Author Topic: 20'w 1 1/2 vs. 2 Storey  (Read 2097 times)

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Offline Gladey

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20'w 1 1/2 vs. 2 Storey
« on: September 02, 2016, 06:38:55 AM »
Quick question: I have the 1 1/2 storey 20'w plans, and plan to begin building next spring, but am toying with the idea of going a full 2 stories and picking up the 2 storey plans. I noticed on the PDF for the 2 storey plan that a central beam is used to support the 2nd floor, while they are not used for the 1 1/2 storey, which recommends doubled 2x12s (we would be building a full-length loft) for the loft joists. Would it be possible to use doubled 2x12s for the 2-storey 2nd floor platform and omit the beam?

Offline John Raabe

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Re: 20'w 1 1/2 vs. 2 Storey
« Reply #1 on: September 02, 2016, 07:02:59 AM »
The Universal Cottage plans (sheet 9 - framing plan) uses engineered joists 11 7/8" @ 16" oc. That layout can be done for both the main and 2nd floor framing. Check what spec your supplier can provide. If you can, ask for "enhanced" or low deflection joists.

While there are other ways to frame the floors, I think this option gives you the most flexibility.
None of us are as smart as all of us.


Offline Gladey

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Re: 20'w 1 1/2 vs. 2 Storey
« Reply #2 on: September 02, 2016, 07:20:38 AM »
Thanks, John! Our plan was initially to build the 1 1/2 storey with a full length loft and exposed doubled 2x12 joists 16" oc/TG subfloor over the kitchen living area (closed ceiling in downstairs bedroom and bathroom). I've been briefly distracted by the thought of building a two storey instead ("If we're building a full loft, why not build a whole 2nd storey!") but I think I'm coming back around to the 1 1/2. Thanks for all of the support!

As a follow up question: we had hoped to frame 2 6' flush shed roof dormers with the 1 1/2 storey and read in a few threads that a 6' dormer should be fine with a ridge board only (as opposed to a ridge beam). Would that still be the case if the dormers were opposite each other (both dormers framed onto the same section of ridge board)?


Offline Rys

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Re: 20'w 1 1/2 vs. 2 Storey
« Reply #3 on: September 05, 2016, 09:04:02 AM »
Following as I too want dormers in the loft.
 ???

Offline John Raabe

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Re: 20'w 1 1/2 vs. 2 Storey
« Reply #4 on: September 05, 2016, 09:13:21 AM »
A shed dormer from both sides of the ridge board will counterbalance each other. The ridge board is not working as a load carrying beam. It just transfers the roof load to the walls. Make sure those connections are secure.
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Offline Don_P

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Re: 20'w 1 1/2 vs. 2 Storey
« Reply #5 on: September 05, 2016, 12:50:59 PM »
Also with a ridgeboard you will need ceiling joists to tie the rafter feet together. As the pitch becomes shallower the spreading force becomes greater. The dormers across from each other is better balanced and stronger as John said.

 

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