I guess I'm not quite sure what your question is. If the vent from your dryer to the roof has a 4 inch gap, you need to close that gap. I had a similar experience back in 95 after my house was built. The vent tube was not well attached to the vent on the roof, which had a flap and a screen. But one day I went into the attic and found lint all over the place! The tube had fallen off the roof fixture and the dryer was venting into the attic. I secured it back on with A/C foil tape and then fastened it to the nearby rafter with some wire and duct tape. Worked like a charm.