Tuesday, July 23, 2013

Front Porch Framing

      In the last post we left off with the porch posts and headers, and we've been working on the rafters since then.

     My name is Steven, and I am a Simpson Strong-Tie-aholic. In the porch project I used five different ties; Ridge Rafter Connectors, Hurricane Strap H2.5A, Cap Base BC4, Post Base ABA 44, and Mending Plate MP24. I have seen where people have used common nails, but I like to use the Strong-Tie N10D5HDG and 10d5HDG nails. I have seen other people install the ties using other types of fasteners but to me it seemed that a Strong-Tie 10d nail was a bit bigger than a regular 10d and would insure a snug fit with the connector. I prefer contact around the entire nail instead of just were the head meets the plate.

     Hipped roofs are composed of four different framing components: ridge beam, common rafter, hip rafter, and jack rafter.

     The board to the far right, attached to the front of the house, is the ridge beam (special thanks to Ryan!). The diagonal rafters, attached to the ridge beam and the porch header, are the common rafters.


     Before the ridge beam was lag-screwed to the house, we attached the Ridge Rafter Connectors, which are used to secure the common rafters to the ridge beam. This became a time saver when I was installing common rafters alone. I could lift the rafter on to the porch header, place one end in the connector and nail it, then square up the other end on the header and nail it into place.

     The 2"x8" ridge beam was attached to the house so that it was roughly centered with the porch and mounted 10' above the concrete porch floor. It was first nailed to hold it in place, then lag screws were used to attach it to the studs. Porch roofs will often pull away from a house over time. Lag screwing the ridge beam keeps this from happening and also helps transfer some of the weight to the studs of the house.

     Once the ridge beam was in place, it was time to put in the common rafters. The rafters were cut using a construction calculator. I used an iPhone App (Builder's Helper by My Pie Interactive), and it made calculation very easy. I would highly suggest getting a construction calculator before starting a project. Most of them seemed to run between $10 and $16. After two rafter installations, I was able to install a rafter with the rafter connector and a Hurricane Strap in under ten minutes.

     The corner of a hipped roof is made up of a center hip rafter and paired jack rafters.

    The hip rafter is essentially the roof's sloped corner. The end that meets the ridge beam is mitered at 45° on both sides to meet with common rafters that are perpendicular to each other. Since the length of the hip rafter is much longer than the common rafters, the pitch will be different but a good construction calculator will give you the difference. It was amazing to see how ridged the framing became after the hip rafters were placed.

     The jack rafters are common rafters that meet at the hip rafter. They change in size but the pitch and angle are going to be the same. Theoretically, they should be the same pitch as the common rafters with a 45° cut to meet the hip rafter. However, that is in a perfect world where boards are not twisted, cupped, or bowed. I am a stickler for a good connection and the gaps on this theory weren't cutting it (haha, puns). So I came up with a way to transfer the compound cut to my miter saw.


     Starting from the last common rafter, I marked out the jack rafters' placement on the header (16" on center) using the short leg of a framing square. [If you didn't know already, the short leg of a framing square is the thickness of a 2x for ease of laying out framing.] I then used the framing square to find where the inside edge of the jack rafter would hit the hip rafter. If you are particular like me, put a speed square against the header as a fence, that way you know your marks are perpendicular to the header which will make a nice, straight rafter. I used this process for two of the rafter locations. I then can measure between the two lines to find where the other rafters will land, since they should all be equal distances apart. I then nailed a string to my marks on the header and hip rafter and used a bevel gauge (above photo) to measure the horizontal and vertical angles that would come in contact with the hip rafter. Using a compound miter saw, I set the first angle, then went back to the rafter, measured, and set the second angle on the miter saw. After a test cut and some minor adjustments, I was ready to cut the jack rafters.

     Here's the front view with most of the subfascia in place.

     If I were to do it all over again, I would definitely have cut the rafter tails much longer and then trimmed them after installation. The tails that I have were cut using one common rafter as a template. They are fine, but there are too many variables to consider when installing them, and you can see some slight waves in the subfascia. You can only really see it at one angle, on a ladder, and I am sure it will be even less noticeable when I attach the fascia. But for now, it bothers me. 

Helpful tools

Compound Miter Saw
Circular Saw
Jig Saw
Stair Gauges
Construction Calculator (or App)
Hammer Drill (for drilling holes in concrete for post, wedge bolts.)
Impact Driver ( for driving lag screws)
Framing Nailer


Believe it or not, this post was not sponsored by Simpson Strong-Tie!
-Steven