I would imagine most people don't even know what it wood stair cleat is, in construction we have so many words that describe the same thing. A stair cleat is another word for a thread bracket. In other words it's the part of the stairway that connects the stair stringer to the stair step. These have been used for years and over time, most of them will develop the same problem.
Most wood stair cleats loosened up and create a safety hazard. If the stairs are located outside in extreme weather conditions, for example, if it rains or snows a lot, extremely humid humid weather, or extremely hot and dry temperatures, your staircase might not last that long, if it is or isn't maintained properly. It's not a bad idea to use steel or concrete for stairways in these climates.
If you're ever walking up a set of stairs with wood cleats and the stair steps feel a little loose or wiggly, make sure you examined the stair cleats for safety. It's not uncommon for someone to be walking up or down a set of wood stairs and having the stair step or tread giveaway because the wood cleats has loosened.
If the wood stair cleats are nailed to the stair stringer, the nails can loosen up, causing it to become loose, as you walk up and down the stairs applying pressure to the stair cleat, this will create movement in between the stair step and the stair stringer. This could cause the cleat to crack, break and separate the connection between the stair step in the stair stringer.
I would suggest using metal brackets instead of wood cleats. The metal brackets will not crack or disintegrate like some wood cleats. Stair building brackets of course can loosen up and should be maintained regularly.
If you decide to use wood stair cleats, I would suggest using screws instead of nails and drilling holes in the wood stair cleats, most of the time this will prevent cracking the cleat. Try to use a thicker material for the stair cleat, for example using a 2 x 4 with lag screws and washers would be better than using a 1 x 4 with nails.
If you're walking up a set of stairs and a stair step feels loose, contact the owner of the property and let them know, they have a problem with their staircase.
Greg Vanden Berge is working on the internet to promote the education for creating simple to follow guides and home building books to help professional building contractors as well as the weekend warriors. He is currently working on more stair building books and adding useful content to help solve problems created by the lack of construction knowledge in the building industry.12 Apostles Of Jesus Christ