Hi everyone,
I have to add a support beam under my bathroom floor to adequately support the tile I intend to install to reduce the flex of the floor. I have 2×8 joists that span 12ft. I plan to place the beam at the 6ft mark. The width of the bathroom goes with the joists. The bathroom is 8ft long. I live in Seattle, and have a crawlspace, and I don’t believe our frostline is very deep, if we even have one. The house is a rambler. I want this to be quick, but sound. What would be the best way to add the beam, size of beam, posts, blocking, etc…?
Thank you anyone and everyone!!!
Ryan
Replies
Quick? Hire it done.
I'm guessing this is over a crawl?
I would simply get a couple of those concrete, trapezoidal deck-base blocks, scootch out any loose under-house dust down to relatively firm soil, put them at either end of the span; spike a couple of 2x12s together for a beam, tack it to the floor joists, shim under the high joists, and support it some of the threaded Home Depot column pillars / jacks, available in three handy lengths.
Easy, and about $100 at Home Despot.
For maxiximum cuteness, less money and more time, you could "T" the existing joists. Using the resourcinol glue and a screw jack, each day glue a flatwise 2x4 as a bottom flange for a joist, jacking in a slight crown in the center as the glue sets up. Next day, remove the screw jack and repeat. Don't use construction adhesive - you must use a hard-setting creep-free glue.
Some smart guy can tell us how much this increases the stiffness. IIRC, the stiffness goes up with the 3rd or 4th power of the depth of the beam, so we're talkin' significant.
Just sistering the joists is often a problem because of penetrations and the like.
Thanks,
Sounds like I was on the right track. Yes, over a crawl space. Do you think a 4x6 or a 4x8 would work?
Ryan
Your new underfloor beam is only 8 feet long, so a 4x8 will work fine. Put the support posts about 18" from the ends to cut the span, make it stiffer. The screw adjustable posts are best, so you can tighten things up as the 4x8 shrinks.Bill
watch the screw adj posts. the paint on them fails really fast and they will rust. go thwe cost of putting some thing on them to stop that. (spray epoxy) works well. 4X8 sounds good to me. Jim
Don't rely on the screw posts. Add cribbing as the beam is jacked, and also wire the screw so it doesn't untwist with temperature swings, etc.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
Thanks for the advice!
What do you mean by cribbing in this situation?
Would lock-tite work to prevent the nut from loosening?
I'll look into the rust prevention.
Ryan
Cribbing is just blocks of wood, worked into place to support something. "Official" cribbing is layers of beams in alternating directions, creating the # character, more or less, but basically any configuration that's stable and can support the weight is good. When you get things to where you like them, drive in some wedges on top to make the cribbing tight.Lock-tite isn't a good idea, since it would make later adjustment difficult.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
cool, thanks.
i'll get 'er done.
Ryan