Does anyone know if/how much Tyvec helps your energy bill and about how much it runs to install it? We're moving along in talks with a builder and I kind of want it. Thanks---

 

I am not sure how much it actually saves you, but up here in the northeast much pretty every house is wrapped in it.

 

Midwest too... It's everywhere here...

 

I think depends on builder - many just wrap around the windows and doors and then black paper the rest of the house.

 

Isn't Tyvek just a vapor barrier?
As a vapor barrier, it should be a standard part of the building, not an option.(Maybe not the DuPont brand, but some sort of Vapor Barrier)

It would seem like the insulation is where the actual money savings comes in.

And houses are completely wrapped in TX.

 

Exactly.

 

Well codes vary from state to state and county to county. Not many places REQUIRE a vapor barrier by code.

That said, Tyvec is both a vapor and moisture barrier. Our entire house is wrapped in it. Our builder is one of the only builders who uses it... and they use it on all of their houses... from their $200k homes to their $800k homes... they all get it. Don't get me wrong, A LOT of builders use that stuff down here, but many of them only wrap their higher end homes in it. The less expensive homes just get some standard black paper wrap.

If you're looking for help with energy effeciency, you should be negotiating the R value of your insulation with your builder, not the Tyvac. The better insulation you put in the better your house will be with holding/keeping out the heat or cold.

That said, you still may want the Tyvec as it never hurts to have a vapor/moisture barrier, but don't plan on saving any significant amount of money on your utilities as a result of having it...

 

http://construction.tyvek.com/en/con...rs/index.shtml

 

^ Good link. Interesting info.

I still don't think that you really save that much money having it. Other builders in our community just use standard stuff and there really isn't that much of a discrepancy in utility bills. Of course it's very tough to compare apples to apples since there are waaaaay to many variables involved to directly compare. But hey, if even what half they say is true, works for me... especially since our builder uses it standard

 

Yeah I guess if the builder doesn't put anything over the plywood sheathing you would allow air infiltration in the gaps. BUT I can't imagine in TX that they don't use some type of barrier. Remember it prevents air from infiltrating the house, cold or hot. In TX it's gotta be a cost savings to keep the hot air out of the house.

 

I guess I didn't even bother to ask but what is the construction materials to be used for the exterior of the home? I guess if it was a brick home you might be able to get away with not having a VB.

 

^ Actually with the brick you really want a vapor/moisture barrier. A guy I played golf with Monday is head of construction for a builder, and they did a test where they just ran a hose on a brick wall and within 20 seconds the moisture penetrated the brick and was on the wood. If that keeps happening over and over, that wood will eventually rot. So the barrier is just as important to have with brick as with other materials...

 

Moisture barrier yes, vapor barrier no.

Roofing felt is an acceptable moisture barrier but not a vapor barrier.

 

^ True. They're usually one in the same with the builders down here so I confused myself

 

But the price is significantly cheaper. Considering it's something that most homeowners would never catch, and once they finish the exterior walls no one will ever see.

 

Be aware that if a house is wrapped to tight, moisture can be trapped inside helping to cause mold. Might want to crack a few widows open from time to time.

 

I am in the same boat thinking they were one in the same. That said, even the low end 80-100k houses are wrapped. Probably for the reasons mentioned above reducing air exchange some to keep heat out in the summers.

Additionally the moisture barrier is needed because a majority of houses here are brick.

Great info, thanks JB and NSX.

 

^ Yeah, most houses down here are wrapped as well. Actually, whenever I see a new construction going up, they're all wrapped... it just depends on what they're wrapped with (generic stuff or Tyvec).

 

The house will be nearly 100% brick. I want it to keep hot/cold wind from blowing through the weep holes in the brick - a wind breaker as the tyvec site says.

I'm not sure if they can put more insulation into a 2X4 wall - the R value is I believe only 13 for these walls, 19 for 2X6 walls. I'll ask them if there is another material that would impart more insulation for a given thickness - seems like there should be something short of the self expanding foam that is sprayed in. I don't know, I'll ask my neighbor who builds really high end homes about that.

In terms of it trapping moisture, we have 4 adults, 2 young children and three dogs - letting the house breathe in shouldn't be a problem.

So Junior, do you have any idea how much the stuff costed on your house (even though it was standard)?

 

^ Unfortunately I have no idea. It's like asking how much the roof was... no clue.. just part of the house. I'll try to get in touch with the builder as we have a good relationship with them... but they may not be willing to divulge such info... but worth a shot.

 

We actually did a cocoon insulation, where instaed of batts of insulation, they put up nets and blow in insulation, yielding an R value higer than the standard batt insulation. It was supposed to be about 25% better, so the R13 would be ~R16.

It only ran us about $500. Yhey can do it on most of the exterior walls, and will use batts wher is isn't practical.

Seems to make a pretty big difference. My AC/Electric bill in TX in June was only $200, where people with smaller, new houses had close to $500.

 

Yeah blown insulation will definitely fill in all the gaps. In new construction it should be easier to do.

Even better is the stuff that comes out of the gun like a liquid and they spray it on the inside of the sheathing between the joists. Then they slice it so it's level with the studs.

 

tyvec (and the off brands) are standard with all construction up here.

And also a bitch to do any thing to the house after wards (if your a guy who likes to tinker and add stuff) its a pain to run wires afterwards (like speaker wires ect...)