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Yorkshire Coop and Wyandottes7 have given you great advice.
It also depends on how you build your coop to how it smells. If it is not properly ventilated, it will smell bad.
You need good venting in your coop ceiling to rid the coop air of all this unwanted, moist air. If you don't put in good ventilation, during those really cold winter nights, all this moisture is going to rise up to the ceiling since warm air rises, and if it has no place to go, it will fall back down as water or frost making your birds very cold and uncomfortable.
The ideal way to create good venting is put in 1 square foot per bird of venting in the roof. Split it half and half on either side of the ceiling, one vent higher than the other. If the coop ceiling is not very high then position the roosts lower to the ground. You don't want any venting near the floor. This will create drafts. So what really does this do? It makes it so the moist air from the chickens slowly rises into this positive air coming in the lower vent and out the upper vent. Birds themselves put out heat. So they literally are roosting in a nice warm bubble of air. The moist air rises and goes out these vents. You don't want to disturb this air space around the birds with drafts. So make sure to seal up all cracks above the birds a foot or two.
Venting can be worked on those cold winter nights by closing off some of the lower vents to slow air movement in the coop. You never want to close off the higher vents. You will not retain much heat by closing off the vents, but you will keep the birds drier, especially if it is a bitterly cold night and you use heat lamps. Hot air meeting cold air creates condensation, so keep the air moving to prevent this.
Yorkshire Coop and Wyandottes7 have given you great advice.
It also depends on how you build your coop to how it smells. If it is not properly ventilated, it will smell bad.
You need good venting in your coop ceiling to rid the coop air of all this unwanted, moist air. If you don't put in good ventilation, during those really cold winter nights, all this moisture is going to rise up to the ceiling since warm air rises, and if it has no place to go, it will fall back down as water or frost making your birds very cold and uncomfortable.
The ideal way to create good venting is put in 1 square foot per bird of venting in the roof. Split it half and half on either side of the ceiling, one vent higher than the other. If the coop ceiling is not very high then position the roosts lower to the ground. You don't want any venting near the floor. This will create drafts. So what really does this do? It makes it so the moist air from the chickens slowly rises into this positive air coming in the lower vent and out the upper vent. Birds themselves put out heat. So they literally are roosting in a nice warm bubble of air. The moist air rises and goes out these vents. You don't want to disturb this air space around the birds with drafts. So make sure to seal up all cracks above the birds a foot or two.
Venting can be worked on those cold winter nights by closing off some of the lower vents to slow air movement in the coop. You never want to close off the higher vents. You will not retain much heat by closing off the vents, but you will keep the birds drier, especially if it is a bitterly cold night and you use heat lamps. Hot air meeting cold air creates condensation, so keep the air moving to prevent this.
