Short answer. The 2017 Therma-Tru guide identifies a damaged door bottom and a damaged sill saddle as separate potential sources when water reaches the threshold. source A saddle problem is specifically associated with the lower bulb bunching or wrinkling during closure. source Locate the part before describing the repair as “replace the sweep.”
Identify the piece that appears affected
Door-mounted candidate: look at the flexible component attached to the moving slab, especially whether its condition changes as the door closes. The manufacturer directs damaged-door-bottom concerns to the door-bottom service pathway. source
Sill-mounted candidate: focus on the surface the bottom seal meets. The illustrated adjustable sill has a separately identified saddle. source A damaged saddle associated with a wrinkling bottom bulb is one of the manual's named causes. source
| Observation | Useful written finding | Do not conclude |
|---|---|---|
| Lower flexible piece is torn or visibly distorted away from the sill | “Door-bottom condition needs confirmation.” source | Every threshold part must be replaced. |
| Lower bulb bunches as the door closes, with saddle damage visible | “Sill saddle and bulb contact need a joint inspection.” source | A thicker sweep will correct the sill. |
| Only a puddle is present | “Leak path not located.” | The puddle identifies the damaged component. |
Safe documentation sequence
- Take a wide photograph of the entire closed opening and the first wet area, if any.
- Open the door normally; photograph the moving bottom piece and the sill surface separately. Do not pry the seal or disturb adjustment hardware for this assessment.
- While closing normally, observe whether the lower bulb seems to fold, wrinkle or catch; stop if the door resists normal operation.
- Compare the observed sill configuration with the 2017 Adjustable Sill Threshold Replacement illustrations, which label the saddle as part of the threshold assembly. source
- Record what is not known: threshold style, manufacturer edition, original strip number, and whether both parts are damaged.
What to do next
If the door-bottom piece itself is demonstrably damaged, request the door-bottom identification/installation reference for that exact door system. If saddle damage and bulb bunching are seen together, request the correct adjustable-threshold service guidance instead. If the condition is unclear, keep both as hypotheses. The 2017 guidance does not provide a universal part number or universal sweep-to-saddle interchange rule for your unidentified door.
Primary sources and claim locator register
- — Therma-Tru original, 2017 Site Manual — SITE 4, US; p.4.5, damaged door bottom row. Publisher document.
- — Therma-Tru original, 2017 Site Manual — SITE 4, US; p.4.4, damaged sill saddle row. Publisher document.
- — Therma-Tru original, 2017 Site Manual — SITE 5, US; p.5.22–5.23, adjustable saddle labeled diagrams. Publisher document.
Evidence and safety boundary
Therma-Tru’s 2017 SITE 4 (printed pp. 4.4–4.5) and SITE 5 (pp. 5.22–5.23) distinguish door-bottom sweep conditions from adjustable sill saddle/gasket conditions. Identify whether damage is on the moving door bottom or the fixed threshold, and photograph both with the door safely open. Ask for the instructions for that exact threshold and door system; the two assemblies are not interchangeable merely because the draft appears near the floor.
A warped or humped sill is a different observation
If the threshold surface itself appears uneven, document the contact gap and whether the moving door-bottom sweep is torn. The 2017 Therma-Tru troubleshooting categories distinguish sill condition, door-bottom condition and weatherstrip contact; a hump or dampness alone does not identify a replacement gasket. Request the precise sill assembly service information before considering adjustment.