New sill wood after removing old rotted porch. Old House Remodeling:

Porch Replacement:
Sill Preparations

In This Article:

We cut away wood sheathing that interferes with the new porch, apply primer to the old framing to deter rot, and install a new 2x6 ledger board.

Related Articles:
Skill Level: 3 (Moderate) Time Taken: 2 Hours

By , Editor


Modern deck framing often employs a ledger joist that is attached to the exterior wall of the house. Perpendicular joists connect to the ledger using metal joist hangers.

After the old porch decking was removed, there was a beaten and weathered layer of wood underneath.


These grayed boards exposed at the corner are part of the solid wood sheathing that covers the outside walls of this old house. This sheathing is nailed directly to the outside of the wall studs. 

Some of these sheathing boards are almost 20 inches wide (i.e. a 1x20 plank). Try finding that kind of lumber today!

In the corner, the lower part of the sheathing was reasonably intact. But other parts were badly cracked. I didn't want to install our porch ledger board over a weak and uneven substrate, so I decided to cut away part of the sheathing.


Some of the nails in the sheathing were rather rusted. This is a common occurrence in old houses.


This is typical of the point where the old stone foundation meets the wooden sill plate. Sill plates often rot because they are in contact with masonry, which can absorb water and dampen the wood, which will rot whenever the moisture content is above 29%.

The loose rocks will allow cold air to enter the house in the winter, and these gaps also let bugs gain entrance to the house.

I believe that this house has experienced no sill rotting problems because the foundation extends about 2 feet above the soil. This makes it difficult for water to wick upwards into the wood. Also, since the house has a basement which receives some heat from the furnace, the lowest parts of the framing are not exposed to damp crawl-space air. It's benefits like these that make me a firm believer in full-depth basements.

Once I had calculated the exact level of the ledger joist, I snapped a chalk line and ripped the sheathing board with a circular saw.


Since I could not cut all the way to the end, I used a reciprocating saw to cut the last few inches (red arrow).


I applied a coating of oil-based primer to the exposed sill and rim joists. Why? Because it can't hurt and might help.

Primer will deter moisture from soaking into the wood, if some water ever gets behind the ledger joist.


This inexpensive drill bit is good for drilling counter-sunk pilot holes. 


I used 3" Deck-Mate screws to install the ledger joist to the house. With the pre-drilled and counter-sunk holes, the screw heads were easily buried below the surface of the wood.


The installed ledger boards, which were 2x6 pressure treated pine. Ledger boards installed on old house to anchor new porch framing.

Note:  One thing I omitted in this task was a metal flashing strip to keep water from getting behind the ledger joist. Many new-home builders employ such flashing strips (often called a Z-flashing because of its shape), but I was not able to pry the siding away from the house to insert the upper leg of the flashing. 

We plan on replacing the siding on most of this house (with original wood siding), and at that time we will install an appropriate flashing.

Warning About Deck Ledgers:

I have read numerous accounts lately (2004) about serious injuries and deaths caused by collapsing decks. In most of these cases the culprit was an improperly installed deck ledger which pulled away from the house when the deck was loaded with a crowd of people. 

Some of these ledger boards were simply nailed to the side of the building with common (smooth-shank) nails, which offer very little resistance to pull-out forces. Deck screws are definitely better than common nails at resisting pull-out, but deck screws may still not be enough.

Current building codes specify the number and size of fasteners used to attach a ledger board to a building. I have seen some hefty requirements, such as 2 rows of  " lag screws spaced at most 16 inches apart. Your actual requirements will depend on your conditions, so contact your local building department or construction codes office for exact information.

Continue to the Porch Framing article.




Tools Used:

  • Cordless Drill/Driver
  • Circular Saw
  • Reciprocating Saw
  • Basic Carpentry Tools

Materials Used:

  • Treated Lumber, 2x6
  • Deck Screws


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Copyright 2001, 2005

Written March 9, 2001
Revised January 6, 2005