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Definition of "Structurally Sound"

Definition of "Structurally Sound"

Definition of "Structurally Sound"

A client has requested that we provide a letter stating a certain structure is considered "structurally sound".  The structure is older, but in good condition.  The design is governed by wind loads but the current building code in the area has much more substantial requirements than the code under which the structure was originally permitted.

For this case, since no modifications whatsoever are being made to this structure, I would consider it to be structurally sound if it complies with the building code under which it was originally permitted.

This leaves me with a few questions:

1. Is it possible to call something structurally sound without referencing a specific building code or standard?

2. Is it possible to call something structurally sound by evaluating condition only, provided that the structure had been previously designed and built according to the current building code at the time?  (This question assumes that orignial drawings are accessible)

3. Is it possible to call something structurally sound by evaluating condition only if drawings do not exist, and no calculations are performed?

Additionally, does someone have a good definition of "structurally sound"?

RE: Definition of "Structurally Sound"

In my opinion, just because it complies with the building code at the time of construction does not make it "sound".  I would think a significant amount of your effort should be in inspection of the building to observe any signs of structural distress which might indicate whether it is sound or not.  Some attempt should be made to determine what the underlying structure is and then depending upon the importance, size, cost etc. some analysis should be done to determine it's ability to withstand normal forces such as wind, snow, seismic.

RE: Definition of "Structurally Sound"

In any report such as this I would avoid the term "structurally sound" as it is way to vague and general and could be totally mis-construed.

For an older structure there will most always be areas where:
1.  The original design doesn't meet the current applicable code and
2.  The current condition of the structure has been deteriorated, changed, or damaged in some fashion to also reduce the load capacities and serviceabilities of the members.

My approach would be to first determine from your client what they are actually looking for from you in terms of engineering services.  Are they:
a)  Concerned about specific portions of the building that appear damaged or deteriorated
b)  Concerned about floor loading capacities for a proposed intended future use.
c)  Want some sort of assurance, since it's old, that the entire building is code compliant with today's code.
d)  Want someone to take the blame for anything and everything that might go wrong in the future structurally.

So ask them some more probing questions to tie them down a bit.  But foremost, you as an engineer, can only state what you know.  And you can only know what you can determine either visually, by tests, by calculations, by research, etc.

This then requires you to lead the client in determining the extent of what you can and cannot tell them about the building.

A report to a client might include services such as:

1.  Visual examination of the physical condition of some or all visible elements of the building.
2.  Testing of key materials to verify strength.
3.  Some local demolition to reveal unseen conditions in key areas - this could include partial chipping of concrete to reveal hidden rebar, cutting to indicate thicknesses and quality through the thickness.
4.  Research - finding the original contract documents and performing calculations to determine load capacities
5.  Floor load tests.

The report you provide should always be very specific as to its limitations...again, you can only state what you know.  The owner cannot expect you to state that the whole building is structurally sound...only that you have looked at features x, y, z, etc. and these are in good shape, conform to the code, etc.

Also, older buildings do not have to necessarily always meet the current code.  Some areas require that if you renovate a building up to 20% of its value or so, then you do have to upgrade the entire structure to code.

The original code, in my opinion, is meaningless.  No longer is a standard on which to verify building compliance as it is no longer a legal binding standard.

As far as wind loading capacity - what you can state is that, under the current building code, the MWFRS has a capacity of, say, 84 mph wind vs. the required 90 mph wind....or something like that.

Here's some resources - there are many more out there:


Or specifically this document:

RE: Definition of "Structurally Sound"

To me 'structurally sound ' means that the original structure has not substantially deteriorated or been modified so that it cannot perform as it did when originally built.
My answers are:
1. Yes
2. Yes
3. Probably depends on structure type. Eg. a historic building can be classed as structurally sound if it has stood the test of time and it is in good condition without doing calculations. In your case it may be obvious that no modifications have been done so drawings are not required.

I wouldn't state that it complies with a past code unless  the original calculations have been checked, or recalculated, and it's been confirmed that the structure was built as designed.

RE: Definition of "Structurally Sound"

I just want to reiterate the most important point, made by JAE.

"But foremost, you as an engineer, can only state what you know.  And you can only know what you can determine either visually, by tests, by calculations, by research, etc."

This is the crux of the matter, before you take on the work you need to manage client expectations. You need to state to them exactly what you intend to do and the extent to which you are willing to 'certify' the building.

Be prepared to let the job go if they are not happy with your response.

You should also talk to your insurance company to see if there are any policy limitations on what you are allowed to say in this letter and still be covered.

Craig Dolby

RE: Definition of "Structurally Sound"

     Be specific: This building is designed for x.x MPH wind.  the floors are designed for 50 psf live loads and the framing for 30 psf live loads.  The seismic capability is 80% of required by 2003 IBC.
     Phrases like "structurally sound" have no meaning in an engineering context.  All structures can be overloaded and good judgement is normally expressed by code requirements.

RE: Definition of "Structurally Sound"

I would throw in with the answer given by apsix on this one.  Structural soundness is what you assess in a structural condition report, and is not the same as determining the strength of the structure by analysis.  A structurally sound building is one which has not decayed, deteriorated, or been damaged.  Of course, if the building had inherently built in faults those too affect the structural soundness.  I especially disagree with trying to put numbers on percentages of compliance with some modern code.  You don't have to use the words "structurally sound", and you should stipulate that the building is not built to current standards, but that doesn't stop you from giving an honest opinion as to the structural condition of the building.

RE: Definition of "Structurally Sound"

Just to clarify, I absolutely do agree that you need to know exactly why your client wants your report.  For instance, a report for a potential purchaser would be presented in a different manner from a report to be used for preventative maintenance.

RE: Definition of "Structurally Sound"

I don't think that I've ever used the term 'structurally sound' unless I'm able to do the sums and then it is usually to provide a capacity and possibly a comparison to current standards.  For forensic stuff, depending on the jurisdiction, I may state that it is in conformance with the code in effect at the time (many areas have a grandfathering clause).  Most of the reports I've done state that no signs of structural distress were observed (assuming none).  I also caution about latent defects as well as changes in use and occupancy... eg, higher humidities and sealing of historic masonry can have a serious effect.  Like JAE... also fairly specific about what was reviewed and make sure I get the scope clear at the beginning and caution the client that almost anything can be reviewed if he has the financial resources to do it... I like to put the onus on him as to the scope and often offer the service... such and such is beyond the scope of this report and can, however, be undertaken should we be instructed...


RE: Definition of "Structurally Sound"

An excellent book to guide you in preparation of a structural assessment report is ASCE 11-99 Guideline for Structural Assessment of Existing Buildings.   

If there are no visible signs of structural distress or deterioration and the loads are not different from what it has been carrying historically, then I have no problem stating the building is "structurally sound". As other posters have correctly pointed out, you need to clearly state your basis for this determination (visual observation, nondestructive or destructive materials testing, detailed structural analysis, proof loading, etc.)  

Most clients are OK with a visual inspection and do not want to spend the fee $$$ to do a serious formal assessment.  Get this clear in writing up front with your client and a limitation of liability clause is not a bad idea.  Your small fee does not constitute an insurance policy that the structure is 100% OK if all the client paid for was a visual inspection/observation.     

I include the following CYA paragraph on simple letters with a visual inspection and go into significantly more detail (i.e. similar to ASCE 11-99) for more serious assessments.

Per your request, on WHEN we visited the WHAT located in Durango, Colorado.  The purpose of this visit was to observe the WHAT and render a professional opinion regarding its current condition and recommend any repair schemes.  This observation consisted of a visual survey only, made solely to evaluate the structural integrity of the building at this time.  The observation was not intended to cover any architectural, electrical or mechanical items or features, nor was it intended to uncover or evaluate any hidden or latent structural defects in the WHAT building.  In addition, it should be understood that this observation was not a guarantee or certification that the original construction and/or design of this buildings was without defect or deficiency or that the structure complies with the requirements set forth in the latest edition of the International Building Code.  

RE: Definition of "Structurally Sound"

Hokie66 makes a good point.

You could put in some words to the effect of:

" The building has been checked for any signs of deterioration such as decay,cracking e.t.c. that may be of structural concern. Compliance of the structure to current codes and to the original building codes has not been checked as this is considered beyond the scope of this report."

RE: Definition of "Structurally Sound"

I've had clients ask me to perform due diligence inspections on various existing buildings before they purchased the building.  They wanted a report on structural soundness.  When I asked what that means to them, my clients wanted to know if the building showed any signs of a potential structural problem or failure.  These are items we discussed and they agreed were items they were interested in knowing existing in the buildings:  corrosion of steel framing or concrete reinforcing, water or insect damage of wood framing, damaged framing that needed to be repaired or replaced, foundation settlement or evidence of swelling soils, cracked floor slabs indicating swelling soils or settlement, damaged load bearing masonry walls, damaged veneer or siding that might cause a structural problem, visual evidence that the roof is leaking.  All of these items were determined by visual inspection.  Not always, but a few times minor demolition of gyp board walls was performed to expose framing.  I have not been asked to make any statements about whether or not the buildings meet or exceed current building code requirements.  ALWAYS I included a statement that the report is based on visual inspections only and that no testing or calculations were performed.

Recently, I had two clients ask me to make a statement about the expected lifespan of the building.  They wanted me to "certify" that the building will last a certain number of years beyond the date the report was written.  I refused to make such a statement because I won't "certify" anything.  I do not know how to address that request other than to say with proper maintenance the structural framing will last almost indefinitely.  Any thoughts?

RE: Definition of "Structurally Sound"

How long a building will last is more related to how well it is maintained over the years rather than the condition it was in when it was purchased. Additionally, there could be many hidden conditions that cannot be determined by a simple visual walkthru or even by selective destructive or non-destuctive observation.

RE: Definition of "Structurally Sound"

Quote (archeng59):

ALWAYS I included a statement that the report is based on visual inspections only and that no testing or calculations were performed.

Archeng59 - we do that same thing.  Our statement usually goes like this:

"This report is based upon visual observations of the structure at the time of our visit.  There may be non-visible conditions that currently exist that may affect the conclusions and recommendations found above."

RE: Definition of "Structurally Sound"

Use a lot of "appears at the time of this site-visit"

Use the word "observation" in lieu of "inspection"

Use "opinion", & "to the best of my knowledge and belief"

and as said above, be very specific.  If it is based on observations alone, state no destructive measures were taken for observation, but, give them the option that it could be done if they think it is neccessary.  Put the liability back on them.

My standard letter states, "The scope of this report is limited to matters discussed herein.  No opinion is offered and none should be inferred regarding other aspects of either the structure or the structure taken as a whole."

and if everything looks okay:
"appears to retain the majority of its original structural integrity"

NEVER use the word "certify"

RE: Definition of "Structurally Sound"

there is a whole list of words that should be avoided.  Call your insurance company and they will supply it...  In fact, they might even provide constructive comments on your letter / proposed language if you asked.

RE: Definition of "Structurally Sound"

do any of you have the CASE guidelines for report writing?  It contains some great disclaimer statements.

RE: Definition of "Structurally Sound"

This is the typical front end of my reports:

This report is in response to a request for services from ??? (“the Client”) to whom it is addressed.  This report was prepared by ??? (“the Consultant”) for the express use by the Client.  The material in it reflects the Consultant’s best judgment in light of the information available to the Consultant at the time the report was prepared.  Any use of which a third party makes of this report, or any reliance or decisions to be made, based on it, are the responsibility of such third parties; the Consultant accepts no responsibility for damages suffered by any third party as a result of decisions made or actions based on this report.  This report has been based, generally, on a non-intrusive visual review and is not an exhaustive study and should not be interpreted as such.  No opinion can be rendered regarding obscured items and, specifically, items not included in this report.  If a more definitive statement is required, it will be necessary to undertake additional study.

RE: Definition of "Structurally Sound"

"This report is based upon visual observations of the structure at the time of our visit.  There may be non-visible conditions that currently exist that may affect the conclusions and recommendations found above."

Brilliant, JAE!

I don't "hate" clients who push for our inspections (really "assessments") to be quick and accurate and assume we have x-ray vision, etc. But I sure don't like 'em.

RE: Definition of "Structurally Sound"

dik - I like your last sentence as well - referencing that additional study may be required if a more definitive statement is required.

RE: Definition of "Structurally Sound"

It puts the onus on the Client to provide funding for additional work...


RE: Definition of "Structurally Sound"

Archeng... I've never had that sort of cash cow... you should be able to 'certify' it with qualifications, realizing that maintenance items be addressed as well as annual reviews for a fee that may vary depending on what is uncovered... unless the building is a wreck whose capacity cannot be determined...


RE: Definition of "Structurally Sound"

dik, not sure what you mean by "cash cow."  

also, my E&O insurance company regularly reminds me never to use the word "certify" in a report.

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