What is the world keel and light steel keel? What is the use of ah?
Light steel keel includes: partition keel (vertical keel heaven and earth keel), ceiling keel (main bone, bone)
In the partition between the roof and the roof and the ground at the junction of the laying of the keel, called the heaven and earth keel, which will have a vertical keel to do support, as well as through the keel from the vertical keel interspersed into the middle, play a reinforcement
