Old House Remodeling: Porch Floor Framing

By Bruce W. Maki, Editor

This is a photo from an earlier stage. Note how the porch roof is supported by the house on two sides. The porch post only supports one-fourth of the total roof and  floor loads. Nevertheless, the porch roof structure is heavy and must be supported during remodeling. We installed a pair of long 2x6's to prop up the roof. I was never very comfortable relying on these boards, so I added a hydraulic jack for part of the duration.

The starting point for the porch framing is the ledger joist, which was attached to the house with deck screws.

We used this hydraulic jack with a post to lift up the porch roof slightly. We also had in place a pair of long 2x6 boards for additional support.

We made this odd-looking U-shaped block to avoid lifting on the fragile millwork that runs across the front edge of the ceiling.

Let The Framing Begin:

First we installed a 2x6 to define the edge of the porch. We supported it temporarily with a pole and a Quick-Grip clamp.

We installed the 6x6 treated post that holds up the corner of the porch deck. The white post (part of the original porch framing) was simply dangling from above.

We backfilled the post hole. We placed gravel right next to the post and plain soil everywhere else.

View the article about building the post foundations.

We installed a pair of 4x4 treated posts to provide extra structure for the steps and handrail.

We completed the initial framing that defined the outer limits of the porch. The long treated 2x6 in front is supported in the middle of its span by those two 4x4 posts.

The old porch column had some minor rot problems. We filled the holes with epoxy wood filler.

We digressed at this point and did two little extra jobs... we parge-coated the stone foundation wall and we laid 8x16 concrete patio pavers (the cheapest we could find) on the dirt under the porch.

Why did we do these minor steps?

Parge coating the wall, which involves simply troweling on a thin coating of mortar and brushing it smooth, will help hold the stones in place. This house uses large cut stones for the visible sections of the foundation, but under the porches it uses plain round rocks. Figuring nobody would care if the barely-noticeable sections of the foundation were not original, we decided to add an extra layer of protection against air infiltration and bug invasion.

We installed the patio paving stones to provide a reasonably smooth floor under the porch. We laid the pavers with a 3/8" gap between them and then dumped a bag of pre-mixed masonry mortar into the cracks. We used a broom to spread the mortar and then wetted the cement with a light sprinkling from a garden hose. Before we laid the pavers we laid down a sheet of plastic to keep water away from the foundation. (This section of foundation once leaked badly, now it does not leak even during the worst rain storms.)

We plan to use this under-porch space as storage for outdoor things like ladders and garden tools. Having a clean concrete floor will help keep these things from deteriorating. Also, a seamless concrete floor will keep weeds from germinating in the under-porch space, and will discourage insects and rodents from living there by creating a hostile (i.e. clean) environment for them.

After we finished the parge coat on the foundation we applied a bead of caulking between the cement and the ledger joist. This will reduce cold-air infiltration and eliminate many entry points for insects.

With those minor tasks complete we resumed the framing of the floor structure. We installed a pair of double-2x6 beams between the house and the front of the porch.

The other end of the beam is attached to the 4x4 post that will support the steps and handrail. Note how the 2x6 that dead-ends into the post has a metal framing bracket to securely attach it to the post.

The other 2x6 overlapped the post so we secured it with 5 long deck screws. These are Deck-Mate brand 3" deck screws, not drywall screws.

A common problem in framing is warped lumber. But two boards placed side-by-side can present an opportunity to remedy the situation. Note how much mis-aligned the boards are, even though they are aligned at the far end.

Our solution was to clamp the two boards together with Quick-Grip clamps and tap them with a hammer to align them.

Then we drove in some 3" deck screws to connect the boards together.

Afterward the same boards are aligned much better.

This is a joist hanger for a double 2x6, available at Home Depot and other stores.

Our installation procedure for joist hangers is not what most professional carpenters do. Most carpenters install the hangers first, aligning one edge with a vertical line on the wood and only fastening that one side initially. Then they install the joist and "wrap" the un-attached side of the hanger around the joist and drive in the nails.

We don't follow that technique because the tops of the joists never seem to line up adequately. It is difficult to get the hangers in the exact position when there is no joist present to guide them.  

After putting the double joists in position, we clamped the joist hanger to the joists. Our approach only works if the joists are cut a little bit extra long, so they fit snugly and don't fall down.

With the hanger clamped in place we drove in a pair of 3" deck screws on each side. These screws go through the joist and right into the ledger. Note: In many cases building inspectors require 16d nails in these diagonal holes in joist hangers. They often won't allow deck screws because there is a requirement that the fastener must have the same shear strength as a 16d nail.

Then we drove in some 1-1/4" Simpson Strong-Drive screws, which are meant for installing these hangers. They also sell short galvanized nails for this purpose. Again, many building inspectors require a certain size of nails here, such as 8d or 10d. There are short, thick joist hanger nails made just for this purpose.

The double-2x6-beam framing after completion. It's important to keep this in perspective... the only reason we made these beams was to reduce the span of the 2x6 floor joists. The original porch on the opposite side of the house has 2x6's that span 13 feet, which is way too long.

The beam framing from another angle. Note how we attached the beams to handrail support posts. (These posts were later lopped off and turned cedar newel posts were installed.)

Installing The Joists:

We installed the joists at 12 inches on center. This narrow spacing kept the tongue-and-groove flooring from deflecting (bouncing) too much.

We first installed the joists with no hangers, because we had made them long enough to fit in place by their own friction.

Then we installed the joist hangers as before, by clamping them in place and securing them with screws.

The joist framing after completion. The joists all have a span less than five feet, which means they are far stronger (and far more rigid) than the minimum structure that local building codes would specify.

A view of the connection between the double-2x6-beam and the 4x4 post.

The 6x6 corner post has a double-2x6-beam connecting to it. The steel angle bracket is the heaviest bracket we could find, it is much thicker metal than the usual joist hangers. We also drove is some 3" deck screws on an angle to hold the beam to the post.

The other end of the beam in the previous photo. Again, the metal bracket is heavy-duty.

Some Notes:

The direction of the floor joists was determined by history more than anything else. We wanted to rebuild the porch very close to the original technique, which is why we used tongue-and-grooved yellow pine flooring instead of the usual pressure-treated 5/4x6 deck boards.

Since the original flooring ran parallel to the short dimension of this 5' x 13' porch, we had to make the joists run parallel to the long dimension. Most people building modern decks would do the opposite of what we did.

We also gave the floor framing a slight slope away from the house, just less than 1/4" to the foot. Proper drainage is important to keeping the wood dry and making it last as long as possible.

Continue to Installing Handrail Newel Posts

Copyright © 2001, 2005  HammerZone.com

Written March 13, 2001
Revised January 5, 2005