# Concrete block insulation



## CFarmerLady (Dec 1, 2011)

Would it work to fill the holes with straw?


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## TnAndy (Sep 15, 2005)

No. Not only wouldn't it insulate much, you might end up with a mold problem at some point. 

Use pour in vermiculite made for just that purpose.


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## MushCreek (Jan 7, 2008)

Even the best insulation has very little effect in the holes. There's too much heat transfer through the webs. Glue or otherwise attach sheet foam to one side or the other- or both.


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## CFarmerLady (Dec 1, 2011)

Ooo! That's a great idea! How thick would you recommend?


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## Darren (May 10, 2002)

They make 2" thick panels. More is better especially to overlap the seams.


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## Nimrod (Jun 8, 2010)

MC has it right but burning foam gives off very toxic gases. Only put it on the outside. If the cement block is below grade I would waterproof the outside first.


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## Darren (May 10, 2002)

There are foams that meet more restrictive flame spread requirements. ASTM has the standards. You'll see the standard the foam meets printed on the sheet.


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## K.B. (Sep 7, 2012)

CFarmerLady said:


> Ooo! That's a great idea! How thick would you recommend?


In our area, code requires R21 for the walls. There is a product that provides R21 with 3.2 inches of foam. It is called, R-max, I believe. We will be applying it to our new block home later this winter or next spring.


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## MushCreek (Jan 7, 2008)

Most states are at R-19 now; a few are still R-13. I would recommend 2 layers, with the joints staggered. You can even tape the joints for a really tight installation.

You can put the foam on the inside if you put up drywall. 5/8" gives you a one hour fire barrier, I believe. You'd be dead long before the flames got to the foam. If a house catches on fire, you need to be out in minutes.


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## K.B. (Sep 7, 2012)

the other advantage to putting the insulation on the outside is that you keep the benefit thermal mass of the block and concrete in-fill to stabilize interior temp swings.


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## houndlover (Feb 20, 2009)

I have two homes on my property and one is cinder block. We are currently refurbishing it and living in our other house, but the house we call "the cement house" stays warmer in winter and cooler in summer (we live at 1000' in Oregon's coast range, with temps in the 90's for a solid month in the summer and below freezing from Dec - Mar). The walls are not filled. We have cedar board and batten on the outside, and 1 1/2" thick sheets of foam insulation on all outside walls inside the house, covered with sheet rock. My husband ripped 2 X 4's and those are placed vertically, allowing for space to plumbing, wiring, and insulation between the cinder blocks and wall board. Additionally, we replumbed the entire house with pex. Before, we lived in it without siding and it was pretty well insulated, but ugly. Inside we had no insulation between the wall boards and the cinderblocks and it stayed pretty warm but we used a lot of cords of wood. Now, during construction, it stays warm inside while working with just a kerosene heater (2000 sq feet). It's amazing, really.


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## CFarmerLady (Dec 1, 2011)

I'm trying to use as little timber as possible, to lessen the costs. I figured I'd have to have it for the subfloor, the roof skeleton, and the interior walls. The house will _probably_ be in the Texas Panhandle, depending on where DH can get a job after he's done with school. Really hot and dry summers with fire danger, and mostly mild winters. Snow load has only been heavy once or twice that I remember. (I'm 33.)

So, if I can use 2" foam and sheet rock on the inside of the block walls, then use pink for the roof, subfloor and interior walls, would that work?


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## Darren (May 10, 2002)

Article about ASTM standards.

Techs & Specs - National Insulation Association


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## MushCreek (Jan 7, 2008)

In an A/C dominated climate, you want a LOT of attic insulation. Blown cellulose would probably be your best bet. Interior walls are not usually insulated, unless you are separating an area that won't have HVAC. Fiberglass is good for the subfloor.


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## darkwing (Oct 14, 2012)

Mostly mild with 70mph winds. A couple of ''80mph gustandoes'' . Snowload rarely last more a couple days but its a wet packed mess that weighs up to 20lbs to the sq ft. 
South of Amarillo on top of the caprock.


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## K.B. (Sep 7, 2012)

If you go with a raised heel truss you can keep a good insulation rating along the ceiling to join up with the insulation on the walls. Ours is a 14" heel, and should let us get close to R40 in the ceiling.
example pic:
http://images.inmagine.com/img/aspireimages/drk003/drk003128.jpg

A mono-slab foundation (also insulated on the outside down to the base of the footing) will also give you a lot of thermal mass to further stabilize indoor temps.


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## CFarmerLady (Dec 1, 2011)

I want to show my house plans. Do I have to start a new thread for this?


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## CFarmerLady (Dec 1, 2011)

Okay, here's the pictures I've been working on.


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## orionrising (Nov 18, 2012)

my first though with that design is why do the hall way go all the way to the outside wall? unless you plan an exit there, end the hallway at the entrances to the second set of rooms, then make the master bigger with the formerly wasted space.


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## Bat Farm (Apr 21, 2010)

If you insulate the crawlspace walls, you do not want to insulate the sub-floor - the crawl space becomes a part of the house envelope.


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## houndlover (Feb 20, 2009)

My house has a slab floor with radiant heating, copper pipes through which solar heated water is pumped, and we have a second floor under the peaked roof, with blown in loose insulation between the ceiling and second floor, and "pink stuff" under the roof.


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## Wendy (May 10, 2002)

> my first though with that design is why do the hall way go all the way to the outside wall? unless you plan an exit there, end the hallway at the entrances to the second set of rooms, then make the master bigger with the formerly wasted space.


Yes, in the bedroom on the upper right in the bottom picture. Can't you move the doorway over to the left? Make a wall right after the doorways of that bedroom & the master bedroom. Use that space as a big closet.


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