Block house similar in R value to a basement?

[rmcfall]

I was browswing the net and came across the following article regarding stove installations in basements:

http://www.woodstove.com/pages/basement_install.html

While my Woodstock Keystone is not installed in my basement, my house is a brick and block home with plaster applied directly to the interior block. Since my house was built in the 50s, there is no insulation either inside of, or in between the brick and block. While I understand stove installations in unfinished basements are generally not a good idea, I hadn't really considered my home to be like one giant basement. However, because my house is block instead of frame built, does this mean that the heat from my stove is leaving my house about the same as it would in an unfinished basement, as described in the article regarding the area of basement walls above the frost line? If so, I seriously need to begin putting up some stud walls with insulation.

 

[begreen]

Heat might be leaving the house even faster. With most basements that are not daylight basements, there is a lot of earth surrounding it. That keeps the temps more constant.

 

[rmcfall]

You are probably right, since about half of basement is below ground and the other half isn't. So then I am correct in my thinking that I need to begin building some new walls? Would you recommend doing standard stud walls with fiberglass insulation, or using furring strips with foam board?

 

[jqgs214]

rmcfall,

where are you located?? Describe your setup in more detail. These guys are a wealth of knowledge. Give us all the gory details and we will help you out as best we can

 

[rmcfall]

I am located in the northeastern part of Kentucky, so winters are generally pretty mild. Summers are typically hot and humid. Right now it is about 100 degrees outside and it seems like the heat is just infiltrating my house. This is even with a new 5 ton heat pump. Anyway, my home is sprawled out with an <almost> full unfinished basement and small 300 sq. foot crawlspace. My woodstove is on our main level and heats an open family/kitchen/dining area that is about 1400 sq feet. The bedrooms add another 700-800 sq. feet and are on the same level; there is not a second story. I have my house zoned so that in the winter I will be able to supply heat to only the bedrooms, and the stove will heat the open family/dining/kitchen area. That is, of course, unless my block walls allow all the heat to escape. I did have my stove running 24/7 this past winter and it did OK, and I attributed the slight lack in performance to the fact that I didn't have floors at the time because I was in the process of repairing the subfloor and putting down hardwood, etc. So I am hoping for better performance, but am not so sure anymore after reading that article. Plus, right now it seems awfully warm in our house with the heat. So I figure if putting up some new walls would help retain heat, then it would surely help keep the hot air out in the summer as well!

 

[mtarbert]

Would you recommend doing standard stud walls with fiberglass insulation, or using furring strips with foam board?

Think about using Metal Studs and the Spray Foam insulation. The studs are all straight as an arrow and easy to install...
Mike

 

[rmcfall]

Good idea. I haven't used metal studs before, but they do look pretty simple. I like the idea of the spray foam because it seals everything up, but I haven't done enough research to know where to buy the kits. Any suggestions?

 

[webbie]

I concur that insulating the basement is a must if a stove is to be installed. I have a feeling that the heat loss though block and cement walls is larger than the listed R and K values because of the large mass of earth surrounding them. This may cause a "cold radiation" effect, and as we discussed in earlier threads, building material R values DO NOT take radiant heat into effect but rather just air temperatures.

 

[rmcfall]

I may have to reread the article I posted a link to, but I thought they stated the heat loss for a basement was greatest for the part of the basement that is above the frost line. I'll have to look at the article again, but I thought they indicated that the basement area below the frost line had significantly less heat loss than the area above.

I concur that insulating the basement is a must if a stove is to be installed. I have a feeling that the heat loss though block and cement walls is larger than the listed R and K values because of the large mass of earth surrounding them. This may cause a "cold radiation" effect, and as we discussed in earlier threads, building material R values DO NOT take radiant heat into effect but rather just air temperatures.

 

[KeithO]

Mr rmcfall

If you want to insulate, please put the insulation on the OUTSIDE of the wall, not the inside. I know that is not how its commonly done, but putting the insulation on the inside provides a lovely cold surface for condensation to form and mold problems to develop. The drywall prevents the surface of the concrete from getting heat (as it now does) so it becomes really cold and there is generally enough air infiltration to provide a constant source of condensation water.

If you put the insulation outside, the thermal mass of the wall works for you, storing heat and moderating temperature swings inside the house. You also avoid the condensation issue, since with the insulation outside, all of the wall is heated so no opportunity for condensation. You will need to extend the insulation to at least 3 feet below the surface of the ground if you have a basement. This is about how deep the frost penetrates. If you can afford it and have the equipment to dig, take the insulation most of the way down to the footings. It will make an incredible difference to the comfort level in the basement, particularly when you try heating down there. *edit* Insulating the outside of the wall also reduces temperature cycling of the structure, meaning that stress cracks are less likely to form or take much longer to form due to either uneven cold in winter or heat in summer. *edit*

I would suggest rigid foam insulation. Use as much as you can afford, but in your location 2" will make a very significant difference compared to none. If the summers are hot, get the rigid insulation with the foil on the outer surface to block radiation from the sun. Try a 2" extruded polystyrene (not the white bubbly stuff which is expanded) with a thin layer of the foam that has the foil on.

I'm personally all for building with masonry and concrete. If done properly the home is a lot quieter, airtight, rodent and insect infiltration resistant, less succeptible to fire and stronger in cases of extreme weather. The thermal mass stabilizes temperature swings and removes the need for any form of convective heating which improves air quality. I would also do concrete floors on all levels though, again something seldom seen in residential buildings in the US. One puts radiant heat in the concrete floors and if one does a good job, no ceiling is even required on the underside of upper level floors. Of course one needs conduit for all electrical wiring (including some "forward planning" for future requirements), but that just takes some planning and costs a few bucks more. Adding new wiring later just requires fishing the new wire through existing conduit, not tearing up drywall all over the house.

best of luck
Keith

 

[wg_bent]

Keith has the right idea, but I would implore you to look at the building sciences web site on how to insulate. If doing the inside, I'd use 2" of polystyrene (not the foil backed type), then a stud wall insulated with non-faced fiberglass. The foil backed insulation, either foam or fiberglass will not allow any moisture to pass. The Polystyrene is semi-permeable and reduces the condensation problem. Best option would be the spray foam and metal studs.

Keith is correct that if possible, find a way to insulate the outside. An interesting trick in most cases, but foam board followed by stucco is a way that could work.

 

[KeithO]

Something that occured to me after I posted is that the same companies that make SIP's (structural insulated panels - do a google serach) also do a version of the panel which has the extruded polystyrene bonded to 5/8" OSB on just 1 side. The great thing about this stuff is that one can bolt the panels directly to the masonry (no studs required) and then finish the outside with whatever you want in the way of siding etc.

I would say that for a retrofit to an existing building this must be way easier than trying to add internal walls and insulation on all levels which requires re-trimming and moving all the vents and electrical / cable outlets etc. Much easier to deal with the mess outside, leave the inside the way it is and best of all, it actually functions better this way around.

Keith

 

[rmcfall]

I hear what you all are saying about insulating the outside of the walls, but my house is mostly brick so there is no way to insulate the outside without some major work. Plus, the brick is a somewhat uncommon roman brick, which I would really hate to cover up. Also, the mess inside isn't much of an issue since I am redoing most the interior anyway and will also be redoing all the wiring, plumbing, etc.

Any suggestions on where to get the spray on-line?

 

[KeithO]

Warren, you're right. For insulating the inside, one basically has to PLAN on dealing with condensation, which is why the unbacked insulation is preferred. The spray on foam of course is an ideal method of avoiding the condensation since if done properly there are no voids to allow air infiltration. Unless one bonds the 2" extruded polystyrene to the concrete, there remains a risk of air infiltration around all edges and no matter how little it is (driven by the heating and cooling cycles of the uninsulated wall and any air trapped in there) it is a steady additive effect since the air in the home is heated and has a higher capacity for moisture than the air outside. How much moisture is actually in there depends on how the air in the home is managed, but for comfort it normally has to be over 40%

On the outside, the foil is able to block summer sun radiation "close to the source" whereas it would make little sense having the foil underneath the drywall on the inside. Masonry should always have one surface which can "breathe" to allow for equilization of the moisture inside the material vs in the air. PVA paints allow this to work just fine and plaster has no impact on this either. One has to be more careful with oil based and epoxy paints since the "other" surface then needs to breath or else the paint will lift from hydraulic pressure over time.

 

[KeithO]

http://www.tigerfoam.com/

Ideal for the home DIY type of person. Otherwise you need to hire a contractor.

 

[rmcfall]

Funny you sent that link...I was just browsing their site!

 

[KeithO]

sorry, didn't realize you had a nice brick home. Thought it was block, that doesn't appeal to most people. In South Africa, where the primary environmental issue was the high temperatures in summer (very high radiant heating) we had air cavity outside walls required by code. All walls inside and outside were brick, the junction of inner to outer walls made the structure very strong so that 130mph wind never created the slightest problem. Even if the roof blew off (200mph freak storms) the rest of the house stayed standing intact.

The cavity was vented top and bottom by leaving out a brick every so often one row on top and at the bottom and this prevented the radiant heat from the sun penetrating through to the inner wall. By nightfall, when the temperature of the outer wall had peaked, the outside temperature would start dropping fast (cloudless skies) and the heat from the outer wall would radiate back out to the cold night sky. It worked pretty good. I never lived in an air conditioned house all my life until I moved to Michigan, although I have to add that we never had 90% humidity to deal with either....

Keith

 

[rmcfall]

That is really interesting...shows how people can come up with ingenious ways to adapt to their environment.

While reading some literature on the Tiger Foam website, I came across a PDF that mentioned some builders do a combination of foam and then fiberglass bats. Have you had any experience with this? I wonder if a thinner layer of foam could be placed to partially insulate and seal out moisture, etc., and then be followed up with fiberglass to attain the needed R value? I haven't priced fiberglass insulation, but perhaps this method might save some $$.

 

[KeithO]

When the foam is sprayed on it actually goes on quite thin and then expands to its full thickness as the chemical reaction proceeds. To get a thin layer of this foam would be nearly impossible with the risk that you would potentially miss patches. Since you need 2" I think that it is already quite thin. I'm also not sure you would be saving a whole lot of money with the 2 different materials and would add a lot to the aggravation.

 

[elkimmeg]

Before anything should be considered is moisture proofing your existing block walls

Every basement build out I coat the foundation walls with 2 coats of drylock I also use silicone sealant of n the concrete floors

All partition walls require bottom plate pressure treated 2/4 when in contact with concrete. I use fiberglass bats but pull the walls out atleast 1" from the foundation or more so that no fiberglass contacts the foundation. No drywall maked contact with the concrete floor I use galvanized stops on the bottom piece of hold it up 1/2"..

Before any build out should be donea good effort is needed to seal the top of foundation and the wood nailing plates the space between floor joist and the box sill needs insulation.
This is a huge infiltration heat loss area. Keith is right about insulating the outside but practicality excavation makes it more costly with the ensuing regraging and landscaping

you will spend more money than the entire finished room much more. He is right it is a better way but economically not practical. Foam filled also is a better way but in most cases its not DIY
and too will be much more expensive, the negative inpact is running future wiring or future remodeling just got more differcult.

Fiberglass bats on the other hand are cheaper and within the DIY range.Again everbody is saying un faced I differ here as faced insulation should be directed towards the heated space.
stapled correctly it will resist future sagging..

This is not saying Keith is wrong , but pointing out what a normal skilled DIY can do and economically feasiable


Another possibility is if the blocks are hollow then they could be injected with styrofoam

 

[KeithO]

What I find so surprising is that it would be really inexpensive to insulate the outside of poured basement walls when they are built. If code would simply call for at least 2" of rigid foam insulation, people would get a vastly superior product. The retrofitting process is certainly a giant PITA.

I have exactly this issue to deal with in the house I am living in. Last winter (the first in the house) the finished basement living room was essentially unuseable because of how cold it was. The cheap sod who built the house fitted the heating ducts in the ceiling of the finished basement but it is impossible to get an acceptable temperature distribution in the room without having the ceiling fan at max speed which makes the room feel drafty. The room needs the walls insulated properly on the outside and radiant heating in the floor.

Keith

 

[wg_bent]

Before anything should be considered is moisture proofing your existing block walls


Fiberglass bats on the other hand are cheaper and within the DIY range.Again everbody is saying un faced I differ here as faced insulation should be directed towards the heated space.
stapled correctly it will resist future sagging..

The reason for non-faced when insulating a basement is that the space must breath or you end up with mold. Elk, go read the building sciences site. They explain it very well there.

 

[elkimmeg]

The major reasons most builders don't insulate the outside of the foundations is in the backfilling process rocks roll in and dammage the insulation
the second issue is this insulation breakes ground both to exposure and more so under ground. Many homes done this way a dozen years back are not getting the R value
they originally had due to de gradation of the styrofoam used at the time ode allows then the option of insulating the cellar floor joist cavity area as an alternative prescription to the energy code compliance.. If one is real concerned about heat loss in basements then it is proven that heating equipment pipes /ducts should all be positioned in the living space.
Placing it it in un conditioned spaces like attics lends its self to tremendeous heat losses and reduced effeciencies All these recomendations can be found in the energy star home recomdations

One of the biproducts of making home tighter is the mold issues increase. In one way the oflder drafty homes have healthier internal air conditions

Most HVAC systems are grossly ineffecient Combined syetems are a compromise to begin with Most do not have adequate and properly located return systems.

Ac requires larger duct work than heating requirements more flow most combined systems are only designed for heating and lack the s proper sizing for AC.
If one sizes the Ac end the larger areas of ducting reduces heating vollume and flow rates. Almost all systems are located outside the insulation envelope andy heat loss never makes it to the heating spaces. Many cases Flexible duct latterals are used and miss used, creating too much friction to unsure proper vollumes. My biggest gripe is using ceiling returns on the second floor of homes returning air from the hotest section of the living area. Again another compromise better suited for AC purposes and not optium for heat.

What ever happened to dampered high low feeds and returns? Many return plentums consist as part of the joit cavities exposing areas not within the insulation envelope. Most anre really not designed for vollume flow and tend to be leaky drawing in air that comes outside the living space, futher reducing effeciencies.

HVAC systems today are the least effecient way to heat of cool a home due to poor application design and materials installations. Some willk say it works in my home but it works because it has to be oversized to do so. It has to compensate for the losses and poor installations and designs.

I take a well designed FHW baseboard system over HVAC any day or correctly installed radient heating system. It is not uncommon to have 35% heat losses in the transmission end of HVAC systems..

There are ways a DIY can reduce the heat losses and leaks

As much as the emphisis is to bet alternative heating sourses one may save more money attending to draft reduction pipe duct insulation and adding more insulation

did you know your celler ceiling area can account to 20% heat loss R19 there and sealing the sills premiter goes a long way saving energy.

Duct mastic to seal all HVAC joints or 260 degree HVAC tape can work wonders preventing leaks Did you know the flexible elbows leak a lot more than one your think.

Most take of flanges on you trunk lines need sealing they neven fit properly and leak all connection seams leak and should be sealed.

Duct r wrap should be r5. 0 or greater 6.0 being even better.. All hot exposed hot water / heating pipes again R5.0 insulation

lots of things to do to save the heat/ energy we use Economically it may be more cost effective that supplememtary heating to overcome ineffeciencies or your current home

Did I mention electrical outlet draft covers or better wondows more attic insulation and better ventalation of attic spaces

Lots of things we can do and yess save your receits you can take energy tax credits What about the equipment just like your stove oil burners need tuneups.
and there are ways to improve their effeciencies motorized dampers fire retenshioners and I mean a real cleaning including the oil pump screen the exchanger fins.

One can also change nozzels and flow rates one can adjut the electrode gap for mpre effecien hotter sparks..

When one has water pipes that now will sit a long time because that stove shuts the zone down, What have you done to prevent freeze ups?

If water sits there long enough and get exposed to cold drafts most the time in outside walls It will freeze I know been there done that finally antifreezed the entire system to prevent it

 

[elkimmeg]

Before anything should be considered is moisture proofing your existing block walls


Fiberglass bats on the other hand are cheaper and within the DIY range.Again everbody is saying un faced I differ here as faced insulation should be directed towards the heated space.
stapled correctly it will resist future sagging..

The reason for non-faced when insulating a basement is that the space must breath or you end up with mold. Elk, go read the building sciences site. They explain it very well there.

that is why I first suggested damp proofing with out the moisture sourse mold is a non issue. Also Code mandates an air exchange system for basement buildouts.

Most inspectors either do not know this of do not enforce it, air flow and exchange rates are required. Most are connected to humiditastats and temper the humidity of the inflowing air to prevent this. ITS not just the Vapor barrier here but designing it correctly. Which most don't have a clue in what is involved ,
nor do they want to pay to have it done right There are two sourses of moisture concerns sealed conccrete takes care of one the outside influences of the ground the Vapor barrier takes care of the interior moisture collecting on the insulation. I don't have to be a scientist to figure that out factor in the proper tempered air exchanges it is a non issue

 

[karl]

I don't mean to steal this thread, but I have some questions about my house and I would like Elk's advice and anyone elses who cares to chime in. I have a 2600 square foot ranch with another 1500 square feet or so in the basement. My crawl space is under the bedrooms. The house was built in the 1960's and is really well insulated by 1960's standards, but not by today's. It's granite block with 2x6 exterior walls, that are filled with bat insutaltion. The attic has insulation in the joists. I'm guessing 10" or 12", I'm not sure how big my joists are. It also has bat insulation stapled to the roof itself, so another 4" of insualation there. The floors have none. The windows are Anderson double pane of 1960's era. I think they're pretty good. I certainly don't think I would see a return on my investment if I replaced them.

I want to gradually improve the insulating properties of the house. I'm going to do a little bit each year. This year I want to put new storm doors on my back two doors. This is for asthetic purposes as well as for the insulation benefit. I also have a little bit in the budget to do something else. I can blow insulation into the attic for about 500 bucks. This will bring it up to modern standards as well as help seal the attic from where the bat insulation that is up there is starting to settle and get leaky. Or I could spray foam the floor joists in the crawl space. My crawl space currently consists of dirt, crawl space, joists, subfloor. This will cost me 600 dollars for the spray and I don't think I will have enough to do all of it. I can't swing 1200 dollars of foam and the storm doors. Is there anywhere I can get spray foam for less than a dollar a board foot? This is what I've been looking at http://www.tigerfoam.com/products.php What would be the best to do this year? Blow more attic insulation in or spray foam as much of the crawl space as I can and then do the rest next year? Also when I'm under the house can I spray foam my duct work with this stuff to insulate it or should buy duct insulation to put on it? My ultimate goal is to get the whole basement and crawl space insulated. I have heard great things about the spray foam and from what I've been reading it's good to spray a light coat of that stuff on even if your'e going to put bat up. What thoughts do you guys have?