Heat loss to cinderblock?

[smmm]

If you put the insulation outside your are exposing it to many things that can damage it. (animals, insects) Insulate inside and go from top to bottom. Better to be safe than to do it again

 

[begreen]

And uninsulated basement can suck out 25-35% of the heat through the walls. Insulation is good. It can be done on the exterior if properly attached, flashed and protected, but often inside is easier.

 

[Butcher]

I'm gonna buck the status quo here and say that those blocks holding up your house are a sorce of stored heat. That has been proven through centuries of building with stone and concrete. While the R value may be low as to keeping the cold out on a cinder block it is a great heat storage unit which will hold and release its heat over time. I may be biased in my opin but having worked for years with stone and concrete products here in the midwest I am sold on what I have seen, felt, and lived with. Do a search of thermal mass and concrete on the internet and there are all kinds of studies that will say the same. But like I said, I'm kinda biased. Grew up reading the 3 little piggies to much maybe.

 

[PLAYS WITH FIRE]

Thermal mass for sure Frank Lloyd Wright designed some of his homes with this very much in mind. But there needs to be a thermal break....otherwise it's sucking up the heat that it can't hold.

 

[begreen]

Exactly. It can act as a conductor just as well. With an outer insulation jacket, it would have the potential as thermal storage. As long as you didn't let it cool down too much. If you do ,the time to recover may exceed your patience.

 

[Black Jaque Janaviac]

Plays With Fire,

Yep. In my house only the top two rows of cinder blocks are exposed to atmosphere. So that portion accounts for only 25% of the wall area. That's the only reason the lower portion loses more heat is because it is so huge. From a cost-benefit standpoint, a dollar spent on insulating the top two rows of blocks is worth almost two bucks spent insulating the lower part of the wall.

Is there anyone here who only insulated the exposed part of the foundation? What has your experience been? Did it make a noticeable difference or do you wish you insulated top to bottom?

 

[Ehouse]

If you don't want to excavate below the exposed part of the foundation, you can insulate horizontally ( moderate slope away from the wall) a few inches down. Use flashing at the vert. to horiz. transition. I think it's an Alaskan slab detail but should be an improvement from just insulating the above grade portion.

Ehouse

 

[Yagminas Masonry and Wood-heat]

If given the choice, always insulate and leak-proof the exterior. The heat storage and moderating effect is well worth it. Kinda like living inside a masonry heater.
Kev

 

[tecumseh]

I have found the perfect product and would just love to use it. Great rvalue, soundproofing, moisture prevention and even a bit of bug repellent. It is called Core fill500 and/or Tripolymer and because my entire house and basement (on a hill) are concrete block with just a 1.5 inch of wood and insulation behind the dry wall it would be awesome. The foam injection takes the average r-1 of the block to to almost r30 in the block and evened out over a normal wall gives r20. However, because of this absurdly warm weather my gas bills are almost nothing because my smallish stove is heating my house like a champ. Convincing my wife to spend 6K on it for a small savings in winter and summer cooling is tough right now. The salesperson says most people can get payback in 2-4 years. However with the wood stove, low gas prices and cheap electric in NW Ohio convincing the financial wizard of the house will take some doing. The company I called mostly does this type of insulation for commercial buildings but were willing to come to my home and do it.

I despaired that I couldn't ever find something that would insulate my house. This if it does what they says would be great and since I have to paint the walls any way in a year or two the 3/4 inch holes they need to drill and patch would get covered anyways.

Just thought I would pass on the product and see if it makes sense for anyone or is even available in your area. If you order it tell them Tim from Ohio sent you, maybe they will give me a credit! lol

Tim

 

[StuckInTheMuck]

Might be worth taking a look into this product to get you started on the exterior of the house. http://styro.net/FoundationInsulationPanel.htm Seems to be more durable and better looking than standard foam board. Can't seem to find a price anywhere online.

 

[Black Jaque Janaviac]

I thought I remember reading somewhere that there was some synthetic stucco that was applied over these foam boards that was giving the practice of stuccoing over insulation a bad reputation. In other words, if you put up the foam board, cover with metal lath, then a healthy layer of stucco that is actually fairly resistant to weed whackers.

 

[StuckInTheMuck]

I guess I should have said, that I know nothing about the above product.. Just saw it when I was looking for a solution for my house. I ended up using the 2" foil backed foam insulation on the interior of my foundation walls.. Don't know the best way to handle insulating on the exterior, but I think I would have preferred to be able to do that..

 

[sesmith]

The fact that the stove my stove room is blazing hot while the rest of the house could use a five degree lift leads me to suspect that my problem is moving the heat about, not loss to the concrete foundation. Am I correct?

You are correct. If you insulate and don't find a way to move the hot air upstairs, your cellar will be even warmer and your upstairs will still be cold. I heated many years with my stove in an uninsulated cellar. It isn't the most efficient way to do things, but the key is in moving the air upstairs. I laid up an unmortared short block wall around 3 sides of my stove to help keep it from just radiating the heat at the cellar walls and act as more mass for the stove. The 1st course were set on their sides to allow air to flow up between the stove and the wall. I wasn't using the oil furnace most of the time, so I left the blower box open for cold air return. The hot air went up the stairwell and also up via a duct fan and vent through the floor. This setup wasn't ideal, but it worked. Close up the furnace blower door or shut the door at the top of the stairs and it didn't work very well at all. Insulation will certainly help with heat loss, but it won't fix the air circulation problem.

FWIW, before you insulate, try air sealing the rim joists first. That will probably be a bigger bang for the buck to start with. Depending on how leaky they are, it may also help in getting the air flow upstairs. I used to have a problem moving the air up through my house in a strong south wind, due to leakage and air pressure from the leaks.

 

[DickRussell]

I have found the perfect product and would just love to use it. Great rvalue, soundproofing, moisture prevention and even a bit of bug repellent. It is called Core fill500....

Tim

While filling the voids of concrete block with a foam insulation undoubtedly would improve the R value of the whole wall some, I doubt that it would be the hoped for great improvement. The inner and outer faces of the block remain exposed to the inside air and outside air or soil, and these faces still would be connected by highly conductive webs of concrete. The heat loss through those webs of concrete still would dominate the heat transfer (thermal bridging). Even with the block voids not filled with foam, the mostly dead air cavities still have insulating value, much like the air space between an old double hung window and an exterior storm window. Improving the R value of a part of the assembly that isn't contributing much to heat loss in the first place won't help the whole wall R value too much.

It's no surprise that building highly insulated wall structures requires near elimination of thermal bridging of wood framing. This is can be done by using double frame walls, applying a continuous layer of rigid foam on the inside or outside of the wood, or using structural insulated panels (SIP, a sandwich of foam between inner and outer skins of OSB). In the case of a foundation wall, about the only way to insulate it well is to apply a continuous layer of insulation on one side of it.

Insulating on the outside lets the foundation mass be a heat storage device, which would release heat long after the fire has died. However that mass will soak up a lot of heat for a while when the fire is started, resulting in a delay of availability of heat for the rest of the house. Insulating on the inside doesn't provide the thermal storage of the concrete mass, but it does mean a faster heatup of the basement space and earlier availability of heat for the rest of the house. Then it's just a matter of leaving the basement door open or providing other means of moving air between basement and the rest of the house.

 

[Black Jaque Janaviac]

Sesmith,

Thanks. I couldn't quite understand how not insulating the basement was causing the basement to be 80+ degrees while the next floor up could barely push 65 when the outside temps were in the 20's.

I think I have decided to insulate the top part of the foundation in the summer when I can dig down a bit.

In the mean time I will work on small-dollar projects to help move the air around. Floor vents are easy. I'm also tearing down the tongue-and-groove ceiling tiles to expose the heat directly to the floor-boards of the next floor. In removing these tiles, I learned that for the entire portion of the tiled ceiling the previous owners never insulated that part where the joists rest on top of the cinder blocks (what do you call that?). So $30 worth of 6" batting is going up there.

 

[jimbom]

I have found the perfect product and would just love to use it. Great rvalue, soundproofing, moisture prevention and even a bit of bug repellent. It is called Core fill500....

Tim

While filling the voids of concrete block with a foam insulation undoubtedly would improve the R value of the whole wall some, I doubt that it would be the hoped for great improvement. The inner and outer faces of the block remain exposed to the inside air and outside air or soil, and these faces still would be connected by highly conductive webs of concrete. The heat loss through those webs of concrete still would dominate the heat transfer (thermal bridging). Even with the block voids not filled with foam, the mostly dead air cavities still have insulating value, much like the air space between an old double hung window and an exterior storm window. Improving the R value of a part of the assembly that isn't contributing much to heat loss in the first place won't help the whole wall R value too much.

It's no surprise that building highly insulated wall structures requires near elimination of thermal bridging of wood framing. This is can be done by using double frame walls, applying a continuous layer of rigid foam on the inside or outside of the wood, or using structural insulated panels (SIP, a sandwich of foam between inner and outer skins of OSB). In the case of a foundation wall, about the only way to insulate it well is to apply a continuous layer of insulation on one side of it.

Insulating on the outside lets the foundation mass be a heat storage device, which would release heat long after the fire has died. However that mass will soak up a lot of heat for a while when the fire is started, resulting in a delay of availability of heat for the rest of the house. Insulating on the inside doesn't provide the thermal storage of the concrete mass, but it does mean a faster heatup of the basement space and earlier availability of heat for the rest of the house. Then it's just a matter of leaving the basement door open or providing other means of moving air between basement and the rest of the house.

+++1 Absolutely correct in my opinion. Standard engineering knowledge for decades.

 

[DickRussell]

......
In the mean time I will work on small-dollar projects to help move the air around. Floor vents are easy. I'm also tearing down the tongue-and-groove ceiling tiles to expose the heat directly to the floor-boards of the next floor. In removing these tiles, I learned that for the entire portion of the tiled ceiling the previous owners never insulated that part where the joists rest on top of the cinder blocks (what do you call that?). So $30 worth of 6" batting is going up there.

The sill (aka mudsill) rests on the foundation wall, and the floor joists rest on that. There also is a rim joist perpendicular to the floor joists and also resting on the sill, the purpose of which is to hold the floor joists vertical. Yes, in some houses, the rim was not insulated, and it's a big heat loss. There also can be significant air leakage both between the sill and the foundation and between the sill and the rim board. Stuffing a 6" FG insulation batt up against the rim board isn't really the right way to insulate the rim. FG insulation won't prevent diffusion of interior humidity through it to the rim, but it will provide insulation, resulting in a cold rim surface. That can lead to condensation on the rim and thus mold. One good way to insulate the rim is with the use of a couple of inches of spray foam. Another is to cut pieces of rigid foam to fit up against the rim sections between the joists, and then seal those pieces to the wood all around using can foam. FG batt insulation could be applied over the rigid foam for additional insulation. This latter option is an easy DYI project and not all that expensive for materials.

 

[sesmith]

Sesmith,

Thanks. I couldn't quite understand how not insulating the basement was causing the basement to be 80+ degrees while the next floor up could barely push 65 when the outside temps were in the 20's.

I think I have decided to insulate the top part of the foundation in the summer when I can dig down a bit.

In the mean time I will work on small-dollar projects to help move the air around. Floor vents are easy. I'm also tearing down the tongue-and-groove ceiling tiles to expose the heat directly to the floor-boards of the next floor. In removing these tiles, I learned that for the entire portion of the tiled ceiling the previous owners never insulated that part where the joists rest on top of the cinder blocks (what do you call that?). So $30 worth of 6" batting is going up there.

Do what Dick Russel suggested on your rim joists. I used 2" xps on mine, cut pieces to fit in each rim area, and sealed the edges with can spray foam (great stuff). It made a huge difference. Also seal any other leaks to the outside you find (like plumbing and electrical entrances, and weatherstrip doors, etc.

One thing about cutting direct floor vents into the cellar is it isn't code (fire could spread more easily from cellar to the upstairs). I believe you can get duct doors that close in the event of a fire. You might check into that.

 

[Black Jaque Janaviac]

I could not find anything in the building code that would outlaw a floor vent. There are required fireblocks that must go into concealed spaces which can have the effect of outlawing laundry chutes. But these floor vents are not in a concealed space.

Do you have a reference to a code that you can point me to?

From a practical standpoint I don't think such floor vent pose any more hazard than open stairways.

 

[sesmith]

I could not find anything in the building code that would outlaw a floor vent. There are required fireblocks that must go into concealed spaces which can have the effect of outlawing laundry chutes. But these floor vents are not in a concealed space.

Do you have a reference to a code that you can point me to?

From a practical standpoint I don't think such floor vent pose any more hazard than open stairways.

this should do it:

(broken link removed)

#4 pretty much covers it, I think (this is the code in NY, though). I'm not sure if it's the only place this sort of thing shows up, but I'm pretty sure a building inspector wouldn't allow through floor venting (at least in new construction or a remodel). There's also mention of mechanical system ducting having to be done so that it satisfies the fire block rules I linked to above.

 

[Black Jaque Janaviac]

That wording is similar to Wisconsin's. The way I read it #4 states that the openings around the vents must be sealed. This is not supposed to prevent vents in the first place. So maybe I'd have to goop around the floor vent with fireblock foam.

And again the entire code on fireblocks is in reference to "concealed" passages. Without that word "concealed" in the code this section effectively outlaws stairways.

Of course that's just my interpretation but I'm not an expert either.

 

[Butcher]

Do you have any duct work close to your stove? If so an inline fan like this would be very easy to intall.
(broken link removed to http://www.homedepot.com/Building-Materials-Heating-Venting-Cooling-HVAC-Parts-Accessories/h_d1/N-5yc1vZapt7/R-100067594/h_d2/ProductDisplay?catalogId=10053&langId=-1&storeId=10051)
You would of coarse have to put a vent in the pipe to suck the warm air from your basement cieling into the exsisting heat runs. With a little imagination a themostate and a reostate could be wired in to controlle its operation. I actually did try this with our old stove but it put out so little heat it didnt work. Now that I have this Oslo huffin and puffin away I may try it again as it gets to damned hot in the basement after 3 loads.
Just a thought.

 

[Black Jaque Janaviac]

Butcher,

No duct work. House has hot water baseboard.

Yesterday evening the temps were in the teens. Had both the NC-30 going in the basement and the Montpelier in the living room going house was comfortable to me. 74* in living room 60s in the upstairs bedroom. Wife seemed a bit dissappointed though.