EPDM roofing membrane (weight vs. seams)

Hello everyone,
I would like to ask for your opinion / experience:
I have a gable roof with a 9° pitch, 6.8m wide and approximately 5.9m on each side (eaves to ridge). The whole thing is on an outbuilding with about 5.5m eaves height. I would like to lay EPDM membrane here and am unsure whether to cover the entire surface with a single piece of membrane or to work with seams that of course would have to be welded. One piece of membrane would weigh around 120kg. With a block and tackle, I would definitely get it up there but the question of handling remains. Gluing 12m long longitudinal seams with seam tape is also not cheap.
By the way: all as DIY... ;-)

If it's somehow possible, preferably in one piece. If necessary, a second person to help. I have EPDM on the flat roof myself with a fleece layer in between because there is already a welded membrane on it. I glued two together with a special rubber solution. Cleaned the edge, roughened it, then glued it, like a patch on a bicycle tube. It was simple and good, and it has held for about 10 years now. I was able to order the appropriate adhesive as well.

Hello, yes, I also tend to go for a piece...

if you put EPDM on, don’t cut off what is too long on the sides exactly to fit right away but muuuch later. I unfortunately did it that way. Although it was fixed with edge strips, it still retracted over time. o_O

Do you have a few helpers on the roof? The slope is relatively walkable. I would say with 4 people you can manage it in one go, although the gluing is not exactly simple given the dimensions.

Hi, yes many hands, quick end ;-) I already had several helpers on site. In the meantime, I once followed up with a foil supplier regarding the above question, and he said the foil is also easily movable (glides) because of the sebum, so alignment should work well. I will do the bonding in stages, first one ridge side then the other. The only difficulty when folding back one side is securing the weight on the other side or preventing slipping.