Basement Insulation

Dear Tim: I understand what you are saying about the financial savings being small, but do you feel that the comfort level on the first floor would increase? We live in the midwest and have wood floors that set bare on the joists and are thus directly exposed to the basement air. I already bought $200 worth of insulation, but after reading your column, I am a bit concerned that I may be doing the wrong thing. The basement is unfinished and has 120 year old concrete/stone foundation for it's walls, so I am not sure how foam insulation (as you recommend) would install, as I do not want to frame in the entire basement in order to install insulation.

Any recommendations for making the first floor more consistently warmer?

Thank you.

Ihave a five year old home & am plannig to finish my basement. I have never had any moisture problems and have asked several people how to insulate the walls & have got several different answers. Do I need a vapor barrier and do I put it on the concrete side or the room side. I have also been told to use 3/4 foam against the concrete walls. I have also been told to leave an air gap between the interior walls & the concrete walls. The cost is not a big factor to me. I do not want to have any mold problems & do nt want moisture to wick into the insulation. THANKS

Robert,
I answer all of these in other articles here at AsktheBuilder.com. You need to read all of the ones I have about basement remodeling and insulation.

There is no subfloor under the wide pine boards on our parlor, dining room and guest bedroom floor. (Our kitchen floor does have one from an old linoleum floor we have pulled up and replaced with wood.) The cellar is very cold and damp and oil prices are out there. Although you do not recommend insulating the basement ceiling, wouldn't it advisable for us to staple up plastic sheeting on the basement ceiling?
Thank you!

Fred,
The plastic will be of no value as water vapor will escape through the stairwell to the first floor.

Tim,
sorry for re-asking roberts question but i was unable to find the answer without taking the day off work ;). i live in newfoundland. it gets pretty chilly here. do you recommend using 3/4 foam against the concrete walls combined with r12 fiberglass? i've been getting many mixed opinions regarding this topic. some say to just leave the air space behind the 2x3 and use a layer of r-12. what do you recommend i do? if you have answered this question already could you post a link to the answer? thanks.

Mark,
A day off work to read my stuff.....can it get any better than that? :->

If this is an old home with the likelihood of foundation leaks, you will thank yourself for creating the air space.

its a new built home we just purchased. ive been getting so many conflicting opinions. holy cow! I plan to use 1.5-2 inch polybead foam. and a layer of r12 batt insulation. sound good?

Mark,
Go for it.

I am making a bed room in the basement and my question is what should I use on the basement ceiling for sound. as this room will be directly under another bedroom and I want to stop the amount of sound that travels between floors.
we have laminate floors through out the main floor.

Clarence,
Please go read all of my past columns on Sound and Noise Control. The issue is more complicated than you think.

Is it o.k. to use a polystyrene in between studs on the basement walls? or even a styrofoam. does it really need to be between the concrete and the studs in a solid to each other, taped together fashion? One long wall of material taped together. Wondering if I can put it between studs and have no moisture issues. I am paneling but was thinking about that type of insulation and drywall under the paneling, but dont want to create any kind of moisture build up area. Thanks and I cant find this answer in the question area..

Adam,
You can do that, but a continuous sheet of foam between the cold concrete and the back of the stud wall would be better.

I will put a twist on the basement insulation question with the following scenario that I need help with for a house I just bought. I have a large 23'x30' vaulted ceiling great room that is set about 2 1/2 feet above a concrete slab (Why the previous owner didn't just expand the basement is beyond me). Anyway, I discovered a portal to this crawl space (which is actually one of the original house's basement windows). I noticed that there is no insulation under the floor to this room. As you can imagine it is hard to keep the room warm and the floor is quite cold. What type of insulation should I use to correct this obvious oversight by the previous owner

Dom,
Unfaced fiberglass insulation.

My basement is always very cold in the winter. One part of the basement is a finished gameroom and that is cold but not as cold as the unfinished laundry room. We keep our dogs down there in the laundry room and it is much colder than the finished part of the basement. The laundry room has bare blocks with no drywall or anything covering the walls. Any suggestions on how to warm the basement up especially the laundry room?

Jeff,
Add additional heat into the ecosystem. Obviously the heat loss is greater than the amount of Btus you are injecting into the room.

Dear Tim,

I am refinishing my basement and found 2x3's instead of 2x4 behind my concrete foundation (1955 cape here in the Boston area).

When it comes to insulation, can I use the traditional R11,R12,R13 insulation or will squishing it be a waste? Or do I get that harder R-10 pink insulation?

Thank you,
Dave

Dave,
Compressing fiberglass reduces its R-value, but you will be fine with 3.5-inch batts.

Hi, I have a question about insulating basements. I have all my walls framed up and in the process of getting insulation. What do you recommend? Faced bats or foam board. Also, if I do use faced bats do I put plastic over the walls after I have them insulated?

Thanks!

Hello. I have an old home, built in the 20's. the kitchen is an add on, that has about a 6 inch poured cement floor, which is over an unheated garage. The kitchen is always cold, especially the floor. I'm wondering if adding insulation to the ceiling of the garage would make a difference. I have plenty of room to add at least a foot of any kind. Foam, airkrete, fiberglass, etc. Would any of these types help the floor and room stay warmer? I understand that concrete is inherently cold, but the room below gets down to the 10's and 20's in the winter.

I have a split entry house and it has a 2' overhang on the first level floor. The pipes for my kitchen go through that over hang, they freeze quite often. Should I insulate that area or is it relying on heat from downstairs to transfer that area to keep it warm

I have a 20yo house with a concrete block basement. I intened to finish the basement in the next six months and I have several questions. First, is it worthwile to insulate the area above the block wall between the floor joist to help block any air infultration? Second, when finishing the basement what is your oppinion on metal studs and having a contractor spray foam the basement walls before drywalling.

Don,
The space needs to be insulated and the pipes in contact with the warm floor above.

Bill,
Insulating the rim joist is a great idea. Foaming the walls sounds like an interesting way to get great results.

Tim, I think you may be giving bad advice here. Your nail example is an extreme case using a material that has very poor thermal properties. Your basement temperature greatly affects the temperature of the first floor and your overall efficiency. The more foundation that is exposed to the outside the more it affects the temperature. You also failed to mention the affect on any HVAC ducting in the basement. Take a look at the thermal images on energyQue.com, they tell a very different story than you described above.

Brent,
I need to disagree with you on a few points. First, the examples of the nails is accurate. They are conductors just as a foundation wall. Yes, the example is a little dramatic, but it was done to prove a point.

I urge you to take a second look at the question that begins this column. Bill was asking if it was a good investment to put insulation in the floor joist between his basement and the first floor. My answer in the column is clear. Because there is not a great temperature difference between the basement air temperature and the living space temperature, the insulation in the floor joists would be of little value.

This column was not the end all and be all of insulating basement *walls*. We all know that it is a good idea to insulate them. Even basements that have little exposed foundation on the outside can get very cold as the ground outdoors freezes.

As for heat leakage from ducts in basements, I have discussed that in other past columns here at AsktheBuilder.com. I can't put every fact I know in every column. Once again, this column was written to answer a very specific question.

What disappointed me about your comment was that you have a dog in this fight and didn't say so in your comment. You are the owner of the website you mentioned, and didn't identify that. Your comment was very self-serving. That is really bad form.

Typically I delete comments like this because they are not the best thing for the AsktheBuilder ecosystem, but I am going to leave up yours as an example to visitors. The point being that they really need to be careful of advice they may read in comments posted here by others and comments they may see on other forums.

Tim, Point well taken about completely reading thoroughly the comments. After re-reading your comments I see what your saying now. I understood your comments to mean it would not be worth while to insulate at all. Don't take my comment or intention the wrong way, I simply mis-read yours and happened to see someones basement walls that day through a thermal camera.
I do think insulating the floor joist might make sense if you had a walk out basement where a great deal of wall area was exposed to the outside. This particular basement I was in was 40 degrees that day. If I were not going to finish the basement, wouldn't it make sense to insulate the floor like you would for a crawl space?
I guess this is the difficulty answering these types of questions, variabilities.

Thanks for your response and keep up the good work!

No fighting dog here, just want to see the best info out there to reduce emissions...Brent @ energyQue.com

I am going to insulate my basement with Cellulose Insulation and would like to know how to put it up. Do I need a Vapor Barrier in the inside wall or outside wall ? I do not want Mold to start in the Basement because I did it wroung.

Please help me out here?

John,
Start by reading all of my Condensation and Mold columns. You need to get up to speed on what you are battling.

I had an additional with full basement added to my existing home November, 2006. I was around while the building was going on and saw that the contractor had used a water seal on the blocks and then followed up with a tar coat. It's a lakefront home and the soil is rock/sand so drains well. I'm noticing though that some of the blocks on one wall inparticular have moisture wicking through (below grade). My existing home (full basement) never had that problem and my question is two-fold. Is new block more apt of wick than 20 year old block and since I know they put the sealer and tar on, would it be beneficial to use the waterproofing paint (purchased a 5-gal bucket of UGL Drylok) on the block prior to putting rigid foam on or would I end up ruining the block in any way. I also had my excavator put gravel down prior to slab being poured and have a crock in the basement with tiles for draining as well as tiles around the entire footing so there is no other problem other than the wicking. (Feel free to edit question for space but didn't know how else to explain).

Jack,
New concrete block may be more porous, but I have no scientific data. The entire foundation should have been waterproofed, no matter how well-drained the soil is.

I have the same question as Clarence...only my bedroom is under part of the kitchen, and the floors are hardwood.

Tim,
I echo the first comment above made by Matt on Dec 4th, 2007.

My house in Nova Scotia is 130 years old with three walls of concrete/stone masonry and one dirt wall. The first floor floorboards rest on the original joists. I never want to finish the basement and was thinking of insulating the headers and between the floor joists with either spray foam or batt insulation.

Will this make a difference to the temperature of the first floor? And, do I need to install a fire break?

Thank you,
Geordie

I bought a house thats about 100 yrs old. The first floor is extremely cold. I was thinking of insulating the basement ceiling. Should I use baffles?

I have a six year old home, which i framed ,insulated and dry-walled ,but not plastered the joints yet. Only because i was sceptical about the way i was told to frame. This is what i did and was told to do :foundation wall ,3/4 inche air gap , 2 X 4 wall suds with R-12 pink insulation ,vapour barrier and sheetrock. My question is , should i go ahead and plaster the walls , or remove the sheetrock and vaper barrier and stuff some white foam sheets to fill the air gaps ,then finish up the walls?

Tim,

Just stumbled onto this thread.

I'm in Mass and have an unheated fieldstone basement. The low temp in the winter is in the mid to high thirties. Can I assume insulating the floor joist bays would be beneficial?

If so, what about a moisture barrier? In the winter the floor is warmer, in the summer everything in the basement is damp from humidity.

many thanks

Hi Tim, we are contemplating doing a complete basement finishing system by Owens Corning. We have removed all of the R30 insulation in the walls and ceiling (due to a dryer unknowingly venting directly into the basement). After completely cleaning the surfaces with 1/2 and 1/2 bleach and water, we are wondering whether we should re-insulate the walls and ceilings before Owens Corning installs their R11 rated walls and .95 acoustic rated ceilings. Half of the walls in the basements are 2" X 6" wood studded walls and 1/4 is 1/2 concrete and 1/2 studded; and the other 1/4 is concrete wall. We don't want to waste $ on insulation if we don't need to, but we also want to have some sound barrier in the ceiling and their .95 seems to be a good barrier. We have notice a considerable difference already since the insulation has been removed. Any advice would be appreciated. Thank you! Paul L.

I have block walls in my basement 1/2 above ground and 1/2 below ground. How will I install the vapor barrier when installing fome sheets of insulation. The house is in N.E. Pa.
Thank you

I am a single lady and I live in the midwest. Last year my heating bills were over $300 for 2 months. I am on a budget plan now but would like to insulate my basement. Work is slow and I don't have much money. I friend at work says she would show me how to put plastic sheeting over the basement walls. The house is almost 100 years old and was not properly maintained. I have had leaks come into the basement. I just need to know if it will help to put the sheeting up to keep my house warmer. Last year my thermostat was set at 55 all winter except when it got to below zero. I really need some good advice. We spend most of our time upstairs to keep warm. Please help me. God Bless

I was reading your comments about insulating basements and saw no reference to insulating the outside of the walls. Insulating the inside could cause problems due to the freeze point being changed to inside of the concrete wall, which could cause deterioration to them. I live in N. Wisc and feel that insulating from the outside is the correct way and have talked to many builders that feel the same way.

I want to insulate my ceiling in the basement. I am only going to do the joyces that contain the duct work. I am using r-13 with a kraft backing. Do i need to have plastic placed over those joyces after the insulation is installed? We don't plan on finishing the basement and i have already re-taped all of the duct intersections. We are doing this to keep the heat from excaping to the basement.

Hi Tim,
I've got a small home with a crawl space and a dirt floor. I covered the floor with 6mil plastic. I want to insulate the floor but am unsure what to use. Any suggestions?

Unfaced or faced fiberglass? Spray insulation? Help!

Tim, I live in NJ in an older home the basement is actually a 4 foot, unheated crawl space with a concrete floor. The space is open to the elements because the last owner neglected to place windows in the basement walls just wire mesh in small opennings to the outside. I believe I know the answer but I have to convince an 85 year old mother that insulating the underside of the first floor would help save heating.
Please I need a professions opinion.

I used bat 19, and 13 insulation around my duct work in my basement to help keep the ducts warm, i have returned home and my house has a strange odor, was wondering if is from the insulation and is it safe?

Thank you for the info.