Thread: Negative Slope Question

I searched as much as I could on this site so I don't think this is an oft asked question, but if so, sorry. Let me give background first though. I am relocating via Ford and they require an inspection of the house I'm selling up front. US Inspect did the inspection and flagged 7 or 8 things that have all been satisfactorily remedied per a follow up inspection. The one I struggle with is a negative slope in the rear of the house. I wasn't there when he did the initial inspection, so I filled in two areas near the corner of my deck and downspout that had sunk significantly.

I was there for the followup and he still stands by the negative grade. In my opinion, it's level at worst. I know for a fact that no water stands in this area and I don't have issues with water in the basement. So trying to research further I found the following on the US Inspect website:

"The soil around the perimeter of the home should slope away (at a minimum of six inches for the first 10 feet) from the house to prevent rain water from accumulating next to the foundation. Soil in this case does not refer to the topsoil but the layer of soil that is impervious to water such as clay, which directs the water away from the house. Many times the topsoil is porous (as would be used for planting) and absorbs the surface water. The sub-layer of clay or similar non-porous soil prevents the water from continuing in a downward movement and directs the water laterally. If non-porous soil next to the foundation slopes toward the house, water will begin to accumulate."

So now my question is, if grading doesn't refer to the topsoil, how am I expected to repair this and how is a quick visual inspection sufficient to determine?

More info: House is 8 yrs old, Ryan Homes Built. I'm the original owner. Lot's are fairly flat approximately .3 acre. Poured concrete foundation. The area of interest is adjacent to the attached garage under which the basement does not extend.

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Underlining the dumb part.

Originally Posted by Dan Bell

I found the following on the US Inspect website:

"The soil around the perimeter of the home should slope away (at a minimum of six inches for the first 10 feet) from the house to prevent rain water from accumulating next to the foundation. Soil in this case does not refer to the topsoil but the layer of soil that is impervious to water such as clay, which directs the water away from the house. Many times the topsoil is porous (as would be used for planting) and absorbs the surface water. The sub-layer of clay or similar non-porous soil prevents the water from continuing in a downward movement and directs the water laterally. If non-porous soil next to the foundation slopes toward the house, water will begin to accumulate."

So now my question is, if grading doesn't refer to the topsoil, how am I expected to repair this and how is a quick visual inspection sufficient to determine?

How dumb can US Inspect be? (Rhetorical question, I know how dumb they can be.)Many areas have no soil impervious to water such as clay.

THE CODE only requires:

From the 2006 IRC. (underlining is mine)

- R401.3 Drainage.

Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection so as to 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).

I would first tell them to show you IN THE CODE where the requirement says what they are requiring.

Then, if the US Inspect inspector continues to insist on something NOT REQUIRED, I would insist on speaking to their supervisor, going up and up until you find someone with some sense.

It would also be beneficial to you to stop by your building department and obtain something from them as to what their requirements are for drainage away from the foundation. Then give that to the US Inspect inspector, and fax it to higher up as needed.

Surely *they cannot be all dumb enough* not to be able to think on their own.

Granted, the inspector is just following policy, but if they can think on their own, they will side with you as you go up the chain of command finding someone who not only understand construction, drainage, and their liability - such as preventing you from selling when your house meets code, maybe ... they would like to buy it? You could suggest that you will be speaking with your attorney on this matter, that should at least get their heads out of their butts and think.

Flat, is not graded away from the structure. The building code requires a slope away from the home, unless alternative drainage methods (such as a french drain) have been installed.

I glad to hear that they at least wrote up something. I've been behind some of these guys and they all use the same boilerplate comments to CTA on everything.

Not much substance on the reports I've seen, but you get a nice binder.

rick

I agree with Jerry.

Pictures would help...

You could also measure out 10' from the foundation. Then pound in a stake at the foundation and at the 10' mark. With a nail or thumbtack secure a piece of string from the foundation stake to the 10' mark. Then measure the distance. I would do this on all side of the home. If it does have the proper slope, take some pictures and tell them to pound soap!

Maybe I am reading this wrong, but the OP says the grade could be considered flat.
Don't get hung up on the type of soil since that is not required by code as Jerry noted. The boiler plate on their site is technically correct, you don't want porous soils (sand) next to the foundation but believe me he won't be testing the soil. Native soil is fine, don't use sand, gravel, etc.
Get the grade correct and he will be happy.

Originally Posted by Dan Bell

So now my question is, if grading doesn't refer to the topsoil, how am I expected to repair this and how is a quick visual inspection sufficient to determine?

Jim,

The above was his question because he has to correct it to meet the report, and the report is wrong.

I would have US Inspect pound sand until they correct their report, then it become a simple mater of correcting the grading.

As stated in the US Inspect report, he is only going to be able to correct it by bringing in heavy excavating equipment, digging out half the yard, putting in layer of clay sloping as required, then a couple of inches of topsoil, then sod.

If US Inspect does not correct their report, I am sure a few well placed messages with the Ford relocation department will get US Inspect off their list of approved inspectors. No one wants junk any more, and Ford knows that as much as any one else.

Originally Posted by Jim Luttrall

Maybe I am reading this wrong, but the OP says the grade could be considered flat.
Don't get hung up on the type of soil since that is not required by code as Jerry noted. The boiler plate on their site is technically correct, you don't want porous soils (sand) next to the foundation but believe me he won't be testing the soil. Native soil is fine, ...

With native soil being fine, then their boiler plate is not technically correct, their boiler plate may represent theoretical desires, but technically correct is what the code says.

Originally Posted by Jerry Peck

With native soil being fine, then their boiler plate is not technically correct, their boiler plate may represent theoretical desires, but technically correct is what the code says.

"The soil around the perimeter of the home should slope away (at a minimum of six inches for the first 10 feet) from the house to prevent rain water from accumulating next to the foundation. Soil in this case does not refer to the topsoil but the layer of soil that is impervious to water such as clay, which directs the water away from the house. Many times the topsoil is porous (as would be used for planting) and absorbs the surface water. The sub-layer of clay or similar non-porous soil prevents the water from continuing in a downward movement and directs the water laterally. If non-porous soil next to the foundation slopes toward the house, water will begin to accumulate."

Technically correct is not limited to what the code says.
How many times have you said "code is the minimum you can legally get by with"?

Again, I would recommend correcting the grade and be done with it. Do you know any inspectors that do a core sample or carry a shovel to test the subsurface drainage?

The one I struggle with is a negative slope in the rear of the house.

Originally Posted by Jim Luttrall

Technically correct is not limited to what the code says.
How many times have you said "code is the minimum you can legally get by with"?

I say it many times, but technically correct means it applies to all conditions it covers, and the code is "technically correct" because that is "the minimum allowed".

Theoretically correct would be better, however, when there is a slab on grade and no crawlspace, that might not be "theoretically correct" either.

Combine that with houses which have, as part of their design, embedment into a soil base to help resist wind forces, and clays would allow for side slip, then neither technically correct nor theoretically correct would be applicable.

Being "minimum required" is more "technically correct" than any higher standard as the "technically correct" aspect would represent the minimum level of accuracy, with improvements above and beyond that level.

First off unless the guy is a geotech, he shouldn't be quoting soil conditions. Second if you have a basement, you should have a sump pit and pump which remove water from around the foundation. Soil strata can change several times within four feet and unless he has an area soil chart he can't be sure water is leaching around the various layers of different soils. Best thing to do is call the builder if possible or check with the local bldg dept and see what requirements were needed for filling in the overcut when the basement wall was placed. Some cities want fabric over rock or stone, some want flowable fill, others want the overcut replace with in kind save pile material. Better yet, dig about a foot below grade and see what waterproofing was used. Anything over 1/4" (1 degree) sloping away from the wall moves water. A 6" drop over ten feet is three times the slope required to move water (3 degrees). You want to move water not create a tsunami.

Originally Posted by Jim Luttrall

Native soil is fine, don't use sand, gravel, etc.

In our area, the native soil IS sand. We just do our best and make sure everything slopes away from the foundation.

Pictures would be nice to see the area in question.

rick

I am not sure from reading everything as to the type of foundation.
I think you mean slab on grade - maybe not.

- R401.3 Drainage.
Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection so as to 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).

The foregoing code refers to "foundation walls" . Slabs on grade do not have walls.
Someone referenced the 3 degree slope. My understanding from an engineer - I dont have a written reference - is that the requirement for a slab on grade, or anything without "foundation walls" is 3 degree elevation from the curb to the building. The 6" /10' rule would be 4.5 degrees in only 10 feet. (If my math is right)

Originally Posted by Richard Stanley

The foregoing code refers to "foundation walls" . Slabs on grade do not have walls.

In a sense they do, slab on grade 'is' the footing/foundation/floor all rolled into one.

The footing is the thickened edge part, the foundation wall goes from the bottom of the footing to the top of the slab, or at least to the top of the slab minus the slab floor thickness.

Appreciate all the replies. I haven't been home for 2 weeks. I'm going to take a measurement this weekend based on techniques discussed here. I'll let you know what I measure. I guess part of what pissed me off is the guy didn't specify where he thought the grade was negative. Anyway, how exactly do I fix it? Dump topsoil along the foundation?

Originally Posted by Dan Bell

Anyway, how exactly do I fix it? Dump topsoil along the foundation?

Depends on how 'flat' it is, or if negatively graded ... etc.

You could always lay some sod next to the house, typical sod pieces are about 2" thick, if the area is 'flat' then lay one layer three rows (pieces) wide, then on top of that lay another layer two rows (pieces) wide, then on top of that lay another layer one piece along the house.

You have now created a stepped drainage plane which will cause water to run off toward the lower point.

Or, yes, bring in some fill and place it next to the foundation, leaving enough height for one layer of sod on top of it.

However BE FOREWARNED that any height you add to the soil will reduce the height clearance to the wall above, and you need a minimum of 6" to the framing above ... which means if your grade is only down 6" from the framing above that you will not be allowed to raise the grade at all.

[quote=Jerry Peck;79229]Depends on how 'flat' it is, or if negatively graded ... etc.

You could always lay some sod next to the house, typical sod pieces are about 2" thick, if the area is 'flat' then lay one layer three rows (pieces) wide, then on top of that lay another layer two rows (pieces) wide, then on top of that lay another layer one piece along the house.

You have now created a stepped drainage plane which will cause water to run off toward the lower point.

Or, yes, bring in some fill and place it next to the foundation, leaving enough height for one layer of sod on top of it.

However BE FOREWARNED that any height you add to the soil will reduce the height clearance to the wall above, and you need a minimum of 6" to the framing above ... which means if your grade is only down 6" from the framing above that you will not be allowed to raise the grade at all.[/quote]

None of that is really important here. The most stressed part of this is sloping the soil away from the home. If you only have an inch left so what, at least the water won't just be sitting next to the foundation/slab and causing more concerns than no concerns at all about maintaining 6 inches. As long as one can see the edge of slab/foundation and the soil has enough slope to drain water away from it is all that matters here.

Many slab homes I inspect are only 6 inches if that from soil to bottom of the brick ledge. The grading is flat around the home. Again the slope away from the edge of slab is of much greater concern than trying to maintain 6 inches to the bottom brick line. In these cases the slope far overides any code required distance between soil and bottom of frame/brick ledge/siding.

If none of this can happen then inground drainage must be added to move the water away from slab edge/foundation. Keeping the water away from the edge of the foundation is of great importance. Distance from soil is as well but does not outway the other.

I disagree Ted. I would not recommend creating a clearance problem when trying to fix a drainage problem. Heck, they may have created the drainage issue while trying to fix a clearance problem.
Fix it right the first time, create a drainage swale if need be, but I would never recommend to bring soil up too high on the wall, just asking for termite, rot, water entry issues.

Originally Posted by Jim Luttrall

I disagree Ted. I would not recommend creating a clearance problem when trying to fix a drainage problem.

Agreed, as the next inspector in will likely write up the lack of clearance, and then what does he do? Remove what was added and end up making it flat again?

What a waste of time, money and effort that would be - and it would still end up *wrong*.

The splash back can be countered. The termite situation can be kept in check by monitoring the edge of the slab or foundation as you should anyway. As long as you have a visible side to the slab/foundation the termite thing does not become involved. They can build a tube in about twice the amount of time in six inches or 2 inches and that is no time at all.

If the lot is flat there is no swail digging. The ideal situation would be inground drainage but most are not goiung to go to the costly expense for inground drainage on a flat lot where they have to dig a sump and install a pump and french drain etc etc etc.

In all the cases I am talking about the less of a distance say 2 inches instead of 6 inches with gutters is about the least expensive way to go. If you get into the thousands range (last small home, about 1100 sf, that was priced was 3500)

Back splash to the home and a rot issue if you don't take care of back splash to the home is no different at 6 inches as it is 2 inches. I am talking six inches to the grass or 2 inches to the grass. I am not talking bring the soil up that high so the grass is growing against the bottom of the siding.

If you dont have water entry issues with flat soil next to the home you will have even less water entry issues with the soil sloped away from the home.

If the next inspector sees the soil a few inches to high but sees that by bringing the soil down will cause a greater issue then that is what he will right. He is not just writing code he is also giving an opinion.

The only alternitive for a totaly flat lot is gutters, inground drainage around the home a sump pit and pump and then that pump has to be plumbed out to the strret or where ever allowed. Add that to the gutters and you are talking 4 to 5gs for all that work. That would be part of my opinin as well. They have a choice. Monitor their home like they need to anyway add gutter and add a slight slope or spend up to 5 gs, take your pick.

Not to mention the soil around the home remains at a higher moisture level from the water settling to get to the drainage.

All this will be in the report. Requirements and options and opinions.

Not much substance on the reports I've seen, but you get a nice binder.

Rick: I think you meant blinder.

Wait a minute! This is at the garage? And someone's making an issue of it? That's nuts. This is a weekend project for the buyer after he moves in. What happened to issues of habitability and safety?

If I were the seller I'd tell the buyer to stick to the serious stuff - if there was any. Who lets such stupidity get out of hand?

As a buyer, the one thing you don't want is spending your weekend bailing out the basement full of water and tossing all your personal belongings...

A negative slope IS ab big deal. It may not have been for a few years, but just wait til one of these big weather events happens. The new homebuyer will swear that you (the seller) knew there was a problem all along and didn't disclose it.

A good atty will throw a blanket over the whole lot.

We see a lot of negative slope issues here in California. The most cost effective "repair" would be a French Drain around the back. If possible, pipe the drain to a natural outlet so it is automatic.

While this does not create "slope" it creates drainage which is the issue at hand.

If you work with a licensed contractor and pull a permit for the job, you should have adequate documentation of meeting code requirements to "address" the issue with any home inspector.

Compare this strategy with digging out the yard to create the needed slope and dealing with the new landscaping this will require.

I would check in with the local building department. They can not design a solution for you, but they can say "yes that will comply with our interpretation of the code(s) in force".

I've been hired twice to go over their lousy (my opinion) reports.
To many possible solutions without pics. Do a Swale, like Jim showed; add some decorative gravel; plant a row of water sucking shrubs in the area; if you think it is essentially level then add a few plants and forget about it.

The local applicable code will trump standards and recommendations, so go to your code. This is the 2003 IRC language. I would suggest that this refers to backfilling and final grading, but not material set for landscaping that is subject to maintenance. Nothing here about the underlying soils. You may be able to go to the code in effect at the time of construction if you want less precise language to stand-on, but since this is a negiotiation and not a sense of actual, legal code defects, you will probably have to meet the minimal standards of the local or State code adopted at this time to get the deal done.

18033 Site grading. The ground immediately adjacent to the
foundation shall he sloped away from the building at a slope of
not less than one unit vertical in 20 units horizontal (5-percent
slope) for a minimum distance of 10 feet (3048 mm) measured
perpendicular to the face of the wall or an approved altemate
method of diverting water away from the foundation shall be
used.
Exception: Where climatic or soil conditions warrant, the
slope of the ground away from the building foundation is
permitted to be reduced to not less than one unit vertical in
48 units horizontal (2-percent slope).
The procedure used to establish the final ground level adjacent to
the foundation shall account for additional settlement of the backfill.

Originally Posted by Clark Griffith

The local applicable code will trump standards and recommendations, so go to your code.

Not really, but kinda sorta.

From the 2006 IRC. (underlining is mine)
- R102.4 Referenced codes and standards. The codes and standards referenced in this code shall be considered part of the requirements of this code to the prescribed extent of each such reference. Where differences occur between provisions of this code and referenced codes and standards, the provisions of this code shall apply.
- - Exception: Where enforcement of a code provision would violate the conditions of the listing of the equipment or appliance, the conditions of the listing and manufacturer’s instructions shall apply.

Also from the 2006 IRC.
- R401.3 Drainage. Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection so as to 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).
- - Exception: Where lot lines, walls, slopes or other physical barriers prohibit 6 inches (152 mm) of fall within 10 feet (3048 mm), the final grade shall slope away from the foundation at a minimum slope of 5 percent and the water shall be directed to drains or swales to ensure drainage away from the structure. Swales shall be sloped a minimum of 2 percent when located within 10 feet (3048 mm) of the building foundation. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped a minimum of 2 percent away from the building.

Originally Posted by Clark Griffith

The local applicable code will trump standards and recommendations, so go to your code.

Exactly!

Many jurisdictions adopt amended versions of the model codes, or selectively adopt them (excluding chapters and substituting other language or parts of different model codes). Some insert tables, specifications, etc. for the specific regional requirements.

A call to your local authority having jurisdiction verifying what may or may not apply in your location, and pertaining to your specific home would be a good idea. Plus considerations if you're in a wetlands or flood zone, etc. There are areas which have problems with storm water management that could have very specific and stringent rules/provisions; soil errosion rules, etc.

If the surrounding grade is too high to allow bringing the grade higher at the house due to clearance from wood being comprimized, there is an alternate solution.
Granted, it is work and is more expensive as you will probably need a bobcat and may have to haul out the dirt.
You could go ten feet out from the house and cut a swale to maintain the grade at the neighbors house, while still creating enough slope to properly drain water away from your house.
Any good landscaper should be able to do this, or you could rent the machine ( typically about 300.00 / day ) and try to do it yourself. If you are not comfortable running one of these, you might be better off hiring it done.

Originally Posted by Clark Griffith

The local applicable code will trump standards and recommendations, so go to your code. This is the 2003 IRC language. I would suggest that this refers to backfilling and final grading, but not material set for landscaping that is subject to maintenance. Nothing here about the underlying soils. You may be able to go to the code in effect at the time of construction if you want less precise language to stand-on, but since this is a negiotiation and not a sense of actual, legal code defects, you will probably have to meet the minimal standards of the local or State code adopted at this time to get the deal done.

18033 Site grading. The ground immediately adjacent to the
foundation shall he sloped away from the building at a slope of
not less than one unit vertical in 20 units horizontal (5-percent
slope) for a minimum distance of 10 feet (3048 mm) measured
perpendicular to the face of the wall or an approved altemate
method of diverting water away from the foundation shall be
used.
Exception: Where climatic or soil conditions warrant, the
slope of the ground away from the building foundation is
permitted to be reduced to not less than one unit vertical in
48 units horizontal (2-percent slope).
The procedure used to establish the final ground level adjacent to
the foundation shall account for additional settlement of the backfill.

Clark, I see you referenced the 2003 IRC but I don't find this wording nor reference numbers that you use. Can you clarify?

Jim - I stand corrected in that I used the 2003 IBC Section 1803 Excavation, Grading and Fill - I gave that language just as an example and my slip actually reinforces the point that one has to look at the specific language of the specific code adopted by the jurisdiction - as language changes and the subtle nuainces can help or help one in each case...

Thanks Clark, I was driving myself crazy looking for that wording in the IRC!
Very similar wording, but as you said slightly different.
Of course in most residential settings the IRC would be applicable but you never know without checking. The 5% grade seems pretty consistent though.

I decided to resurrect this thread. Why, throughout my home inspection carrier, agents, god bless their misdirected attempt at selling homes, typically/usually, ALWAYS reply to me about negative or flat lot slope by stating that, we all know 80% of lots are poorly graded Mr. Young.
Always grabs my attention.
My reply, so that makes it OK?

I charged $5,000 a side on average.

We can not see below grade but we can hypothisize on how it should have been done.
Backfill, impervious soil, is used to fill the excavated lot/trench for the foundation. An excavated ,trench is typically 36" inches wide. Mine were.
So bear in mind one can now reasonably presume, if all things are soil equil, if the lot is flat, the backfill has settled, as well as the topsoil, the growing medium for sod or other plantings, flowers and shrubs has generally eroded.

If the backfill has settled the required gradient, water and moisture will be capable of foundation contact until evaporation has taken place.

If there are plantings and shrubs close to the foundation the likelihood of the earth being excavated/trenched for root systems creates ruts to contain any topsoil growing medium. A great place for water to pool or be redirected.

If there is concrete, patio or flagstone, unit paver paths/walkways, heavy impervious materials, they to had been tranched/rutted for water management cutting a rut into the soil that should grade continuous in one direction.

To answer Dan's question, how to correct the lot deficiency? Repairs are not a subject for home inspectors. We recommend the required professional, which brings me to another reason why I decided to resurrect this thread. I re-sloped/corrected negatively sloped lots. As well I performed lot water management prior to inspecting homes, along with other building and restoration practices.

To correct lot slope is labour intensive. Everything if heavey.
Materials are not costly per say, but you have to have the knowledge the task you are about to undertake.

1: You have to remove all organic material, sod, plantings.
As well, pervious and heavy impervious materials. IE: Aggregate, sand, concrete in any form, patio or flag stones, unit pavers,etc...
2: Grade backfill soil for a minimum of 5 to 6'.
3: Apply topsoil and sod.

Grading lot.

Originally Posted by Jim Luttrall

Thanks Clark, I was driving myself crazy looking for that wording in the IRC!
Very similar wording, but as you said slightly different.
Of course in most residential settings the IRC would be applicable but you never know without checking. The 5% grade seems pretty consistent though.

First off. Thank you all for the great posts.

I concur with 5%.
1:20 / 2.86° / 5%