We are building a three season attached screenroom. We are uncertain how to attach the gable roof to the present roof (gabled in the opposite direction, so the attachment is on the flat side). We have spent hours trying to locate do it yourself instructions and can only find do it yourself kits which is not what we want. We have built houses and can build an attachment to the roof and screen it in ourselves as long as we know how. Any suggestions for locating instructions such as these? Thank you for your time.

Are you attaching the sunroom roof to the roof, or to the outside of the wall on the gable end of the building? Q is not too clear. You would either nail a header directly to the outside of the existing siding (lean to) and add the rafters or open up the wall and add an interior header (knee wall) and slip the rafters inside past the wall studs.