# Deck Pier/Footing Size and Tributary Loads



## jar546 (May 11, 2012)

Around here, we are often lucky to get soil compaction tests for commercial projects of 2,000 psf.  For residential, it is beyond rare that we have tests performed (I did have 1 person pay for one within the last year) just to find out it was 1,500 psf.  We could have just assumed a 1,500 psf bearing capacity right from the IRC and saved him money, but that is another story.

We consistently get deck designs that have undersized piers/footings.  I usually tell people to just download the DCA-6 manual and go from there but some of the deck designs are more complicated than the simple tables that they have making it hard to use realistically.

Even when we go over the requirements for simple residential stuff, it is still not what we find when we get out there.

Yesterday's inspection for a pre-pour with 12" Sono-Tube was as follows:

Rectangle deck 16 x 32, long axis with the house.

They had planned 4 - 12" sono tubes to support the beam.

The tributary load for that worked out to 3,200# per pier.  Not even close.

This is based on a live-load of 40# per deck requirements and a 10# dead load.

I was not a very popular guy yesterday.  I even had to explain that a 12" sonotube is only about 75% of a square foot.

Do you guys have the same problem?  It seems like most inspectors in our area just don't give a crap.


----------



## mtlogcabin (May 11, 2012)

http://www.bigfootsystems.com/include/best_footings.htm



> http://www.bigfootsystems.com/include/best_footings.htmDo you guys have the same problem?
> 
> http://www.bigfootsystems.com/include/best_footings.htm


http://www.bigfootsystems.com/include/best_footings.htmNo we see these used about 90% of the time and we check the pier footing loads with Strucalc

http://www.bigfootsystems.com/include/best_footings.htmhttp://www.bigfootsystems.com/include/best_footings.htm

http://www.bigfootsystems.com/include/best_footings.htm' rel="external nofollow">


----------



## Francis Vineyard (May 11, 2012)

We have more of a concern with footings not deep enough on slopes than undersized. Historically there has not been a failure of simple spanned decks with plain footings 6 inches thick. For 2-tier decks I use the calculator but most of the time they are submitted 24 inches square and 10 inches thick regardless.

It may be the inspectors don't know how to use a calculator or as you say don't care.

Francis


----------



## TheCommish (May 11, 2012)

Decks have allways scared me, I have seen a few fall off. I have attached my excel caculator for sono size, the unfinished draft om my guidance for  decks (based on the DAC manual) and a deck templete drawing, it is amazing how many cant draw a simple deck. well I was going to but the files are to large

Any hints group?

I recomend spread footings for any deck that there is a slight chance of a roof being put on and require spread footing for anything that has a roof even the 6' farmers porch.

I find that the center pier of anyhing over 10x10 the center tube need to be at least 16" diamater

I tell customers it is easyer to fix it on paper than have to take a do over.


----------



## DRP (May 11, 2012)

I keep my spreadsheets here; timbertoolbox.com I'd be happy to stick it there and you could link to it if you're comfortable.

I've never been comfortable with an unfooted sonotube, I can't recall a plan that didn't at least start with a 2x2x8" w/2 #4 bars ea way. Personally I prefer to bury a .60 6x6 post from footing to top of rail and avoid hinges. The decking will need replacing well before the post at which point the frame is being scrutinized again.

One of the form companies is touting "code approved" for it's forms in the glossy mags and there is an ESR that acknowledges that the form is made to hold concrete. I'm seeing houses on the net going up on these and it's "code approved", just like the ad says.


----------



## Mark K (May 12, 2012)

When manufacturers claim their product is "code approved" because they have an ESR they do not understand what an evaluation report is and they do not understand that the only approval that counts is the approval of the local building official.


----------



## DRP (May 12, 2012)

Oh, the manufacturer knows exactly what they are doing when they print that ad.

But the other side of that is that we do not have good prescriptive guidelines for typical pier situations.


----------



## jar546 (May 12, 2012)

Another issue we contend with is when they want to frame a roof over an existing deck.  Depending on what elevation they are building at, we have a ground snow load that varies from 40-55.

I make them dig up at least one pier to see what size it is.  They are usually ****ed about this because most of the time it is nothing more than a 4x4 in the ground with sakrete poured around it.  Something we don't allow


----------



## peach (May 12, 2012)

16x32 is a pretty big deck.

Plan review needs to catch it up front.  4 piers may not work, 5 or 6 might.

It's up to the designer whether to go 4 bigger piers or more of the 12" circular (or a design that utilizes soil friction against the posts).

Should not get to the construction phase when there is so much delta on the bearing capacity.


----------



## TheCommish (May 12, 2012)

DRP

nice site, can i link it on my web page? http://townofcharlton.net/buildinginspect.htm

i wll send you my excel caculator if you pm me


----------



## DRP (May 12, 2012)

Sure, feel free, check your PM's.


----------



## Francis Vineyard (May 13, 2012)

jar546 said:
			
		

> Another issue we contend with is when they want to frame a roof over an existing deck. Depending on what elevation they are building at, we have a ground snow load that varies from 40-55.I make them dig up at least one pier to see what size it is. They are usually ****ed about this because most of the time it is nothing more than a 4x4 in the ground with sakrete poured around it. Something we don't allow


Could place the new roof column footings on outside perimenter of the deck footings.

Francis


----------



## jar546 (May 13, 2012)

Francis Vineyard said:
			
		

> Could place the new roof column footings on outside perimenter of the deck footings.Francis


Absolutely, which is what we often recommend.


----------



## Builder Bob (May 14, 2012)

Often times a quick checklist made avaialble to the public will help.... not a design guide but a generic checklist with most common violoations/errors/omissions on it.


----------



## steveray (May 14, 2012)

We fight it here a fair bit, we have decent soil, I figure most of them at 2000#psf they usually are pretty close. They can add more piers, hog out the bottom of the holes, or put bigger tubes in.....


----------



## Papio Bldg Dept (May 14, 2012)

jar546 said:
			
		

> Do you guys have the same problem?  It seems like most inspectors in our area just don't give a crap.


Eveeeeery day!  ...and we even make sure they are sized correctly at plan submittal.  We get a lot of, "i've been doing this for twenty years and haven't needed anything bigger than an 8" footing."  They often balk at the frost protection requirement when attached to a house.


----------



## DRP (May 14, 2012)

Are we only concerned with vertical loads?

Are there conditions on where the column is hinged and how it is footed?

A picture of a pier several feet tall in a basement with a post on it supporting a girder drew comments the other day. If I have a 12" pier 4' tall into and top flush with grade and then place the post on it then there is an assumption that something is somehow different. Now start extending that post to pier connection into the air, when does your discomfort rise or does it?


----------



## jar546 (May 14, 2012)

DRP said:
			
		

> Are we only concerned with vertical loads?Are there conditions on where the column is hinged and how it is footed?
> 
> A picture of a pier several feet tall in a basement with a post on it supporting a girder drew comments the other day. If I have a 12" pier 4' tall into and top flush with grade and then place the post on it then there is an assumption that something is somehow different. Now start extending that post to pier connection into the air, when does your discomfort rise or does it?


My post was specific to footing sizes and did not address other issues.  All other issues are also dealt with but this was specific to vertical loads.  Don't forget that the 2009 IRC improved the requirements for lateral loads with R502.2.2.3 and ledger attachment addresses both vertical and lateral loading under R502.2


----------



## brudgers (May 14, 2012)

jar546 said:
			
		

> Another issue we contend with is when they want to frame a roof over an existing deck.  Depending on what elevation they are building at, we have a ground snow load that varies from 40-55.  I make them dig up at least one pier to see what size it is.  They are usually ****ed about this because most of the time it is nothing more than a 4x4 in the ground with sakrete poured around it.  Something we don't allow


  SSTD 10-99 has buried column requirements with and without concrete.  They're for uplift, but similar resistance will occur in the other direction.


----------



## dhengr (May 14, 2012)

Jar546:

Maybe one of the things you should do in permitting a deck or porch, is to make a list of a few things like a potential future roof over the deck or porch, if this is a regular problem, so you can make a determination on the lower structure, posts, piers and footing, and make this part of the file for future reference.  And, at the same time they sign off on this, I would explain the need for larger structure now, for these future loads, otherwise forever hold your peace.  This list might include any other areas which are typical problem areas in your experience.  In working with a client at the beginning of a design project, I certainly want to know all the potential load conditions.  We can’t design for or accommodate conditions we don’t know about.  I would also question a little the intended use of such a large deck, large parties, dancing, etc. for increased LL considerations, joist flexibility (vibration/deflection) and for lateral load considerations.  The 16' long deck joists are pretty long and they will require some special attention at the ledger at the bldg.  Also, on a deck with the outer handrail 16' from the bldg. ledger beam, where a lot of wild action can occur, I would pay some special attention to lateral stability out there.

Given the 16' x 32' deck and 4 posts with 12" sonotubes, I get a larger footing load than your 3.2 kips per footing.  You have over simplified your tributary area calc., thus (8' x 32')(40 + 10)/4 = 3,200 lbs., but it’s not quite that simple.  The two outer corner posts have a lesser load, about 2 kips and the inner two posts have loads of about 4.8 kips, these are just off the top of my head proportions, no actual calcs., and a 4' deep pier weighs another 500 lbs.  But, if the outer beam is moved in under the deck a foot or 18" which is common, and the outer corner posts are moved in so the beam cantilevers a foot or 18", also common, we could actually run some reaction calcs., and the posts would be even more highly loaded.  The 12" dia. sonotube is most likely o.k. from a column strength standpoint, but the footing sized must be sized for the loads and soil bearing capacity.  The 12" sonotubed could be belled out at the bottom to pick up bearing area.  The biggest warning about these piers or footings is that they bear on undisturbed (virgin) soil, or at least well recompacted, at the bottom of the hole.  They should not be cast on 6" of loose crap, or they become settlement problems.  I would also like to see some vertical rebar in these type piers.

DCA-6 is certainly a good general knowledge guide for deck design, but you still have to read all the footnotes and read between the lines and do some interpolation at times.  Like all the tables in the IRC, they cover the simplest, most basic conditions conservatively, and can be easily abused if you don’t have a reasonable idea of what’s really involved in a complete structural design.


----------



## Keystone (May 14, 2012)

Jar,

Deal with the same issue, many unhappy residents along the way. Picked up PlanAnalyst software and now cross check with that.

I believe big orange and blue box stores may have added to the problem in conjunction with the well intended weekend warriors and Johnny be Builder by utilizing positive assumptions in design values for deck calculators, hence the abundant acceptance of 10 and 12 inch piers.


----------



## Sifu (May 14, 2012)

IRC lack of prescriptive requirements for decks surprised the heck out of me when I first read it.  My old code had an appendix for prescriptive deck construction that gave minimum sizes. (it also had prescriptive minimum sizes for interior pier footings as well).  I have found the area MOST lacking here is deck construction.  It has been an after-thought forever, they can't seem to understand that at its base it is a floor system and one that is subject to wet use and likely will be under greater stress at times than other floors.  I use the booklet but for the mist part they treat it the same as the code (we don't need no stinkin' code).  My old state had some pretty bad deck failures before they got on the ball.  Unfortunately that may be what it takes in other places as well.  BTW, the absolute minimum was 16x16x8 depending on trib size (if I remember correctly) in that code.


----------



## twistr2002 (Jul 27, 2012)

Here is a link from our website for a deck guide book that we use, to help people understand the codes for deck construction.

http://www.erbinspections.com/Forms%20&%20Guides/DeckGuide.pdf

The most common issue we have in our area is header sizing more so than footer size but footers are a close second


----------



## Francis Vineyard (Jul 27, 2012)

Twistr I refer to that handout and have the original edition too.

Has anyone link this calculator? http://www.ideasfordeckdesigns.com/calculators/deck-load-calculator.php

Francis


----------



## jar546 (Feb 27, 2014)

I am revisiting this as it gets a lot of views.

Does anyone have anything to add to this?


----------



## georgia plans exam (Feb 27, 2014)

http://www.dca.ga.gov/development/constructioncodes/programs/documents/2012IRC-DeckManual2014Amendments_001.pdf

This is an optional method in Georgia.

GPE


----------



## georgia plans exam (Feb 28, 2014)

Oops! I don't think that link worked. Will try again tomorrow

GPE


----------



## Glenn (Feb 28, 2014)

This subject is being discussed by the group I am working with on deck codes.  We did not propose a deck foundation table for the 2015 because we could not agree.  It is the only part of a deck vertical load path that won't have a prescriptive design method in the 2015 IRC.

There are many areas where 10 and 12 inch round piers, 36 to 48 inches deep have been performing just fine, though undersized according to IRC methods.  It is hard to suddenly begin requiring 16 inch round piers on backyard decks when 10's have been there for 20 years doing just fine.  This is on areas with 1500 to 2000 PSF soils (soils reports)

On the contrary, regions without frost depth have no problem with wide footings, as they are only 12 inches deep.

Regarding your average deck, here's the deal...

Everyone shoots for a 2 to 3 bag hole, whether wide and shallow or narrow and deep.  That's my observation.

Though skin friction is disregarded in the upper 10 or so feet for deep piers, perhaps shallow piers for decks can still generate side shear.  From what I have studied on this topic, the lateral forces of a building impose the most lateral force at the top of the piers, which reduces the friction at the sides of the piers at the top...thus the discredit.  On a typical upper level deck, there is no lateral system that extends to the top of the piers.  Therefore loads on a deck may move the deck, but only rotate the top of the post about the pier below.  For this reason, perhaps a shallow deck pier maintains friction against the adjacent soil and thus has some side shear value that helps support the pier.  I've also read that the side shear will engage first, before the end bearing, thus taking some load off of the soil below.

But there's more.  There is also a wonder if the tabular compressive strengths for spread footings in the IRC, designed for rigid structures like a home, are appropriate for more flexible structure like a deck.  For example.  A 40 foot long spread footer supporting a house cannot tolerate much differential movement across it's length.  The slightest will result in cracking and noticeable serviceability issues in the house.  A deck, however, is on isolated piers or footing pads.  Slight differential movement between these do not create near the damage or issues as the former.  There are safety factors included in the derivation for the compressive values.  It has been questioned whether different, more liberal, safety factors could be used in decks.

8" diameter piers are even common for decks around here.  Here's the deck handout from the Colorado Chapter ICC... "8" minimum"  Why is that?  Because they seem to have been working for decades.

This topic is definitely being discussed amongst the deck industry.  I don't know what the best answer is yet.  This is something still to be discovered.

Hey Jeff... You asked for it.


----------



## JBI (Feb 28, 2014)

I agree with Glenn (I think... :? ). The Residential Code's floors are rigid diaphragms and intended to be a part of a much larger system of components that resist a variety of lateral forces while supporting various loads.

Decks are not. They are more like large kites bolted to the exterior and subject to much different forces.

Every cycle the IRC moves closer to prescriptive deck design, be that good, bad or somewhere in between.

Though not generally a fan of big box retailers, the plans I've seen from their software seem to be conservative in design - 6 x 6 columns and 2 x 10 joists for a 4' deep, 6' foot wide entery deck for example. In my NYS jurisdiction that was a tad bit of an overdesign.


----------



## jar546 (Feb 28, 2014)

The issue with soil bearing can never be a one or two size fits all due to the complexity and variation of soil types beyond bearing capacity and frost or no frost.  I for one do not see any massive simplification changes of the codes in this area.  The amount of solid data from all inclusive testing would be extremely expensive to attain.  The situational variables are too numerous to even attempt to dumb this down for the profit of a niche industry.  Engineers and architects for the most part seem to get it as their designs routinely exceed the prescriptive code requirements by a pretty good margin.  It is the contractors who push the envelope in the opposite direction due to their ignorance of the codes and simple math.

I see this as really simple math based on soil conditions and soil bearing capacity.  What has "always worked" in the past is nonsense because it is not scientific.  Much of this is based on the fact that the structure is still standing.  No deflection or elevation data during, and post construction was ever recorded over a period of years.  In many areas of our coverage covered decks have obvious defects 5, 10 and 15 years later with stretched roof flashing, open "v" gaps at the point of attachment and deck floors that are wavy due to sinking of piers.  In all of those situations, improperly sized footings and piers were to blame.  The soils in many areas of coal country is loaded with old coal ashes that were dumped in back yards for over a hundred years and worked their way into the soil.  We saw this same issue outside of the coal region too in better soil conditions.

Until a micro-niche, for profit industry is successful is changing basic mathematical, time proven physics in order to change the code, we will continue to use common sense and prescriptive methods as enforcement.  Life will go on for all of the successful, profitable contractors who have a grasp and understanding of soils and bearing capacity and have been designing and installing deck piers this way for years.


----------



## JBI (Feb 28, 2014)

"What has "always worked" in the past is nonsense because it is not scientific."

That is actually the basis for most of the masonry provisions in the code... 'Empirical' design.

Other than that I agree with you Jeff.


----------



## mjesse (Feb 28, 2014)

jar546 said:
			
		

> What has "always worked" in the past is nonsense because it is not scientific.


I have to disagree with you here. Empirical methods of design DO work and are often retroactively verified.

Joist spacing, joist spans, rafter tables, etc. have all "evolved" from the tried and true of our great-great-grandfathers.

Just because grand-dad couldn't multiply the modulus of elasticity by the moment of inertia doesn't mean his knowledge was nonsense.

{JBI beat me to the punch}


----------



## jar546 (Feb 28, 2014)

JBI said:
			
		

> "What has "always worked" in the past is nonsense because it is not scientific." That is actually the basis for most of the masonry provisions in the code... 'Empirical' design.
> 
> Other than that I agree with you Jeff.





			
				mjesse said:
			
		

> I have to disagree with you here. Empirical methods of design DO work and are often retroactively verified.Joist spacing, joist spans, rafter tables, etc. have all "evolved" from the tried and true of our great-great-grandfathers.
> 
> Just because grand-dad couldn't multiply the modulus of elasticity by the moment of inertia doesn't mean his knowledge was nonsense.
> 
> {JBI beat me to the punch}


Both of you are taking one part of a statement without taking the explanation into consideration for reasoning.  That is not a blanket statement, it was specific to deck piers and came with an explanation.  Just because it is still standing does not mean there are not defects and movement, deflection.  Taking this to lumber and grand-dads is going out of context to the initial intention.


----------



## mjesse (Feb 28, 2014)

jar546 said:
			
		

> Both of you are taking one part of a statement without taking the explanation into consideration for reasoning.  That is not a blanket statement, it was specific to deck piers and came with an explanation.  Just because it is still standing does not mean there are not defects and movement, deflection.  Taking this to lumber and grand-dads is going out of context to the initial intention.


Fair enough.

Engineering and science are key to good design, no dispute.

There are folks with local experience can look at an excavation and tell you if the soils are good for 1500 or 3000 psi no test required. They've been digging the same dirt for a long time.

As Glenn says, hard soils technically require a larger footing than history proves is necessary. The first time I had an architect spec 24" diameter piers for a ground level deck, I was floored! I and others had built untold numbers of decks with 8" or 10" piers in same area over many years. Why the giant increase? Someone finally took the time to do the math.

Should this cause immediate concern that all the decks on 8" piers are danger? Probably not. Are they subject to undesirable movement? Maybe. Should they all be discounted as defective? No.

As you've said, this niche industry shall continue to use common sense _and_ prescriptive design, and life will go on.


----------



## Glenn (Feb 28, 2014)

jar546 said:
			
		

> Until a micro-niche, for profit industry is successful is changing basic mathematical, time proven physics in order to change the code, we will continue to use common sense and prescriptive methods as enforcement.  Life will go on for all of the successful, profitable contractors who have a grasp and understanding of soils and bearing capacity and have been designing and installing deck piers this way for years.


Jeff you seem to be going off about the evil contractor just wanting to make an easy buck.  I said nothing about that.  I spoke quite a lot of science and research in my post, but you state I am trying change physics?  Uh...no, I was quite exactly talking about science and physics.  You are also speaking for roof assemblies, which is a different animal entirely from a "deck" (the subject of the thread).

I simply share with you the facts about my region.  The decks aren't settling.  I would prefer no one takes that as an attack at how things are in their region, nor attack mine.  The link I provided with 8" piers is not from a group of greedy contractors, it's from the state's very recognized ICC chapter of building officials.  The owners of the properties are the one's that don't want a 24 x 24 block of concrete in their planter boxes when for the last 20 years, they've had a 10" round pier.  Sensitivity to that perception must be recognized, especially when you are trying to explain "why" it has to change suddenly...and can't.

Again... I was very much speaking about science and engineering, and yet you did not comment on any of it.  (skin friction, safety factors, when compressive strength engages....all science...all important).  Please stop thinking of me as some enemy just out to help sloppy contractors make a quick buck.  I think the nature of my post deserves a little more credit than that.  

I love the discussion, though.


----------



## Glenn (Feb 28, 2014)

jar546 said:
			
		

> Engineers and architects for the most part seem to get it as their designs routinely exceed the prescriptive code requirements by a pretty good margin.  It is the contractors who push the envelope in the opposite direction due to their ignorance of the codes and simple math.


This is not true for my region by any stretch.  I regularly see engineered plans for decks come across my desk with piers undersized when using end bearing calcs only.  No evil contractors or profit driven devils anywhere to be seen.

Here is a photo I took this week and recently shared with the deck study group.  I will share it with you all too.  I would love some scientific talk.

In this photo, the above document is the original soils report from the 90's.  A side shear value of 500 psf is provided for deep drilled piers, but the upper portion is discredited.

The document below is the design criteria for the newly engineered deck.  The current engineer provides end bearing of 1500 psf, but a side shear of 2,000 psf for a 36" deep pier.  The end bearing alone did not calc out when I checked it.  This is from a licensed professional engineer, and this is not the first time I have seen this.  36" deep piers that engineers are accounting for side shear.  These piers are 12" diameter (undersized when only looking at end bearing).

The comfort level with narrow shallow piers is across all kinds of professionals in my region.  I suppose it's because there is no failure of them.


----------



## jar546 (Feb 28, 2014)

Glenn said:
			
		

> Jeff you seem to be going off about the evil contractor just wanting to make an easy buck.  I said nothing about that.  I spoke quite a lot of science and research in my post, but you state I am trying change physics?  Uh...no, I was quite exactly talking about science and physics.  You are also speaking for roof assemblies, which is a different animal entirely from a "deck" (the subject of the thread).I simply share with you the facts about my region.  The decks aren't settling.  I would prefer no one takes that as an attack at how things are in their region, nor attack mine.  The link I provided with 8" piers is not from a group of greedy contractors, it's from the state's very recognized ICC chapter of building officials.  The owners of the properties are the one's that don't want a 24 x 24 block of concrete in their planter boxes when for the last 20 years, they've had a 10" round pier.  Sensitivity to that perception must be recognized, especially when you are trying to explain "why" it has to change suddenly...and can't.
> 
> Again... I was very much speaking about science and engineering, and yet you did not comment on any of it.  (skin friction, safety factors, when compressive strength engages....all science...all important).  Please stop thinking of me as some enemy just out to help sloppy contractors make a quick buck.  I think the nature of my post deserves a little more credit than that.
> 
> I love the discussion, though.


My apologies if I seemed a bit strong.  I too am being factual.  There are simply too many variables in this situation and only the local officials and contractors know their soils.  If it is working in Colorado then great, just don't think this needs to be a future code change on a global scale.  As far as the issue with building a roof over a deck, it happens all the time and is certainly an issue, especially when 9 times out of 10 they think the existing deck piers are adequate for the new roof and snow load.  Concerning skin friction, safety factors, etc…… I can't comment on something that I need to do research on.          Yet.


----------



## Glenn (Feb 28, 2014)

jar546 said:
			
		

> My apologies if I seemed a bit strong.  I too am being factual.  There are simply too many variables in this situation and only the local officials and contractors know their soils.  If it is working in Colorado then great, just don't think this needs to be a future code change on a global scale.  As far as the issue with building a roof over a deck, it happens all the time and is certainly an issue, especially when 9 times out of 10 they think the existing deck piers are adequate for the new roof and snow load.  Concerning skin friction, safety factors, etc…… I can't comment on something that I need to do research on.          Yet.


I completely agree...folks get real surprised when they realize that changing their deck into a covered deck or sun room changes things big time.

I may have not been clear in my intentions.  I DO NOT think there is enough data to make a prescriptive table specifically for deck foundation in the IRC.  I DO NOT think the DCA 6 table is appropriate for all areas and all foundation types.  I was one of the leading voices to STOP the table proposed for the 2015 IRC.  It proposed to make all decks have a minimum 15 inch diameter pier/footing.  My involvement in the deck group and my comments in this post are the argument for why it should NOT be made prescriptive and apply to decks following the current IRC methodology for IRC footings.  In absence of a specific deck foundation table, jurisdictions can continue to use empirical experience and judgement and curious minds can continue to find more information and research.

That said, forces continue to work to put the DCA6 type of table with large diameter piers into the 2018 IRC.  That is exactly why I ask "why" is it that narrow, shallow piers seem to work in many regions.

We're all good.  I don't doubt your local experiences at all.  I found the coal ash comments to be quite interesting.


----------



## jar546 (Feb 28, 2014)

Concerning the coal ash.  Along with garbage pickup was coal ash pickup but then it went away and people needed somewhere to put it so gardens, driveways, yards and just about everywhere you can think became a dumping ground. (the tomatoes are excellent from this area, best in the world).  On many projects soils engineers had to be called in due to the amount of coal ash uncovered, even in residential settings.  In our area, even with pre construction boring and testing, the soils eng. companies follow the excavation and do testing as the footer is being prepped.  More often than not, the values change and the engineers have to modify the original design due to changing conditions.

When you get up into the mountain areas where there is more rock and shale, we have less issues.  Just an FYI


----------

