My little powder room has been such a headache, hoping someone here can shed some lights. Little background of the house, built in 1909 on post and beam foundation with perimeter of the house sits on linear( continuous footing) sometime 1920-30’s or earlier, then owner built 3ft x 23ft bump out that has cinderblock footing 2ft away from the original perimeter footing with 1ft cantilever.

When I opened the 3/4” thick solid diagonal subfloor, I see that the added joist are only 3ft and looks like there weren’t an adequate fastener attached at the beginning of 3ft added joists. Because the powder room is about 6ft parallel to the joist, where added joist beginning is the highest point and each ends of the room is sloping down by 1/2” to 1”, planning on adding plywood to install tile, this current waviness is no go unless I address this issue, I’m willing to add 8ft added joist on the area to give itself enough back span so the tile deflection is high enough, this means also raise the beam, I was hoping if I can just add longer joist and add shims on top of the joist so I don’t have to take recent earthquake Retrofit work done by a professional foundation company( has plywood up against to sill and post). Or any suggestion on how to go about? Thank you!

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  • Welcome. A couple clarifying questions... Do you know what caused the sag? If the new beam/wall is settling any repair will be temporary. Are you hoping to lift the wall over the cantilever, or just level the floor? – isherwood Mar 5 '19 at 14:53
  • Hi Daniel, hope my reply will get to you, When I moved in , the floor were so way throughout the house, naively thinking that I could lift the floor, a structural engineer came by, advised me to add a beam where the longest beam spans were( not sure how far between beams at the moment) so I added a beams but the licensed structural engineer’s recommended licensed contractor left me in the middle of the job so lifting never proceeded ( this is in middle of inside of the house, no cantilevered area) anyways, since the original perimeter of the footing areas being the highest point, – Laostrich Mar 6 '19 at 3:03
  • I’m hoping recent beam to be lifted little bit to meet the highest point ( the original perimeter footing section) and by adding new 2x6x8–on 16” o.c—— longer span than current 2x6x3 will have enough long back span to support 1ft cantilever. I’m planning on lif the cantilever wall side 1/4” a day,but eventually after new joists are placed, the area will be still cantilevered. will I still be in trouble down the road? I hope I’m explaining the situation clear... – Laostrich Mar 6 '19 at 3:08
  • I’m sure the softest way to go about is pour new footing on the cantilever area... but this would be my last resort and I’m not even sure I can achieve perfectly leveling without damaging typical craftsman house windows and molding etc.. – Laostrich Mar 6 '19 at 3:11
  • Yikes, typo on the last post, I meant to say the surest way to go on the cantilever side not sagging would be pour a concrete, and add piers and siding to finish it off( I sure I’m skipping few elements here) I would very much leave current cantilever as how they look, just strengthened them so my tile job won’t crack – Laostrich Mar 6 '19 at 5:34

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