Gas vs Electric

General Off Topic
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Ok, it’s not too late to save big bucks, it’s all about the basics

Infiltration - this is the air that leaks into the house, cheap to address while it’s under construction, the goal is to seal every penetration that goes from the inside to the outside, some of this may be done by the insulation installer, check behind them
o Foam the electrical and plumbing holes
o Foam around windows and doors after they are installed
o Tyvek type exterior house wrap, tape all seams and wall penetrations (windows and doors)
o Use a foam seal or caulk under the sole plate (the bottom 2x4 of the exterior walls), if the wall is already up then remove all sawdust and put a caulk bead where the 2x4 hits the sub floor

  • The goal is to make the house air tight but that’s just impossible.
    No matter how hard you try you’ll still have plenty of leaks. If not you can add them later.

Ventilation - continuous ridge vent and soffit vents, need plenty of attic ventilation

Insulation - R-19 in floors, R-13 in walls, R-38 in flat ceilings

  • you said the 3rd floor (attic) will be finished, big problem
  • it probably has vaulted ceilings framed with 2x6s, that doesn’t give enough room for insulation, add a 2x2 nailer to get more space
  • must use a baffle to allow upward air flow then R-19 is all that will fit
  • the walls are probably exposed to “attic” space (knee walls), use R-13 but put an insulation board on the back side to add more insulation
  • if the space is used for storage the insulation won’t be exposed, those walls need as much insulation as possible.

HVAC is the most tricky. This is definitely not a place to cut corners. The unit needs to be properly sized. Too large and the power bill will be high. The goal is that on a 95 degree day it should run and never shut off. When it shuts off the humidity is not being controlled. Air conditioning is not about just cold air it’s about humidity control. 78 degrees and 50% humidity feels the same as 75 degrees and 65% humidity. That 3 degree temp difference will cost you 3

22

Blueskyguy, do you do consulting? Like could I pay you to inspect the house at a few key milestones for a reasonable price?

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That is some good advice except he said he was using spray foam, which means you seal up the attic, no ridge vent or soffit vents.
Be very careful when you foam around windows and doors. Some foam will expand too much and cause doors and windows to stick.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

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Ok… Off topic, but spiders… I hate spiders… Anything you can do to keep them out? I’m guessing make sure there are no cracks or holes around, but any other tricks?

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quote:
Originally posted by on a fishin mission

That is some good advice except he said he was using spray foam, which means you seal up the attic, no ridge vent or soffit vents.
Be very careful when you foam around windows and doors. Some foam will expand too much and cause doors and windows to stick.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

NOT using spray foam... Too much money from what I was told...
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quote:
Originally posted by skinneej
quote:
Originally posted by on a fishin mission

That is some good advice except he said he was using spray foam, which means you seal up the attic, no ridge vent or soffit vents.
Be very careful when you foam around windows and doors. Some foam will expand too much and cause doors and windows to stick.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

NOT using spray foam... Too much money from what I was told...

Spray foam in the attic with batt in the walls is fairly common. Open cell spray foam for rafters is a little over $1/sf for easily accessible areas. I would highly look at this as an upgrade. It will pay for itself in a couple years.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

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If your footprint is 2000sf it would put open cell spray foam at about $3-4000 depending on pitch of roof.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

28

spiders and other bugs - a gecko or two eliminates that issue

I don’t do consulting work, at least not yet but when I retire…

I live in Columbia but get to Charleston sometimes, would be glad to look at it, no charge

that’s how I roll

and BTW the spray foam is good stuff but expensive, not too many folks use it, you said you weren’t using it so I didn’t say anything

one good application is for the third floor attic construction applications, it moves the thermal barrier to the outer most part of the structure, requires different building techniques and most builders haven’t learned it yet, one issue that hasn’t been concluded is the impact on the life of the shingles, it could make them degrade quicker

Pioneer 197SF

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quote:
Originally posted by Blueskyguy

spiders and other bugs - a gecko or two eliminates that issue

I don’t do consulting work, at least not yet but when I retire…

I live in Columbia but get to Charleston sometimes, would be glad to look at it, no charge

that’s how I roll

and BTW the spray foam is good stuff but expensive, not too many folks use it, you said you weren’t using it so I didn’t say anything

one good application is for the third floor attic construction applications, it moves the thermal barrier to the outer most part of the structure, requires different building techniques and most builders haven’t learned it yet, one issue that hasn’t been concluded is the impact on the life of the shingles, it could make them degrade quicker

Pioneer 197SF

Sure, let's connect. I would like to have you do a walkthrough when the time is right...

I can’t NOT pay you for “work”… That’s how I roll!!! That being said, usually a fishing trip is a good form of payment…

This gives me something to think about…

So are you guys saying that it’s worth it to just spray foam up in the roof (versus entire house)?

OFM, When you say “footprint”, are you talking about whole house or just attic part?

Also, the other thing is that the finished out attic is a large space that will have 1 bedroom and 1 large game room… We won’t be up there every day, so I kind of want to “close it off” and set the thermostat up there at an efficient mark until we actually do decide to hang out up there. Most bedrooms and my office will be on the floor just under that which is where the AC will be running 24x7.

Also, my main concern is more about “cool” air escaping rather than heat escaping… Our large power bills are in the summer time when we have the house feeling like an ice box. Since heat ris

30

fishing is always good

the 3rd floor lack of use is another reason to use a separate HVAC unit for that space

the use of foam upstairs is difficult to evaluate without seeing the plans or the framed house, two important differences between traditional insulation and foam are:

  • where they are installed upstairs is different
  • with foam the attic is not vented because there is no hot space
  • foam is an air barrier, insulation in not

if infiltration is properly controlled then the cold and hot air leakage are both managed, depending on how the floor is built - most floors have very little leakage due to the at least 2 layers of material

there is a ton of info on the web on this

I’m off for some flying and jumping, so may not reply further until Sunday

Pioneer 197SF

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The footprint is how big your foundation is in square feet, not including decks. Essentially its the first floor heated square footage.

The best thing you can do is spray foam the roof. Hot air rises and escapes thru the roof. The hot air that escaped is then replaced as the house temperature starts to rise. Its a viscous cycle. Foam will stop this cycle. Knowing what I know now after building over 400 houses, I would do everything possible to make foam happen.

If you foam, your HVAC installer needs to know so the units can be sized correctly as blueskyguy said. If the system is to large it will not run long enough to efficiently remove humidity. They come on, blast the temperature down 5 degrees in a minute and cut off. This drops the temp, but not the humidity. The humidity is removed as the air circulates thru the hvac system. It sound like your 3rd floor space would be perfect for a mini split. In a/c mode they run constantly which will keep humidity down. I have a drive under as well and we closed off 1/2 and made it conditioned space with a mini-split. Our electric bill actually went down. As blueskyguy said, don’t skimp on hvac equipment. If you do, it will cost you in the long run.

With a drive under, do all you can to seal the ceiling. This is another spot for extra insulation. Air flow is another important factor and you have to take your cars into consideration. They bring in a lot of heat right under your cooled living space. If it is possible I would look at 2 layers of drywall on the garage ceiling as well, if that’s what you intend to use. The drywall has little r-value but will help stop drafts and adds an added layer of fire protection. Google garage fires and you’ll see how many fires start in the garage.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

32

OFM, so you are saying that in a multi-story home, 2000 on first floor footprint, the entire house would only be $4-6K??? Sqft is as follows:

1rst - 1846
2nd - 1710
3rd(attic) - 1064

With the original contractor that we talked to, his estimate was something like $15K.

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PS, almost forgot… Happy birthday OFM!!!

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quote:
Originally posted by skinneej

OFM, so you are saying that in a multi-story home, 2000 on first floor footprint, the entire house would only be $4-6K??? Sqft is as follows:

1rst - 1846
2nd - 1710
3rd(attic) - 1064

With the original contractor that we talked to, his estimate was something like $15K.

So guesstimating here but with an average size pitch your roof over heated sq ft should be around 4000 sf. The foam would be $4-6k. Using batts in the walls and garage ceiling on a house that size should be about $4k putting total at $8-10K for insulation.

Call Jeff Hoppe, 843-360-1045. I’ve worked with him for close to 20 years. He can get you a quote pretty fast.

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

35
quote:
Originally posted by skinneej

PS, almost forgot… Happy birthday OFM!!!

Thank ya!

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson

36

Do you have to worry about not being able to detect a leaking roof with the spray-in foam?

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Open cell foam does is not water proof so water would make its way thru it. May take longer before it was noticed

“Those who have the ability to make a difference have the responsibility to do so.” Thomas Jefferson