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tilted floor in hillside house

tilted floor in hillside house

tilted floor in hillside house

(OP)
I am checking a house which is sitting on a sloped lot. Assuming you are facing the house, the front left side is two car garage and right side is downstair entry leading you to a living room. All the rest of the rooms are located upstair, one the back side of garage there is a door which leads you into crawl space underneath the partial 2nd floor, the grade sloped up to higher level where there is a 2' tall masonry stem wall supporting the upper floor joists. At back side of garage wall line, there are regular 9' tall wood stud walls in the crawl space you can see which is supporting the upper floor joists.

The house was built in 1971, the floor are tilted towards to the front side of building. I am not sure if this shall be a concern, it is not quite noticeable when people work in but it may be observed by some expert. the floor is not level but how bad will this cause normal people's concern? Let's say the elevation drop 2" over 25' distance on 2nd floor, is it too much or can it be more? Building code doesn't define the limit and there is no crack found in foundation or interior walls, there are hairline cracks everything on exterior stucco wall, that's about it. All doors and windows are easily opened without any problem.

What's the maximum acceptable slope on floor level in a residential house? is 1/8" to 1 feet slope a concern or 1/4" to 1 feet drop a concern?

I found that one side of floor joists sit on masonry stem wall (with rock base) and the other side of floor joists sit on wood stud wall (9'-0" tall at crawl space) with regular concrete stem wall on surface soil (I guess), I think this is the reason causing the differential settlement. it seems the foundation has evenly settled on a bearing line, therefore this is no crack found anywhere in the house except stucco hairline crack.

Please let me know what you think I need to do to make me comfortable with this issue. I can send some layout if it helps you understand what I asked.

Thanks

Janet

RE: tilted floor in hillside house

A cross section would help...  Immensely.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: tilted floor in hillside house

I don't think there is a code provision that requires a certain limit on floor slope.  It is usually what the owner will put up with and also whether the slope is indicative of an on-going settlement or a settlement in the past that has now stopped.

You could monitor the elevations around the perimeter of the house over time to see if the settlements are still occurring.

Underpinning the house is an option - an expensive one.  You can underpin to simply stabilize or you can also try to jack up the house to level - but that can be difficult depending on the house configuration.

 

RE: tilted floor in hillside house

Agree with Mike, I got lost in your narrative. A picture or sketch is worth a thousand words.

Where is the location? Is that area known for unstable soils such as plastic clays, organics, etc?

I deal with this type of stuff every day. What it boils down to is if there is no distress, especially structural, and the owners are OK with the slope, there is no problem. If the slopes are barely perceptible and have led to no decrease in function of the house, then what is the issue..?

How much of the floor slope is due to original construction and how much due to settlement? Nobody knows unless you have a floor elevation survey soon after construction.

For monitoring purposes you could have a floor elevation survey done for future comparison so that you have an established baseline.

RE: tilted floor in hillside house

Call you local inspection agency. Often they have deflection and levelness criteria not specified by the code.

For Ontario, Tarion sets the gov't standards for final inspections and they have rise over run limits for walls, foundations, floors etc. (I can't remember them off the top of my head).

The number of houses with floors sloped or uneven is significant, most people either just don't notice or care to repair the floor.

If the settlement, progressing over 40 years, can only be noticed by an expert. I don't think there is much of an issue.

I would suggest go buy yourself a laser level from Home Depot ($120) and get an accurate measurement of key points on the floor joists and foundations. Record the relative settlement accross the structure and tell the homeowner to call you, or to hire someone who can measure and compare your data in a year's time. Ongoing or recent settlement is a problem. Existing settlement which is barely noticeable after 40 years, not so much.

RE: tilted floor in hillside house

Difficult to follow without some diagrams or photos.  There could be numerous reasons.....?

Also, what is your scope?  Are you hired by a current owner?  Prospective buyers?   Did they specifically ask you to review the sloped floors or did you notice?

Are all the floors sloped the same (first and second)?   Are there interior bearing walls?   

RE: tilted floor in hillside house

(OP)
I went back did more measurement accurately and had some concern and questions.

The main concern is there is a 3 inche drop from grid line 2 to line 3 (13' distance) it seems too much. I included house layout in this post.

a)all floor joists run up and down assuming north is up
b) grid line 1 to 2 is upper side of sloped lot (flat)
c)grid line 2 to 10'down toward south direction is sloped down soil, (the crawl space can be accessible from back side of garage at grid line 3)
d)At grid line 2, there is 4' tall masonry stem wall supporting the 2nd floor joists.
e) At grid line 3, there are 8' tall stud wall supporting upper floor
f) all floor sloped down towards the front at a 2" drop over 20' distance, the worst one is 3" drop over 13' distance between grid line 2 and 3.
g) I don't understand why floor sloped down in E-W direction from A and C towards the grid line B, as I don't think grid line B has load bearing wall (since floor joists run N/S direction), grid B is the lowest point line in E/W direction.
h)I measured garage stem wall top elevation, it shows only 1" drop in N/S direction over 20' distance, it seems that soil has not settled too bad due to the help from concrete slab in garage. where is the 2" difference on 2nd floor come from? Maybe from wood construction.

Based on the above information. do you concern if this house is worthwhile to buy as I could not monitor its settlement change and have to make decision to proceed. Is this required to be retrofit or will you live with it. What do you feel the best way of solving the problem.

Thanks so much for your help!

Jan

Again the house is built in 1971, no crack on footing and interior wall of the house except hairline crack everywhere on exterior stucco, the doors and windows open smoothly.

aaaaaaaaaaaaaaaaaaaa         grid 1
a                  a
a        2nd floor a
a                  a
a          51'     a
aaaaaaaaaaaaaaaaaaaa         grid 2
a                  a
a    2nd floor &   a   13'
a     crawl space  a
aaaaaaaaaaaaaaaaaaaa         grid 3
a        a         a
a        a1st floora   13'
a garage a Liv rm  a  
a        aaaaaaaaaaa         grid 4
a        a   
aaaaaaaaaa    30'  
   21'

A        B         C

RE: tilted floor in hillside house

Seriously? Don't you own a scanner? They are like 50 bucks...

 

RE: tilted floor in hillside house

(OP)
Sorry don't know how to delete the previous post, but this layout works. Garage size is 23'x21'.

           51'
aaaaaaaaaaaaaaaaaaaaaaaaaaaa                        grid 1
a                                              a
a        2nd floor                         a                18'
a                                              a
a                                              a
aaaaaaaaaaaaaaaaaaaaaaaaaaaa                         grid 2
a                                              a
a    2nd floor &                          a                13'
a     crawl space                        a
aaaaaaaaaaaaaaaaaaaaaaaaaaaa                         grid 3
a                     a                       a
a                     a  1st floor         a                 13'
a  garage         a  Liv rm            a  
a                     aaaaaaaaaaaaaaa                       grid 4
a                    a   
aaaaaaaaaaaaaa            30'  
   21'

A                    B                        C

RE: tilted floor in hillside house

Jan,
This seems pretty involved.  (And the scanner comment is true - hard to decipher).  Not sure if you are a structural engineer, but you should consult with someone in person regarding this because it seems too involved/complicated for this site.

Not trying to be rude, but this would either take a bit of time/energy to get into, or I would just be 'throwing guesses' out there, based on my understanding of the issue(s).   Either way, seems beyond this forum.  

Maybe someone else thinks differently.    

RE: tilted floor in hillside house

since this seems to be a settlement issue, I would expect to see some information regarding the foundation conditions, soil types,cut/fill/depth to bedrock, groundwater, drainage etc. which could be used to evaluate settlement. Kind of hard to render any opinion with nothing to go on but a "schematic floorplan". The problem can't be "solved" until the cause has been identified.

If I had to guess I would say there are multiple issues with this house, not the least being the fact that everything rolls towards the front door. This is a big red flag and personally I would look for something better to buy.

RE: tilted floor in hillside house

(OP)
The soil in this area is typically good. (correct my previous post, there is no bedrock base under, it's only soil). No foundation cracks were observed as I mentioned, there is only less than 1" drop in both directions between 20' distance on top of garage stem walls.

For this kind of problem, they usually asked you to consult a structural engineer, which I already have the knowledge, I understand 90% of time, engineer will say, the house needs to be leveled, but I hope to talk to some engineer with construction experience or experience contractor, who can give me some valuable insight,personally, I think this may not be a problem but I need some backup/knowledgeable opinion. Where can I find this kind of service?

Thanks for reading such a long post.

Janet

RE: tilted floor in hillside house

I would definitely investigate settlement of the footing line at the top of the slope.  Don't know which gridline that is .  Classic condition for a slip or rotational failure.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: tilted floor in hillside house

(OP)
This line is the line of masonry stem wall I mentioned which is sitting near the top of high side of sloped grade, I agree with you that you think it may slide down as section shows too close to the sloped grade, but the top of floor joist does not drop down that much at all at higher grade elevation, about 5/8" drop over 12' distance at higher grade.

This wall is on the north side of 3" drop I have measured over 13' distance. I am more concerned why this 3" drop occurs.

I don't think this stem wall slides towards to the bottom of the sloped "hill", otherwise floor elevation on this line shall be lower instead of 3" higher. (my section may not be accurate since it drew stem wall too close to the sloped edge.)

Thanks.

Janet

RE: tilted floor in hillside house

A number of years back, we lived in a house where one end was about 2" lower than the other.  The only effect of this was that the gutters were sloped the wrong way and wouldn't drain.

RE: tilted floor in hillside house

Is there any possibility that the house could be sliding down the hill as well as settling?

I would be very wary of that house.

It could be symptoms of a larger ongoing problem.

It indicates that the current owners are not high into the maintenance.

If it was a simple fix then the current owners may have done it.

RE: tilted floor in hillside house

LOCATION?

I would have a company come in and do a floor elevation survey of both stories so you have the complete picture of what is going on with the floor slopes and elevations. Maybe you see the whole house is sloping one way, or maybe this is a localized settlement issue. This should be a pretty cheap test, at least it is when we do it. Also gives you a baseline for monitoring purposes.

Then you can investigate all the things the other engineers have mentioned above.

You said not foundation cracks that you could see so far, that is a good sign, but as others have said this may be a global movement issue.

 

RE: tilted floor in hillside house

(OP)
Remember this is a upsloped house, not downsloped one. The lower level stud walls are sitting on street level, therefore, it can not persuade me that the house will slide down. Because the middle potion of the house is supported by concrete stem wall close to the sloped edge, so if the house slides down, the middle line shall be lower but the floor is tilted down from that line to the front 3" over 13' distance. My guess is differential rigidity of support walls (one side concrete and one side wood....not exactly sure??)

Anyway, I guess I have to find some retrofit expert for wood construction.

Do you know that if I am a potential buyer, should I write a report of this investigation and give it to the contractor for estimating the cost of repair? We will then submit it to the seller, is there any legal issue to cause problem of my license?
Should I hire other structural engineer since this may not convince seller what I did is based on professional's opinion.

Janet






 

RE: tilted floor in hillside house

A 3" drop in 13' from Gridline 2 down to Gridline 3 seems a little excessive but part of it may be due to shrinkage of the wood.  I am attaching your sketches with gridlines shown for ease in discussing.

If the Living Room floor consists of wood joists platform framed as opposed to balloon framed, you could have substantial shrinkage relative to the masonry wall which has none.  Your section does not indicate the First Floor structure, but I am guessing it is stick framed over a crawl space.

If the material was very wet during construction, each plate could shrink by 1/8" and the joists another 3/4".  Assuming 3 plates below and 3 plates above the First Floor, this could account for 1.5" differential movement.

That still does not account for 3", but the remainder of the floors seem to have moved a similar amount when the shrinkage is discounted.  Perhaps the contractor had a wonky level.

If were purchasing the home, I would want the Second Floor leveled or at least one constant slope.  A buyer should be advised of the discrepancy in levels so that he may consider the potential for additional movement.

BA

RE: tilted floor in hillside house

(OP)
Thanks for your valuable comments.  Please explain why there are "3 plates below and 3 plates above the 1st floor". The total number of plate on stud wall line 3 below 2nd floor level is only 4, therefore the no. difference is only 4-1=3, with 3x3/8+3/4, I only get 1.125" please explain where you get 1.5", also my field measurement of top of stem wall elevation along line 3 from grid 3 to 4)gives 1" difference. Therefore I got 2.125" total difference here. Just .875" short from 3".

What do you think the best way to fix this kind of leveling problem? please note that I have not noticed any drywall crack at all inside the house, I assume drywall shall respond to this 2" shrinkage change with cracks.

Unfortunately, the floor elevation drops 2" from grid line 3 to grid line 4 on 2nd floor between line A and B too. How do we explain this, both floor joists were supported by sticked framing. (Yes the crawl space is supported by sticked frame per your assumption)

Janet

RE: tilted floor in hillside house

(OP)
Assume the leveling problem is caused by wood shrinkage, I don't think it will be a cheap fix too.  If we put 2-2x flat on lower side of 2nd floor level and install plywood above, the problem shall be solved. what do you think of this solution?

Janet

RE: tilted floor in hillside house

Normally, there is a single bottom plate and a double top plate in every story.  If your situation is different, then please advise.  My assumption was that the stub wall below the First Floor would have a single bottom plate and a double top plate below First Floor.   

Above the First Floor, I assumed a single bottom plate and a double top plate at the underside of Second Floor.  I cannot confirm this in your case, but it is standard practice in my neighbourhood.

Leveling the Second Floor by adding another plate under the Second Floor joists seems like a reasonable solution to me, but if the problem is foundation settlement, it will not help if the foundation continues to settle differentially.

As for the 2" drop between Grids A & C down to Grid B, there is not enough information to make a reasonable guess.  In northern Canada where I live, I would suspect frost heaving on the outer walls, but in California where you live, that is not likely to be the case.

BA

RE: tilted floor in hillside house

(OP)
"Leveling the Second Floor by adding another plate under the Second Floor joists..." will be expensive fix. I was proposing a cheap fix (definitely not a perfect one) by adding 2x flat on top of floor joist as long as you don' have door/opening near these area....

There is no pony wall at crawl space therefore, only three plates shall be calculated, right? (one plate on top of stem wall at crawl space, two top plates under 2nd floor joist, that's about it)

Thanks.

Janet

RE: tilted floor in hillside house

Janet,

Your solution seems okay to me.  A doorway should not be a problem.  Simply cut off the plate at the edges of the door.

BA

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