Almost always the result improper footing under the pier. Have specified many underpinning repairs where that has happened.
Nothing …
For 2-2x10 bearing on an 8" wide pier … that would be 3" x 8" x 1,900 psi = 45,000 lbs. Thats not how ya do that calc, but you get where I am going with that. The typical pier loading is not even close to the actual capacity even at the upper end of typical pier spacing. Been there & done that with actual structural calculations.
Not really standard practice, but good practice to minimize building materials. Not a defect for a home inspector though.
Very true, and another reason to have the pier cap
The bottom line is a pier with the blocks transverse to the girder is just not a home inspection defect based on that alone. If I got called in to evaluate a typical residential pier just because it was transverse to the girder with that pier spacing I would have coffee shooting out of my nose … :mrgreen:
Bob, isn’t the 1,900 psi determined by the net area of the block in a Prism Test when testing for compression strength of the mortar and the block itself? I know damn well that this installation, the floor would not collapse, but the common sense that should be applied in the installation to begin with.
It is not a standard of practice to orient a block that way for floor support. I have been a builder long enough to know that and don’t need an engineer to tell me that it is OK.
Might have been like that for years, but nothing tells me that block won’t break tomorrow due to pin point loading on the center web.
Not something I would call out on an inspection under normal loading of a small house, but would under different loadings and know damn well this would not be acceptable in a commercial envioronment.
Where the concrete block is used for piers described in sentence (2) they shall be laid with cores placed vertically and when the width of the building is 4.3 m (14 ft 1 inch) or less they are placed with their longest dimensions at right angles to the longest dimension of the building.
This is Ontario’s way of doing things.
I don’t agree with it but it is what it is!
A Prism Test gives you the Masonry Compressive Strength (f’m), similar to cylinder tests giving you Concrete Compressive Strength (f’c) … http://www.astm.org/Standards/C1314.htm
Typical f’m values for hollow CMU with Type-M/S mortar are around 1,500 psi … the 1,900 psi is a typical compressive strength of the block itself. When calculating bearing stresses, an effective bearing area is used, which is actually more than the contact area due to load distribution (up to twice the contact area).
A typical failure load for a single 8" block is about the entire weight of a small to average size house … :shock:.
That is why prescriptive model codes only require 3" of bearing for a beam or girder on masonry … and those requirements consider that the very edge of the masonry may crack from deflection movements, leaving somewhat less that 3" as an effective contact bearing.
We are on the same page Marcel. I agree that its better to to have a CMU pier parallel to the beams in terms of the span if there is full bearing (typically not due to shims/spacers), but its more stable transverse to the beam. Orientation of crawl space piers doesn’t relate to their capacity, and is just not a defect for typical residential construction. Commercial is a whole different story.
Others dont seem to agree. Flagging a typical block pier on a home inspection just because it’s perpendicular to a wood girder and doesn’t have 16" of bearing has to be in the top five list of the dumbest things I have ever heard in over 9 years on this and other HI boards … or in my 25 years doing structural designs and evaluations.
That would also mean that all the model codes are wrong, and every single wood girder that has shims or bears on an 8" or 10" perimeter block foundation wall also needs to get flagged, because there isn’t enough bearing … really unbelievable … :shock:
I guess in your galaxy HI’s also flag every single residential block pier that has a 4x6 steel or PT wood shim/spacer between the girder and pier, because your not bearing on the full 16" pier length … :shock:
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So in the “It’s All About Safety Galaxy” you would need a 1-1/2" thick 8" x 16" ASTM A572-GR50 high tensile strength skyscraper style steel bearing plate, instead of smaller steel or wood shims/spacers the way the rest of the galaxy does it, just to make super sure a residential wood beam has full bearing and the individual pier can support more than twice the entire weight of the house … :roll:
Hollow core block should always be positioned to maximize the net surface area of the block to obtain the most value. I would think that is a standard of practice in Canada only using cmu masonry for bearing units.
Nevertheless, I disagree with calling out piers simply because they are in “the wrong direction”. Number 1, there is no code that prohibits it. Number 2, nobody’s going to change it based on only on your experience and opinion. Number 3, any home inspector who calls that out is going to made to look foolish.
Not something I would call out on an inspection under normal loading of a small house for the main beam or girder, but would under different loadings and I know that this is not acceptable in Canada for most contractors.
3 floor house with a center beam YES
1 floor NO
Old house supported with CMU YES
CMU not filled with mortor YES.
CMU with no support in sand YES
To tell an inspector he is dumb is just setting yourself up to be off the MB.
