Two boards, two jobs
Single wall and double wall are separate ranges because they are not the same board. The single wall category describes those boxes as a combination of strength, affordability and versatility for a range of packaging. The double wall category describes a stronger board for valuable, heavy or fragile items, and says those boxes are manufactured in the UK.
Choose single wall when the goods are a normal dispatch weight and the box is close to the right size. Move to double wall when the contents are heavy, when they need more protection, or when the carton will be stacked. A larger single wall box is not a substitute for a stronger board.
Size still comes first
Board strength does not fix a box that is the wrong size. A double wall carton that is much too big still lets the goods move, and it still needs void fill. A single wall carton that is the right size will often travel better than a stronger box with a large empty space inside.
Both ranges are inside the boxes category, so you can compare them with postal boxes, crash lock boxes and the other styles. If the pack is going through Royal Mail as a small parcel, check the dimensions on the Royal Mail changes page before you commit to a size. That page gives the current maximum as 450 mm long, 350 mm wide and 160 mm deep, measured on the outside.
Removal and storage
The double wall range is also where removal boxes sit. A house move and a storage job put more weight in a carton, and the cartons are stacked. That is the use the double wall description is written for. Wardrobe boxes and removal kits are listed separately when the pack is a garment carton or a mixed set rather than a standard cube.
Archive boxes with handles are the storage style. They are for files and stock you will lift again, not for a one-way parcel.
Closing the carton
A stronger box still needs tape that holds the seams. Brown packing tape, clear tape and gummed paper tape are all in the tapes category. Gummed paper tape is the water-activated tape, listed as a paper seal rather than a plastic one. For a heavy double wall carton, look at the vinyl and crossweave tapes as well as the standard packing tape.
Orders placed by 3pm are dispatched the same day, with free UK delivery on orders over £50 ex VAT.