I have an old loft hatch that simply sits in a frame and pushes up to open and therefore have to use an external step-ladder to reach. I want to have a loft ladder which means changing the hatch to a hinged opening. Not being a carpenter I'm wondering how to do this. I was wondering if I could push the hatch up underneath the existing frame i.e. instead of sitting on it from above you push it up to seal from underneath. The concern is the fittings and insulation i.e. for it to seal nice and tightly. How do I go about checking this ?