Internal membranes on jackets can break down easily, but to combat that, these jackets usually have some type of abrasion resistance built into the outer layer of the jacket. Plus, with these jackets, you’ll get an effective internal membrane, an outer membrane that is abrasion-resistant and coated with DWR for extra weather protection, good ventilation, and a soft liner on the interior. So, jackets with just a DWR coating and no internal membrane for waterproofing protection won’t protect you from the weather as much as jackets that do come with internal membranes. However, how much weather protection you really need is up to you.