Thread: Floor Insulation & Cross Bridging?

I rarely encounter pier & beam foundations here in Corpus Christi. There are plenty of them, but I just don't get many calls to inspect them. Not sure why? Anyway, I always find them without any insulation in the floor cavities and I always recommend to my clients that insulation be installed. My reading of the IRC is that R-11 is required for climate zone 3 so that is what I reference. However, I've begun to question my understanding of this issue since I've never found one insulated at the floor in more than seven years of doing home inspections. Am I right about this?

This one was also without any kind of cross bracing, bridging or blocking to provide lateral support at the floor joists. The perimeter is a poured-in-place concrete stem wall where the joists simply sit on a wood plate. No band or blocking at the perimeter. The span is about 24-feet. Shouldn't there be some kind of lateral bracing? Bridging? Blocking? Something?

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Robert,
You would need to know what codes have been adopted for your specific area. I myself never quote code unless being chalenged by a builder. I would simply recommend adding cross bracing or bridging and state the advantages such as lateral support.
As far as insulating below the sub-floor, I often find insulation installed improperly or not at all. In our region the vapor barrier should be against the conditioned side( the floor ). Problems with moisture can ocurr when the insulation sags away from the floor. I am seeing more and more spray foam being used and have heard good things. Time will tell.

Originally Posted by James Bohac

You would need to know what codes have been adopted for your specific area.

Back in 2001 or 2002 the Texas legislature mandated that all counties, municipalities and cities in the state adopt the IRC.

I myself never quote code unless being chalenged by a builder.

I rarely do, but this house was built in the 40s, as are most of the pier-and-beams I inspect, and I simply mention the modern code requirements to the client to make them aware that there really should be insulation in the floor. Our clients are aware, by virtue of language in the report form, that I'm not providing a code compliance inspection and that all code issues are grandfathered. Of course, now our Real Estate Commission is moving away from the concept of grandfathering when it comes to some safety issues. For example, we now have to report the absence of arc fault circuit protection based on the 2008 NEC. Doesn't matter when the house was built.

I would simply recommend adding cross bracing or bridging and state the advantages such as lateral support.

I never see any bridging or solid blocking at the ends of floor joists. Never! I don't do that many pier-and-beam foundations, but I haven't found one in seven years that was properly cross braced. This one had nothing. No perimeter band, no blocking at the ends or the middle and no lateral bracing of any kind.

In the Southern part of the country (even South TX) I'm not a fan of subfloor insulation with an unsealed crawlspace. Especially on an older home that has been retrofitted with A/C. Why?

Well for starters, older homes were never really designed for A/C. You have all types of open cavities and spaces for the crawlspace air to rise and then meet the cool air in the house and then you have condensation problems. Same goes for the subfloor insulation. With the A/C on and the inside of the home nice and cool the floor is also cool. The insulation allows for a nice location for the two temps to meet and then we have condensation.

Older balloon construction homes are the best when it comes to the "stack" effect in a home.

Originally Posted by Scott Patterson

In the Southern part of the country (even South TX) I'm not a fan of subfloor insulation with an unsealed crawlspace. Especially on an older home that has been retrofitted with A/C.

Well for starters, older homes were never really designed for A/C. You have all types of open cavities and spaces for the crawlspace air to rise and then meet the cool air in the house and then you have condensation problems. Same goes for the subfloor insulation. With the A/C on and the inside of the home nice and cool the floor is also cool. The insulation allows for a nice location for the two temps to meet and then we have condensation.

Oddly, the IRC calls for R-11 in the subfloor in our climate zone (3), but specifically does not call for a vapor barrier. Corpus is an odd sort of place. While right on the Gulf, we are also right on the edge of the West Texas mesquite wilderness. We are far less humid than most would assume. In any event, I see so few crawl space foundations I've never seen what you are describing. I'm sure there are plenty of them here, but I'm guessing they are in those parts of town where the homes just don't get inspected.

Originally Posted by Scott Patterson

Older balloon construction homes are the best when it comes to the "stack" effect in a home.

I'm not sure I understand the distinction you're making here. Either way, balloon or platform, the subfloor is still exposed to the air in the crawl space. I can see how a balloon frame would provide lateral support at the floor joists, but I don't see any difference with regard to the condensation issue. In any event, this was a platform frame. No studs extended through the floor framing.

BTW, I was pretty hard on this house. Called out sagging beams, no lateral bracing and no insulation. Recommended further evaluation. I always feel a bit uncomfortable being harsh on a floor frame at seventy year old house unless it is literally rotting. Now, however, my client's realtor tells me that he also had an engineer take a look. He ripped it to shreds. This after the seller reportedly just spent $45k on foundation repairs. It is a two-story with about 2,200 SF. How do you spend $45k on a 1,100 SF wood platform? I didn't see any new wood anywhere? No new nothing! Maybe the guys just crawled under there and smoked all day with an occasional bit of banging on a joist with a hammer for the sound effects?

I've crawled a many of pier and beams and none in this area are bridged between the floor joists or have insulation. Just unheard of in the Dallas area.

rick

Originally Posted by Rick Hurst

I've crawled a many of pier and beams and none in this area are bridged between the floor joists or have insulation. Just unheard of in the Dallas area.

rick

Same here
I found one over in Royce City (is there such a place) that had insulation all under it . It actually had three seperate sections of crawl. I think it was 4200 sq feet, one floor. Anyway wood rot and termites abounded. They had to pull it all out, fix the rot, treat for termites, oh yeah, no bridging either.

Bridging is not required unless the material is greater than a 2X12...
2003 IRC
R502.7.1 Bridging. Joists exceeding a nominal 2 inches by 12 inches (51 mm by 305 mm) shall be supported laterally by solid blocking, diagonal bridging (wood or metal), or a continuous 1-inch-by-3-inch (25.4 mm by 76 mm) strip
nailed across the bottom of joists perpendicular to joists at intervals not exceeding 8 feet (2438 mm).

The problem with NOT insulating underfloor is if you do have a home with AC the underside of the floor will condense anyway. I just finished a large commercial project in Schulenburg Texas and I know the dew point often gets above 75° in the summer.

Sorry this is a bit off topic.

The span is about 24-feet.

Not even 2x12's 12" o.c. can span 24', would have to be a truss or i-joist.

I know this is an old thread, but I had read half way through it before I realized it.........

Originally Posted by chris mcintyre

Not even 2x12's 12" o.c. can span 24', would have to be a truss or i-joist.

I know this is an old thread, but I had read half way through it before I realized it.........

I didn't intend to imply that the clear span of the floor joists was 24'. Just that 24' seem a long span without any bridging. They were supported by a beam that ran down the centerline. Probably some smaller outboard of that as well. It has been too long now and I don't remember it anymore.