Originally Posted By: rdawes
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Originally Posted By: bkelly2
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Have you tried the technical links page Ron?
http://www.nachi.org/bbsystem/viewtopic.php?t=13602
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“I used to be disgusted, Now I try to Be amused”-Elvis Costello
Originally Posted By: roconnor
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Typical Pier & Beam foundations would have reinforced grade beams that span from pier to pier. In fact in areas that have expansive soils, a compressible filler material is placed between the soil and the grade beam to allow for soil expansion.
Look carefully at the grade beams for potential cracking that may indicated it might not have been reinforced, and be mindful of possible moisture penetration and soil erosion, depending on the circumstances, if the voids are not filled.
See this link for additional info ...
http://www.houston-slab-foundations.info./
JMO and 2-nickles ...
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Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: rdawes
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Thanks for the references gentlemen. Much appreciated.
Ron
Originally Posted By: mcyr
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Robert; Hope you are not confusing this person.
You talk about grade beams and typical pier & beam foundations.
I might not be aware of how they do this in Texas, but here in Maine, footing piers are poured over engineered structural steel piles and the structural grade beams span these footing piers from 10' to 20' depending on the design.
We do not deal with expansive soils up in this area, and therefore, you are correct in stating that a cushion is required in that area for this.
What kind of piers are you talking about, and what size are the grade beams you are referring to?
Realizing that this geographical area is different in structural designs, I am a little curious as to what you are trying to say.
In my opinion, all this information is above and beyond the scope of a regular HI and might confuse some in technical terms as such.
Again, the terms that you use, I convert to Commercial applications more than residential and I sometimes get confused as to what I am suppose to comprehend.
Are you talking of grade beams and piers for a small residential dwelling?
If you are, I would be interested in how this is accomplished on a small scale for that area of the country.
Marcel
Originally Posted By: roconnor
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The actual construction of pier and beam (P&B) foundations varies greatly. However, the basic components usually consist of piers or piles spaced somewhat apart that are drilled/driven to suitable soils, and then there is a steel reinforced concrete beam that spans between the pier/pile supports. Note that the correct term for the beam that spans between piers or piles is called a “grade beam” (it’s a beam that rests on grade, but the soil does not support it like a spread footing …
).For residential construction in my neck of the woods I will usually design 16" to 24" diameter drilled sonotube concrete piers or light/medium duty drilled in helical steel piles (e.g. AB Chance piles) spaced about 6' to 8' apart. The concrete beams that span from support to support (called "Grade Beams") are usually about 12" to 24" wide and about 30" to 48" deep. In areas with expansive soils, or where frost heave is an issue, I usually call out for a pretty thick layer of compressible but stable bead board under the grade beam to allow for movement.
Another type of common residential foundation construction with poor soils in my area consists of more closely/regularly spaced driven wood piles or drilled in helical steel piles, with a heavily reinforced footing (essentially a "grade beam"). But that is just referred to as a "pile foundation", and not a "pier and beam" foundation.
Usually the heavy steel piles (or concrete "pile caps" with multiple piles at each support) spaced about 10' to 20' apart, with very heavy grade beams is only used in commercial construction around here.
However, the basic concepts of a visual inspection of the foundations is also applicable to a home that has that type of construction (deterioration, movements, cracking, etc.). Make sure to also look for indications of movements at the supports or the building as a whole, and check for any significant cracking of the grade beams ... particularly near the supports which could indicate some type of support/shear problem, or cracking near the middle of the grade beam which could indicate poorly constructed or undersized grade beams.
JMO and 2-nickels ... 
--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: mcyr
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Thank you, that was interesting.
It does somewhat appear to be similar in design, but on a smaller version of commercial work.
Marcel