for support for shed as well as the horizontal beams they stay,and to add more support I will be placing 4 scissor jacks 2 at the front and 2 at the back placed on concrete,as for electric wiring this will run from fuse box in house run up through the loft and run underground in plastic piping,then connected to another fuse box with cut of points,still have to put a worktop in so I will post pics when completed,with the artic conditions we have had not exactly been the right weather for working in.as for the shed it is made of 3/4 redwood and has been treated properly,when spring comes along I will put more protection on it as the shed is new,as for air getting into it I believe it should be ok.still got to put beading around the joins.incase you guys are wondering about the date on my pics,the wife forgot to change the date to todays 14/2/09