Author Topic: 24x24 in Alabama  (Read 9133 times)

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Offline scottbama

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24x24 in Alabama
« on: May 15, 2011, 07:18:21 AM »
I am building on a 24x24 and trying to think ahead. I found some plans online that I have taken and modified to add a loft in the rear of the building 12x24. There are no permits or anything that I have to face where I live. My question I cannot figure out in my head is how to exactly build the loft area. the walls below will be 8 foot tall with a 4 foot wall in the loft to give enough head room. The forward half of the house will have 12 foot walls to accommodate.

Any and all help is appreciated since I am no contractor or builder.

Scott Gleaton

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #1 on: May 15, 2011, 02:30:04 PM »
24' is a pretty good span.  Unless you are using TJI's, you are looking at a bearing wall in the middle downstairs.   Per the TJI span table, you are looking at 14" or 16" TJI's to clear span the loft, and possibly web stiffeners.

If you use 12' in the front, and want 4' sidewalls in the back your ceiling height is 8' less the height of your second story joists and subfloor.  That makes for a low ceiling downstairs in the back, or loft sidewalls less than 4'.  

If you use 2x10 across a 12' span (assuming you place your bearing wall in the exact middle of the downstairs back-end, you would have to build a small pony wall on the deck of your loft to line up with the top plate of the 12' walls.  To tie the two sections together, I'd think you would need a top plate that spans the entire length of the 24', with one piece spanning the two sections to tie them together.    Even if you use TJI's, you are still building a small pony wall on the deck.

The roof plan now becomes an engineering issue, as you need to accommodate the outward pressure across the pony wall section.  You are looking at trusses or an engineered ridge beam, as opposed to a simple ridge board.  

The pony wall is also a standard 2x framed wall.  You will end up with a 24' top plate spanning both directions to set your roof rafters.    With a 24' width, I think you are looking at attic trusses or scissor trusses.  At the width, you would still end up with decent height in the center, even if you only have a ~3' pony wall to accommodate 16" joists (assuming you want to clear span).   Trusses would be much easier to install and handle.

« Last Edit: May 15, 2011, 02:53:22 PM by Native_NM »
New Mexico.  Better than regular Mexico.

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #2 on: May 15, 2011, 02:38:26 PM »
New Mexico.  Better than regular Mexico.

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #3 on: May 15, 2011, 02:51:48 PM »
IF you really want the 4' pony wall in the loft, you can frame the outer walls from 2'x6, using 8' lumber in the back, and 14' lumber in the front section.  This will give you sidewalls as follows":

Rear: 

96" (to top plate)
16" TJI
3/4" T&G deck
48" pony wall (including double top plate).

Front:

~13.5' walls inclusive of double top plate.





New Mexico.  Better than regular Mexico.

Offline Squirl

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Re: 24x24 in Alabama
« Reply #4 on: May 15, 2011, 03:40:32 PM »
NativeNM makes a good point about the roof.  It will be difficult to span a ridgebeam 24' but not impossible.  You will probably need a crane and some help.  Trusses would be easier.  John includes a good homemade truss design in his plans.  Others can be found on many agricultural web designs.

Offline scottbama

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Re: 24x24 in Alabama
« Reply #5 on: May 15, 2011, 06:30:16 PM »
Native_NM has rhe right idea in his drawing. I failed to mention i have two walls downstairs that will help support the span plus there is a 4x6 center of the hom as part of the support system. If I do 2x6 exterior wall can I not kerf the studs to accomodate a 2x10 and tie the deck floor joists to the studs? using the one 2x10 as a support?

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #6 on: May 15, 2011, 07:40:06 PM »
There are two complete threads here on the pros/cons of notching and kerfing.  Generally, a 2x6 is not deep enough to notch 1.5" out of to meet code, as 1.5/5.5 is greater than the allowable factor. 
New Mexico.  Better than regular Mexico.

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #7 on: May 15, 2011, 09:02:41 PM »
Another missing piece of info is the roof pitch you plan to use, as well as the proposed layout of the loft. 

For a 24' wide plan, a steep pitch will result in a very tall final structure.  Assume 12/12 pitch, like many of the smaller plans here use, and your building could would up 26' tall, with a interior deck-to-ridge height of 16' if you went with a full 4' pony wall.  It might be better to alter the pitch to meet the headroom desired.  For example, if you were using scissor trusses, and wanted a full 8' of headroom in the center of the loft, you could get away with 6/12 to 8/12 depending on the truss design.  On the other hand, if you plan to carve of the loft area into two rooms, you might need to think about dormers to get the needed height and headroom.   

New Mexico.  Better than regular Mexico.

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #8 on: May 15, 2011, 09:05:01 PM »
New Mexico.  Better than regular Mexico.

Offline Native_NM

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Re: 24x24 in Alabama
« Reply #9 on: May 15, 2011, 09:12:51 PM »
On a 24' wide plan, with a 10/12 pitch, you can get almost 16' of interior space with minimum 8' ceilings in the loft off of a 4' pony wall.  The height at ridge will actually be taller.  It will vary depending on the type of truss of rafters a bit.  The total height is ~24', again dependent on the truss type.    If you added dormers to both sides, you could get two nice rooms under the loft with plenty of headroom.  Truss companies can design dormer trusses easier than you can frame them.

My drawing does not account for the height of the TJI's and the decking, which is why the height is shown as 22'.  You have to add 16" for them, but at least a foot if you use dimensional lumber.  I was just illustrating ceiling height.

The total floor-to-ridge height on the non-loft end will be much greater, so plan for that.


New Mexico.  Better than regular Mexico.