What is the difference between a dock seal and a dock shelter?

A dock seal and a dock shelter do the same job in different ways. A dock seal is a set of foam pads that the trailer backs into and squeezes, so it closes the gap around the trailer with pressure. A dock shelter is a frame around the door with fabric curtains that wipe against the sides and top of the trailer, so the trailer never presses into it. Pick a seal when your trailers are mostly one size and you want the tightest seal for the money. Pick a shelter when trailer sizes vary or your crews need the full width of the trailer open for loading.

What each one does

Both close the space between the building and a parked trailer while the dock door is open. DASMA, the trade group for door makers, says in its technical data sheet on dock doors that shelters and seals help the dock door control air infiltration and weather when a truck is at the dock. Without one, heated or cooled air pours out of the opening, and rain, snow, dust and bugs come in.

• Dock seal. Two foam side pads and a foam head pad, each in a heavy fabric cover, mounted on the wall around the door. The trailer backs in, compresses the foam and stops against the dock bumpers. The foam takes the shape of the trailer and springs back when it pulls away.
• Dock shelter. A rigid or flexible frame that stands out from the wall, with side curtains stiffened by fiberglass stays and a head curtain across the top. The trailer backs into the opening of the shelter, and the curtains press against its sides and top.

Dock seal vs dock shelter, side by side

• Sealing. A seal is pressed tight against the trailer, so it usually seals best. Rite-Hite, which makes both, says in its guide to replacing dock seals and shelters that seals give a tight seal for a relatively low price, while some shelters seal less well.
• Trailer sizes. A seal works best when trailers are close to the same height and width. A shelter fits larger door openings and handles a wider mix of trailer heights and styles.
• Access to the load. The side pads of a seal push into the trailer opening, which can block the edges of the load. A shelter leaves the full width of the trailer open for a forklift or pallet jack.
• Wear. Seals take the impact of every trailer and the bounce of every forklift trip, so they wear faster. Shelters see less daily wear, though a trailer backing in off center can still tear a curtain or bend the frame.
• Cost. Rite-Hite notes that shelters, as a group, can cost more up front than seals.

How a dock seal works

The trailer backs straight in, compresses the side pads and the head pad, and comes to rest on the dock bumpers. The bumpers set how far the foam is squeezed, so worn bumpers let the trailer crush the pads harder and wear them out sooner. Some seals use a head curtain instead of a head pad so the top seals on trailers of different heights. Equipment World's overview of dock seals and shelters also lists inflatable seals, with air bags that fill around the trailer, and hybrid designs that mix the two.

Which one fits your dock

• Cold storage, food and climate controlled docks. A seal usually fits best, as long as the trailers are consistent. A tight seal keeps the cold in and condensation down.
• Mixed fleets and carriers. If box trucks, 53 foot trailers and refrigerated units all use the same door, a shelter or a seal with an adjustable head curtain keeps a usable seal across that range.
• Full width loading. If pallets run wall to wall in the trailer, a shelter keeps the side pads out of the way.
• Oversized doors. Larger openings usually take a shelter, since foam pads are sized to standard openings.
• Your operation changed. Rite-Hite points out that a dock built for one kind of truck often ends up serving another. If you now see new trailer sizes or need full access, check that the enclosure still fits.

Denver weather and dock enclosures

Front Range docks see snow, freeze and thaw, strong winds and summer storms. A worn seal or a shelter with a gap at the top lets snow and rain onto the dock floor, where it makes the leveler and the floor slick. In winter, the heat that escapes around a trailer is what you pay for. A quick check with the lights off and a trailer parked at the door tells you a lot: any daylight at the corners or along the top is a gap.

Questions about dock seals and shelters

What is a dock door in a warehouse?

It is the overhead door at a loading dock, usually a sectional or rolling steel door set at truck bed height. The seal or shelter mounts on the wall around it. See our guide to loading dock door sizes.

How does a dock seal work?

The trailer backs into the foam pads and compresses them, and the foam fills the gap at the sides and top of the trailer. The bumpers stop the trailer before it crushes the pads too far.

How much are dock shelters?

It depends on the size of the opening, the frame and the curtain features, so get a price for your own dock. As a group, shelters tend to cost more up front than seals, and seals tend to need replacing sooner.

How long does a dock seal last?

That depends on how many trailers it sees and how straight they back in. Signs it is done include tears, exposed foam, pads that stay flat and daylight around a parked trailer. Our guide on when to replace loading dock seals covers the signs.

How G Brothers helps

G Brothers repairs dock seals, dock levelers and dock bumpers, along with the loading dock doors themselves, for warehouses and businesses across Denver, Lakewood and the metro. We work on every brand, carry stock on the truck for most repairs, dispatch 24/7 when a dock cannot wait, and can send a certificate of insurance, usually within 24 hours. See dock leveler, seal and bumper repair and loading dock door repair, or call us to have your dock looked at.

Sources

• DASMA, TDS 182: Technical Considerations for Dock Doors
• Rite-Hite, Is it Time to Replace Your Dock Seals and Shelters?
• Equipment World, Dock Seals and Dock Shelters