Advice please. Building a home with suspended timber floor. 300mm Ijoists at ground level with sheeps wool insulation. Wondering whether to use copper or plastic pipes for radiators/hot water and where to locate them in the ground foor. Within the joists inbetween the insulation? OR Underfloor - in which case how best to lag and avoid mouse issues? There's a 400mm void below the ijoists. Plastic is flexible making it easy to bend and go through holes made in ijoist OSB webbing however can I rely on it not to leak? If I use copper I wonder if this is flexible to bend a little and push through slightly larger holes in the ijoist webbing?