Floor joist spacing and size

[devildog]

Hi eveyone. I havent posted in awhile, but I peek  on occasion to see how others projects are going.

Ive been waiting to sale my mobile home in florida so Id have more money to move forward. Well......, a week later,last week I got fired.
But, Im  tired of waiting and GOD has provided for me and my family this far.Ive got to trust him!

This is my layout

The contractor that did my foundation put the piers the same height as the crawlspace walls. He said I should use 3-2x10s(piers are 8' apart) to build the beam,and put a ledger on the bottom, and 2x8s as my floor joist 16"o.c..Some of my joist will be 12' long(bedroom),but the main build is 10' because Ill have a center beam.
When I asked him how the beam and joist meet up,since theyre 2 different sizes,he said to notch the bottom of the beam at the pier.
I checked all this out and sounds right. Actually I think youll helped me with that.

But I think Id rather use 2x10 as joist as well and not have to notch beam. I should be able to go to 24"o.c. andit shouldnt be that much in cost difference. Id still have to notch joist at ledger.

Do youll think 2x10s 24" apart is a strong floor?

I appreciate your thoughts and experience on this. Ineed to get a final material list together.
Darrell

[rocking23nf]

Why not just use joist hangers no matter what size you pick? they are easy, cheap, and hold a crazy amount of weight.

[rocking23nf]

and I would not personally do 24" centers, the cost is minimal in the scheme of things, your adding what, 7-8 boards? 10 tops?

[John Raabe]

I agree about the 24" centers. Then you will probably want to go to heavier sub-flooring and all cost advantage is lost.

At 16" o/c a DF#2 2x8 will span 12'-9". A 2x10 will go 15'-7" (If 24" o/c then back to 12'-9" on the max span.)

I would probable go with 2x8 @ 16 as your max span is closer to 11' and that in the bedroom. The limits of these spans are in the deflection not strength.

[Don_P]

#2 SPF is what is commonly available here, that'll take a 2x10 @ 16" o.c. I would agree with using joist hangers. 

[devildog]

Thanks everyone. I thought about using hangers, but read somewhere that theyre expensive and more likely to have sqeaky floors.But people use them all the time.
Apparently I dont understand span charts. I also dont know common wood for this area.Am I looking for 40 live and 10 dead.
But Ill take your suggestions  and keep it at 16"o.c., 2x10, and use hangers.
Thanks again Darrell

[rocking23nf]

a 2x10 joist hanger is 99 cents here in my city.

My floor doesnt squeak yet..........

these things are peanuts in the overall picture of building a cabin.  Same with 16 inch spacing, it will cost you like 100$ more to go to 16" spacing, its peanuts.

2x10x16 - $13.25   EACH
2x10x10 - $8.78   EACH

Same with 2x6 walls, it will cost a margin more, but you get more insulation, and a stronger frame on your house.

The real expense comes when you start finishing inside the house, and also the foundation can be pricey also.

[considerations]

"My floor doesnt squeak yet.........."

Mine does - now, finally.  I have one board in the living room floor, on the where it butts up against the next one.  Its about 6 feet from the front door in a place where I walk a lot. 

I've pondered it all summer.  Here's what I decided.  I live alone and sleep upstairs.  The cats don't set it off, only people.  So, if that board squeaks and I'm not stepping on it, that means some one else is in the house.   I think I like that it squeaks. There is a squeak on the first step of the stairway as well....I might leave them both alone.  Hillbilly motion detectors. 

[John Raabe]

Hillbilly motion detector   

Great tip Considerations!

[Redoverfarm]

Consideration that is better than feeding a couple of guineas.

[Don_P]

The squeek was intentionally built into the homes of some samuri for that reason.
A ledger has pretty much fallen into disfavor, they can "roll" out putting the connections into withdrawal rather than the intended shear. Notches are allowed and help with the ledger rolling but the square cornered notch, called a re-entrant corner is prone to splitting. If you look at well done old timberframes the notch was swept in an arc down to full thickness avoiding the stress concentration at that notch corner, never seen a stick framer do that. Subfloor glue is supposed to help prevent hanger squeeks. If it is a hanger squeeking some baby powder would probably work as well. Often a squeek is a nail that just missed the joist and is rubbing.  If the finish floor isn't down yet they are usually pretty easy to fix.

[devildog]

I reellt do appreciate all your thougts and suggestions, Thank you.

I found some simpson hangers that range from about .89 - almost $20 a piece. Which type is right for this application? I like the top flange. They seem like it would automatically make joist flush w/beam. But cheaper is better.
Darrell

[Bobmarlon]

If I can give you any advice its not cutting corners at this stage.  Its really hard to go back and change things and can cost you more in the future.  Also for piece of mind Ive never regretted buying the more expensive choice but have regretted cheeping out.

Also For no squeaks put some subfloor adhesive in the joist hanger before you nail it down.

I like these hangers because they have to tabs that alow you to set the hanger without starting a nail and the nails are drove in on a 45 which makes it easeir inside of a stud spacing.

http://www.strongtie.com/products/connectors/LUS-HUS.asp