Block the wind, and face the opening away from it
Young sheep do not need a heated barn; they need to be out of the wind and off wet ground. A three-sided shelter or a barn corner works if its open side faces away from your prevailing winter wind, so the lambs can lie in still air while weather passes over them. Check the roof like a pessimist before the season turns: young sheep standing under a drip all night lose body heat through a wet fleece far faster than dry cold alone would take it. If the shelter sits in a hollow where water pools, move it or build up the floor before the ground freezes into a skating rink of mud and ice.
Bedding deep enough to nest into
Young sheep rest by nesting, so bedding is insulation, not decoration. Lay straw deep enough that a lamb lying down is hidden to the belly, and keep adding fresh layers through the season rather than letting it pack into a damp mat — the top must stay dry even when the base is working hard. Straw works better than shavings here because lambs can burrow into its hollow stems. A lamb who comes up with a wet, cold belly in the morning has slept in bedding that failed overnight. Watch the doorway especially: the entrance churns into mud first, and a dry shelter behind a swampy gate still means wet legs and cold lambs. Hardcore, a pallet platform or a moved feeding point can rescue a ruined entrance.
Fresh air above, no draught at lamb level
The winter shelter mistake that harms young sheep most quietly is sealing it tight. Warm, moist air from breathing and bedding rises and must escape, or ammonia and humidity build up and lambs start coughing in air that smells sweet and stale. Aim for ventilation high up — a gap under the eaves or a raised ridge — while the walls at lamb height stay solid against draughts. Test it yourself: kneel where the lambs lie. If your face feels fresh air moving at that level, the lambs are in a draught; if the air at head height smells of ammonia, the top is not breathing. Both are fixable with a board, not a rebuild.
Feed and water that keep the internal fire lit
A lamb's rumen is a small furnace, and forage is its fuel: in hard weather, young sheep with constant access to hay generate their own heat far better than lambs waiting on two bucket feeds a day. Site the hay rack inside or beside the shelter so eating does not mean standing in the wind, and check water at least twice daily in freezing spells — a skin of ice is a locked door to a lamb who will not break it himself. Keep the group sized so the smallest lamb is not bullied off the hay on the coldest nights, and give thin or lagging youngsters their own sheltered corner rather than hoping the flock warms them.
Winter care is a rota of small checks, and KinsLe Care Teams lets you assign the bedding top-ups, ice-breaking and hay rounds for the young sheep and mark each done with a timestamp.