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-   -   Insulating & Vapor Barrier Basement (http://www.diychatroom.com/f103/insulating-vapor-barrier-basement-142109/)

thetroups 04-30-2012 10:08 AM

Insulating & Vapor Barrier Basement
 
Hello all,

I am currently demoing my basement because the framed wall's were built right against the concrete block... So I am ripping it all down and will redo the work. This is my first home as well with my new wife so it is important that materials I use will be safe and protect our future family.

So with that said my plan is to use a "rigid foam" and adhere this right to the block and the floor... What is the best buy for the money to provide me with the insulating power but also provide the vapor barrier all in one. Currently all the walls have been dry locked as well.

I would like to purchase the product from Lowes as FYI. I saw 4x8 foam board there for 9.45 or something like that but I am not sure if this will protect against moisture.

Once the foam board is installed and seems tapped and things have been properly spray foamed I will stud against the foam board.

Thanks in advance for your help.

itsnotrequired 04-30-2012 02:36 PM

do you have a link to the foam you are thinking of using? not all are created equal. you will want to use a closed-cell xps foam. check out the following link for more info.

http://www.buildingscience.com/docty...ion-assemblies

xps is nice because it provides insulation as well as vapor retardation. thickness will depend on how much r-value you want. the fiberglass batts provide additional insulation level. you can skip it if you are in a warmer climate.

thetroups 04-30-2012 03:20 PM

something like...
http://www.lowes.com/pd_41503-46086-RPP-12-S8+%284X8%29_4294858106+5003695+5003697+5003696_42 94937087_?productId=3362406&Ns=p_product_prd_lis_o rd_nbr|0||p_product_quantity_sold|1&pl=1&currentUR L=%2Fpl_10%2B15_4294858106%2B5003695%2B5003697%2B5 003696_4294937087_%3FNs%3Dp_product_prd_lis_ord_nb r|0||p_product_quantity_sold|1&facetInfo=$5%20-%20$10|$15%20-%20$25|$10%20-$15

If I am wrong please direct me to the proper product.

itsnotrequired 04-30-2012 04:05 PM

you'll want this stuff

http://www.lowes.com/pd_337591-210-M48150LOWES_4294858110_4294937087_?productId=33086 86&Ns=p_product_qty_sales_dollar|1&pl=1ĄtURL=%2Fpl _Foam%2BInsulation_4294858110_4294937087_%3FNs%3Dp _product_qty_sales_dollar|1&facetInfo=

you'll want extruded, not expanded polystyrene

Gary in WA 04-30-2012 11:37 PM

Either f.b. will work, just need it thicker if ESP.

Where are you located?

Gary

thetroups 05-01-2012 07:17 AM

Located in York, PA it gets cold here in the winter and humid in the summer.

thetroups 05-01-2012 07:19 AM

That stuff is not cheap that is for sure... to do all the walls and floor that would be a large investment on just foam.

itsnotrequired 05-01-2012 09:06 AM

Quote:

Originally Posted by GBR in WA (Post 911562)
Either f.b. will work, just need it thicker if ESP.

Where are you located?

Gary

i thought xps was the preferred choice for interior basement panel insulation, since eps is more permiable and doesn't create as good a vapor retarder when compared to xps. or is the solution to use thicker eps to get effective vapor protection?

Windows on Wash 05-01-2012 02:27 PM

Quote:

Originally Posted by itsnotrequired (Post 911709)
i thought xps was the preferred choice for interior basement panel insulation, since eps is more permiable and doesn't create as good a vapor retarder when compared to xps. or is the solution to use thicker eps to get effective vapor protection?

Vapor permanence is not as important as air tightness at the end of the day.

Bulk air transfer will carry far more water (about 100X) as diffusion.

Gary in WA 05-01-2012 10:01 PM

Page 33, 57-61: http://www.buildingscience.com/docum...study-analysis

Figs. 13, 14: http://www.buildingscience.com/docum...lation-systems

As WoW said correctly, it's the air gap that will get you: http://www.carb-swa.com/articles/in%...Insulation.pdf
I forget some of the info in my links occasionally too, LOL.

Compare your HHD with these Cities for the foam thickness: http://www.buildingfoundation.umn.ed...timum-main.htm

Or find the dew-point, let me know...

Gary

itsnotrequired 05-01-2012 10:08 PM

so what is the preference of xps over eps? looks like xps gets you more r-value per inch and isn't as fragile as eps. i plan on finishing my basement with xps but was curious what other opinions are.

mikegp 05-02-2012 07:29 AM

Use 2 inch XPS if you want decent insulation and vapor barrier properties. I don't suggest using fiberglass insulation in basements. If it gets wet it becomes pretty useless and it also can mold. There are nice alternatives like Roxul.


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