Threshold Attachment for Wind

The door threshold is where your door meets the floor. It needs to be bolted down tight and sealed against water. Watch how the sill pan, threshold, and anchors work together during a storm.

8" Anchor Spacing

1/4" Anchor Dia

Sill Pan Required

Threshold Cross-Section

CONCRETE SLAB

SILL PAN FLASHING

THRESHOLD

Step Ready

Anchors 0 / 4

Threshold Components

Three parts work together to keep water out and hold the door down during hurricanes.

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Sill Pan Flashing

A waterproof tray under the threshold that catches any water getting past the weatherstrip. Weep holes drain water to the outside.

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Threshold

The aluminum or composite bar that seals against the door bottom. Must be bolted through the sill pan into the structure below.

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Anchor Bolts

Stainless steel bolts every 8-12 inches that hold everything down. Must penetrate at least 1.5 inches into concrete.

Frequently Asked Questions

Common questions about door threshold installation in hurricane zones.

Why is threshold attachment so important for wind loads?

The threshold is the bottom anchor point for your entire door system. During hurricanes, negative pressure (suction) tries to pull doors outward from the bottom. If the threshold lifts, the door can fail completely. Thresholds also block wind-driven rain from entering under the door.

How should door thresholds be fastened in HVHZ zones?

HVHZ thresholds typically need stainless steel screws or bolts every 8 to 12 inches into concrete or the subfloor. For concrete, use 1/4 inch Tapcons or wedge anchors. For wood floors, use #12 screws minimum 2 inches into solid framing. The threshold must also be sealed to the sill pan.

What is a sill pan and why do I need one?

A sill pan is a waterproof tray under the door threshold that catches any water that gets past the weatherstrip. During hurricanes, water can be pushed horizontally at high pressure. The sill pan slopes to weep holes that drain water to the outside, preventing interior flooding.

Do impact doors have special threshold requirements?

Yes, impact doors are heavier and experience greater forces during debris impact. Their thresholds need more fasteners - typically every 6 inches - and deeper embedment into the substrate. The manufacturer NOA specifies exact requirements that must be followed for the approval to be valid.