If you want to ensure your grow room is completely air tight then don't settle for gaps in your sheeting, use a Grow Room Zipper.

Grow Room Zippers are 7ft long adhesive zippers with stick on side strips designed to make an air tight entry/exit from your sheeted grow area. Rather than simply leaving a hole in your sheeting to gain access to your grow room and risking unpleasant smells escaping use a Grow Room Zipper and know that your grow room is completely secure!

Grow Room Zippers are an incredibly affordable preventative measure, for such a reasonable price there really is no reason not to keep your grow room sealed and safe from outside influences.