8x16 masonry piers installation in Crawl Space

[dannyypk]

Hi all, I cannot find any code reference ( except modular home code) regarding 8x 16 masonry pier orientation.

Is the 8x16 piers supposed to be :
Pier Long side parallel to the girder
Pier Long side perpendicular to the girder

Or it doesn’t matter.

 

[XR250]

Perp. gives you a little more slop in the girder placement and is a little more stable.

 

[BridgeSmith]

I would orient them with the long direction parallel to the highest expected lateral loading. If lateral loading is negligible, and the bearing area is sufficient with the blocks perpendicular, for the reasons XR250 mentioned, I'd also say perpendicular would be better.

 

[dannyypk]

Thanks for the reply.

Most of the girder and pier design in residential are not designed to take any lateral loads. (no positive connection from girder to masonry piers, wood girder just seat on top of the piers)

Per code, a solid masonry block should be installed on top of the piers to distribute the loads to the piers.

 

[BridgeSmith]

Even without a positive connection, there's easily enough friction to transfer lateral loading to the pier, if it exists and is not resisted elsewhere. If there's not bracing for wind loads, etc. elsewhere in the foundation system, then those loads must be carried through the piers. It would seem prudent (or required?) to consider the lateral load the pier might be subjected to, and check whether the vertical load and height to base width ratio of the piers is sufficient to prevent overturning.

 

[dannyypk]

HotROD10,

so what if you look at the mobile home with only dry-stack piers?

Let's not considered there is any lateral load for these piers.

 

[TheDW]

Dry stack piers with no positive connection to the structure above? Sounds like a temporary structure to me, whether intended or not

 

[Ron247]

Is this a mobile home or a house? Mobile home foundations are not similar to housing unless someone sets up the mobile home foundation per the "Permanent Foundation Guide for Mobile Homes (PFGMH). The state I live in has a State Mobile Home commission. They allow dry-stack block, concrete foundation pads set on top of the ground etc. Houses are not allowed to be built in the same manner.

 

[BridgeSmith]

I definitely would consider lateral load from a mobile home on its foundation system, especially with dry stacked piers. Typically not too hard to keep the eccentricity within the footprint of the blocks, but I would want to be sure.

 

[dannyypk]

My original question is the orientation of 8x16 masonry piers in a crawl space relatively to the girder.

I just don’t buy the idea the interior masonry piers will need to take lateral load. The designed lateral load path is through the sheathing to the sill plate through anchor bolts onto the perimeter foundation wall.

 

[XR250]

I just don’t buy the idea the interior masonry piers will need to take lateral load. The designed lateral load path is through the sheathing to the sill plate through anchor bolts onto the perimeter foundation wall.

Exactly. The only lateral load would be from girder instability.

 

[BridgeSmith]

XR250 and dannypk, I agree with you; where another load path exists, through the sheathing, etc. there is no no need or opportunity for the piers to take lateral load. That is why I qualified my suggestions by saying "...lateral loading to the pier, if it exists and is not resisted elsewhere. If there's not bracing for wind loads, etc. elsewhere in the foundation system, then those loads must be carried through the piers." Many mobile home installations do not have sheathing, but rather skirting, which does not provide much in the way of a diaphragm for bracing.