How to make a lightweight sleeping bag / bivvy bag
I will start with a list of materials, then describe how to make the bag, then show some photos.
- Pertex for the top cover of the bag. 2m x 1m rectangle of standard pertex. Pertex is a windproof and water resistant lightweight fabric suitable for wind jackets and bivvy bags. I could have opted for Pertex Quantum which is half the weight of standard pertex and saved some weight.
- Lightweight silk inner lining for the inside of the bag, again 2m x 1m. This is not strictly neccessary as the climashield is robust if treated gently.
- Climashield Apex. I used two layers of 133g/sqm climashield synthetic insulation. The area of the cover is about 1.5sqm so 3sqm of climashield might be enough. The weight is 400g
- Cheap foam camping mat from Argos
How to make the bag
The sleeping bag is 180 cm long, the cover is 100 cm wide at the hood tapering to 60 cm at the foot. The integrated mat is 50 cm wide and 180 cm long. This is the same length as my body. The cover, insulation and lining can be stitched together with a sewing machine, and with the lightweight mat that I used, it was possible to stitch the cover to the mat using the machine. The climashield insulation is quite robust and does not need quilting, especially when the bag has an inner lining. It might be useful to include a zip at one side in case the bag is too warm. There is a shock cord drawstring at the hood which is also used as a strap when the bag is rolled up, and there is a small battery torch attached to the side. An extra foam pad can be used inside or outside the bag. The total weight of the bag is just under 800g, half of that is the top insulation, 200g for the mat, about 140 grams for the pertex and 60 grams for the silk lining.