2 story universal Joists and rafters

[cedarglen]

I am deciding on I beams or Josits, rafters or trusses today. I am nor sure one a couple of things.

1. Can I use engineered I beams on the 1st and 2nd floors and still use 2x joists and rafters in the attic? Or do I have to have trusses with I beam floors?

2.  Which setup would be cheaper to build? I am leaning toward joist and rafter over trusses since it would be tough to get a crane to our site. Can the trusses on a small house like this be installed by a few guys with no crane?

3. What is the unsupported span on the rafters if I go that way? (need to know for a snow load chart I have).

Thank you
Charles

[Amanda_931]

I've seen, and helped put up trusses by hand.  Even with my dislike of heights.

Stick one end up onto your plate, then the other, so they are hanging upside down.  then turn them right side up  do some (temporary if necessary) fastening.  

It gets a little awkward, but with ingenuity still doable as you put the last ones up so you don't have to take the end wall out.  

Might be enough of a pain to get them up to the second story to make it worthwhile to go with joists and rafters, and besides, then attic storage is possible.

[Jimmy C.]

I am deciding on I beams or Josits, rafters or trusses today.  

Hi Charles,
Did you ever get a price on I-beams and joists?
I am curious about the price difference of an I-beam vs a joist.

[John Raabe]

Charles:

If you do the engineered joists for the floors you need to do trusses for the roof and attic since there will be no support beam (see Typical Section and the three options for the truss configuration).

The Typical Roof Framing diagram shows the stick framed roof and the 2x8 rafters span something less than 10' (their design span). If your snow load is over 50 psf you can upsize the rafter to 2x10. The local truss company will design trusses for whatever the local loads are.

It shouldn't be too hard for two men to get those trusses hoisted up and in place safely.

[Larry]

My experience was that the engineered I joists and the 2x12s were about the same price.  I would expect that as lumber prices go up the engineered joists would become even more cost effective.

For what it's worth I am an old fashioned person and I had never used the engineered joists before.  I found them to be very easy to work with and the performance is great.  I would definitely use them again.

[cedarglen]

I saw that the plans state an 8' span on the rafters. That seems impossible since the length of the rafter must be about 15' total. Is the span not the distance from the ridge board to where it meets the floor joist?

Charles

[John Raabe]

Charles;

Aren't you thinking of the span for the attic joists rather than the rafters? The floor and attic joists span to the beam but the rafters span 1/2 the horizontal width of the roof (OK, less than that to the wall line).

The span is not the length of a rafter but its horizontal component.

Also, when calculating spans for snow loads, ask you building department how they calculate for the reduced snow load on a steep roof. Usually there is a considerable reduction allowed for steep roofs such as this one. Meaning that you can probably handle a higher flat surface snow load than I mentioned above.

[cedarglen]

OK, so the "span" of the rafter is not the legnth of the span, but the horizantal distance traveled?

What I saw was on page 4 (roof details) of the plans which says "contineous 2x8 attic joist to 2x8 rafter @ 24" o.c. (span 8'). Since that note is on the side which looks to be the longer 12' joist span I couldn't figure out what that was referring to.

great, I have a snow load table from my building department. Says we can get the 75 lb/sqft snow load requirement with 2x10 rafters which span no more than 11'7" spaced 24" o.c. on a 10:12 pitch roof.

thank you