- Mortise
- Mudsill
- Mullion
- Muntin
- Muriatic acid
- Mushroom
- Nail inspection
- Natural finish
- NEC (National Electrical Code)
- Neutral wire
- Newel post
- Nonbearing wall
- Nosing
- Notch
- Note
- Nozzle
- O C (On Center)
- Oakum
- Open hole inspection
- Oriented Strand Board or OSB
- Outrigger
- Outside corner
- Overhang
- P trap
- Pad out, pack out
- Padding
- Paint
- Pallets
- Panel
- Paper, building
- Parapet
- Particle board
- Parting stop or strip
- Partition
- Paver, paving
- Payment schedule
- Pedestal
- Penalty clause
- Penny
- Percolation test or perc. test