Interior sheating for a cement block house 3

[handler1]

I own a two story, 50 years old house made of cement blocks on a cement foundation on heavy clay soil.
I wanted to renovate it so it was completely striped inside( save for the floors).
Last year in winter it went un-heated for a while and developed four long cracks from top to bottom, not far from the four corners of the house. After re-heating the basement, it went back to the original position

a) The contractor placed a metal strap across each crack on the interior side of the exterior walls at each level (basement, first and second floor)

b) 2x6 walls were build on the interior side of the block cement walls, then insulation was installed and covered with vapor barrier (first and the second floor).

I will like to increase the lateral load resistance (although the contractor does not think is needed) :

1) Place OSB sheets on the interior side of the 2X6 (sort of interior sheathing- make it more like a framed house with the cement blocks wall like siding) and then cover the OSB sheathing with drywall.

OR (AND)

2) Strengthen the 2X6 wall with diagonal braces (2X4)

a) Is this a good idea ?
a) Is it any drawback of having drywall on OSB ( humidity problems)?
b) Are diagonal braces going to giving comparable strength to the sheathing ?

 

[ToadJones]

None of it will be effective unless the new "lateral system" can actually transmit loads to the foundations.

 

[handler1]

The interior 2X6 walls are bolted to the floor and ceiling.
The floor is also bolted to the cement foundation wall.
Wouldn't the whole system act like a rigid box ?

 

[MiketheEngineer]

Like noted - if properly bolted to foundation - it "might" work.

 

[cvg]

so the floor and ceiling are now all part of the interior framing, but it sounds like nothing is bolted to the concrete (not cement) block walls and the concrete block walls are non-reinforced. Are you sure those metal straps are good enough? What about the concrete (not cement) foundation, is it adequate? I would think possibly not. What will happen during a good wind storm or even an earthquake? you need to hire a structural engineer before your contractor spends any more of your money.

 

[handler1]

The floors/ceilings are tied to the concrete block walls so I guess they act as diaphragms of the structure.
The foundation has only a couple of hairline cracks.

My questions were related to the fact that without interior sheathing or diagonal braces the interior wall add no strength.

1)Is the internal sheathing adding significantly more strength the the diagonal braces?
2)Is the interior sheathing even used in general practice ?
3)Does it mater how the OSB sheets are placed (horizontal or vertical)?

 

[cvg]

so going back to your original issue, it went unheated, the foundation heaved causing the cracks. after heating, the subgrade dried out, the foundation may have settled some and the cracks closed up. sounds like the foundation is inadequate because a) not below the frost depth or b)not founded on non-frost susceptible material. or possibly there are drainage or groundwater issues causing the heavy clay to swell under the foundation. when did you observe the foundation cracks, before or after re-heating? Shouldn't the foundation be investigated and repaired first since it apparently caused the cracking in the first place?

 

[handler1]

The cracks were noticed after a week of temperatures below 10F and they closed shortly after the house was re-heated.
Contractor's opinion was that it was due to insufficient drainage. Actually the house did not have a perimeter drainage system.
Also the house was not supported properly inside at that time since all interior walls were removed. The second floor and the roof were supported with 4X4 beams.
An exterior drain tiles system is scheduled for the spring.

 

[JAE]

Don't you think you need to get an engineer involved in this?

We don't know the local codes, the required seismic or wind design criteria for the location of the building. We can't see all the conditions of construction, we don't have the exact building dimensions, can't do any calculations to verify if your diaphragm has the required capacity, etc.

We can offer suggestions but this sounds like you need to get someone on the site to properly review it.

 

[handler1]

Thanks
I will get an engineer on site.