How To Replace Door Sill Rot

By Robert Robillard on Home Repairs And Remodeling

How To Replace Door Sill Rot

Poor Flashing, Water Damage And Carpenter Ants Defeat Entry Door

A quick look at this entry door did not show anything unusual but a closer inspection revealed that the bottom of the door and sidelights had been spliced “quickly and poorly” prior to us.  This article is about how to replace door sill rot.

Two Clues To Improper Flashing

Two notable clues that I saw was that the porch decking was to close to the inside floor height.  A 7″ step into the house would have helped keep water and melting snow out. The second was there was a fairly new gutter above this door and no gutters anywhere else on the house.

The gutter was added after the repair to the door. Rain run off from the roof must have pelted this porch landing and door.

How To Replace Door Sill Rot

Part of this project was to remove this glass entryway.  When we were removing the tile floor we discovered that water had leaked in and rotted out he floor sheathing and a few floor joists.

Remove The Door

We also discovered that this was the second repair to this area, this is when we realized that the door needed to be removed to repair the house sill and joists below.

Once the trim was removed we discovered carpenter ants had eaten into the door jamb, sidelights and surrounding framing.

How To Replace Door Sill Rot

Carpenter Ants Follow Water!

Carpenter ants are large (¼–1 in) ants and are indigenous to many parts of the world. They prefer dead, damp wood in which to build nests. They cut tunnels into the wood grain to provide passageways for movement from section to section of the nest. [see photo below – click to enlarge]

Sometimes their presence can be detected by the saw dust they leave behind.

How To Replace Door Sill Rot

The glass entry and door was removed. The door was for a 2×6 wall and this house had 2×4 walls.

A prior installer had padded out the wall thickness in the glass enclosure to hide the difference in jamb thicknesses. This door also had odd size side lites and a side lite modified and used as a transom above the door. The whole assembly had been cobbled together.

Now the floor and framing had to be repaired.

How To Replace Door Sill Rot

Worn out and damaged aluminum flashing had long since failed. Nail penetrations into the flashing allowed water to enter the house. It is imperative never to nail through flashing for this reason.

How To Replace Door Sill Rot

Rotted 2×4 sill plates, studs and exterior sheathing were found on either side of the door.

How To Replace Door Sill Rot

Door was thrown in trash and a new one ordered. The only problem was that the new door was 5 to 6 weeks away and we had a large opening in this house.

Where is the structural door header??????

How To Replace Door Sill Rot

The difference in height between the porch deck and the interior floor was only an inch or two.

Unfortunately this deficiency will have to be corrected someday when the porch is replaced.

How To Replace Door Sill Rot

Floor joists, sill and sub floor was replaced. Area flashed with rubber.

How To Replace Door Sill Rot

This is a non-bearing wall but it still has weight. We replaced the ant infested studs, added a structural header and boarded up the opening .

Tar paper sealed the outside to keep the area dry until the new door arrived.

Inside view.

New door arrives. Fine tuning to the framing and flashing.

A Simpson fir flat panel, 3-lite door with matching side lites is the new entry door of choice. Because of the low step we chose an aluminum sill and rot saver jamb option for the door.

Door installed

Installing vapor barrier, tar paper and rubber flashing around the door.

Unfortunately the transoms were larger than normal and the clapboards had to be removed and replaced which adds a significant amount of work and material to a door swap out.

The top of the clapboards terminates into a flat trim board and crown molding. We were able to splice new crown where the transom used to be.

A dental head PVC pediment detail and fluted column trim finishes off the door.

~ concord carpenter


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About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

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