Not sure what tt you have, but if it's a Prime Time you can walk on the slide out roof. Below is a statement from their web site.
Prime Time Manufacturing, Manufacturers of travel trailers and fifth wheels
Slide Out Construction
On a large percentage of Prime Time recreational vehicles, you will find a slide room enhancing the livability and function of the RV. Recognizing that the slide out construction is critical to the long term performance and durability of your RV, ETERNABOND Construction means advanced construction techniques are utilized in the slide rooms, too. All three walls of the slide out are built using our 5-layer, aluminum frame, bonded construction offering lightweight, yet strong construction that also provides excellent insulation and sound deadening properties. A Prime Time RV is unique in that the SLIDE OUT ROOF is aluminum framed and bonded with EPS foam to create a slide out roof strong enough to walk on.