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floor sagging-Joists need replaced?

crseedee's Avatar

Join Date: Nov 2009
Posts: 4

11-04-09, 11:41 AM   #1  
floor sagging-Joists need replaced?

The floor in our house is sagging & upon inspecting under house in crawl space found that some floor joists need replacing. They are on a sill & are 2x8 & 16 OC-not sure what other info may be pertinent. Want to repair without damaging existing (interior) floor. Need help to make sure I do this right. thanks for any info.

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GBR in WA's Avatar

Join Date: Mar 2009
Posts: 1,167

11-04-09, 04:07 PM   #2  
Are they over-spanned to begin with? Standard today is 12'8" for a 2x8, 16" o.c.

It a lot are sagging, the span may be too great, a wall load above may be built after the house was built, or someone never had it inspected when built. You can go one size bigger, to a 2x10, and leave the extra below, sistered to the old ones. Just notch the new ones 2" deep on the bottom, enough to get 2" of bearing each end. Before you notch, drill a hole at the apex as in this article: http://www.finehomebuilding.com/PDF/Free/021184090.pdf
You are allowed to notch the ends 1/4 of their thickness: http://arch.umd.edu/Tech/Structural_..._Guide_A11.pdf
Be safe, Gary

Claw Hammer's Avatar

Join Date: Oct 2009
Posts: 105

11-04-09, 07:09 PM   #3  
What I would do is see if you have enough room to put in a couple of parallam beams and jack up the existing structure and then add the Parallam beams and then let the weight down on the engineered beams.

Parallam PSL Beams are strong, beautiful, and can help turn open floor plans into reality.

Or you could measure the existing beams - floor joists etc and tell us what you have and how long the span is and we could try to figure out how much support you need to strengthen the floor to get rid of the sag.

How old is the house and what type of house is it.

It is hard to give a good diagnosis when you don't know anything about the patient.

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