Insulation, Radiant and Vapor Barriers - insulating basement walls
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frankieromance
11-27-08, 11:17 PM
drylock has been on my basement walls for several years now. walls have always been dry. i was wondering if i could put CodeBord Extruded Polystyrene Rigid 2" insulation on the walls. if yes, would i use construction adhesive to secure them?
afterwards, i would frame the walls out a few inches from the wall, using 1/2" x 4' x 8' DensArmor Plus Interior Wallboard. I will not be putting any insulation in between the studs. I feel the basement will be warm enough doing it this way. do u agree? (have plans to insulate ceiling & do a proper subfloor as well).
afterwards, i would frame the walls out a few inches from the wall, using 1/2" x 4' x 8' DensArmor Plus Interior Wallboard. I will not be putting any insulation in between the studs. I feel the basement will be warm enough doing it this way. do u agree? (have plans to insulate ceiling & do a proper subfloor as well).
newidea1
11-29-08, 02:33 PM
Your approach is way to complicated and labor intensive.
Lets git rid of the 2X4 framing. Preserve as much of the floor space as you can. even two inches adds up all around the peripheral and for resale home appraiser will value your home based on square footage that they measure. What we will do is glue the EPS direct to the drylock painted wall, add 1X2 furring strips bolted to the conrete to further secure the EPS to the concrete and glue other furring strips as necessary for nailers for your wall finish. You will use a hot knife to melt slots in the EPS for electrical wire preferably in plastic conduit terminated in plastic junction boxes
Interior finish assembly
EPS, glued to drylocked coated concrete - 4 inches
1X2 vertical furring strips 4' OC bolted 3 places to concrete
1X2 vertical furring strips 2' OC glued to EPS
wall finish, any (drywall, wood paneling (may need a backer), plastic sheets (can be glued to furring))
I feel the basement will be warm enough doing it this way.
It is not about feeling warm it is about how much energy do you use to maintain the desired inside air temperature.
Lets see if it is worth adding more EPS.
Below is schematic of basement wall.
The earth is at a constant temperature and is Function of latitude.
The portion of the basement wall exposed to outside air will have greater temperature extremes than the bermed part. Notice the R factor vs various basement floor depths below grade. So concrete and the earth berm provides pretty good insulation by itself. The exposed concret has R1.7.
http://i444.photobucket.com/albums/qq170/focusonz/basement_small.gif
Now you said 2" EPS. Well here are the heat transfer through the wall assembly given various EPS thicknesses. The calculations assume 55 degree earth temperature and 75 degree inside air temperature. As the temperature difference across the wall assembly goes up the more heat is lost.
Thermal performance 8' floor depth 8 inch concrete
1"inch EPS Interior finish assembly - R12.3 - 2.0 BTU/sqft-hour
2 inch EPS Interior finish assembly - R16.1 - 1.55 BTU/sqft-hour
3 inch EPS Interior finish assembly - R19.9 - 1.25 BTU/sqft-hour
4 inch EPS Interior finish assembly - R23.7 - 1.05 BTU/sqft-hour
Increasing the EPS thickness from 2" to 4" then the heat transfer through the wall assembly difference is 0.50 BTU/sqft-hour. Given a 30'X50' basement and 8 foot ceiling height then that amounts to 360 BTU/hr or 259,000 BTU/month. Now if you heat this space insulated with 2" of EPS using and 80% AFUE natural gas furnace at $0.13 per cubic foot price then it will cost you an additional $46 per month or $552 per year. New EPS can be obtained at about $1.45 per sq ft or less if you buy used (shipping not included) $1044 total.
Your payback for the additional 2" of EPS is 1.89 years.Payback will be less, less, less if the price of natural gas goes up, up, up.
In these uncertain energy pricing times insulate, insulate, insulate.
Now the calculations did not consider the ceiling above or the basement floor.
But the rule of thumb - R24 walls and R50 ceiling is a good cost effective one to abide by.
References
R-Value (http://www.roofhelp.com/Rvalue.htm)
http://www.nafa.org/Content/NavigationMenu/Resource_Center/Alternative_Fuels/Energy_Equivalents/Energy_Equivalents.htm (http://www.nafa.org/Content/NvigationMenu/Resource_Center/Alternative_Fuels/Energy_Equivalents/Energy_Equivalents.htm)
Fox Blocks Pricing Guide (http://www.foxblocks.com/product_info/pricing.shtml)
Liquid NailsŪ - Projects & Foamboard Adhesive (LN-604) (http://www.liquidnails.com/products/product.jsp?productId=34)
PS you can find cheap EPS locally. Hunt around you may have to drive 100 miles to get it but it is worth it
Lets git rid of the 2X4 framing. Preserve as much of the floor space as you can. even two inches adds up all around the peripheral and for resale home appraiser will value your home based on square footage that they measure. What we will do is glue the EPS direct to the drylock painted wall, add 1X2 furring strips bolted to the conrete to further secure the EPS to the concrete and glue other furring strips as necessary for nailers for your wall finish. You will use a hot knife to melt slots in the EPS for electrical wire preferably in plastic conduit terminated in plastic junction boxes
Interior finish assembly
EPS, glued to drylocked coated concrete - 4 inches
1X2 vertical furring strips 4' OC bolted 3 places to concrete
1X2 vertical furring strips 2' OC glued to EPS
wall finish, any (drywall, wood paneling (may need a backer), plastic sheets (can be glued to furring))
I feel the basement will be warm enough doing it this way.
It is not about feeling warm it is about how much energy do you use to maintain the desired inside air temperature.
Lets see if it is worth adding more EPS.
Below is schematic of basement wall.
The earth is at a constant temperature and is Function of latitude.
The portion of the basement wall exposed to outside air will have greater temperature extremes than the bermed part. Notice the R factor vs various basement floor depths below grade. So concrete and the earth berm provides pretty good insulation by itself. The exposed concret has R1.7.
http://i444.photobucket.com/albums/qq170/focusonz/basement_small.gif
Now you said 2" EPS. Well here are the heat transfer through the wall assembly given various EPS thicknesses. The calculations assume 55 degree earth temperature and 75 degree inside air temperature. As the temperature difference across the wall assembly goes up the more heat is lost.
Thermal performance 8' floor depth 8 inch concrete
1"inch EPS Interior finish assembly - R12.3 - 2.0 BTU/sqft-hour
2 inch EPS Interior finish assembly - R16.1 - 1.55 BTU/sqft-hour
3 inch EPS Interior finish assembly - R19.9 - 1.25 BTU/sqft-hour
4 inch EPS Interior finish assembly - R23.7 - 1.05 BTU/sqft-hour
Increasing the EPS thickness from 2" to 4" then the heat transfer through the wall assembly difference is 0.50 BTU/sqft-hour. Given a 30'X50' basement and 8 foot ceiling height then that amounts to 360 BTU/hr or 259,000 BTU/month. Now if you heat this space insulated with 2" of EPS using and 80% AFUE natural gas furnace at $0.13 per cubic foot price then it will cost you an additional $46 per month or $552 per year. New EPS can be obtained at about $1.45 per sq ft or less if you buy used (shipping not included) $1044 total.
Your payback for the additional 2" of EPS is 1.89 years.Payback will be less, less, less if the price of natural gas goes up, up, up.
In these uncertain energy pricing times insulate, insulate, insulate.
Now the calculations did not consider the ceiling above or the basement floor.
But the rule of thumb - R24 walls and R50 ceiling is a good cost effective one to abide by.
References
R-Value (http://www.roofhelp.com/Rvalue.htm)
http://www.nafa.org/Content/NavigationMenu/Resource_Center/Alternative_Fuels/Energy_Equivalents/Energy_Equivalents.htm (http://www.nafa.org/Content/NvigationMenu/Resource_Center/Alternative_Fuels/Energy_Equivalents/Energy_Equivalents.htm)
Fox Blocks Pricing Guide (http://www.foxblocks.com/product_info/pricing.shtml)
Liquid NailsŪ - Projects & Foamboard Adhesive (LN-604) (http://www.liquidnails.com/products/product.jsp?productId=34)
PS you can find cheap EPS locally. Hunt around you may have to drive 100 miles to get it but it is worth it
frankieromance
11-29-08, 06:12 PM
have to put the wall away from the concrete due to sewer waste pipe and plumbing.
newidea1
11-29-08, 06:47 PM
have to put the wall away from the concrete due to sewer waste pipe and plumbing.
No you don't. Just use hot knife and notch the EPS. And if 4" don't cover the sewer pipe and another 2" just there and just sculpt the EPS around it. ICF Tools (http://www.demandproducts.com/icf_2.php)
Don't cover water pipes with the EPS especially up by the sill because that concrete up there expose to outside air will stay very cold and the pipe might freeze if it is on the outside of the thermal envelope.
No you don't. Just use hot knife and notch the EPS. And if 4" don't cover the sewer pipe and another 2" just there and just sculpt the EPS around it. ICF Tools (http://www.demandproducts.com/icf_2.php)
Don't cover water pipes with the EPS especially up by the sill because that concrete up there expose to outside air will stay very cold and the pipe might freeze if it is on the outside of the thermal envelope.