Plumbing vents

[Sandy St.Louis]

I am in the process of rebuilding a 1979 chevy class c made by Okanogan and have just removed the entire roof it had 9 sizeable holes installed for vents and skylights and hope to eliminate 8 of them . I am interested in putting internal wall vents for the plumbing and would like opinions on using this type of vent .  The R V toilet will be replaced with a seperator composting unit so black tank will not be needed or combined with the grey tank for added capacity  . The refrigerator is replaced with a compressor ac dc one so no roof vent required . The main vent will be a single Fantastic fan . I am interested in all comments positive or negative . I should also mention it is 22 ft. long  and is being built as a low maintenance very functional 4 season camper .     

[Sandy St.Louis]

A little update , The new roof is coming along , the framing is complete and interior ceiling installed . I framed the roof with 2x2 [ ripped from construction 2" stock ] in 4x8' sections on 1' centers and sheeted with exterior 3/8 rough plywood . The ply wood had all edges sealed with 4 coats of spar varnish the first 2 thinned to soak in far , the best face left rough and stained white the glued and stapled to the framing . The roof sections were then installed on the unit and secured to each other and the walls with 3, wood screws spaced on 12" centers .  I am now installing the interior lights and wiring , testing , insulating [ 1 1/2 " foam ] , putting exterior sheeting on , fiberglass taping all seams and joints , and fiberglassing the complete roof . This roof will be able to be used as a viewing platform . It is hoped to have the exterior complete with in the next 30 days . 

[david craft]

Crowned roofs seem to hold better.  I use 2x3 and then taper ends down to 2. 16" on center with 7/16 Osb  for a full walk on roof.  Vents let a lot of light in. Taper on roof would resist water pooling as snow melts as well. Your structure is strong enough but the vent in not made 12" on center structure so you will be weak there...

[Sandy St.Louis]

Thanks for the information , At the vent it was stretched to a 14 " space  the sheeting inside and out side is 3/8" exterior  glued and screwed  and the span is between the bathroom wall lowering it by 50% . The construction of the roof has made it a torsion truss as it is a single piece , the only hole is for the fantastic fan which will be elevated on a bevelled 1x4 frame . The roof will be fiberglassed with 6 oz matt and 3 application of resin any pooling of water will be slight  and snow load would have to be to a historic level . This renovation is designed for minimal maintenance and all weather use . The 30 day window went out it could end up double that .