Cold draft

A friend has a two unit brick building in Chicago which was built around 100 years ago. The question involves the garden apartment. There is wood flooring on top of the concrete slab which is just about 3 feet below grade. My friend says that in the winter it gets unusually cold in that apartment. The furnace heats the rooms, turns off and then shortly thereafter it is cold again. A contractor suggested that he could blow insulation in behind the drywall and that would take care of the problem. I told her that not knowing the exact cause of the cold she shouldn't go through the expense of insulating the walls which might possibly not fix the problem anway. I am guessing that there is a very small draft somewhere. Does anyone know of some tool or method which accurately measures the rate at which a room is cooling and point out possible coldspots where heat transfer is greatest. Please hold your thermometer jokes.
I also noticed that the first 15 or so courses of exterior brick are in serioius need of tuckpointing. Is it possible that a draft is getting through the eroded mortar lines in the brick and seeping into the unit ?
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And here I thought the subject was referencing my favorite adult beverage.....
In most major cities there are energy consultants who can be hired to identify where air is leaking using some combination of thermal imaging, blower tests etc. They can identify energy losses and make recommendatoins for fixes.

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The most effective way to hunt down air leaks is a blower door test. In many jurisdictions, gas and/or electrical utilities offer this service as part of a no/low cost home energy audit. Alternatively, your friend could use a smoke pencil or incense stick to search them out herself (preferably on a cold, windy day). The usual suspects: window and doorframes, baseboard trim, electrical outlets, fireplace dampers, plumbing stacks, etc.
Bear in mind cavity wall insulation can significantly reduce heat loss and dramatically improve overall comfort -- an uninsulated wall can literally suck the warmth out of your body and make a room feel cold, even at higher temperature settings. Likewise, insulating the floor or crawl space makes good sense (ensure proper freeze protection for any pipes and utilities that may be put at risk).
Chicago is known for its long, cold winters and natural gas prices will most certainly move higher over the long-term; proper insulation and good air sealing will reduce utility costs, improve personal comfort and most likely add to the home's resale value and market appeal. There's also the peace of mind of knowing rising utility rates won't place an undue burden on future budgets.
Cheers, Paul
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A little over 50 years ago I lived in a slab house. I must say it convinced me I would never own one. But on a windy day, you could hold a match along the base and the wind would darn near blow it out. Guess that was before they even heard of sill sealer. The only thing I could get to was the inside so I caulked along the base. Helped only some, it was a cold house. Slab was not thermo broke either. That house taught me a lot of what not to do building for the rest of my working life. [g]
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Hi Glenn,
Scary, isn't it? I have a walkout basement with a twelve foot wide exposed slab at grade level. I haven't been able to insulate it, because this would require tearing up the driveway and I'm not ready to go down that road just yet. Even though I installed a DRIcore sub-floor, the first five feet closest to this outside wall is uncomfortable cold. The heat loss must be horrendous.
For more information on DRI, see: http://www.dricore.com/en/eIndex.aspx
Cheers, Paul

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Glenn wrote:

I wouldn't blame the style of house for poor construction technique. I wouldn't want a slab either, but the reason is I like the extra low-cost space and having a place to hide if a tornado comes through. We don't get many in PA, but every now and then...
Matt
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Hey Gang - Some thoughts on rehab heat-saving projects. I advise picking the low- hanging fruit first, them move sequentially upwards to your expenditure threshold. Most likely, you will run out of cash before you run out of investment worthy projects on a dinosaur building like this. Of course, if you can secure the financing, and plan to hold on to the building long term (10+ years), then you should do all the smart heat-saving projects. For the OP's situation, we already know where the cold spots are (the entire apartment :-) ) without pulling out fancy IR and blower gadgetry: Hey Gang - 1. Single pane windows SUCK, literally, suck heat out the building as Astro Man noted. However, in Chicago you don't need to buy a Porsche to fix a VW Bug problem. Double pane windows with quality seals are all you need. Low-e, triple-pane, argon filled, and other "high tech" gadgetry is just throwing your $ out the window. Filling in cracks around the frame with insulation is not. Thermal shades will help, but not much bang for the buck. Savings ~ 1/2+ 2. The walls in the garden apartment are probably losing the most total heat, but it will likely cost the most. And no, the deteriorating mortar joints aren't the solution to your troubled heat pollution. Unless you plan to gut the apartment soon, the contractor was right about blowing insulation into the cavities, but this must be done correctly or you will generate a moisture problem. And on this, Astro scored again with his recommendation. I bet there is some moisture sometimes behind the sheet rock now, but not much, if any mold/funky fungi. This could change dramatically after insulating the wall, depending on the approach taken. I suspect the best solution for this situation is to blow in polyurethane foam - better R/in and I think it will deal effectively with moisture, but at a higher cost than other materials. The final selection will require some brain power to make sure you don't end up with the black plague growing behind the drywall. Savings ~ 3/4 + 3. Doors are likely the second worst heat pig (Btu/ft2), but the fix is usually not a big payoff ($/Btu). Good looking replacement doors are pricey, and insulated doors I've seen are aesthetically challenged. You can rehab existing doors, but this will require some tedious toiling to do it right. Probably weatherizing the existing door to some extent is the best bet, but the door will remain a heat sieve (once a pig, always a pig). Savings ~ 1/4? 4. The floor. No easy rehab solution for this, but it also is not the largest contributor to your cold apartment. Again, unless gutting is in the near future, I'd leave this one be. Given the floor is 3' below grade, even doing some exterior work to insulate the slab perimeter is too much for too little. {You may be able to do some exterior insulation work if the outside wall is reasonably accessible below grade, but I doubt this is the case in a city. But, on the other hand, if even one side is accessible, its worth it. But again, some brain power is required to calculate optimal insulation amounts and depths. Savings ~ 4/5}
And don't forget the little buggies. If termites and ants are a problem there (and I can't imagine termites are not), you should deal with them in some way, which can be quite tricky. For most rehabs, I'm not aware of easy "green" solutions, and the non-green remedies aren't great either.
If money is an issue, then the focus is on "smart". And part of "smart" is to make sure any builder you choose is on the same page as you with respect to quality and cost. Reach agreement with the builder upfront on the quality level, then make sure they perform to this standard DURING the rehab. Remember, the most important stuff will be covered up after the project. Be your own inspector; you care more about the outcome than anyone else. Details make a significant difference in heat loss, and a huge difference with air leaks and condensation.
Regarding other comments made:

evidenced by all the hell-a-balloo raised about mold in the past 20 years with NEW houses. In fact, most older houses have a better chance of avoiding funky-fungi than the plasticized "modern" houses, even when air-sealed. Of course, you can't put your brain down when you pick up your hammer, either, to rehab an old house.

properly, quite warm. In both your cases, you point out how the slab was not properly insulated and air-sealed. Even so, the slab heat loss is a far cry better ft2-to-ft2 than windows and doors, no matter how many bells and whistles you add to them. However, Matt makes a good point about the tornado benefits of a basement, as underscored by Dorothy :-)
- Good luck with the Heat Hog! Bob Stanley - Handy Man
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Hey Gang - Some thoughts on rehab heat-saving projects. I advise picking the low- hanging fruit first, them move sequentially upwards to your expenditure threshold. Most likely, you will run out of cash before you run out of investment worthy projects on a dinosaur building like this. Of course, if you can secure the financing, and plan to hold on to the building long term (10+ years), then you should do all the smart heat-saving projects. For the OP's situation, we already know where the cold spots are (the entire apartment :-) ) without pulling out fancy IR and blower gadgetry:
1. Single pane windows SUCK, literally, suck heat out the building as Astro Man noted. However, in Chicago you don't need to buy a Porsche to fix a VW Bug problem. Double pane windows with quality seals are all you need. Low-e, triple-pane, argon filled, and other "high tech" gadgetry is just throwing your $ out the window. Filling in cracks around the frame with insulation is not. Thermal shades will help, but not much bang for the buck. Savings ~ 1/2+ 2. The walls in the garden apartment are probably losing the most total heat, but it will likely cost the most. And no, the deteriorating mortar joints aren't the solution to your troubled heat pollution. Unless you plan to gut the apartment soon, the contractor was right about blowing insulation into the cavities, but this must be done correctly or you will generate a moisture problem. And on this, Astro scored again with his recommendation. I bet there is some moisture sometimes behind the sheet rock now, but not much, if any mold/funky fungi. This could change dramatically after insulating the wall, depending on the approach taken. I suspect the best solution for this situation is to blow in polyurethane foam - better R/in and I think it will deal effectively with moisture, but at a higher cost than other materials. The final selection will require some brain power to make sure you don't end up with the black plague growing behind the drywall. Savings ~ 3/4 + 3. Doors are likely the second worst heat pig (Btu/ft2), but the fix is usually not a big payoff ($/Btu). Good looking replacement doors are pricey, and insulated doors I've seen are aesthetically challenged. You can rehab existing doors, but this will require some tedious toiling to do it right. Probably weatherizing the existing door to some extent is the best bet, but the door will remain a heat sieve (once a pig, always a pig). Savings ~ 1/4? 4. The floor. No easy rehab solution for this, but it also is not the largest contributor to your cold apartment. Again, unless gutting is in the near future, I'd leave this one be. Given the floor is 3' below grade, even doing some exterior work to insulate the slab perimeter is too much for too little. {You may be able to do some exterior insulation work if the outside wall is reasonably accessible below grade, but I doubt this is the case in a city. But, on the other hand, if even one side is accessible, its worth it. But again, some brain power is required to calculate optimal insulation amounts and depths. Savings ~ 4/5}
And don't forget the little buggies. If termites and ants are a problem there (and I can't imagine termites are not), you should deal with them in some way, which can be quite tricky. For most rehabs, I'm not aware of easy "green" solutions, and the non-green remedies aren't great either.
If money is an issue, then the focus is on "smart". And part of "smart" is to make sure any builder you choose is on the same page as you with respect to quality and cost. Reach agreement with the builder upfront on the quality level, then make sure they perform to this standard DURING the rehab. Remember, the most important stuff will be covered up after the project. Be your own inspector; you care more about the outcome than anyone else. Details make a significant difference in heat loss, and a huge difference with air leaks and condensation.
Regarding other comments made:

evidenced by all the hell-a-balloo raised about mold in the past 20 years with NEW houses. In fact, most older houses have a better chance of avoiding funky-fungi than the plasticized "modern" houses, even when air-sealed. Of course, you can't put your brain down when you pick up your hammer, either, to rehab an old house.

properly, quite warm. In both your cases, you point out how the slab was not properly insulated and air-sealed. Even so, the slab heat loss is a far cry better ft2-to-ft2 than windows and doors, no matter how many bells and whistles you add to them. However, Matt makes a good point about the tornado benefits of a basement, as underscored by Dorothy :-)
- Good luck with the Heat Hog! Bob Stanley - Handy Man
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Hey Gang - Some thoughts on rehab heat-saving projects. I advise picking the low- hanging fruit first, them move sequentially upwards to your expenditure threshold. Most likely, you will run out of cash before you run out of investment worthy projects on a dinosaur building like this. Of course, if you can secure the financing, and plan to hold on to the building long term (10+ years), then you should do all the smart heat-saving projects. For the OP's situation, we already know where the cold spots are (the entire apartment :-) ) without pulling out fancy IR and blower gadgetry:
1. Single pane windows SUCK, literally, suck heat out the building as Astro Man noted. However, in Chicago you don't need to buy a Porsche to fix a VW Bug problem. Double pane windows with quality seals are all you need. Low-e, triple-pane, argon filled, and other "high tech" gadgetry is just throwing your $ out the window. Filling in cracks around the frame with insulation is not. Thermal shades will help, but not much bang for the buck. Savings ~ 1/2+ 2. The walls in the garden apartment are probably losing the most total heat, but it will likely cost the most. And no, the deteriorating mortar joints aren't the solution to your troubled heat pollution. Unless you plan to gut the apartment soon, the contractor was right about blowing insulation into the cavities, but this must be done correctly or you will generate a moisture problem. And on this, Astro scored again with his recommendation. I bet there is some moisture sometimes behind the sheet rock now, but not much, if any mold/funky fungi. This could change dramatically after insulating the wall, depending on the approach taken. I suspect the best solution for this situation is to blow in polyurethane foam - better R/in and I think it will deal effectively with moisture, but at a higher cost than other materials. The final selection will require some brain power to make sure you don't end up with the black plague growing behind the drywall. Savings ~ 3/4 + 3. Doors are likely the second worst heat pig (Btu/ft2), but the fix is usually not a big payoff (Btu/$). Good looking replacement doors are pricey, and insulated doors I've seen are aesthetically challenged. You can rehab existing doors, but this will require some tedious toiling to do it right. Probably weatherizing the existing door to some extent is the best bet, but the door will remain a heat sieve (once a pig, always a pig). Savings ~ 1/4? 4. The floor. No easy rehab solution for this, but it also is not the largest contributor to your cold apartment. Again, unless gutting is in the near future, I'd leave this one be. Given the floor is 3' below grade, even doing some exterior work to insulate the slab perimeter is too much for too little.
And don't forget the little buggies. If termites and ants are a problem there (and I can't imagine termites are not), you should deal with them in some way, which can be quite tricky. For most rehabs, I'm not aware of easy "green" solutions, and the non-green remedies aren't great either.
If money is an issue, then the focus is on "smart". And part of "smart" is to make sure any builder you choose is on the same page as you with respect to quality and cost. Reach agreement with the builder upfront on the quality level, then make sure they perform to this standard DURING the rehab. Remember, the most important stuff will be covered up after the project. Be your own inspector; you care more about the outcome than anyone else. Details make a significant difference in heat loss, and a huge difference with air leaks and condensation.
Regarding other comments made:

evidenced by all the hell-a-balloo raised about mold in the past 20 years with NEW houses. In fact, most older houses have a better chance of avoiding funky-fungi than the plasticized "modern" houses, even when air-sealed. Of course, you can't put your brain down when you pick up your hammer, either, to rehab an old house.

properly, quite warm. In both your cases, you point out how the slab was not properly insulated and air-sealed. Even so, the slab heat loss is a far cry better ft2-to-ft2 than windows and doors, no matter how many bells and whistles you add to them. However, Matt makes a good point about the tornado benefits of a basement, as underscored by Dorothy :-)
- Good luck with the Heat Hog! Bob Stanley - Handy Man
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Without hiring an inspection agency. A little thought regarding the loss of heat in this space might solve the problem. When masonry or concrete walls are below grade usually rigid insulation is installed on the outside of the wall. One of the reasons is that in cold weather there usually is a requirement for frost level for foundation design. Sometimes it can be very deep depths anywhere from 1.5 ft and deeper. Don't know the frost line is in Chicago. So, it sounds like if there is a interior stud wall built using batt or rigid installed on the stud wall for the depth of the wall to finish floor might solve the problem. You should also use insulation in the walls above the masonry or concrete wall if they are stud walls. Also if they are masonry or concrete the same insulation should be used similar to the wall below finish grade.
____________________________________________________________ Charles I. Dinsmore, PE SE RA, M.ASCE ~ snipped-for-privacy@gmail.com

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A quick and easy way to evaluate the issue is to get an infrared inspection. In a matter of minutes, the inspector should be able to scan the property and find cold spots.They can also use a blower door to suck cold air in through all the cracks to really highlight the problem points. In a building of this age, you're likely to find lots of issues. The below grade slab with wood flooring is very likely sucking heat out at a pretty good clip. Three feet is close enough to the surface for it to be affected by the seasonal temperature variations, so there's a good chance that the edges of the slab see 30-40F during the winter. With essentially no insulation between that and the floor, the room will lose approx. 25 BTUs/hr /square foot. The below grade wall, if uninsulated will see larger swings because of the proximity to the cold outside temperatures. Call that an average of 40 BTUs/hr /sq. ft. on a winter day. And above grade walls that are poorly insulated and leaky could be considerably worse. Old single glazed windows will be worse. They're likely highly leaky and provide minimal insulation. on a 10F Chicago night, they'll be losing ~60BTU/hr/sq.ft. not even including the energy lost due to air leakage.
Obviously, these are all back of the envelope calculations, but it should give a starting point for analysis. The main thing is, get the IR inspection, find where the cold spots are, and address those first.
The good thing about this is that you've got several high leverage areas. Replacing windows with properly installed, basic, low-e double glazed windows would easily cut the window loss to half or 1/3. Add thermal shades (cellular shades, for example) would reduce the total loss even more.
Be aware that older houses were not designed to be tight and if your friend airseals the place, he should ensure that there is adequate fresh air ventilation. Depending on how seriously he wants to go with weatherization, he'll need to take more things into account. It might behoove him to buy "The Builder's Guide to Cold Climates" by Building Science Corp.
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