Cabin Design – 12ft House – Part 11

Last time we drew the basic cabin section and today we will add the porch. We will start with the building section we completed in Part 10.

As always, we will start with what we know:

  • The posts are 6″ square
  • The porch is 8 ft wide
  • We will set the beam height to 6′-8″ to the bottom.
  • The porch roof pitch will be 4:12 (1:3 ratio)
  • The porch floor thickness will be 8″ (2 x 8 floor joists)
  • The porch roof thickness will be 6″ (2×6 rafters)
  • And the roof overhang will be 1′-0″

Some of these assumptions will need testing, but for now that is where we will begin. And remember, we are completing this section for the purpose of finding the heights needed to draw the elevations (exterior views).

Follow along with the section drawing below (figure 1) as I take you through the order in which I normally construct the building section.

First we will draw the porch floor line (#1).
This will be the base line for all that comes next. Draw this horizontal line 3″ below the cabin floor line.

Next draw the outside of the porch posts. (#2)
This vertical line will be 8′-0″ from the outside wall of the cabin.

Draw the post thickness next. (#3).
We know that the posts are 6″ square, which would be 1/8″ on the graph paper.

Next we will draw the bottom and top of the beam. (#4).
Draw a horizontal line 6′-8″ above the porch floor line (#4a), that will be the bottom of the beam. Draw another line 8″ above this line (#4b)… that will be the top of the beam.

Cabin Plan Porch Section Outline

The porch roof pitch comes next. (#5).
This line is drawn beginning at the top of the beam on the inside face. The inside face of the post is where the rafter will sit and represents the inside face of the roof. Draw this line at a 1:3  slope . I usually so this by measuring over 12ft (in scale) and then up 4ft and connecting the two points.

Now draw the floor thickness. (#6).
Since we will be using 2 x 8 floor joists, draw a horizontal line 8″ below the porch floor line.

The roof thickness comes next. (#7).
In a similar manner as we did for the floor thickness, draw parallel lines 6″ above the inside roof line you drew in #5. This line will represent the outside of the roof.

Next draw the roof overhang. (#8).
Draw a vertical line 1′-0″ (to scale… 3/8″) outside of the post line. This will be the roof overhang and will determine the gutter or eave height for the elevations.

Last draw the grade line. (#9).
Draw a horizontal line 8″ below the cabin floor. This will be the ground or grade.

Now finally darken in all the structure that you have just outlined (figure 2 below).

Cabin Plan Porch Section

So now you have all the information you need to draw the elevations. Next time we will draw the end elevations.

As always, your comments are very valuable not only to me but to the others who drop by.

Best,

Andy

4 Comments

  • Ryan

    Reply Reply July 8, 2012

    Andy,

    As most structural boards are 1/2″ under the stated size won’t there be issues with drawing them the stated size instead of the actual size?

    • Andy Sheldon

      Reply Reply July 14, 2012

      Good question Ryan… Most builders know the difference between nominal and actual dimensions and so noting an exterior wall as a 6″ wall will not confuse them. If you think of a 1/4″ scale drawing, that 1/2″ is a pencil line (or ink line), and really won’t make a difference. When dimensioning a set of plans, it is best to dimension to either the center of a stud or to one side of a stud… then there will be no confusion. When larger scale drawings and details are done, the actual size would be used so there is no confusion. You can find our post on Nominal vs. Actual dimensions Here.

  • Richard Rose

    Reply Reply July 7, 2012

    Hi Andy;
    Seems pretty straightforward. I like that you set the porch 3″ lower than the main floor level. If I were drawing it for this climate (Canada) I’d also put a slight downward slope to the porch…so any water that made it’s way onto the porch would drain away from the main foundation wall. Wouldn’t take much, maybe 1″ over the whole width of the porch. My concern is that if your seal between the porch and the wall isn’t 100% tight, water can get in between and freeze overnight….which would spread the joint open further. I’ve seen it happen. Siimilar issues when using plywood on porches, further aggravated by some people who like to put indoor/outdoor carpet on the whole thing…which traps water beneath it and causes rot….seen that too. Takes a while though. Maybe treated wood would work better, though you haven’t really covered materials for this part of the project yet.
    Regards,
    Richard

    • Andy Sheldon

      Reply Reply July 7, 2012

      Thanks Richard… Most often I would build the porch as a level deck, with spaced boards installed parallel with the wall and with a small space between. What you do not see in the section yet is the deck ledger board that is furred off the rim about 1/2″ which will allow water to drain and not be trapped. Instead of sloping the deck, the grade below the deck is sloped so that water drains away from the cabin.

      If you build a “tight” porch, you are correct that there should be a slope, and ideally the T&G boards would be installed perpendicular to the wall and sloped about 1/8″-1/4″ per ft. depending on your climate.

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