Thermwell U37H Aluminum Drip Cap Door Bottom 36 Inches

Product Description

The THERMWELL U37H is an aluminum drip cap and door bottom combination designed to seal the gap between the base of an exterior door and its threshold. The U-shaped door bottom integrates a drip cap to block air infiltration and moisture intrusion at one of the most common leak points in residential and light commercial door assemblies. Sized at 36 inches, it fits 1-3/4 inch thick doors and features slotted fastener holes that allow precise positioning during installation. Weatherization contractors, general contractors, and skilled DIYers install this product as part of door weathersealing work.

This door bottom is suited for residential and light commercial exterior door applications where air and moisture sealing at the door base is required. The combination drip cap and U-channel profile addresses both downward moisture runoff and threshold gap sealing in a single component. When the vinyl insert wears out, it can be replaced separately using TV 176-740 without replacing the full assembly, reducing long-term maintenance cost and labor time.

Key Features

• Aluminum construction for corrosion resistance in exterior door applications
• U-shaped door bottom with integrated drip cap seals both air and moisture at threshold
• Fits 1-3/4 inch thick doors at 36 inches in length
• Slotted fastener holes allow installation position adjustment for proper threshold contact
• Replaceable vinyl insert — use TV 176-740 for insert-only replacement

Compatibility

Designed as an OEM-style replacement or new-installation door bottom for exterior doors measuring 1-3/4 inches thick with a 36 inch width. Replacement vinyl insert TV 176-740 is compatible with this assembly.

Installation Notes

Installation is typically performed by a general contractor, weatherization specialist, or experienced DIYer using basic hand tools. The door should be removed from its hinges or held stationary before fastening the door bottom to allow accurate alignment with the threshold. Slotted holes allow incremental adjustment so the seal contacts the threshold evenly without binding door operation. Follow local building code requirements for exterior door weathersealing where applicable.