How do i determine if cracks in a wall are due to the foundation sinking?

I think you’ve done the right thing. If you don’t trust the contractors, maybe you can find one you do trust. Or see if you can find a civil engineer or building inspector to look at it. Or you could get them fixed or have the foundation shored up. Are you on a concrete pad?

I’m trying to make sense of what you’ve written, as it is written.

You own a house in the Caribbean. Okay, I’m with you so far.

There was some flooding a year or two ago. (No mention of how that affects your house, but I got it: flooding in the area a year or two ago.)

Last year (so this would be (around the time of or a year after the flooding) you noticed cracks in the walls. (I presume that you mean the walls of the dwelling itself, and I also presume that you don’t have a “dug” foundation, but only a slab, since you don’t have to dig below the frost line for a foundation to work properly there. In other words, we’re not talking about “the walls of the foundation or basement”, but the house itself—I presume.)

Now you omit most of the key points:
1. How big are the cracks? Length and width.
2. How do they run? Vertical? Diagonal? Horizontal? Combination? All the same orientation?
3. How many cracks are we talking about, and how are they located? “Many” cracks, all on one corner of the structure? Or “one or two” cracks, widely separated? (Yes, you did say “all on the same side of the house”, but that’s not much to go on.)
4. What is the relationship of the cracks to the foundation itself? That is, do you also have cracking in the foundation?

Of course, the other vital information necessary is the type of construction: wood frame? brick? something else? Single story (assumed) or multi-story? Age of the structure and general condition otherwise? Details, details.

Photos would be helpful, if you can post them to a Photobucket or similar account.

If you want to be absolutely sure of the import of the cracks, then you need to be absolutely confident in the contractor giving you the assessment. If you want to have any kind of confidence in what we tell you here, you have to either
1. Give us a satisfactory description of the cracks, or
2. Fly us down to the Caribbean for a personal no-other-cost-to-you inspection and written report.

I can clear my schedule for next week, if that’s good for you.

I’m with @CyanoticWasp Fly us down and I’ll be the mixologist .
Get a civil engineer to look at it NOT a contractor.

To be honest, i was considering it. 80% of teh contractor down there migt have expirience with buidling homes, but they have no clue about dealing with the issue i have. and then u have some other ones who know how to deal with it but just want to scam u into making them rich by telling you to rebuild the whoole house. so it might be worth it to send someone down there and let them do the inspection.Let me give u some additional info:

1. How big are the cracks? Length and width.
> I didnt really measure the cracks, but they are not very wide…I can not fit a penny in them.
>Lenght varies from 2 feet to 5 feet

2. How do they run? Vertical? Diagonal? Horizontal? Combination? All the same orientation?
>combination. So none are a straight line.

3. How many cracks are we talking about, and how are they located? “Many” cracks, all on one corner of the structure? Or “one or two” cracks, widely separated? (Yes, you did say “all on the same side of the house”, but that’s not much to go on.)

>Let me try to illustrate it as best as i can…the wall with the most cracks is the north wall. That walll has a window in it. at each corner of the window there is a crack and it goes away from the window. on that same wall the is anothe crack that starts about a foot from the ceiling and goes down to about halfway of the wall…and that one is diagonal.
>Now on the wall adjacent to that one..the east wall..there are a few cracks going from top to bottom. They are located closer to the corner of the north wall. The east wall separates the living room from the kitchen. i am not able to see the wall in there due to the tiles.

4. What is the relationship of the cracks to the foundation itself? That is, do you also have cracking in the foundation?
>The house is on a slope, the bottom floor also has cracks on the same walls. Only on additional thing is that under the main floor we have a cistern(rainwater reservoir) it seems like the water has damamged the concrete wall and is cauing it to crack. so that east wall is not stable. the north wall on the bottom floor has had issues in the past. Water seeps inside from where it touches the foundation. this happens when it rains alot.

House was constructed in teh early 80’s. Its all brick. its a two story home on a hillside. I dont have much info on the foundation. it sseems that they do not keep records for more than 5 years…so the plans for the home are gone.

I hope I describe it well enough…if not just ask for more…
This is all new to me…I inhereted the home from my dad 10 years ago and I get to go there maybe once a year for 2 – 4 days. so i have limited time to inspect the home. its remains shut down for most of the year in that 90 degree weather. So i am assuiming the heat might be deterioating the home.

Just keep an eye on them. Measure them. Record your measurements. Next year do the same and see how much change there is. If it is changing only half an inch a year in length and a quarter of an inch in width, I wouldn’t worry until later on. If things are moving a lot faster, I would get it fixed. If they are moving a little bit faster, I’d be concerned, but I’d feel I had time to work on it.

I’m no expert. I’m just a homeowner who has holes in his basement walls through which rats are coming. We are having the walls fixed today. Well, one of them. I have a porch that slowly leans out and I have bay windows that have been settling. But the settling has been going on for 110 years. I’m not worried. The porch roof was rebuilt about fifteen years ago. I’m worried about that one.

Just to set you straight on one fact about contractors, @payochi, the highly competent ones have enough work on their plate as a rule already that they don’t want to be called for nickle-and-dime repair work… of a lesser contractor’s mistakes. So it’s not that the competent ones want to rip you off or scam you, but it’s true that they would rather rebuild from scratch rather than patch and patch.

But okay… you have brick walls. (Not cinderblock? Real brick?) And the cracks don’t run “through” any bricks, but are cracks in the mortar joints, correct?

Based on the detail you added about the house being on a slope, the damage to the “bottom floor” (so this is a two-story structure?) and instability of the “concrete wall” (I’m assuming this is a poured foundation wall), then it does sound like the foundation is part of—probably the major part of—your problem.

But “settling” is a problem mostly with newer structures where the soil was improperly compacted prior to the foundation pour, and the newly built structure gradually compacts the soil beneath until it reaches a stable point. You’re talking about a house that’s nearly 30 years old. “Erosion” could certainly be a problem, if rain / flood waters have weakened the support for the foundation and it seeks a new stable point.

As @wundayatta suggests, the best thing for you now is to monitor that (assuming there haven’t been major changes and the thing is in danger of failing completely) year by year to watch for additional cracking or growth in the existing cracks. As a general rule, horizontally aligned cracks are somewhat less severe than vertical ones. Vertical cracks indicate a structure pulling apart, and horizontal ones (unless they start to gape, run through the wall, allow seepage of water or entry of insects and vermin, etc.) will tend to refill as the upper structure settles back down onto the crack. Floors going out of level will suggest instability in the foundation, too.

But any crack that widens over time is serious, and should be looked into. If you can, find a surveyor who can “shoot” the corner elevations of your foundation against a stable benchmark and monitor those elevations year by year for settling and exactly where the problem lies. What you might want to do before fixing the walls (a temporary fix only, if the foundation continues to subside) is pumping in hydraulic concrete under the lowering part/s of the foundation in order to stop the subsidence and stabilize it. Then anyone can patch the mortar joints that have already cracked. If the subsidence is so bad that floors are warped and pitched, then it may be necessary to excavate underneath the low point and jack up the structure first, and then pump in concrete to stabilize.

That can all be pretty darn expensive. So I guess the first thing you need to do is ask yourself, “Is it worth all this aggravation and expense for a house that I only use for four days out of each year?” Yeah, I’m sure you have some emotional attachment to the place, but how much is that worth in dollars and cents?