House Shifting? How Concerned Should I Be?

[crokett™]

My house is modular.  7 years old.  2 boxes, the back half and front half.  The marriage wall runs lengthwise down the middle of the house.  I was doing the last of the plumbing on the new main line for the sprinkler and happened to notice the siding on the front of the house was spaced off the foundation.  The sheathing hangs down about 3" from the bottom of the bottom plate on the wall.  At first I thought the sheathing was pulling away from the wall.  I can fit my fingers in the gap between the sheathing and the foundation.  I can feel and see that the bottom plate overhangs, the sheathing is still tight to it. It seems to be a fairly consistent gap along the front of the house.  The front porch is tight to the front of the house and it is lined up with the foundation along the front edge.  My presumption is if the front of the house had moved at all, it would have pushed the porch forward as well, or be bowed in because the porch isn't moving.  The treated sill plate has not moved.  The edge is still lined up with the foundation. At the moment I am assuming that the front box was just placed poorly, or the foundation was built 3/4" too small, or something like that.   Should I be concerned enough to go under the house and check things out? There's no evidence inside the house that the boxes are separating - no cracked drywall, no doors that stick, etc.

[Snipe Hunter]

I've seen a home like yours where the interior doors weren't seating against the stop molding. They doors were tight against the stops at the bottom bot not touching the stops at the tops of the doors. The house was about 15 yeas old (iirc).

I hadn't gone through the crawlspace yet, usually I go in the crawlspace last. In the attic there were metal ties, about 10" long strapped across the two halves of the structure. Effectively connecting the two halves together. The ties were screwed into the top of the plate of the two abutting walls. About half of the straps/ties had pulled loose and the top of the two abutting walls had moved apart about 1" at one end of the building. About 1/2" movement in the middle of the building and almost no movement at the other end. That's pretty significant movement as far as I'm concerned.

We found a crack in the middle of the foundation on the side of the home with the movement. The crack was fairly small, about 1/8" at the top of the crack and hairline at the bottom.  All I could see was about 18" of the foundation above grade. I could sight along the sill plate in the crawlspace and see that it was bowed upward in the middle. I guess that was enough.

I don't remember seeing any issues with the siding but this was about 5 years ago so details like that didn't stay in my brain. I would assume there would have been some loose siding. Have you looked at the siding by sighting along the bottom for an upward bow? Or have you looked in the attic? A lot of times I miss foundation problems but because they get amplified on the roof or in the attic, I see the problems there... Just about all foundations have cracks so I don't get too worked up abut them unless I see it causing other problems.

They didn't buy the house. Not because of the problem but because the seller wouldn't cut the price of the home enough to get it fixed.

If the seller would have worked with them, the plan of action would have been:
1. Hire a structural engineer to evaluate it and make repair recommendations.
2. Get bids for repairs.
3. Ask the seller to pay for the engineer and repairs prior to closing or reduce the price of the house that amount.

By the way... failing roof trusses can also cause the two halves spread apart but I don't think you'd see siding problems on the sides of the house.
You will probably see the front and back exterior walls bowing outward where the trusses are failing. You might see a valley/sag along the roof line. This is a pretty easy fix. Pull the two halves back together with comealong winches and repair the trusses. 
The house also had a new roof on the front and about a 30 year old roof in the back.
. Looked good from the street.

The way they fix these is to determine if the foundation is still moving. If it's not, They might just jack and shim up the exterior walls to level and re-seal the bottom plate at the foundation.

[crokett™]

I haven't looked anywhere, except for the front side of the house. The roof line looks straight, no sagging or anything else. I was looking at it yesterday after a big storm, and thinking I needed to clean my gutters. That was before I noticed this. To be clear, the band joist is not lifting off the sill plate. It is still tied down. I don't see any vertical separation between it and the treated plate on top of the foundation. There are no cracks in the foundation, there are no problems with any of the doors in the house. My house is not framed with trusses. It is framed with rafters and collar ties. The rafters are attached to the top of the attic floor on hinges and the roof is laid flat for transport. After the boxes were set, the crane picked up the roof in sections. Kneewalls were then folded up to hold each roof section in place. then the final 3' or so of the roof is unfolded to meet at the peak. Collar ties are added later. These form the ceiling of the 2nd floor.

[Willyou]

I think that if there is movement it will likely continue. Unless there is something that needs immediate attention, try making some reference marks in a number of places and check them from time to time to see if you can detect actual movement. From your description, I would guess that the misalignments occurred during construction/assembly. This is not necessarily good, but if it is not causing problems, it is probably easiest to watch it and live with it.
I live in a stick built 35 year old house on a slab foundation. When doing some deck work, I noticed that the sill plate along part of one side over hangs the slab by about an inch. It's an aggravation, but not a problem. It was just built that way.

[Snipe Hunter]

I haven't looked anywhere, except for the front side of the house.  The roof line looks straight, no sagging or anything else.  I was looking at it yesterday after a big storm, and thinking I needed to clean my gutters. That was before I noticed this.  To be clear, the band joist is not lifting off the sill plate. It is still tied down. I don't see any vertical separation between it and the treated plate on top of the foundation.  There are no cracks in the foundation, there are no problems with any of the doors in the house.  My house is not framed with trusses.  It is framed with rafters and collar ties.  The rafters are attached to the top of the attic floor on hinges and the roof is laid flat for transport.  After the boxes were set, the crane picked up the roof in sections. Kneewalls were then folded up to hold each roof section in place.  then the final 3' or so of the roof is unfolded to meet at the peak.  Collar ties are added later.  These form the ceiling of the 2nd floor.

You won't, it's tied to the foundation. The bow is transferred from the foundation to the sill plate. They both were bowed.

[crokett™]

I think that if there is movement it will likely continue. Unless there is something that needs immediate attention, try making some reference marks in a number of places and check them from time to time to see if you can detect actual movement. From your description, I would guess that the misalignments occurred during construction/assembly. This is not necessarily good, but if it is not causing problems, it is probably easiest to watch it and live with it.
I live in a stick built 35 year old house on a slab foundation. When doing some deck work, I noticed that the sill plate along part of one side over hangs the slab by about an inch. It's an aggravation, but not a problem. It was just built that way.

That's what I was thinking.  So I will mark spots along the front and measure the offset to see of they are growing.  I am thinking the house was just built that way and I am a guy that looks for problems where there aren't any....

[Stwood_]

It's normal to have a little space on a foundation when sitting a box on top of it.
If it was exact, that might be lore of a problem. Sitting that box down and crunching some siding or......
Also if one or the other is a tad out of square, that extra space in invaluable.

[Willyou]

That's what I was thinking.  So I will mark spots along the front and measure the offset to see of they are growing.  I am thinking the house was just built that way and I am a guy that looks for problems where there aren't any....

As some very wise person said long long ago, better safe than sorry.

[crokett™]

It's normal to have a little space on a foundation when sitting a box on top of it.
If it was exact, that might be lore of a problem. Sitting that box down and crunching some siding or......
Also if one or the other is a tad out of square, that extra space in invaluable.

That's a good point.

[jamesglenn]

As others noted, the foundation was likely built slightly too small, or on purpose for ease of setting the house. The overhang is seen quite a bit actually, but in your case with the sheathing hanging down past the sill it's more prominent for noticing. Most foundation walls are not straight if you ran a string line to them, even a 1/2" bow would equal the 7/16" osb sheathing and make it flush in one spot and overhang another. 

With no other noticeable cracks, sags, or shifts; I would be inclined to say it was built this way. Tracking is always a good idea though, to at least ease your mind from worry of nothing else.


I have these moments as well, all the time; and track things so I can sleep at night instead of wondering.