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canuk
Re: sagging floor joists

Alrighty then --- unless your joists are 16" spacing and not 12" spaced then your faced with adding joists --- either dropping in full length 2X8 joists in between each existing to reduce the spacing --- or --- sistering 2X8 full length joists to the existing.

when you tear up the existing subfloor add the full length 2x8 's ( crowns up ) --- for sistering use construction adhesive and use three fasteners vertically --- space those vertical rows 12 - 16 inches apart the length of the joist.
If it were me I would also add solid blocking to beef up the floor to minimize bounce.
Then lay construction adhesive on the edges of the joists then screw down 3/4' tounge and groove plywood subflooring.

I suspect you will run into electrical wiring , possibly plumbing and HVAC ducts which will complicated things.

jkirk
Re: sagging floor joists

who needs electrical, pluming and hvac:D

minimizing teh spacing on the joists will help quite a bit, along with installing blocking or sistering to the joists.. the blocking will transfer loads to other joists distributing the loads more evenly.

for new construction when conventional lumber is used 12" o.c is prett much expected in my region. the only time we do 16" o.c for joists now are for engineered joists if they aren't spaced 19 3/16 o.c (the little black diamond mark on your tape measure)

canuk
Re: sagging floor joists
jkirk wrote:

who needs electrical, pluming and hvac:D

minimizing teh spacing on the joists will help quite a bit, along with installing blocking or sistering to the joists.. the blocking will transfer loads to other joists distributing the loads more evenly.

for new construction when conventional lumber is used 12" o.c is prett much expected in my region. the only time we do 16" o.c for joists now are for engineered joists if they aren't spaced 19 3/16 o.c (the little black diamond mark on your tape measure)

Yep --- those pesky plummin' , lectrics , and heat are a pain in the butt ;):D

16" centers is still used alot around here though I prefer to go one size larger than minimum code -- 12" is used when tile floors are going in or if the engineering requires a special floor system.
I would never use black diamond spacing on floor systems -- sometimes for roof rafters.

vejir
Re: sagging floor joists

Thank you for the advice

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