When a Porch Pulls Away From the Building

If your porch is pulling away from the building, you can usually see it before anything falls: a gap at the wall, trim that has opened up, a door that no longer lines up with the landing. That gap is the connection between the porch and the house letting go. This is not a cosmetic problem, and it does not get better with caulk.

What is failing when a porch separates from the wall?

On many wood porches, the floor framing is fastened to the building along a board called a ledger. The City's porch inspection page says inspectors check joists, beams, columns, stairs, rails, ledger boards, connections and footings (City of Chicago). Ledgers and connections are on that list because they carry the porch's weight into the building, or hold the porch to it.

The City's 2011 porch guidance, which is now old, said ledger beams are bolted to the wall (City of Chicago, 2011 guidelines). Treat the 2011 numbers as 2011 guidance and check anything specific with the Department of Buildings against the current code.

The code that applies to existing porches is plain. They must be kept structurally sound, in good repair, properly anchored, and capable of supporting the loads placed on them (City of Chicago). A porch that is separating is not properly anchored.

Why do porches pull away?

Usually it is more than one thing at once.

• Rot where the porch meets the wall. Serious wood decay needs sustained moisture, above about 30 percent in the wood, from rain, condensation or wet ground (USDA Forest Products Laboratory). A joint that stays wet is where the wood goes soft, and screws and bolts have nothing to hold.
• No flashing, or flashing that failed. The American Wood Council's deck guide calls for corrosion-resistant flashing at the ledger on wood-framed walls (AWC DCA 6). Water that runs down the wall and behind the ledger has nowhere to go but into the joint. That guide is written for single-level decks attached to a house, so use it as an industry reference, not as Chicago code.
• The wrong fasteners. The same guide specifies lag screws or bolts of a stated size, driven in by turning, not hammering, through the board and into the house band (AWC DCA 6). It also calls for hot-dipped galvanized or stainless fasteners and connectors with treated wood (AWC DCA 6). Plain steel is not what the guide allows.
• Weak support. A porch that leans away is often pulling because something below it moved, such as a post, footing or stair. The point of failure shows at the wall.

What did the worst case look like?

On June 29, 2003, a third-floor rear porch in Lincoln Park collapsed onto the porches below, killing 13 people and injuring 57 (CBS Chicago). Officials first blamed overcrowding. City findings later cited a porch that extended too far from the building, inadequate supports, undersized flooring and screws that were too small (CBS Chicago). Those are connection and support details, the same family of problems as a separating ledger. For the full account, read the Lincoln Park porch collapse.

What are the warning signs?

Check for these, from the ground and from the porch itself:

• A visible gap or crack between the porch and the wall that is wider than it used to be.
• Light showing through where the porch meets the building.
• Soft, dark or crumbling wood at the connection. A screwdriver sinks in.
• Rust streaks or loose, backing-out bolts and screws.
• A floor that slopes away from the wall, or a door that sticks or no longer lines up.
• Trim, siding or brick cracked along the line where the porch attaches.
• A porch that moves or flexes when someone walks on it.

Our porch collapse warning signs article covers the rest of the list.

How is it fixed?

The repair depends on what is underneath, and you cannot know that from a photo. Typically a contractor opens the joint, finds how far the rot has gone, and then replaces the ledger or the framing it is attached to, restores flashing, and reattaches the porch with the right fasteners. If a post, footing or stair moved, that gets fixed too, and the post at the base may be the cause (rotted porch posts).

Chicago treats this as structural work. DOB says a permit is always required to repair or replace structural elements such as columns, beams, foundations, stringers and floor joists, with plans by an Illinois-licensed architect or structural engineer (City of Chicago). The Express Permit allows repair of existing structures, including replacing up to 50 percent of an existing single-story porch of conventional materials, but bigger or different work needs a plan-based permit (City of Chicago). Plan-based permits need plans by an Illinois-licensed architect or engineer (City of Chicago). Ask DOB which track your porch falls under. We explain the permit side in the Chicago porch permit guide.

If the porch is in immediate danger, the City allows emergency work that normally needs a permit to be done first to prevent imminent harm. You must apply for the permit the next business day, and the work may not be concealed without an inspector's approval (City of Chicago).

What should you do today?

1. Stop using the porch if the gap is growing, the floor has dropped or it moves underfoot, and keep others off it.
2. Photograph the gap with a tape measure beside it, and date the photos.
3. Do not caulk, fill or trim over it. That hides the problem.
4. Call a contractor who does structural porch work, and ask who draws the plans.

Our porch team can look at the connection and tell you what is needed. For the larger picture of repair and rebuild, see our Chicago porch guide.

Common questions

This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.