A ‘thermal bridge’ – a path of least resistance along which heat is transferred – will be created if the insulation is not also laid over the heads of walls.
Caiff ‘pont thermol’ – llwybr gwrthsafiad lleiaf y trosglwyddir gwres ar ei hyd – ei chreu os na osodir y deunydd inswleiddio dros bennau'r waliau.