14 x 24 Enchilada plan Floor Joists question

Started by knightasylum, July 17, 2014, 11:54:50 AM

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knightasylum

You will have to excuse the questions as this type of construction is new to me so I am learning as I plan/go.

I am using the Enchilada plan and building the Raised Roof option on page E-6 in the booklet for the 14 x 24 plan, which calls for 2x6 joists with a 2' 2" span from where the joist sits on the main support beams to the outside edge. That would mean that the full weight of the structure is being carried on the last 2' 2" of the floor joists. I also purchased the book you recommended on building construction but it advises that for a load bearing cantilever (which is what this looks like) that the distance it extends beyond its support must not exceed the depth of the joists. Which in this case I would seem to not be following (if I am understanding both the plans and the book correctly) if that is the case why?
I am assuming that the small size of the structure may make it alright since in the book they are speaking in general terms and often referring to larger structures then this. but with the raised roof option I am adding more weight, and I am using 2x12's in the roof, so I started to question of choice of boards half that size in the floor (which is supporting the stronger ones above.)
Am I mistaken in that question? Or should I consider larger floor joists?



knightasylum

Thanks but that is generic  in nature and while may be the prescriptive answer that is not what I need as I can look up code online just fine. It is the conflicts of information as it relates to the plans I purchased that I am trying to work with . Nothing to do with codes at all.
Just wanting some clarity n the design/ material list.

hpinson

John usually responds right away to this sort of question, so he may be away.   Keep checking back.

John Raabe

#4
The diagram for the raised roof at loft (E6) doesn't show the main floor structure but it is meant for the full perimeter concrete foundation of the Builders Cottage plan. In that all the loads are carried straight down to the foundation.

The Little House design is a much lighter load and the cantilever joist detail should not be used for a large loft load (as you correctly surmised). Notice the deep pier design for the main floor and foundation shown on the previous page (E5). That would be a better detail to use than the lightweight Little House pier design.

Sorry I didn't respond earlier, for some reason the notifications got turned off.

John
None of us are as smart as all of us.


knightasylum

Thanks for the reply. I am considering a alternate foundation in an attempt to use the supplies I already purchased for the job. I already have the 2x 6 floor joists and two 4x8x24 beams, and was planning for sonotu e concrete colums ( tied into the bedrock below with rebar) with saddles for the beams all for the original floor plan so I was thinkng that I could add another identical beam down the middle, move the other two out to the edge (so the load goes straight down to the beams) and use the same sono tubes every 8 feet like the deep pier foundation calls for. That should offer plenty of support for both extended loft and the floor span, I think. How does that sound? I can scrap the floor joists and beams I already purchased if needed to follow the actual deep peir foundation instructions if that is more safe, just attempting a work around if possible. Thoughts?

John Raabe

Yes, that would be a sturdier floor and foundation. You cut down the spans on the floor and loft joists (support the loft with a similar beam), and the loads go straight to the beams and piers. If you wanted to you could extend the beam support posts at the center and end walls, put in a ridge beam at the top for support of the roof rafters, and then eliminate the balloon framed walls and the loft support ledger for the loft joists. You could platform frame the loft on top of 8' walls and make the loft pony wall higher for more headroom. Or, you could just stick with what you are suggesting. :D

None of us are as smart as all of us.

knightasylum

Thanks for the reply, I am nervous about not just doing the simpler plan without the extended loft but at 6' 2" I really think I will be happy with the bigger space so i think I will risk complicating it (it is my lack of experience that makes the changes complicated, not that they are likely hard to do)

John Raabe

You aren't doing rocket science with this and an experienced local builder will likely help you flesh out your options and make sure you are building safe and strong. I know, when I built my house such a connection was very helpful to me (and we are still close friends!)

Best wishes, John
None of us are as smart as all of us.


knightasylum

What size ridge beam would you recommend if I went that route?

John Raabe

That beam would need to support half the total roof load (usually calculated at 10lbs + snow load) per SF. You should have all your final loads to the beams calculated locally - it will not be a big deal.
None of us are as smart as all of us.

knightasylum


knightasylum

I just realized that I have purchased floor joists based on the original material list (so the are 2x6x14) but I am doing the extended loft with the larger roof rafters so now they may be undersized. I know the deep pier foundation calls for 2x10s but my question would be that while I am doing the deep pier foundation I have added a center beam to the floor of that design so there is not a 14 ft an unsupported span between beams, just 7. With that extra support are the 2x6 joists appropriate ( as I think the increase in thickness is for the expanded gap) or should I upgrade them to 2x10s?
Thanks

John Raabe

Yes, if you have a midline support beam the under 7' span will be fine for 2x6 joists @16". Use #2 or Btr.
None of us are as smart as all of us.


knightasylum

Thank you !
Pouring the foundation piers for the cabin this weekend so I appreciate all the support.