engineering as-built barn from the 1960's to current code..... allowed? 1

[Travis Roberts]

Hi,

This is my first post here. My question in general is if it's permissible to engineer a building to the current code rather than the code in effect the year it was built?

My thought is usually codes become more restrictive if anything, although I know there are some exceptions, and so it should be permissible.

The follow-up question is can the non-structural aspects of the building abide by an older code while the structural aspects follow the current code.

Thank you in advance.

 

[bimr]

The best advice is to check with your local building department and see what you can do.

If the barn was constructed without a permit:
If a building permit was never submitted to the local jurisdiction to confirm that it would meet zoning and building requirements for its intended use, it was never inspected by the local building department to ensure it complied with local codes, and it was never issued a permit. Local jurisdictions have the authority to direct a property owner to permit the structure or remove it entirely from the property. Getting a permit for this type of structure will probably require plans to be drawn up, the local jurisdiction to approve them, the structure to be brought up to building code for the new use, and a local inspector to approve the building. The local jurisdiction will often treat this as a “new build” rather than a “conversion of existing space,” because it does not have permit records for the structure. When converting an unpermitted accessory structure, the local jurisdiction determines whether the project must comply with state and local standards rather than the standards allowed for a conversion.

If the barn was constructed with a permit:
The barn had to meet certain zoning and building codes for the specified uses and pass inspection in order to obtain their original permit. To convert a barn, the owner must obtain local permits to change from the previous usage to the new usage. This permit will require plans to be drawn up, the local jurisdiction to approve them, the structure to be brought up to building code for the new use, and a local inspector to approve the building.

The barn will need to comply with the building code and fire code, including:
Ensuring adequate insulation and meeting energy code
Walls and foundation with structural integrity
Utilities
HVAC

 

[Travis Roberts]

Thank you, bimr....

Yes, I think everything you said was correct.

I am familiar with our building department and will ultimately ask them if it's allowed by them.

Really the barn itself will get permitted, I'm in the plan check phase.

So the plan checker's (from an outside agency the county hires) is making mention of my seismic and wind calc's not being done to the 1968 code....but in a roundabout way.

So I'm wondering if I need to redo a bunch of calcs to get forces that will ultimately be lower most likely.... or if I'm allowed by some part of the code to say "2019 is stricker than 1968" and have that be accepted?

Maybe I should have opened with that last sentence, lol.

Thank you for your time

 

[phamENG]

Has the locality/state adopted some form of the International Existing Building Code? If so, that's would be your go to. Typically, that code (and those derived from it) give you some allowances - if repairing, in kind replacement is often acceptable. If altering/adding on/changing occupancy, then then there are percentage thresholds that trigger new design/strengthening. Typically in the 5% to 10% range. Don't increase the Demand:Capacity ratio more than that, and you can leave it. If you do, the new work has to be designed to the current code.

A lot of engineers like to use the old codes when looking at old buildings. As a structural engineer, I find that to be inappropriate for anything but gaining an understanding of how the original building was designed and answering questions like "it's stood here for 100 years, why do I need to change something now?!" The new codes are based on newer research and more accurate conclusions about that research. Wood is a really good example. Just because 1940s design values assumed that pure tension capacity was equal to flexural tension capacity, doesn't mean you can use that for a building built using that assumption. It was proved to be false a few decades later, and F[sub]t[/sub] has been considerably lower ever since.

So no, I would say there's no need to redo your calcs - especially if they say the building is good. If they say the building is bad and you're reinforcing everything, then maybe look to see if you're taking advantage of the allowances in (today's) codes to provide your client with the most efficient design you can.

 

[EdStainless]

Around here it depends on how much you are modifying the structure/use.
If very little mod and same use, then old codes usually prevail.
If a lot of mod or change of use you will likely be forced to update everything.
Depends a lot on the jurisdiction.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[le99]

.... or if I'm allowed by some part of the code to say "2019 is stricker than 1968" and have that be accepted?

That's what I would do if I can dig out the code of the time the barn was built and make a comparison table. But even with some load intensity has been reduced, the rather complicated load combinations of the modern code may surprise you.

 

[Travis Roberts]

Thanks everyone....

I appreciate it

 

[Travis Roberts]

There is a site that Berkley maintains that has all the editions of the UBC available for free download

https://digitalassets.lib.berkeley.edu/ubc/

very useful.

About the load combinations.... I wouldn't use today's load combinations with the loads figured from the 1968 UBC, would I ?

My wind pressure circa 1968 is only 15psf.... But I don't think I can take a 0.6 factor to it?

Maybe I'm wrong

 

[le99]

IMO, it is better to stick to one code for load and load combination. As I've mentioned, the newer load combinations are tricky with a lot of later developed thoughts/things being built-in.