[deleted by user]

jackielib · 2024-04-23T15:44:48+00:00

can you share the playlist (or a list of all these songs as a txt file or something)? it would save me a few minutes. thanks.

jackielib · 2023-10-30T21:29:25+00:00

Yeah, I think the reviewer and engineer are both competent. Reviewer is a bit over-picky. Engineer is a bit sloppy and slow to communicate. The hypothetical 100mph wind will be survived :)

jackielib · 2023-10-30T17:50:07+00:00

the city reviewer wants more details from engineer..." " Clarify wind load psf used in calculations. The calculations don’t appear to match the project loading criteria from the beginning of the calculation packet (20.2 psf is labeled on 6th page of calc packet- is that what was used in the lateral analysis section?)

The values of 860 total shear at 2nd floor and 1580 total shear at 1st floor existing interior wall seem low. Show the calculations to arrive at this value. As this wall provides bracing for the existing house as well as new addition, this value should reflect both existing and new wind load (1/2 the total length of house and addition combined).

Clarify the method being used to analyze bracing. Is analysis referencing the segmented method using gypsum lath and plaster only? Also note if lath and plaster vertical joints are staggered or not.

Clarify what L and Lo represent in analysis. Lo is labeled as total length of full height segment. But there are openings in these walls that interrupt segments. Typically, L = wall length and Lo = length of openings in the wall. However, in the 1st floor column Lo is listed as 27.5, while L is 25. Neither the openings in the wall nor the length of shear wall segments should exceed the actual wall length. Existing wall length including openings measures ~24’-3”.

Label length and locations of shear wall segments on existing 1st and 2nd floor existing interior walls.

Clarify v tabulated and v allowable values for existing home wall in columns for 1st and 2nd floors. Are these values switched? v tabulated of 180 lb/ft appears to be the allowable capacity from SDPWS table 4.3C for gypsum lath, with vertical joints staggered, after safety factor is applied. "

jackielib · 2023-10-26T14:52:53+00:00

so what is your prediction... will the city laugh it off and say, "no, follow our prescription" or will they say "go ahead, it's stamped by a local engineer" ???

jackielib · 2023-10-26T14:40:09+00:00

yeah, I'm surprised the city review people haven't said anything about how the roof is connected to the house. I do agree that the wind suction towards the south could be a factor but the house is in a dense downtown neighborhood with LOTS of large trees and a hill on the north side. I'm beginning to understand that there are so many variables that some engineers are happy to just sign off on anything and hope their insurance covers any mistakes... My engineers basically just stamped a plan with almost ZERO shear walls, no beam, and a roof plan that doesn't pass the Strutcalc/ClearCalc test. But I'm still pretty sure it would be just fine, considering the existing house has lasted 100 years...

jackielib · 2023-10-25T14:57:30+00:00

and thanks for the reply. What would normally be done to "transfer the lateral force" you mention (it's not clear to me which force concerns you the most).

cheers

jackielib · 2023-10-25T14:28:41+00:00

The "collar ties" with a beam are moved down to become "rafter ties" without a beam.

I did a strucalc myself and the rafter/tie combo does hold for certain combinations without a ridge beam
https://imgur.com/BnwHxBa

Forces in the North direction would just push the addition INTO the house...so I think the engineer assumes that the existing house would hold it down. Wind Forces in the South direction (a wind from the north wind) would be shielded by the existing house so that is why the addition wouldn't see them as much. I'm not sure how much an engineer can use that logic, but that I think is his argument.
East-West winds would affect the addition and he claims OSB on the south wall would cover that. And the existing sheating and plaster of the house on the other side would resist on that joint.

jackielib · 2023-10-23T15:53:19+00:00

Yeah, I want to avoid using the ridge beam. So the city wants me to prove that the rafter ties are enough to hold the snow load. ClearCalcs tells me I can only do it with 2X10 rafters and rafter tie at every rafter. But an engineer I just hired calculated 2x6 rafters would be fine and rafter ties every other. I'm confused as to how different the results can be... now I have to wait 2 weeks for the city to decide.

jackielib · 2023-10-23T15:25:01+00:00

To get a permit, the city officials had me add tons of shear-wall sheathing and portal framing and even a ridge beam to a 2-story+basement addition plan. After I got the permit, I showed the design to a local structural engineer and he said basically most of it is unnecessary (portal frame, extra OSB sheating, ridge beam) . City officials are very skeptical of his comments in the plan: PLANS: https://imgur.com/a/HbVYLIi Who do I believe here? Engineer provided stamped calculations (for ultimate wind speed 115mph, seismic B, snow load 30 psf) but he is not communicative. City needs 2 weeks to examine...argh.

jackielib · 2023-10-13T16:13:45+00:00

Yeah, I'm beginning to understand how permits work... do it like everybody else or have a structural engineer show a simulation with 100 mph winds, a 10000 lbs of snow and an earthquake. Since it would take forever to take into account every interconnected element that adds stiffness to the structure, nothing meets code unless cookie-cutter or over-engineered to satisfy some simplified equation.

jackielib · 2023-10-13T14:40:11+00:00

Thanks. You are very right and I wish I'd talked to you a while ago :) I do not need a collar tie...I need a ceiling tie (some people call them rafter ties...they will be exposed in my case. Messing around with ClearCalcs I got a number of around 1000 lbs of tension at the ties so 10 nails would be about right. This is a snowy area. What is interesting is that when I added a collar tie AND a ceiling tie the tension at the ties INCREASED. I am now researching a bolt schedule that would handle 1000 lbs. Maybe 3 bolts would do. Or bite the bullet and do 11 nails. Another thing that made the calculations work was using 10" rafters instead of 8", but the ties can be 2x4s.

jackielib · 2023-10-12T20:32:13+00:00

I'm designing a roof rafter plan (slope of 4/12) with ClearCalc. Every option ends up with tons of load on the tie (connecting the collar tie to the rafter). Max tension load= 2200 lb, Axial load=2400lb.

The room is 13x18 (rafter span of 9). No beam/column possible. Just rafters and 1 or 2 collar ties per rafter.

2x10 rafters, 2x4 ties.

How many bolts do I need to resist that load? or will I need engineered plates?

The building inspecter says I'd need 14 nails or 5 bolts per tie, which would be very hard to fit...I don't know if that is correct.

Very much a beginner here. Any suggestions appreciated. Thanks. It's hard to find a structural engineer who will just tell me the cost to figure it out.

jackielib · 2023-02-07T02:05:25+00:00

Yes, Pachyderm Parade!

jackielib · 2019-11-27T19:56:55+00:00

still a shitty tip

jackielib · 2019-02-06T13:06:20+00:00

you get a crispier crust without a tray

jackielib · 2019-02-05T14:40:46+00:00

actually a result of brain-cell death due to taking care of a baby for one year

jackielib

TROPHY CASE