As I watched the awful photos of destruction on the West Coast of Florida, I was horrified that there are still wood-framed houses in that area of Florida.
Although the Florida Building Code was substantially modified after Hurricane Andrew, you can still build with any material that you want within Florida. Wood studs are the preferred material for North Florida, and sometimes for West Florida, not like in Miami, which prefers concrete block reinforced every few feet with a steel bar in a grouted cell. In addition, in Miami, we secure the walls to the foundations with that steel bar, and we secure the walls to the tie-beam above with this same reinforcing bar. With these details, our walls are very strong.
The Footing
As Miami residential architects with offices in Coral Gables, we can tell you that in Miami we attach the trusses with straps and/or clip angles of some kind. Many times, in North and West Florida, they toe-nail the trusses or rafters to the wood plate at the top of the studs. There is supposed to be a double wood plate, but sometimes, they only use one. And the attachment from the wood-framed walls to the footings is questionable. Are you getting the picture? Look at the photo above. So, you see how the walls came off the footings?
In South Florida, in addition to having stronger walls, we often have impact windows or doors. In new construction, these windows and doors must have a grout-filled cell with another steel bar that goes from the footing to the tie-beam above. Then, the window has to be secured to a pressure-treated wood buck, which in turn has to be secured to the concrete block wall with Tapcon concrete anchors with a minimum 1” embedment into the grouted concrete block walls. Compare the strength of the attachment of these windows to windows that are attached to wood studs with screws.
If you put all impact windows and doors in your house, you will get a credit from your insurance company and your bill will be substantially less!
The Roof
In my opinion, the weak link in our Miami structures is the roof. We have strengthened the roofing components a great deal since Hurricane Andrew. The roof shingles or concrete tiles go over a secondary barrier which in turn goes over plywood.
In Florida, under the guidelines of the Florida Office of Insurance Regulation, to qualify for a Secondary Water Resistant (“SWR”) discount on your homeowner's insurance, the underlayment you must use is a peel-and-stick membrane bonded directly to the roof sheathing.
Basically, this is a peel-and-stick type of material that is installed before the shingles. A benefit of this type of material is it adheres directly to the roof decking, and if you were to lose your roofing material in a storm this material will stay providing a secondary water-resistant barrier (SWR).
So, whether you have a cement tile or a shingle roof, both go over plywood which is then attached to the roof rafters or trusses. But in no way, can these compare to a concrete slab roof. If you have a cement tile or shingle roof and this roofing is blown off, the plywood can become exposed, in which case the plywood can be torn off or can get holes in it from debris. A concrete slab roof, because concrete is a liquid when it is poured and then hardens as an integral part of the walls, this structure is truly much stronger during hurricane-force winds. But even without the concrete slab roof, with our South Florida construction, the walls and openings are pretty strong.
A concrete slab roof will also give you a substantial discount on your homeowner's insurance. However, they will give you credit for a concrete slab or impact windows and doors but not both.
So if you look at this photo below from the Miami Herald, you can see the devastation caused
to a wood structure. Almost nothing is left of this house.
So, what’s wrong with North and West Florida?
Traditionally, these areas preferred “stick construction”. North Florida is colder than we are. They can use the space between studs for thicker insulation. But wouldn’t they rather put the insulation inside the concrete block walls rather than risk destruction whenever there is a hurricane? If I were a North Florida resident, and certainly, a West Florida resident, I would do anything in my power to build with concrete and concrete block. And if I were FEMA or the insurance companies, I would not settle for anything less. It’s time that they start building like we do! It’s time to change the Florida Building Code and remove the option of building with wood stud exterior walls.