Do the Omlet runs attach securely to a Roost and Root coop or would that leave a gap?

We cannot comment on the compatibility of our products with coops supplied by other manufacturers. 

Our runs have been designed to work perfectly with our own coops and whilst the walk-in runs may work well with other coop designs, if we haven't tried it ourselves, we wouldn't feel comfortable offering our opinion. 

We would recommend purchasing an Omlet coop and run to ensure that your chickens are kept in a thoroughly tried and tested environment.