Hey all,
Just wanted to run a design for a timber framed structure that I am planning on building and wanted to appeal to those with more experience than this weekend warrior for feedback.

I plan on building an outdoor kitchen. I will excavate and pour a 20' x 20' 4" slab with the appropriate turn down on which I want to place timber framed structure. The structure will use 4 12" x 12" Douglas Fir posts set at 16' spacing to support the roof. These will be affixed to the slab using a 18" x 18" x 1/4" steel plate with a schedule 80 1 1/2" x 12" pipe welded to it that will be tapped into the bottom of the posts. These plates will be affixed to the posts with 4 - 18" timber screws. They will be affixed to the slab using 4 -3/4" x 4" concrete anchors embedded in the concrete slab when it is poured. This will handle the uplift forces on the structure, or at least that is the intent, as well as any shear at the base of the posts.

The roofs gable ends will use 6" x 8" beams for the king post truss's principle rafters and tie beams as well as for two struts. The tie beams for the gable end rafters will be framed to the posts using a 2" thick x 4" high x 6" wide tenon on the post and the appropriate mortise on the tie beams. They will also be supported by a 2' x 2' x 3' knee braces between the tie beam and post using the same 6" x 8 " Douglas Fir.

The tie beams between the two posts in the other direction will be 6" x 8" Douglas Fir as well. They will be framed to the posts using 2" thick x 4" high x 12" wide tenons on the posts and the appropriate mortise on the tie beams. These tie beams will be 6" x 8" x 20' and will support 6" x 8" principal rafters that are 4' on center. They will also have 2' x 2' x 3' knee braces between the post and tie beam. These principal rafters on the non-gable ends will also have a 6" x 8" collar beam 2' down from the peak. I will also tie all the rafters together using 4" x 4" beam running the length of the roof halfway up the principal rafters and at the peak.

On top of the rafters I will put 1 1/2" x 6" T & G Western Red Cedar car decking on which a standard felt / asphalt shingle roof will be placed.

So with that context I want to ask a couple of questions. 1.) I want to make sure that the tie beams on the non-gable ends are sufficient to support principal rafters that are on 4' on center as well as the rest of the roof. I had someone say that the span for a 6" x 8" beam shouldn't be any more than 12'. These will span 14' but will have additional knee braces that will reduce the span to 10'. Is this sufficient? 2.) Is the 4' spacing between the principal rafters too large?

Thanks for any advice,

John

On Saturday, October 25, 2014 4:27:56 PM UTC-7, John Sheppard wrote:
Hey all,
Just wanted to run a design for a timber framed structure that I am planning on building and wanted to appeal to those with more experience than this weekend warrior for feedback.

I plan on building an outdoor kitchen. I will excavate and pour a 20' x 20' 4" slab with the appropriate turn down on which I want to place timber framed structure. The structure will use 4 12" x 12" Douglas Fir posts set at 16' spacing to support the roof. These will be affixed to the slab using a 18" x 18" x 1/4" steel plate with a schedule 80 1 1/2" x 12" pipe welded to it that will be tapped into the bottom of the posts. These plates will be affixed to the posts with 4 - 18" timber screws. They will be affixed to the slab using 4 -3/4" x 4" concrete anchors embedded in the concrete slab when it is poured. This will handle the uplift forces on the structure, or at least that is the intent, as well as any shear at the base of the posts.

The roofs gable ends will use 6" x 8" beams for the king post truss's principle rafters and tie beams as well as for two struts. The tie beams for the gable end rafters will be framed to the posts using a 2" thick x 4" high x 6" wide tenon on the post and the appropriate mortise on the tie beams. They will also be supported by a 2' x 2' x 3' knee braces between the tie beam and post using the same 6" x 8 " Douglas Fir.

The tie beams between the two posts in the other direction will be 6" x 8" Douglas Fir as well. They will be framed to the posts using 2" thick x 4" high x 12" wide tenons on the posts and the appropriate mortise on the tie beams. These tie beams will be 6" x 8" x 20' and will support 6" x 8" principal rafters that are 4' on center. They will also have 2' x 2' x 3' knee braces between the post and tie beam. These principal rafters on the non-gable ends will also have a 6" x 8" collar beam 2' down from the peak. I will also tie all the rafters together using 4" x 4" beam running the length of the roof halfway up the principal rafters and at the peak.

On top of the rafters I will put 1 1/2" x 6" T & G Western Red Cedar car decking on which a standard felt / asphalt shingle roof will be placed.

So with that context I want to ask a couple of questions. 1.) I want to make sure that the tie beams on the non-gable ends are sufficient to support principal rafters that are on 4' on center as well as the rest of the roof. I had someone say that the span for a 6" x 8" beam shouldn't be any more than 12'. These will span 14' but will have additional knee braces that will reduce the span to 10'. Is this sufficient? 2.) Is the 4' spacing between the principal rafters too large?

Thanks for any advice,

John

Point of clarity, the knee braces will be 3' long. Not 2' x 2' x 3'. That is the triangle they will describe...

"John Sheppard" wrote:

Hey all,
Just wanted to run a design for a timber framed structure that I
am planning on building and wanted to appeal to those with more
experience than this weekend warrior for feedback.

I plan on building an outdoor kitchen. I will excavate and pour
a 20' x 20' 4" slab with the appropriate turn down on which I want
to place timber framed structure. The structure will use 4 12" x
12" Douglas Fir posts set at 16' spacing to support the roof. These
will be affixed to the slab using a 18" x 18" x 1/4" steel plate
with a schedule 80 1 1/2" x 12" pipe welded to it that will be
tapped into the bottom of the posts. These plates will be affixed
to the posts with 4 - 18" timber screws. They will be affixed to
the slab using 4 -3/4" x 4" concrete anchors embedded in the
concrete slab when it is poured. This will handle the uplift forces
on the structure, or at least that is the intent, as well as any
shear at the base of the posts.

The roofs gable ends will use 6" x 8" beams for the king post
truss's principle rafters and tie beams as well as for two struts.
The tie beams for the gable end rafters will be framed to the posts
using a 2" thick x 4" high x 6" wide tenon on the post and the
appropriate mortise on the tie beams. They will also be supported
by a 2' x 2' x 3' knee braces between the tie beam and post using
the same 6" x 8 " Douglas Fir.

The tie beams between the two posts in the other direction will
be 6" x 8" Douglas Fir as well. They will be framed to the posts
using 2" thick x 4" high x 12" wide tenons on the posts and the
appropriate mortise on the tie beams. These tie beams will be 6" x
8" x 20' and will support 6" x 8" principal rafters that are 4' on
center. They will also have 2' x 2' x 3' knee braces between the
post and tie beam. These principal rafters on the non-gable ends
will also have a 6" x 8" collar beam 2' down from the peak. I will
also tie all the rafters together using 4" x 4" beam running the
length of the roof halfway up the principal rafters and at the peak.

On top of the rafters I will put 1 1/2" x 6" T & G Western Red
Cedar car decking on which a standard felt / asphalt shingle roof
will be placed.

So with that context I want to ask a couple of questions. 1.) I
want to make sure that the tie beams on the non-gable ends are
sufficient to support principal rafters that are on 4' on center as
well as the rest of the roof. I had someone say that the span for a
6" x 8" beam shouldn't be any more than 12'. These will span 14'
but will have additional knee braces that will reduce the span to
10'. Is this sufficient? 2.) Is the 4' spacing between the
principal rafters too large?

Thanks for any advice,

John

Point of clarity, the knee braces will be 3' long. Not 2' x 2' x 3'.
That is the triangle they will describe...
-----------------------------------------------------------------------------------
Some general observations and comments:

1) What is the frost line in your part of the world?

2) 4" of concrete is little more than a dust cover. You need at least
6"
and wire mesh of the correct size.

3) What size footer do you plan having?

4) What do you mean by "appropriate turn down"?

5) Is this free standing or do you plan to secure to an adjacent
structure?

Questions, questions.


Lew

On Saturday, October 25, 2014 8:05:36 PM UTC-7, Lew Hodgett wrote:
"John Sheppard" wrote:

Hey all,
Just wanted to run a design for a timber framed structure that I
am planning on building and wanted to appeal to those with more
experience than this weekend warrior for feedback.

I plan on building an outdoor kitchen. I will excavate and pour
a 20' x 20' 4" slab with the appropriate turn down on which I want
to place timber framed structure. The structure will use 4 12" x
12" Douglas Fir posts set at 16' spacing to support the roof. These
will be affixed to the slab using a 18" x 18" x 1/4" steel plate
with a schedule 80 1 1/2" x 12" pipe welded to it that will be
tapped into the bottom of the posts. These plates will be affixed
to the posts with 4 - 18" timber screws. They will be affixed to
the slab using 4 -3/4" x 4" concrete anchors embedded in the
concrete slab when it is poured. This will handle the uplift forces
on the structure, or at least that is the intent, as well as any
shear at the base of the posts.

The roofs gable ends will use 6" x 8" beams for the king post
truss's principle rafters and tie beams as well as for two struts.
The tie beams for the gable end rafters will be framed to the posts
using a 2" thick x 4" high x 6" wide tenon on the post and the
appropriate mortise on the tie beams. They will also be supported
by a 2' x 2' x 3' knee braces between the tie beam and post using
the same 6" x 8 " Douglas Fir.

The tie beams between the two posts in the other direction will
be 6" x 8" Douglas Fir as well. They will be framed to the posts
using 2" thick x 4" high x 12" wide tenons on the posts and the
appropriate mortise on the tie beams. These tie beams will be 6" x
8" x 20' and will support 6" x 8" principal rafters that are 4' on
center. They will also have 2' x 2' x 3' knee braces between the
post and tie beam. These principal rafters on the non-gable ends
will also have a 6" x 8" collar beam 2' down from the peak. I will
also tie all the rafters together using 4" x 4" beam running the
length of the roof halfway up the principal rafters and at the peak.

On top of the rafters I will put 1 1/2" x 6" T & G Western Red
Cedar car decking on which a standard felt / asphalt shingle roof
will be placed.

So with that context I want to ask a couple of questions. 1.) I
want to make sure that the tie beams on the non-gable ends are
sufficient to support principal rafters that are on 4' on center as
well as the rest of the roof. I had someone say that the span for a
6" x 8" beam shouldn't be any more than 12'. These will span 14'
but will have additional knee braces that will reduce the span to
10'. Is this sufficient? 2.) Is the 4' spacing between the
principal rafters too large?

Thanks for any advice,

John

Point of clarity, the knee braces will be 3' long. Not 2' x 2' x 3'.
That is the triangle they will describe...
-----------------------------------------------------------------------------------
Some general observations and comments:

1) What is the frost line in your part of the world?

2) 4" of concrete is little more than a dust cover. You need at least
6"
and wire mesh of the correct size.

3) What size footer do you plan having?

4) What do you mean by "appropriate turn down"?

5) Is this free standing or do you plan to secure to an adjacent
structure?

Questions, questions.


Lew

Lew,
Thanks for the reply. As far as the concrete slab. I will have 4" of 5/8 minus gravel compacted underneath the slab. The slab will have wire mesh. The turn down I was referring to is making the edges of the slab thicker. In this case 8".

Frost line here is 18". The footings for the posts will be 2' w x 2' l x 18" h. I will also have footings for the counter area. This is because I building the counter from bezer blocks and slate with a granite counter top so I need additional load carrying capacity.

The structure will be free standing.

Thanks,

John