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We are going to be starting to build a townhouse/duplex in South Florida sometime in the next 6 months or so and are working through some of the design decisions. One of them involves whether or not to use wood trusses or concrete for the second floor. Besides the obvious differences in overall sound dampening and strength, I'm trying to get a better idea of what the cost difference would be. Is concrete 2x the cost? 3x the cost of wood trusses? Is there something in between (pre-formed concrete?) that would provide a similar benefit without the full cost of pouring concrete?
I'm still a novice here and I'm sure I'm being very simplistic but I'm just trying to get some clarification on the options so I can look into the cost vs. benefit in more detail.
...whether or not to use wood trusses or concrete for the second floor. Besides the obvious differences in overall sound dampening and strength...that would provide a similar benefit without the full cost of pouring concrete?
You're not making any sense.
Wood trusses "support" the floor and walls. I see no reason to use concrete trusses(?). Or did you mean to say something different?
If the intent is to reduce footfall or other transmitted sound WITHOUT the cost associated with a "floating aerated concrete" floor, I highly suggest other sound attenuation processes that are less expensive. Or build a patio/ranch type house.
Or maybe you're thinking precast floor panels? It's possible, not very cost effective. And they really need to be used where soil conditions are very stable. I don't consider FL a stable soil area.
You're not making any sense.
Wood trusses "support" the floor and walls. I see no reason to use concrete trusses(?). Or did you mean to say something different?
If the intent is to reduce footfall or other transmitted sound WITHOUT the cost associated with a "floating aerated concrete" floor, I highly suggest other sound attenuation processes that are less expensive. Or build a patio/ranch type house.
Or maybe you're thinking precast floor panels? It's possible, not very cost effective. And they really need to be used where soil conditions are very stable. I don't consider FL a stable soil area.
Poured concrete as a second floor. Or maybe that's what you are calling floating aerated concrete floor? I don't know the exact terms.
As much as I would like to have a choice of lot and house style, due to the lot size (65x113), neighborhood and business partnership we have, it's going to be a duplex/townhouse with two stories and two units side by side.
A cousin of mine lived in a home in Denver (Montbello) that was built like an office bldg (concrete floor over basement, steel studs) built when there was a shortage of materials. They grew to hate it.
Also I've lived in ranches on slab. After a while you can tell the difference in the "no give at all" difference vs wood joist/truss-supported floor. Colder, harder on feet.
Also, what would a concrete 2nd floor do to resale value ? Not good, I would think.
If "noise" is your issue, make sure the sub-floor and joists are glued and screwed tightly , and add fiberglass insulation between joists.
A cousin of mine lived in a home in Denver (Montbello) that was built like an office bldg (concrete floor over basement, steel studs) built when there was a shortage of materials. They grew to hate it.
Also I've lived in ranches on slab. After a while you can tell the difference in the "no give at all" difference vs wood joist/truss-supported floor. Colder, harder on feet.
Also, what would a concrete 2nd floor do to resale value ? Not good, I would think.
If "noise" is your issue, make sure the sub-floor and joists are glued and screwed tightly , and add fiberglass insulation between joists.
Thanks for the response. Specifically, the build is going to be in the Coconut Grove/Coral Gables area of Miami where townhouses and duplexes have become very prevalent over the past 10 years or so. Due to the lot size (typically 50x100) or in our case, slightly larger at 65x113, many developers are buying up the lots, knocking down the 50's/60's era bungalows and building a 2-unit townhouse/duplex on the property. These are selling for anywhere from $750k-$975k depending on the area. We have noticed that a lot of the new builds are either concrete 2nd floor or wood trusses with a layer of concrete over the plywood (at least that's what I think it is).
I'm sure it's more prevalent here than in other areas of the country for a variety of reasons, with one being the overall sturdiness of the structure built to withstand hurricanes. A lot of the building codes changed after Hurricane Andrew in 1992 including the elimination of "stick" frame houses and the implementation of cinder-block construction and hurricane-strapped roof trusses.
I don't think that it effects resale value at all, if anything, it increases the value. Being in South Florida, it's all slab construction on the first floor considering how high the water table is and the fact that you can't dig much more than 12 inches into the ground before hitting water.
Thanks for the response. Specifically, the build is going to be in the Coconut Grove/Coral Gables area of Miami where townhouses and duplexes have become very prevalent over the past 10 years or so. Due to the lot size (typically 50x100) or in our case, slightly larger at 65x113, many developers are buying up the lots, knocking down the 50's/60's era bungalows and building a 2-unit townhouse/duplex on the property. These are selling for anywhere from $750k-$975k depending on the area. We have noticed that a lot of the new builds are either concrete 2nd floor or wood trusses with a layer of concrete over the plywood (at least that's what I think it is).
I'm sure it's more prevalent here than in other areas of the country for a variety of reasons, with one being the overall sturdiness of the structure built to withstand hurricanes. A lot of the building codes changed after Hurricane Andrew in 1992 including the elimination of "stick" frame houses and the implementation of cinder-block construction and hurricane-strapped roof trusses.
I don't think that it effects resale value at all, if anything, it increases the value. Being in South Florida, it's all slab construction on the first floor considering how high the water table is and the fact that you can't dig much more than 12 inches into the ground before hitting water.
So is the reason for the prevalence of 2nd floor being concrete that it becomes a huge "paperweight" to keep the house from flying away in a hurricane, and the 1st floor walls are sturdier to support the weight, and/or Floridians are so used to slab floors that wood floors seem wrong/odd to them ?
I do remember visiting in a few homes in the Miami/Ft Lauderdale area, and all were tile over slab. But I assumed that had to do with tracking in sand.
It seems more likely that the concrete over wood joist floors you're referencing are a thin layer of gypsum for leveling and sound deadening. There would need to be a solid substrate of plywood and/or cement board under the gypsum.
I say keep it simple and use wood joists with plywood, screwed and glued.
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