The hood and draft collar of a sleeping bag are responsible for roughly 20 to 30 percent of the bag's total warmth. An open hood allows warm air to escape from the largest single gap in the bag's insulation envelope -- the opening around your face. A draft collar that does not seal properly acts as a chimney, pumping warm air out as you move in your sleep. These components are mechanically simple but degrade in ways that are not always obvious. A sleeping bag that "is not as warm as it used to be" often has a degraded hood or draft collar, not degraded insulation.
The Anatomy of a Sleeping Bag Closure System
A properly designed sleeping bag hood and draft collar consist of:
The hood: An insulated compartment that surrounds your head. On mummy bags (the standard shape for bags rated below about 20F), the hood has an adjustable drawcord that cinches the opening around your face. The hood's insulation should be continuous with the bag body so there is no uninsulated seam at the neck. Premium bags from Western Mountaineering, Feathered Friends, Valandre, and high-end models from REI and Marmot use differential-cut hoods where the outer shell is larger than the inner lining, preventing the insulation from compressing when the hood is cinched.
The draft collar (also called a neck baffle or yoke): A tube of insulation that sits across the neck and shoulders, between the bag body and the hood. When the bag is drawn closed, the draft collar seals the gap between your neck and the bag opening. On bags without a draft collar (typically summer bags rated 30F and above), the hood drawcord alone provides the seal, which is less effective because there is a direct path for warm air to escape along the surface of your neck.
The draft tube (zipper baffle): An insulated tube running along the inside of the zipper the full length of the bag. This is not part of the hood system but works in conjunction with the draft collar -- the draft collar seals the top, the draft tube seals the side.
The drawcord and cord lock: A thin nylon cord (typically 1.5mm to 2.5mm diameter) that runs through a channel around the hood opening. The cord lock (a spring-loaded plastic toggle) holds the cord at whatever tension you set. The cord lock on the hood is typically located at the side of the face opening, reachable with one hand while lying down.
Common Hood and Draft Collar Problems
Broken or Worn Drawcord
The drawcord threads through a fabric channel around the hood face opening. Over years of use, the constant friction of the cord against the channel fabric wears both the cord and the channel. The cord can fray, snap, or lose its outer sheath (if sheathed cord). When the drawcord breaks, the hood cannot be cinched closed, and the bag loses its primary heat-retention mechanism at the face opening.
Symptoms: The cord pulls through the cord lock without gripping (the cord diameter has reduced from wear), the cord is visibly frayed and thin at the cord lock contact point, or the cord has snapped and receded into the channel.
Replacement process:
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If the old cord is still intact, tape a new cord to one end of the old cord with duct tape or athletic tape (a thin, flat connection). Pull the old cord out of the channel, drawing the new cord through behind it. This is the "pull-through" method and it is vastly easier than threading a cord through an empty channel.
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If the old cord has snapped and receded into the channel, use a safety pin or a bodkin (a flat, blunt needle used for threading elastic and cord through casings, about 3 USD at any fabric store). Attach the new cord to the bodkin, insert the bodkin into the channel at the opening, and work it through the channel. This is tedious (expect 15 to 20 minutes) but doable.
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Replacement cord should match the original diameter. Most sleeping bag hoods use 1.5mm to 2mm nylon cord. Thicker cord (2.5mm to 3mm) provides easier gripping with gloves on, which is useful for winter bags, but may not fit through the original cord lock. Check the cord lock opening diameter before buying replacement cord. Replacement cord is available at outdoor retailers (Gear Aid sells replacement drawcord kits for about 5 USD) or fabric stores (by the foot, about 0.60 USD per foot).
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Install a new cord lock if the old one has lost spring tension. Cord locks come in several sizes (micro, mini, standard). Match the size to the cord diameter and the original cord lock. Mini cord locks fit 1.5mm to 2mm cord. Gear Aid, YKK, and generic brands all sell cord locks in multi-packs for about 5 USD. To remove the old cord lock, depress the spring plunger and slide it off the cord. The new one slides on the same way.
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Draft Collar Not Sealing
The draft collar must lie flat and continuous against your neck and shoulders. When a draft collar fails to seal, the gap allows convective heat loss -- warm air escapes and cold air enters with every movement. A draft collar that does not seal is often misdiagnosed as a bag that is "not warm enough."
Causes of poor seal:
- The draft collar insulation has compressed over time. Down draft collars compress from the weight of the shell fabric and from repeated crushing in a stuff sack. Synthetic draft collars compress from the same use pattern. A compressed draft collar no longer fills the gap between your neck and the bag.
- The draft collar has shifted inside its fabric envelope. The insulation inside a draft collar is loose fill (down) or a continuous batt (synthetic). Over time, the fill can shift away from the center, leaving thin spots at the neck contact point.
- The draft collar drawcord (some bags have a secondary drawcord for the draft collar independently of the hood drawcord) is broken or loose.
Fixing a compressed draft collar:
- Wash the bag. Down that has been compressed and contaminated with body oils will loft more after washing. The same applies to synthetic fill, though the improvement is less dramatic. Follow the washing instructions in our sleeping bag cleaning guide.
- Manually redistribute the fill. For down draft collars, you can gently massage the insulation along the length of the draft collar to redistribute down from overfilled areas to thin areas. The draft collar is a tube, and down can be shifted within it by hand manipulation. This is an imperfect fix but works well for minor displacement.
- Accept that some compression is permanent. A compressed draft collar on a 10-year-old bag is not going to loft like new regardless of washing. The down filaments have broken over years of use and cannot hold loft the way they did when new. The fix at this stage is to use the bag with a neck gaiter or a buff worn around your neck inside the bag to supplement the reduced draft collar seal.
Hood Channel Fabric Wear
The fabric channel that the drawcord runs through is typically a folded and stitched edge of the hood shell fabric. This edge sees constant friction from the cord, especially at the opening point where the cord exits. Over time, the fabric can wear through, creating a hole that snags the cord and prevents smooth adjustment. This is more common on ultralight bags that use 10D or 15D shell fabric (the hood channel is subject to higher friction loads than the shell fabric was designed for).
Repair: Apply a Tenacious Tape patch over the worn area, then use a seam ripper to carefully reopen the channel exit point if the tape covers it. The tape reinforces the fabric. This is a temporary fix that buys a season or two. Permanent repair would require replacing the channel fabric, which means opening the seam, inserting new fabric, and re-stitching -- a level of surgery that exceeds what most home sewers can do neatly.
Zipper Draft Tube Issues
The draft tube along the zipper keeps cold air from entering through the zipper teeth. A draft tube that does not lie flat against the zipper, either because the fill has shifted, the fabric is twisted, or the tube has been sewn with a slight curl, allows convective heat loss.
Fix: Inspect the draft tube with the bag laid flat. It should lie smoothly along the zipper line with no gaps. If it is twisted, it may have been caught in the zipper at some point and permanently deformed. A twisted draft tube can sometimes be untwisted by massaging the fill in the opposite direction of the twist. A draft tube that has been sewn with a curl (a manufacturing defect that was not noticeable when new but becomes worse with use) cannot be fixed. The only remedy is to be aware of it and position yourself so that the zipper side of the bag is downward, using your body weight to press the draft tube against the zipper.
The Face Opening Gap: Hood Shape and Fit
Not all hoods fit all head and face shapes equally. A bag that fits a round face well may leave significant gaps on a narrow face, and vice versa. The hood should draw closed to an opening roughly the size of your mouth and nose, with minimal gap around the edges. If the hood opening cannot cinch small enough for your face, the drawcord channel is too long or the hood was cut too large.
On an older bag, this may be due to the drawcord channel having stretched over time. Stitched fabric casings can elongate slightly under repeated tension from the drawcord. The fix is simple: replace the drawcord with a slightly longer one and tie a knot in it to reduce the effective channel length, or add a cord lock that sits farther along the cord. This effectively reduces the maximum opening size.
Maintenance Schedule for Hood and Draft Collar Components
- Every trip: Check that the drawcord slides freely and the cord lock grips. A cord lock that slips during the night means the hood opens while you sleep, and you wake up cold.
- Every season (or every 30 nights of use): Inspect the drawcord for fraying, especially at the cord lock contact point. Replace if frayed beyond about 25 percent of the cord's diameter.
- Every 2 to 3 seasons: Consider replacing drawcords and cord locks proactively. The cord and cord lock together cost about 5 USD and take 15 minutes to replace. The frustration of a cord snapping on a 20F night in the backcountry is worth preventing.
- When washing: Pay attention to the hood and draft collar during the drying process. These areas are thicker than the bag body and take longer to dry. A dryer set to medium heat that fully dries the bag body may not fully dry the draft collar and hood. Run the dryer longer than you think you need, and check by feel -- the draft collar should feel warm and dry, not cool (coolness indicates residual moisture).
Winter Bag Specifics
Winter bags (rated 0F and below, such as the Western Mountaineering Puma, Feathered Friends Snowbunting, or The North Face Inferno 0) have more substantial hood and draft collar systems than three-season bags, and the consequences of failure are more severe. At -10F, a draft collar that does not seal correctly does not just let in a chill -- it can cause frostbite on exposed skin around the face.
Winter bags typically have dual drawcords on the hood: one that cinches the face opening and another that cinches the hood behind the head, creating a "puff" of insulation around the entire head. Both drawcords must be functional. Winter draft collars are larger in diameter than three-season collars (they surround both shoulders and neck, not just the neck). Inspect both drawcords and the draft collar fill before a winter trip.
When to Accept That It Is Time
Hoods and draft collars are the hardest-working parts of a sleeping bag closure system. On a 10 to 15-year-old bag, even well-maintained, the cumulative compression cycles, drawcord friction, and fill degradation in these components mean they no longer perform as designed. At some point, adding a neck gaiter and a balaclava to supplement a degraded hood system becomes the practical solution. Or it becomes time for a new bag, which you can now justify as a replacement for a component failure rather than as an upgrade -- and that is a legitimate reason.