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StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 7188
Experience:  Structural Engineer
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I am interested in keeping as much existing framing as

Customer Question

Good Day.
I am interested in keeping as much existing framing as possible for this +100 year 3 story brick (2 wyths 15" thick) exterior wall.
What is the best way to sister the existing joists at the clg of the garden apartment to support the floor for the 2nd floor unit which has another unit above that one?
ISSUE: Support of upper two floors on existing lower floor modified joist installations to meet Chicago Codes.
FLOOR PLATE SIZE: Outside Bldg Size is 22.3Ft W (+20ft W interior) x 51FT L (49ft L interior) 14" to 15" Thick Brick wall
JOISTS (40 units 16" O.C.):
Existing 2"W x 8"D x 21Ft Length joists pocketed support at ends 2"
Existing 2x8 joists were trimmed to 5 1/2"D & new 2x6 (1.5"Wx5 1/2") joists were secured with screw pattern per specification of GRK Structural Grade Screws 5.16x3.5
POSTS (6 Units 8" x 5 3/4" on Concrete Footers)
8"x5 3/4" Posts are 94" from face of wall to face of posts within the interior dimension of +19' to 20' Span. The 6 posts vary between 7' O.C. to 7'-8" O.C. between the interior 49ft span. The posts support a series of (4) 6x8's along the length of the interior 49Ft span.
Thank you in advance for your assistance.
Sincerely, ***** ***** confirm my direction for resolving prior to a local inspector's assessment.
Submitted: 11 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 11 months ago.

Hello. I will happy to assist you with this.

Expert:  StructuralEng replied 11 months ago.

Typically, each floor supports itself only. Is that not the case for your home?

2x8 going 21' are incredibly undersized. You need 2x12 as a minimum, and that is with a good species and grade.

The rest of the questions really look like they require a sketch or framing plan to understand.

Customer: replied 11 months ago.
Thank you for your interest and prompt professional response. It was truly much appreciated. The response of using 2x12 joists for a 21ft span needs clarification. Please understand one basic fact, the two spans between the 22ftW bldg (19ft W interior span) has an intermediate span between the 19ft span of 7.5ft using a series of 8x6 post and beams. to support the joists spanning between the 21ft to19ft span. My original description may not have been clear.The existing situation is that the existing joists 2x8 joists are trimmed to 2x5.5 and sistered with 1 2x6 and secured with GKF structured screws using their specific screw pattern. If I need to send a sketch/photos to show this; please advise.The goal is fortify the existing installation as required to reinforce and support the upper floors. It appears that the original construction was a (40) 2x8 joist system 16"O.C. with joists supported in a pocket (2" set in); and supported by an intermediate 6x8 Post & Beam System (over 100 years old) on a concrete footing.REQUEST: Please advise of a structural bracing/reinforcement system that does not require existing joists to be pulled out and replaced with (40) 2x12 joists which will reduced the ceiling height to an illegal height.Thank you for your talent, ingenuity and wisdom.Sincerely, ***** ***** Wealth, Abundance and Prosperity for All!
Customer: replied 11 months ago.
Please assist with previous response. I've already been charged. Thank you.
Expert:  StructuralEng replied 11 months ago.

Can you post a sketch for me to look at so I can be sure we're on the same page.

Customer: replied 11 months ago.
Of Course!Will send within 24hrs.
Customer: replied 11 months ago.
Sk-1 & 2 Floorplan Sketches And Photos of Posts, Beams and Joists (sistered). My goal again is to reinforce existing construction as req'd without loosing ceiling height or removing major structural members.Thank you very much for your talent and wisdom.
Expert:  StructuralEng replied 11 months ago.

It appears the maximum joist span is approximately 11'-6". That will require a double 2x6 doug-fir no. 2 @ 16" o.c. if you don't have ceramic tile. If you do have ceramic tile then you will need a triple 5.5 2.0E LVL @ 16" o.c.

Expert:  StructuralEng replied 11 months ago.

Hello. Do you have any other questions for me on this topic? If you could rate my answer, I would appreciate it.

Customer: replied 10 months ago.
Good Day. Thanks for your expertise and innovative wisdom to get to success!UPPER FLOOR SUPPORT
Please clarify your response where you were referring to "ceramic tile" and use of LVL. The 6 posts supporting the 6x8 +100yr old (3) beams is on a 4 inch thick six bag mix with fiberglass slab (per the contractor).END SUPPORT
Once your recommended 2x6 is attached to the existing 100yr 16" O.C. 2x6 's which are pocketed (2" set in* of brick wall) into brick bearing walls, how do I attach the new 2x6's at the ends at the brick bearing wall?*For clarification, please review the photos previously sent.Thanks
Customer: replied 10 months ago.
We did not complete the original discussion.
Expert:  StructuralEng replied 10 months ago.
I sized the beam you need quite a while ago
Expert:  StructuralEng replied 10 months ago.

Hello. Do you have any other questions for me on this topic? If you could rate my answer, I would appreciate it. Experts are credited for each appropriately rated answer.

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