Loft Support

[grover2044]

I am building a 10x10 cabin, which will have a 6x10 loft in it. I am planning on supporting the loft floor with 2x4's on the walls at 7', and build my floor from there. Just curious how many people have supported the front of the loft from the rafters (8/12 roof), versus having posts???

[Abbynrml]

I did something about like that in my project.
Its at:
http://countryplans.com/smf/index.php?topic=6162.0

It gets into it on page 4, msg 71.
Hope this helps.

[glenn kangiser]

Should be no problem to do it without posts.  Most of John's plans have the loft running full span.

[grover2044]

Sorry I havent seen any of John's plans.... So do I need the support from the rafters? Or would a couple of 2x4's on edge be enough to support the front edge?

[glenn kangiser]

The way John commonly does it is to let a 2x4 into the 2x6 studs at the side.  If you use 2x4 wall studs I would let in (notch for) only a 1x4.  The loft joists would sit on top of that at each end and go completely across the room to the other side.  Being only a 10 foot span they would have no trouble supporting the loft. 

I think you are talking about trying to use the front as a beam and put short joists the other way , but that is not really necessary.

[glenn kangiser]

Looks like Doug Fir 2x6's on 16" centers will span the 10 feet unsupported.  Here is a link to the span calculator if you want something else.

http://www.awc.org/calculators/span/calc/timbercalcstyle.asp?species=Douglas+Fir-Larch&size=2x6&grade=Select+Structural&member=Floor+Joists&deflectionlimit=L%2F360&spacing=16&wet=No&incised=No&liveload=40&snowload=-1&deadload=10&submit=Calculate+Maximum+Horizontal+Span

[grover2044]

Thanks Glenn, I played with that calculator before, but did not really know what Live Load PSF and Dead Load PSF I should enter...

[glenn kangiser]

If I recall correctly that is for a regular floor and you could go to a 30 lb live load for the loft. 

[MountainDon]

Examples of code-prescribed deflection limits and live load values are:
    * Living room floors L/360 & 40 psf
    * Bedrooms and habitable attic floors L/360 & 30 psf
    * Attic floors with limited storage L/240 & 10 psf.

Rafters  L/240


Attic = loft I suppose
dead = 10 psf