Basement Insulation

sd900climber · Nov 25, 2008

We just finished with building a new house and the basement was left unfinished. We wanted to get the exterior walls insulated before the long cold days of winter set in. We have poured concrete basement walls and the 2x4 framing is already up.

My question is, which form of insulation is considered the "best" these days, is it the traditional fiberglass batt insulation or the foam core panels?? Anyone have any experience with both?

From the little research I've done it sounds like people are starting to like the panels more and more. Easier to install, don't have to worry about moisture, provides a better seal, and is cheaper.

Are there different R-values for the foam panels?

Also, is it easier to have the wiring done b/4 we put in the insulation? I assume so, especially if you use the batting. We have some of it ran but not all of it.

Thanks in advance...

Disco Dan Richter · Nov 25, 2008

I would not use fiberglass. Too bad the framing is up, because I take 1.5" foam and use the wall framing to smash it to the concrete sotra speak. glue it to the concrete first and them use the 2x4 wall to push it against the concrete. This way the walls are eassier to wire and finish, plus a tighter seal and better insulation. And, if you wanted extra r value, fill in the cavities with fiberglass as well.

adrenaline junkey · Nov 25, 2008

use fiberglass a lot better r value (r11) than the foam panels(r4). A lot of people never even insulate the basement walls because they stay a lot cooler in the summer and absorb the ground tempature. however a lot of building codes vary state to state as for idaho there requiring you to now use a r 19 in the basement walls.

Blu Du · Nov 25, 2008

the code here says, foam on the outside or spray foam the inside wall or poly beetween wall and foundation and fiberglass

switchback · Nov 25, 2008

We built on a Poly-steel foundation, those big foam legos you stack and then pour the wall between. Got a 1,000' basement with 1 heat duct and could have Van Halen down there and not here 'em outside.

X-it · Nov 25, 2008

fiberglass has a better r value but it is deceiving, the colder it gets the more it losses it's r value, too bad this was not factored into the codes. But don't sweat it, run your wiring add the fiberglass. Maybe there is paint or foam under the bottom plate to prevent moister from wicking through to the wood or maybe not.

SLEDIOT · Dec 5, 2008

2XM3 · Dec 5, 2008

We have poured concrete walls with 6" of the spray in foam that hardens, the "R" value is 6.88 per inch, so that gives me a total R value of 41. the stuff is also hell for strong and dead quiet.

Some common roofing materials and their corresponding values for Thermal Conductance (C) and Thermal Resistance (R) are shown in the following table.

Material
Thickness In Inches
C-Value
R-Value

Metal
N/A
0.000
0.00

Concrete
1.0
3.333
0.30

Gypsum
1.0
1.667
0.60

Wood
1.0
1.099
0.91

Tectum
1.0
0.500
2.00

Inside Air Film
N/A
1.087
0.92

Outside Air Film - Summer
N/A
4.000
0.25

Outside Air Film - Winter
N/A
5.882
0.17

Vapor Retarders
N/A
0.000
0.00

BUR Gravel
N/A
2.941
0.34

BUR Smooth
N/A
4.167
0.24

Fiberboard
1.0
0.360
2.78

Perlite
1.0
0.360
2.78

Phenolic Foam*
1.0
0.120
8.30

Fiber Glass
1.0
0.256
3.90

Polyisocyanurate
1.0
0.180
5.56

Polyisocyanurate Composite
1.5
0.240
4.17

Polystyrene Bead Board
1.0
0.280
3.57

Polystyrene Composite Board
1.5
0.301
3.32

Polystyrene - Expanded (EPS)**
1.0
0.260
3.85

Polystyrene - Extruded (XEPS)***
1.0
0.200
5.00

Sprayed Polyurethane Foam****
1.0
0.150
6.88

Cork
1.0
0.280
3.57

0007 · Dec 5, 2008

What's the deal on vapor barrier on basement wall's? barrier agains the concrete? none at all or barrier on the inside of stud's?

woodpecker · Dec 5, 2008

vaper barrier!

Do NOT put vaper barrier on the inside of ANY walls Ya! this was building pratiece back when, but now we've found out the hard way DO NOT do it. it traps moisture around the studs and insulation. we are working on a six year old house that needs the exterior walls replaced (all the Wall). to top it off insurance will not pay for mold or moisture damage!!

X-it · Dec 6, 2008

Ha Ha yep with the barrier, and you never know if your going to have problems with the concrete wall (water coming in) so leave the finish off for at least one spring melt. A good practice is having the 2x4's at least 2" away from the concrete wall that way you can get a straight wall and there is room for R 20, and plenty of clearance from moisture wicking. But those bottom plates can be a problem, their are several products out there that a designed to go between the wood and concrete. If your basement floor was sealed before the plates were added, nothing is needed. A small holed drilled with a nail pounded in or screwed inserted sure makes a nicer job than a spawled out hilti shot that can ruin a large area, more so if you pry off the bottom plates. There nothing wrong with wood and fiberglass it has been used in millions of basements with no issues, and the wiring has been designed around wood and rock....it works. Those c and r value tables are interesting. Insulation can be improved, but the building code can be a pain in the *** when implementing those changes. Spray foam in regular walls (above ground) the 6mil vapor is "not" to be added.

whitefish · Dec 6, 2008

As 2XM3 said, spray in poly closed cell foam via plural pump in the absolute best. The stuff is so tuff that if you didn't care about the look that you could do without the sheetrock.

Search

Basement Insulation

sd900climber

Free Member

Disco Dan Richter

Well-known member

adrenaline junkey

Free Member

Blu Du

Well-known member

switchback

Free Member

X-it

Free Member

SLEDIOT

Well-known member

2XM3

Well-known member

0007

Free Member

woodpecker

Free Member

X-it

Free Member

whitefish

Well-known member

Similar threads