When a room larger than 6 by 12 foot requires a vinyl floor you will need to correctly seam the material to ensure the floor remains waterproof.
Apliy vinyle seems.
This product is designed to economically seal seams in sheet flooring and keep debris and water from collecting in seams.
Roberts 7500 vinyl seam sealer is a strong and durable seaming adhesive.
How to seam vinyl sheet flooring.
Seal the seam with vinyl seam sealer.
As for thread for sewing vinyl on most vinyl you can use general purpose thread but if you expect the seam will experience a bit of a stress use heavy duty thread.
Those holes will weaken the vinyl and make it prone to tearing.
Use a longer stitch than on a regular project typically 3 0 mm.
Nylon is the best second best would be 100 polyester.
Away from the seam to guide the applicator nozzle but don t get sealant on the straightedge.
Cover the seam with a transition strip.
How to seam vinyl flooring.
This non flammable solvent free vinyl sealer saves time and costs compared to heat welding on commercial vinyl applications.
Apply a bead of seam sealant over the seam.