "layman's" terms, we just know that water might sit there and that worries us!

The small extension that picture 3 shows isn't a problem if the soil is graded away properly, the house has the proper house wrap, and there is the foam sill seal caulked to the foundation between it and the rim joist or sole plate. Millions of houses have sloppy construction details like that with no ill effects if the actual primary problem is addressed. Which is the lot grading. It's not ''ideal'', no. Neither was building on top of a patio.

If you slapped 3 blocks on top of what's there, the height of the addition gets raised 2'. The ''designer'' did not plan the addition to account for the higher grade behind the house vs the finished floor height of the existing home. That is 100% the culprit here.

mammatoprincess:

Does you job look anything like 403.1(3)? If not, what's the differences?

sophie, the grade next to the house is the same at the addition and in front of the house and it is lower behind the house and on the other side of the house, nothing is higher (we have a walk out basement on the other side.) When we say built on the patio, the patio was cut out where the cement is. He cut out enough to be able to lay the forms for the footer. We met with probably 20 contracters, designers and design/build people. We heard from people that "some contractors are great and can do the work without hiring an actual architect"... wishing we had actually hired an architect, but hindsight is 20/20... When we went with our contractor, who is licensed and recommended by 2 people we know, including one living in a 600K+ house who he's done multiple projects for and I couldn't see anything negative online and really sounded like he knew what he was talking about and had lots of great ideas for in the house (we gutted our kitchen, put the laundry in the addition, updated our powder, put a mudroom where the old laundry was...), "consulted with his architect and engineer" to make sure the roofline is perfect and for the beam they put in (which both look great, thank goodness! Originally it was a crawl space with 3 CMU blocks with a door to the back or side of the addition, then he said they discussed it and were going to go with all cement instead of the blocks. When I asked why, he said it was a "better application"...he likes to use this term I've come to realize. I figured it's probably even stronger! Once the walls went up, I realized there's no access and asked about it and he said that it was how it had to be. (should have stopped there...) Didn't realize until now (too late) about the possible problem with the outside wall... maybe it isn't problem, but we're worried about water and he's even talking about "solutions" with us since we're worried about water. Will have contractors look at it in person. Are there "foundation experts" other than ones who deal with sealing basement foundations?

Joseph, it's not exactly like 403.1(3), but thanks for the link, I'm looking at them to see if I can see what it looks like...

Sophie, do you just mean the dirt should be put up over the conrete?

Joseph, the closest it looks like is 403.1(1) the one with basement or crawl space with spread footing except it doesn't have the concrete wall, it just has the wood/framing wall and 6" of the footer is above ground with 12" of it below ground. So it's approx in the middle (I think.) It might be like some people have said, that it's like one on a slab, except that if there's any penetration that instead of going into the house where someone would see it, it might go into our "encapsulated inaccessible crawl space"... ugh! Will check in later, headed out to run some errands :)

Not sure what code applies in your area. The following are outtakes from
IRC 2012. Pulled a few based off of your situation for your reference. Some of these may or may not apply.

R401.3 Drainage.

Surface drainage shall be diverted to a storm sewer conveyance or other approved
point of collection that does not create a hazard. Lots shall be graded
to drain surface water away from foundation walls. The grade shall fall a
minimum of 6 inches (152 mm) within the first 10 feet (3048 mm).


R404.1.6 Height above finished grade.

Concrete and masonry foundation walls shall extend above the finished grade
adjacent to the foundation at all points a minimum of 4 inches (102 mm) where
masonry veneer is used and a minimum of 6 inches (152 mm) elsewhere.

R317.1 Location required.

Protection of wood and wood based products from decay shall be provided
in the following locations by the use of naturally durable wood or wood that is
preservative-treated in accordance with AWPA U1 for the species, product, preservative
and end use. Preservatives shall be listed in Section 4 of AWPA U1.


2. All wood framing members that rest on concrete or masonry exterior foundation
walls and are less than 8 inches (203 mm) from the exposed ground.3. Sills and sleepers on a concrete or masonry slab that is in direct contact with
the ground unless separated from such slab by an impervious moisture barrier.5. Wood siding, sheathing and wall framing on the exterior of a building having
a clearance of less than 6 inches (152 mm) from the ground or less than 2 inches
(51 mm) measured vertically from concrete steps, porch slabs, patio slabs, and similar
horizontal surfaces exposed to the weather.R506.2.3 Vapor retarder.

A 6-mil (0.006 inch; 152 µm) polyethylene or approved vapor retarder with
joints lapped not less than 6 inches (152 mm) shall be placed between the concrete
floor slab and the base course or the prepared subgrade where no base course exists.


Exception: The vapor retarder may be omitted:1. From garages, utility buildings and other unheated accessory structures.4. Where approved by the building official, based on local site conditions.@@@@@@@@@@@@
My comments?
Drawings should have been approved by the local AHJ for the permit to have been issued.

The structure should have been built based of of the drawings. It appears that it was not.

I
could see the footings being approved "as is", but the AHJ should have
caught the wood-concrete clearance issues and the pressure treated
versus non-PT issue during the framing inspection.

In general, there's no recourse against the AHJ for missing something during an inspection. No easy recourse, I should add.

Remediation? If grading won't give you proper clearance from wood-to-soil, someone mentioned cutting out the lower portion of the wall and adding a course or two of CMU. That can be done.

If regrading will solve the soil clearance issue, then as you have asked, the outside 90-degree corner on the footing can be chamfered and flashed to protect the sole plate and framed wall from pooling water. Might even be able to forgo cutting the concrete and just add a built-out water table trim board type of detail with appropriate flashing.

water table sample photos

Will still work on the regrading, and will look into the 90 degree corner on the footing to protect the sole plate and LOVE the water table trim board/flashing idea too, thanks MONGO CT! Thanks everyone for all your suggestions! We're meeting with several contractors this week to see what can be done to remedy the situation short of tearing it down and starting over. Thanks so much!

And Mongo, drawings were done and approved and he built it without the blocks and it was missed, until now:(

renovator8, I never did say that the original house has a walkout basement, though the part where the addition is the ground level, the walk out is on the other side of the house. The house is I guess a basement foundation with siding (that just looks like a wall with siding going straight down...

Will post more details later, looking at several options on the foundation part for the outside, most likely doing some kind of ventilation from the inside for the crawl space... when I say "inaccessible", I mean no one can crawl in it. We ( a contractor) are going to open it up from the basement and it should be about 12-14" in height (including floor joists)... but at least can get some kind of ventilation in there and can at least know if there's an issue. (would still have to tear up hardwoods to get to it, but at least we would know...) thanks for all the suggestions!

Talked to the Chief Building Official at the city and said it failed the (I thought he said sheathing) inspection twice and passed on the third time, but shouldn't have. I showed him the picture and he said it shouldn't have passed. He's coming to the house Wed to look at it, said it won't pass final inspection as it is. I guess that's good, but still need a solution. I told him about the original plans having the CMU blocks in it... he said they might be able to (sorry for the "ignorant" terms... put some CMU blocks (smaller ones) against the cement and wood, use a membrane (the black stuff like they use behind brick) and then siding, so it will look better and have the waterproofing... will definitely talk to contractors and get a "picture" of this...

The photos are difficult to understand because the important issues are covered up by the siding. Without a photo of the unsheathed wall only a detail drawing can explain this condition, Tell me what should be changed on this drawing for each of the 3 sides of the addition. It would also help to see the original permit drawing.

The drawing looks dead on, I just don't know the exact measurements of the space between stone and joists, he needs to answer that, if he actually knows... I am making contacts with different companies now that I think will be able to help us, will see what they say... will check out these different waterproofing solutions too. (I've called the waterproofing companies and am scheduling appt's with them or a couple have referred me to someone else...) Not sure if it's different in each state, but here in GA, he filed the permit, so he schedules the inspections and he is the one who failed inspections. (found out he failed quite a few... and the inspection sheets are left at the house, but I've never seen them, so the building chief said "he must be picking them up so you don't see them"...) I will try to scan, or at least take a pic of the plans...

Is the grade level in the drawing correct? Is it really at the top of the foundation with no concrete upturn behind the siding? My drawing is not complete without that information, Is the grade different on the 3 sides?

When the builder fails an inspection he is failing as your agent. Ultimately you are responsible to the city for correcting the work and you do that by enforcing your contract with the builder that requires him to correct deficient non code compliant work. The city can only threaten to suspend his license if there is a complaint which might be enough to force him to meet his obligation to you. But first find a solution, then deal with what it will take to get the builder to do it.

It really is just the footer and then no upturn. The siding is sitting directly on the footer, which might not be a problem if it were at the edge, but it is sitting a few inches in, so water can sit there. (Will pull up the siding to look at what it looks like under there, but afraid to do so until we're ready to cover it up again :) Maybe the inspector will do that tomorrow...

The grade at the moment looks pushed up to the house on one side, but it's just the way the dirt got moved around, it's really the same on all 3 sides and we'll make sure it's the same/correct when we're done. We should be able to keep it at 6 inches concrete above grade and still slope it down, with water being able to slope down to the area behind our house that is woods and eventually the creek.

The builder failed past inspections and corrected them. From talking to the city, he even failed the inspection (for having the siding directly on the cement footer), but passed it the 3rd time, though he shouldn't have passed, according to the city... They do feel bad, though have no liability, for not failing it at the time, because now the project is near completion. The chief inspector is meeting me out here tomorrow to look at it and help figure out possible solutions as well. We are in the process of figuring out solutions, which is why I'm so grateful to you and others for getting us to realize there are things to be done. Over the next week or so, we'll hopefully get it figured out. (Of course I leave for vacation next Tues for almost 2 weeks :) Thanks so much!

This is one possibility that would not be difficult to build and might look OK. To make it look better would probably require an Azek covering that would look like a traditional "water table" but it would be expensive.

I think its important to use Grace's WB (water based) Primer under the Vycor since it greatly increases adhesion especially on concrete.

Don't substitue other brands for Grace Construction Products, they are poor imitations. Grace Vycor Plus flexible flashing is the same as Grace Ice & Water Shield roof flashing without the non-slip surface. An advantage of Vycor Plus is that it can can be bought in widths of 4, 5, 8, 9, 12 and 18 inches with a ripcord that allows the quick removal of half of the backing paper making it much easier to install. When this stuff touches the primer it is difficult to remove. It is polyethylene on pressure sensitive modified bitumen (rubberized asphalt) so always install it in warm weather and with a roller made for installing flexible self-adhering flashing. If installed properly with primer, water will never penetrate the detail and it is self-sealing around nails but it must be protected from UV radiation from the sun.

Do you live anywhere that it freezes? Your footer needs to be below the frost line in your area otherwise you risk getting frost heave. Where I live, the frost line is 4 feet. Yea.

Its in GA where the minimum depth is 12 inches.

Renovator8, as much as I respct you (and that's a lot) I take exception to the wood sandwich you have drawn, it's an invitation to holding moisture and fostering rot/termites. IOW, I would add thin spacers of an inert composite material between the layers, or eliminate the middle layer entirely, substitute 1.5" spacers.
Casey

Sorry Casey, I like renovator8's drawing just fine. Ain't no water gettin' in there.

The added wood won't rot any faster than the sill plate (I hope its PT) but i agree its not an ideal material. Cellular PVC would be best but I didn't think anyone would be willing to pay for it.

If it were my house, I would remove the vinyl siding, add a 3" flare to the bottom 2 ft of the sheathing and shingle the addition and probably the house. I'll shingle anything that isn't moving.

"Ain't no water gettin' in there."
-last words of the captain of the titanic as well.
No-one _expects_ the Spanish Inquisition. (Monty Python reference)
If water wicks up or gets wet in a flood or any cause, it is held for a long time inside that sandwich, that was my only point. In at-grade situations, it's always best to eliminate of mitigate these water traps.
That is all, signing off.
Casey

I showed the inspector the drawing and he said he wouldn't use wood, but would use a material like stone, brick or block. It's not vinyl, it's hardiplank. I think it needs to continue to be hardiplank, though we could do some kind of water table. We had a pretty meticulous contractor come out today, he suggested a metal flashing (in a good color...) would use landscaping to disguise it, after sawing part of the concrete to make it more uniform. He also is addressing the underside of the addition, suggesting us tearing out the hardwoods to get underneath to put down a vapor barrier and keeping ventilation in there...

Whatever is proposed should be drawn to scale for your approval. The building inspector must accept the design but you must accept it first. This isn't really a building code issue. Settling for oral descriptions from builders is what got you in this mess in the first place. Make them draw the detail with their company name on it.

Masonry should be used below the top of the foundation line not above it. Unit masonry is not only difficult to attach to wood framing, it expands and contracts differently and it is difficult to get self-adhering flashings to adhere to it although primers can help. Unit masonry would consist of many individual pieces mortared together I assume. Whatever is used must be continuous for the full length of each wall.

There is nothing wrong with continuous PT wood as a flashing nailer attached to wood framing. The floor framing is already sitting on a piece of PT wood anchored to the concrete foundation as required by the building code. If you believe PT wood will rot and can afford cellular PVC (Azek, etc.) then use it.

Here is how this should be done: Flashing consists of base flashing and counter flashing. The "base" flashing should be Grace Vycor Plus on top of Grace's Perm-A-Barrier WB Primer and it should be rolled well with a professional roller. Not only will water never get behind Vycor in WB Primer, you would never be able to separate it from the wood or concrete without pulling it apart. I've used it on hospitals and college dormitories with the excellent advice of WR Grace.

What goes over the base flashing is called "counter" flashing that essentially protects the Vycor from the weather and UV rays and hopefully improves the appearance of the detail. Counter flashing is usually some form of copper or stainless steel on commercial projects but for a residence it can be powder-coated aluminum. But aluminum gives up its electrons easily and cannot withstand constant contact with water so it must always be sloped never flat and aluminum should never be in contact with concrete or masonry.

The possibilities for using the above flashing system are endless. I have included 2 details to give you some ideas. Use PVC instead of PT wood if you like. Good luck with it.

Whatever is proposed, insist that there be flexible self-adhered (Vycor Plus) flashing that starts under the house wrap and ends below the top of the concrete. If that doesn't happen, water will inevitably be drawn into the crack between the concrete and the framing. Where the flexible flashing adheres to masonry, WB primer must be used. This is an easy detail but there are a surprising number of ways it can be messed up. A few of them have already been recommended to you.

This detail would be the best looking if the concrete cut can be made uniformly. The optional metal flashing could hide any roughness.

As for the space under the floor: the building code would have required joists within 18" of the ground to be pressure treated. I find it hard to believe that both the builder and the inspector didn't respect that requirement. If there is a slab-on-grade the vapor from the ground should be greatly reduced but a lot depends on the soil. Impervious clay, good surface drainage and a low water table would be good.

You could try using a small fan to push conditioned air into the cavity. Find an out of the way place for that air to return into the house. Monitor the moisture of that air and if it is high or has a musty odor then tear up the floor and add a vapor barrier.

There is stone and cement in the space under the addition, so they (contractor and builder) consider this different. I'm thinking it may not be pressure treated since he didn't respond to the email... how much more expensive is pressure treated? Will show these drawings to the contractor we're most likely going to use for the "modification", thanks so much!

The IRC, if applicable, is not specific about the definition of "exposed ground". I interpret it to mean any vapor permeable surface on the ground but it doesn't say that and a slab might retard vapor somewhat.

But the code also requires an unvented crawl space to have mechanical ventilation and an 18x24 access opening, so the builder owes you that in any case. The inspector owes you an explanation for why the work passed inspection not that he owes you any more than that and you shouldn't put him on the spot more than necessary to motivate him to tell the contractor he has violated the building code. the usual problem with those situations is who the inspector's relatives and friends are.

I have shown some of the relevant code requirements in bold below. Italics means a term is defined elsewhere in the code.

2012 International Residential Code:

SECTION R317 PROTECTION OF WOOD AND WOOD BASED PRODUCTS AGAINST DECAY

R317.1 Location required.
Protection of wood and wood based products from decay shall be provided in the following locations by the use of naturally durable wood or wood that is preservative-treated in accordance with AWPA U1 for the species, product, preservative and end use. Preservatives shall be listed in Section 4 of AWPA U1.

1. Wood joists or the bottom of a wood structural floor when closer than 18 inches (457 mm) or wood girders when closer than 12 inches (305 mm) to the exposed ground in crawl spaces or unexcavated area located within the periphery of the building foundation.

2. All wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.

3. Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious moisture barrier

4. The ends of wood girders entering exterior masonry or concrete walls having clearances of less than 1/2 inch (12.7 mm) on tops, sides and ends.

5. Wood siding, sheathing and wall framing on the exterior of a building having a clearance of less than 6 inches (152 mm) from the ground or less than 2 inches (51 mm) measured vertically from concrete steps, porch slabs, patio slabs, and similar horizontal surfaces exposed to the weather.

6. Wood structural members supporting moisture-permeable floors or roofs that are exposed to the weather, such as concrete or masonry slabs, unless separated from such floors or roofs by an impervious moisture barrier.

7. Wood furring strips or other wood framing members attached directly to the interior of exterior masonry walls or concrete walls below grade except where an approved vapor retarder is applied between the wall and the furring strips or framing members.

___________________

R408.3 Unvented crawl space. Ventilation openings in under-floor spaces specified in Sections R408.1 and R408.2 shall not be required where:

1. Exposed earth is covered with a continuous Class I vapor retarder. Joints of the vapor retarder shall overlap by 6 inches (152 mm) and shall be sealed or taped. The edges of the vapor retarder shall extend at least 6 inches (152 mm) up the stem wall and shall be attached and sealed to the stem wall; and

2. One of the following is provided for the under-floor space:

2.1. Continuously operated mechanical exhaust ventilation at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7m2) of crawlspace floor area, including an air pathway to the common area (such as a duct or transfer grille), and perimeter walls insulated in accordance with Section N1102.2.9

2.2. Conditioned air supply sized to deliver at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7 m2) of under-floor area, including a return air pathway to the common area (such as a duct or transfer grille), and perimeter walls insulated in accordance with Section N1102.2.9

2.3. Plenum in existing structures complying with Section M1601.5, if under-floor space is used as a plenum.

R408.4 Access. Access shall be provided to all under-floor spaces. Access openings through the floor shall be a minimum of 18 inches by 24 inches (457 mm by 610 mm). Openings through a perimeter wall shall be not less than 16 inches by 24 inches (407 mm by 610 mm). When any portion of the through-wall access is below grade, an areaway not less than 16 inches by 24 inches (407 mm by 610 mm) shall be provided. The bottom of the areaway shall be below the threshold of the access opening. Through wall access openings shall not be located under a door to the residence. See Section M1305.1.4 for access requirements where mechanical equipment is located under floors.

R408.5 Removal of debris.The under-floor grade shall be cleaned of all vegetation and organic material. All wood forms used for placing concrete shall be removed before a building is occupied or used for any purpose. All construction materials shall be removed before a building is occupied or used for any purpose.

I'm very sorry for your experience.

It should be emphasized that the problem you are experiencing is the product of the combined failure of the builder to build the structure as per the approved plans coupled with ineffective (if at all) inspection by your code compliance inspector(s). It's unfortunate that the code compliance folks get a get-out-of-jail free card since you paid for their services when you paid for the building permit.

Given the low height of the concrete foundation wall above grade, I'm concerned about the potential for moisture wicking up from the footing to the framing. If Dow Sill Seal or something equivalent is installed between the concrete foundation wall and the sill, that would a relief. The other concern is moisture in the void space between the former patio and the joists. I concur that you need a moisture vapor barrier and ventilation of the space. You said that your home--other than the new addition--is on a basement foundation. I'm wondering if it is possible to remove a portion of the exterior basement wall between the basement and new addition large enough to install the vapor barrier without the need to remove the finished flooring in the addition. Ditto for the possibility of ventilating the space.