Floor joist question

[saltkreep88]

Working on a 1960s home with 13ft spans on 2x8s at 16oc. This is maximum span I am but trying to figure out what wood it is to see how over span this is. Who knows what wood species the joists are??

thanks!

 

[myrjon]

joe it looks like fir

 

[redfishbluefish]

joe it looks like fir

I am impressed!!!! The only way I could ever tell species is to look for the label.


Now I'm not sure about wood that old, but pretty much all wood today has a stamp that tells you the species.


As example, if fir, it would be labeled Doug Fir or D-Fir.


Other labels your might find are:
SPF (spruce, pine or fir)
Hem-Fir or H-F (hemp or fir)
SYP (southern yellow pine)


Now Douglas Fir is the strongest of dimensional lumber, but with the loads you will be putting on these joists, regardless of the species, I'd do something.....sister the joists, add load bearing wall, add jack posts, etc.


Joe, the other thing that adds considerable strength to a floor is blocking. These can be cross blocking or solid blocking:

But what is critical is that blocking is to have it in a single line....the entire span of the floor:

Blocking transfers the load to surrounding joists, and on a 13 foot span I would want as a minium at least one line of blocking down the center of the span.


Hope this helps.

 

[myrjon]

btw you could sister some lvl 's alongside of 2*8's

 

[saltkreep88]

Thanks guys! There is cross bracing but having a 2x8 on a 13 ft span the floors are very bouncy. It has last 50 years this way and they are bedrooms but it annoys me. Think I am going to put a lvl header at half span.

 

[myrjon]

joe i made a crude (t) with a 4*6 beam and a piece of lvl from joist to joist;.