A recreational vehicle slide out roof block prevents foreign material such as water, dirt, or debris from accumulating on a recreational vehicle slide out roof. A slide out roof block has a size and shape selected to fill a gap between a slide out roof and an awning sheet extending over the slide out roof. Embodiments of a slide out roof block comprise a compressible bolster having a rain flap along a bottom edge of a front side. The bolster includes a block of compressible polymer foam in some embodiments. One or more pole sleeves may optionally be attached to the front side of the bolster. A pole inserted into a pole sleeve may be used to install or retrieve a slide out roof block. Some embodiments have an airtight cover and a valve, enabling a slide out roof block to be compressed for storage and reinflated for installation.