Sprayway Grendel Synthetic Insulation Jacket Review

© UKC Gear

Designed for cold winter days in the hills, the Grendel's mid-weight synthetic insulation keeps you warm on the move, while its Gore-Tex Infinium fabric offers excellent breathability, windproofing and a measure of rain resistance. The Grendel comes with a good hood and its features are generally well thought out. In this jacket I've been warm and comfortable walking on cold and windy days, and have got by without a shell in light rain and clag.

Absolutely baltic on Carn Liath, but I'm comfy on the move in the Grendel  © UKC Gear
Absolutely baltic on Carn Liath, but I'm comfy on the move in the Grendel

While it isn't ideal for more technical winter climbing, the Grendel is spot on for winter hillwalking and mountaineering.

Weight and packability

On the home scales I make the Grendel in size M to be 498g (in agreement with Sprayway's quoted 500g on their website). For the warmth and performance on offer, this is a good weight although nothing cutting edge.

When it comes to packability, there is a stuff sack provided that allows the Grendel to stuff down to about the size of a large melon: Not too bulky if wanting to strap to the back of your harness on an easy mountaineering day.

Packed into its stuff sack  © UKC Gear
Packed into its stuff sack


Unfortunately, the Grendel is not available in women's fit. For reference, I'm slim and slightly broad in my shoulders. The men's medium is a good fit for me and it feels like it will cater to a good range of body types. It's not too close fitting, but neither is it boxy in the torso or baggy feeling in the arms. There is enough room underneath to wear additional layers if really feeling the cold or stopping for more prolonged periods of time.

The underarms are tailored well enough to reduce hem lift when raising my arms, which is a prerequisite for any jacket you intend to go scrambling or climbing in. The sleeves are slightly tapered towards the cuff where velcro adjustable and semi-elasticated cuffs can bring the fit in closer. These cuffs work well over slightly bulky gloves, but I would prefer if there was more velcro to pull these up tighter onto my skinny wrists.

The collar sits up to my chin and provides good protection from the wind,  and can be brought in closer with the collar/hood drawcord.

Insulated enough to keep you warm on a quick lunch stop in cold conditions  © UKC Gear
Insulated enough to keep you warm on a quick lunch stop in cold conditions


Sprayway have used ThermoSphere insulation across the entire jacket, with 96g, 55g, and 25g in the body, sleeves, and hood/collar respectively. This is a blown synthetic insulation where fibers of varying lengths are blown into baffles where they expand to give high loft and heat retention. In practice, this has kept me warm on cold winter days when moving and I can imagine throwing this on during a mountaineering type winter belay (although I would want something warmer if sitting at a winter belay beneath a long hard pitch). The warmth of this fill means it is ideal for winter, although I may be tempted to still pack it if not working hard on any uphills in the shoulder months. This synthetic fill will still retain much of its insulating qualities when wet, which is ideal for use in the UK.

The insulation also incorporates 35% recycled content, and while this is a lot better than none, it's worth mentioning that some other brands offer synthetic jackets with 100% recycled content.

Fabric beading up light rain well  © UKC Gear
Fabric beading up light rain well


A 30-denier polyamide ripstop Gore-Tex Infinium outer fabric gives you a good amount of durability and weather resistance for an insulation piece of this type, and it's this high-end fabric that may account for the Grendel's premium price tag.

The Gore membrane works as the outer layer providing excellent breathability without a top fabric layer where moisture can build up. This membrane has provided both windproofing from strong winds as well as protection from light rain showers. This has meant that I haven't felt the need to throw on a hardshell if caught out in a light rain shower or stood on a claggy summit. The DWR finish is PFCec free, and works well to bead off light rain, keeping the jacket feeling light and the insulation performing optimally.

The internal polyamide lining is lighter in weight and more comfortable against the skin. The combination of insulation and fabric used in the Grendel means that winter mountaineering is not outside the Grendel's capabilities - although technical winter climbing is still probably best left for a more specialist insulation piece.

The hood cinches down nicely to give a close, snug fit  © UKC Gear
The hood cinches down nicely to give a close, snug fit

The high collar and wired peak offer good protection from the elements  © UKC Gear
The high collar and wired peak offer good protection from the elements

Roll away hood tab. Some may like it; feels unnecessary for me  © UKC Gear
Roll away hood tab. Some may like it; feels unnecessary for me


Overall, the hood is well designed, keeping you feeling protected from the elements, although I do have a couple of very small niggles. The rear drawcord can catch on the outer fabric when bringing the hood close in to your head, which is particularly annoying when operating with gloves on. However, when adjusted together with the collar drawcords, the hood provides an excellent close fitting enclosure which has kept me feeling sheltered. The wired hood provides some added protection and means the full hood sits well across my face, providing a good line of vision. There is also a good amount of freedom of movement provided by the hood's fit. A helmet can be placed under the hood but there is some restriction to movement - still capable enough for mountaineering-type activities, which again points to this being less of a technical winter climbing jacket and more of a mountain all-rounder.

The hood also can be rolled away with a velcro tab. For me, this is an unnecessary feature and only provides a slightly uncomfortable tab that sits at the top of your back; but others may like the ability to fit the hood down round the back of the neck. Overall though, I really rate the fit and feel of the hood.

Cuffs fasten well on bulkier gloves but don't secure quite as well over thinner a pair  © UKC Gear
Cuffs fasten well on bulkier gloves but don't secure quite as well over thinner a pair

Anti-snag draw cord on either side works well  © UKC Gear
Anti-snag draw cord on either side works well


The Grendel also strikes the balance right in terms of features. Two hand warmer pockets are large enough to hold a map and have kept my hands toasty when standing around. An external chest pocket is perfect for carrying light and quick to access belongings and a slightly smaller internal zipped pocket on the other side of the chest is perfect for keeping my phone warm to preserve the battery. The full-length front zip has an insulated storm flap behind which has worked perfectly for keeping the cold and wind out. All zips are YKK and the tabs are easy to use even with bulkier gloves on.

The hem drawcord is easy to adjust, works well keeping the elements out and is anti-snag, which is beneficial when clipping gear to a harness.

Value for money?

We tend to think of Sprayway as a solid mid-market brand offering good functional products but perhaps less cutting edge technologies and the higher prices that go with them. At £330, the Grendel bucks this trend. Price-wise this is at the upper end of synthetic jackets of this weight. Whilst the price may put some people off, it does perform well for its intended use and has some fancy fabrics to justify the cost. This is clearly a well-thought-out jacket, and the fact that I can't find much to fault suggests that it's an investment a lot of users will feel happy making.

For more information sprayway.com

3 Jan, 2023

Great review!

5 Jan, 2023

Not mentioned in the review, is that the zip is ‘one way’. At £330, a two way zip is a basic feature that any jacket should have.

5 Jan, 2023

I'm still struggling with the thought of £330 for what is essentially a showerproof insulated jacket.

Hi Steve,

Sorry, should have included that. The zip is just a one-way. I understand what you mean, with scenarios where it's handy to have a double zip with a harness on. For me though, I think given this is more aimed at winter walking it still seems pretty reasonable to just be a one-way zip. It's not going to be a deal breaker for many, although everyone has their opinions or needs.

5 Jan, 2023

Yep and not all climbers are convinced by the need for two ended zips anyway. I've climbed for 30 years and can't remember ever thinking "I need a double zip on this jacket", but I have had jackets with double zips that wouldn't stay bloody well done up at the bottom end. I think Steve is over egging his pudding a bit - at least to my taste!

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