Maximum lean for building 5

[Jc67roch]

I am looking at a two story residential structure that has extreme lean or tilt to one side. Client is fighting a preservation board which wants the building repaired (at a high cost) were as the client wants to demolish the building. I feel the building is a hazard, as the lean or tilt is 1-2 feet out of plumb over the two stories. Does anyone know of references that might specify a maximum departure from plumb for a building before it can be deemed dangerous or a hazard?

 

[KootK]

I don't know if a defined limit but a gravity and lateral analysis including P-delta effects and that initial displacement would be one way to assess safety. Light frame wood? Cause of the lean?

Folks nowadays build brand new buildings that lean all over the place intentionally. If the structure's light, has enough shear resistance, and isn't sinking into the ground, it may not be a deal breaker. Much depends on the cause of the lean though.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[JAE]

This might help: Residential Construction Performance Guidelines by NAHB, 2011



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[HouseBoy]

Since you've indicated the "preservation board" is involved, I assume the building is old.
Approximately what age?
What is the building material?
Plan dimensions and/or general description o fate plan layout?
Are the floors level?
Do you have a diagnosis of the cause of the out of plumb conditions?

I'd look at the overturning moment vs. whatever is in place to resist overturning.

Regardless, 1 to 2 feet out of plumb over two stories seems pretty drastic!

 

[KootK]

H/12 ish. I'd call that pretty drastic. Pisa's about H/15. Presumably there's a heritage board involved there too.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[racookpe1978]

So, just how does the preservation board suggest "straightening up" the building WITHOUT adding "un-preservationist" and ugly external frames and angles and reinforcements?

 

[kingnero]

for your information:

http://www.fusionpoint.be

http://be.linkedin.com/in/fusionpoint

 

[CELinOttawa]

Kingnero: Storey, Centre and Through are all spelt correctly. The document is practical, and dares to give real advice: Australian/New Zealand standard? British?

 

[CELinOttawa]

Ah, Google. Found it: BS EN 1090-2-2008

My thanks; A most practical guideline, with a real world reference! A star for your troubles...

 

[kingnero]

I should've mentioned where it came from, but your google-fu is correct (but there is a more recent version, EN1090-2+A1:2011).
This standard has a.o. about 30 pages of sketches and tolerances that can (mostly) be readily applied in real life situations.

Thx for the LPS...

http://www.fusionpoint.be

http://be.linkedin.com/in/fusionpoint

 

[Jc67roch]

Thank you All! Great input, and I like this EN reference to hang my hat on. Yes, 1920's wood framed residential garage. Foundations are questionable, significant "sinking" and differential settlement of slabs, and worst of all a lot of decay at the bases of the wall studs. Decay of wall studs is most likely cause of lean, but with sheathing on walls it is difficult to tell. And the sheathing is likely all that is holding the building up.

 

[HouseBoy]

OK BUT.... Seems like the "fix" might not be too terrible. The "high cost" is relative I suppose.
I would think that a lack of lateral bracing (a likely/common shortcoming in 1920's wood frame garages) is a "concern", regardless of whether there is settlement.

 

[CELinOttawa]

Well now, if you have Rot there is another issue to argue with the Heritage Ppl: Rot is biological and tends to spread. In order to curtail spread (since you're very likely far too far gone to cut it all out and replace), you need to be looking at management. Management of rot is hopeless if you cannot keep the moisture levels down. That's rarely possible in the kind of structure you are describing without major impact to the Heritage Defining Characteristics.

Have the wood tested and assessed for Lacrymans (dry) and Coniform (wet) and the extent of same. If the extent is past 30% of the bottom of the structure it is not repairable without demolition as the result cannot possibly achieve a 50 year design life.

QED. Demo.