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Insulation Q's and A's

Noise Reduction | Amount Needed | Attic | Blown-In
Vapor Barrier | Radiant Heating | Basement | Floors | Compressed | Pipes
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Noise Reduction

Noise reduction

I have a problem with noise from outside in the house. I have hard wood floors. My house is old and has plaster walls and wood exterior. I've upgraded the windows and have insulated attic, but that has not helped. I'm thinking of having insulation shot in the walls but I've been warned that can be a nightmare down the road. Are the any inexpensive fixes you can suggest, or any sites I should be looking at.

The insulation in the walls will certainly help. Where do you live? Insulation is usually a good idea anyway(except where you don't need heat or air conditioning) I do not know what the nightmare down the road will be...... what have you heard??

Amount Needed


We are currently having a house built in Southern New Jersey. It was recommended to increase the
insulation in the ceiling from R30 to R38 and in the walls from R13 to R15. The builder came back
with an additional cost of $650 for the walls and $400 for the ceiling. The house is 2 stories with
approximately 2100 square feet. I am looking for a recommendation as to the validity in what we are
doing and what you think of the cost. Would we save enough in our heat and cooling bills to justify the cost?

Without crunching the numbers considering surface area etc., I would bet that the increase in 2 R on the wall is NOT worth it. The ceiling most likely is. How did he propose going to 15R from 13R??

ALL insulation is worth it. It just becomes a question of how long to recover initial cost. If you plan to stay in you house a few years, you will see the recovery in your heating bills tough you may not even recognize it. Though 60% of heat loss is through attics and floors,the other 40% is through walls. Any increase is helpful.
I was once a fanatic about this sort of thing....
Doing some rough figuring, using an 85% efficient furnace, I figure the savings of going from 13R to 15R is about 26 gallons of oil a year. That would be about a 25 year payback.... That isn't much... typically you would like to make your investment payback in 5 years.


I recently bought a raised ranch. There are two bedrooms over the garage that are always cold. I removed the ceiling from the garage and I found that there was R-8 insulation installed with the paper side down (facing you from the garage). There are also heat ducts for the two aforementioned rooms that are uninsulated (forced hot air heat). The beams are 2 x 8. House was built in 1964, steel beam construction. My questions are as follows: 1. Obviously, the ceiling is not properly insulated.... What would be the best way to insulate the garage, which R-value would be correct? Should the ducts also be wrapped before the batts are installed? 2. Should the paper-faced side of the batt face the floor of the room above or face the garage? I'm confused about this. 3. Would it be okay to staple up 4 to 6 mil plastic once the ceiling is insulated until I'm ready to sheetrock? Please help! Just for information, a man at Home Depot suggested installing R-19 with the paper facing the bedroom floor and then putting an unfaced batt of R-11 on top of it for added insulation. Other people tell me to put the paper facing the garage...which is right?

I am in the same boat, (or house). At the back of the garage, but inside the house, is my laundry room. I can see down the length of the rafters over the garage from there, and I see blown-in cellulose type insulation. It is about 8" deep, and there is a good 8" above it. I have no access to the ceiling from inside the garage, since it is already drywalled/plastered. I live in Chicago, and the rooms above are cooler than the rest of the house, no doubt. I am considering blowing more insulation down the length of these rafters, but how do I get that blower all the way down to the far end? My laundry room is only 8 feet across, so I can't use a long pole. I was thinking of pulling that golf-ball retriever out of my gold bag, it has a telescoping handle, to hold the blower tube and fish it down the length of the rafters. Is it okay if the blown-in insulation totally fills the area between under the floor of the room above it?

It would be ok to fill the whole space with insulation if there was a vapor barrier installed under the floor. Probably was not done though, In that case, you should leave a small air gap along the top. Good luck on the long reach!


Definitely some research is needed on your part. My idea would be blown in cellulose since you get a higher R-value in a minimum amount of space instead of using batts. Check out the R-value per inch between batts and blown in and see what would be to your advantage. Home Depot usually lends you the blower for free when you buy blown in insulation. I like to visit this site when I have any insulation questions. He is more modern and against the grain in some aspects when it comes to home insulation and ventilation but with proven facts that sometimes goes against code but for many good reasons.
http// And then for R-value and more technical information here is the link to Cellulose Insulation Manufacturers Assoc.
where you can get some more technical information.


In NY, it is definitely, without question vapor barrier toward the bedroom, not that garage. Vapor barriers in our colder climates go toward the living space because the moisture will otherwise enter the insulation and when it reaches the colder area, condense. Therefore, do your best to keep it indoors. In the winter, the moisture will move from the warm moist air indoors to the cold drier air outside. As for how much insulation. You would do well to fill the floor area as much as possible, that may best be done with cellulose. (I prefer fiberglass but it is a matter of weighing cost and R-value per inch and ease of installation) If you double up insulation batts, as Home Depot recommended, make sure you put the paper right next to the floor. In other words, the vapor barrier goes RIGHT next to the living space. Yes, it would be ok to staple up six mil (or four mil) plastic under the sheetrock ceiling, but don't double up vapor barriers. Use plastic (better) or paper, but not both. Put as much insulation in your ceiling as you can, (R-38 is recommended) But remember to allow for air movement under the roof. There should be gable end vents or a ridge vent and soffits vents and the insulation needs to be held away to allow the air to flow from the lower to the higher vents. They sell styrofoam prop vents to hold the insulation away and provide an air passage. * Check out the article on insulation and vapor barriers on our site... go to the articles page: Articles

Adding insulation

I have a 1953 ranch house with paper backed insulation in the ceiling (attic space) which is very settled. If I add more insulation, do I need to remove this first or is there a product I can apply over the top?

Buy unfaced insulation to lay on top. You don't need to replace the other stuff first. Infact, with the paper vapor barrier already in place (paper down right? right next to the ceiling.) you wouldn't want to remove it, because installing a new barrier will not cover the ceiling as well.

If you're present, insulation comes to the top of the joists now.. just lay the new stuff on top, and the best approach is to go at 90 degrees to the joists so they are covered. If your insulation is not presently up to the level of the top of the joists, You may want to either buy it in two different thicknesses .. and fill in with one first.. then go over with a thicker level. Or you can just lay the thick stuff in-between the joists.

OR... you can buy the blown in kind.. that comes loose and just fill the whole space to the depth you are looking for. Home Depot and stores like that will rent the blower. Now.. make sure you don't block the airflow from the soffit vents.... keep enough space above the insulation to allow the air to flow up.

If you need.. or want they sell a Styrofoam panel called Prop Vents.. which can be used to leave that air gap.

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Mobile Home Insulation (Under)

I would like to replace some of the insulation under my mobile home. Can you help? A cat or something has got in there a tore it up, only section of it, have the skirting, but want to repair insulation first.

You can buy insulation to replace it. Unfortunately, it typically comes in a fairly large quantities.... Measure the space the insulation will fill, or measure the insulation that is in there.

In a floor.. you would have at least 6-inch insulation... But maybe thicker. Buy the kind with paper vapor barrier attached and install it with the paper side up towards the floor. You can buy the insulation in either 16inch width or 24-inch width, so measure the distance between the supports or joists... (the actual distance will be 14.5 or 22.5) so you know what size to buy. You can cut it to length with scissors or a utility knife. It would help to wear gloves, long sleeves , goggles and a paper filter facemask. There is enough fiberglass dust when you are working above you like this to warrant the protection).


Attic Insulation

I recently purchased a townhouse in Miami, FL built in 1991. The builder never insulated the attic and the original
owners didn't either. I have scheduled a couple of insulating contractors to come by and give me estimates for both the blown-in and the batt.
My general question is which is better batt or blown? What are the pros and cons of each (other than initial installation price)?

My local power company did an energy audit of my house and recommended R-19 insulation. Owens-Corning webpage recommended R-38 for Miami. What R value is adequate?

Everywhere I have checked says Miami should only need R-19. The reason Miami can use less has to do with the difference in temperature between your house and outside. In the cold climates.. where the temps can be as cold as 0 degrees or less, you have a 70 degree temperature difference to insulate against. In Miami, most days are less than 100, which is only a 30 degree temperature difference.

As for Batt or blown in? As long as you are using fiberglass for both, and getting R-19 in both cases, just go with the cheapest estimate. Effectively, there will be no difference in performance, life or settling.

Attic insulation

When building storage space in an attic how much loose insulation can be left under the flooring?

You can fill it right up to the top of the joists just under the flooring. There does not need to be any gap at all.

Attic insulation

I have a 3 year old house. The top flow seems a bit drafty. I looked in the craw space and the builder did place fiberglass insulation in between the joists. The thickness is really about 6 inches. I was thinking of laying down another 10 inches on top of that in the other direction. This way it would cover the joists. The attic is well ventilated from the roof. Is this a good idea? Can or should I do this? Is it worth it to do this? Will I see results?

You CAN do it.. you will certainly see the results in your heating bills, though it won't solve your draft problems.. you need to seal air leaks for that. Yes, keep the insulation away from the roof to allow the air to flow up from the soffit vents.

Adding Attic insulation

I would like to add insulation to my attic (snow melts on my roof before the nearby houses) and the house is quite cold [forced hot air]. The contractor thinks the existing insulation is R8 (40 years old, only several inches thick).

I know that the new layer must be unfaced so that there is only one vapor barrier. How much (R?) should be added so that the house is adequately insulated (for comfort and heating bills)? I was informed by one insulation manufacturer that the Dept. of Energy recommends adding R30 to the existing layer. The contractor told me he'd add R 13, to total R20-R21.

Also, I was told to lay the new insulation in the opposite direction (perpendicular to the existing insulation), meaning ACROSS the beams! Is that necessary? Since the attic has almost no floor, you have to walk on the beams. How would we walk on the beams???

Is there anything else I should know before this project gets started?

I would go for as much as possible. You don't say what part of the country you live in, but if you get snow..then go with R-30. Yes, unfaced.

Remember to leave air gaps down at the point where the roof meets the floor to let the airflow from you soffit vents up to your vents in the ridge or gable ends.

About laying it the other way:
Well, if the space between the ceiling joists is full of insulation then the typical recommended way is to run it across as you were told. The reason is, you cover the joists better this way (wood is only R-1 per inch, so it is not as good an insulator as the fiberglass you are putting down). So going across, sort of makes sure there is no gap. By the time you get all that insulation on there, you can't walk anywhere. You will need to be careful you don't put your foot through the ceiling. You will walk on the edges of the joists.

If you find it easier to lay the insulation the same way, go ahead, the gain isn't really worth all that much in hassle. No harm will be done, you may just let a little more heat out than otherwise.

Home Insulation Next Steps

I live in Northern California; inland of the coast. I am looking to make my 30-yr old, single-story ranch house more energy efficient. Questions:

1. Current attic insulation is R-11; what's the incentive to overlay it to get to R-30? At Home Depot, can get unfaced batts of R-19 that would get me to R-30. Or, should I just have some insulation blown in to get to R-19?

2. The air return duct to the forced air furnace/AC is not insulated in the attic. Seems like it should be. Any reason I shouldn't insulate it? Recommendations on how to insulate it? 3. Given the above, am I better off focussing on attic insulation or insulating under the floors, (no insulation there now). The bedrooms are carpeted; the rest of the house is hardwood floors.

Bottom line- other than the usual caulk/weather-stripping, what's my next best move in time and money for making the house cheaper to keep warm in winter and cool in summer?

Something you might check is how well the attic ductwork is sealed. After I moved into my new, house I discovered how poorly, the ducts were sealed. I have flexible ductwork in the attic that had gaping holes everyplace the duct met a distribution box. My rigid metal ductwork in the basement was the same way.

The air supply and return portion of your system that is outside your house (attic) should be one continuous SEALED system. You can use aluminum tape and a special caulk to seal all holes and gaps. It made a HUGE difference at my house.

More thoughts:
The attic insulation is typically the best place to start. R 30 by adding batts is a good level for the attic.

As for the duct, yes insulate it. It will just lose heat to the attic, and that is air that needs to be reheated in the furnace. And it will pick up heat in the summer, which will need to be removed by the A/C. So yes.. insulate it.

And the floors.. If the space underneath is unheated, by all means insulate the floor. Depending on how cold it gets underneath (is it an unheated basement, or crawlspace, slab?) it makes sense to keep the heat from being dumped through the floor.

(Remember.. heat travels from hot to cold.. in any direction.. it does not rise. hot air rises.. but is warm at the floor too, compared to outside.. and the heat will be conducted right out through the floor).

And more ideas:
1. R-19 batts to r-30. Fiberglass is cheaper than cellulose.

2. Either use insulation board to cover square heat/air ducts, or remove the ducts and use insulation beard to create new ducts.

3. Given the above, add more insulation to your attic. About 60% of heat loss is through the attic. You can eliminate much heat loss through the rest of the house by sealing all holes around wires, ducts, pipes, chases....Not to say you should NOT insulate the floor. You really should. But given my druthers, I would add to attic first. It will help much more with cooling in summer as well.

Attic insulation

I am ready to insulate the attic and I saw a movie on pro's and con's of attic insulation in the store so I am wondering what the con's are. Could you help me out?

I think the only "cons" are cost, and the ease of installation of the product. The higher the R - factor the higher the price,unless you get a deal).Installing batted/rolled insulation is not a difficult job.



My husband wants to blow insulation in our crawl space in our garage....he says it will help our air conditioner work better......where can I buy this blow in insulation. And is there a brand name for this?

Certainly adding insulation will help with cooling. You should be able to buy it at any large building supply store (home depot, Loews etc.,) or Lumber Yard. It will come in various brands, Owens Corning, etc. Check with your local store to see what brand they carry. I don't think one brand is better than another.

Insulating breezeway floor

I want to insulate my breezeway floor, however I do not have direct access to underneath the floor. Is it possible to blow foam insulation between the floor joist and have it stay in place? If not, does in make sense to cut into the foundation so that I have direct access?

There are different types of blown in insulation that would work, depending on what is under the joists. Is there nothing but dirt underneath and the gap is large? In other words, is it unrealistic to try to fill the whole space with insulation? There isn't a type that you could blow in to just the floor, making it sick there. What is the floor made of?

Garage Insulation

I am researching how to best insulate our underground parking garage ceilings at our condominium project. Ideally, a spray on application would be easiest. The garages are concrete with cement ceilings. Do you have any suggestions or websites I can turn to?

Do a web search for ICYNENE insulation. It is spray on foam type (like what comes in a can). Used for applications such as yours.

Wall insulation

I live in a 45 years old house in Norwalk , CT., and I wonder if you can give me some advice about insulating the walls. The house is a two stories plus basement. The upper part has aluminum siding. The bottom part has full brick facing. The basement has stone walls all around. And the attic had no insulation at all but I layered it with R-13, it has made a big difference. I wonder what you can suggest? I have thought about having insulation blown in, but I don't know if that's the best solution. Where to get it, or how much it will cost, or can I do it my self?

I live in CT too. Let me take your question a piece at a time.. The ceiling.. you can add more if there is room. You should go to R-49 in the attic... That is a lot of insulation of course.. and you need to make sure you don't block the air flow from any soffit vents ... You can do this job yourself.. make sure you use unfaced insulation. If the attic floor is open, you can lay the insulation right on top of the joists. This does of course make the room inaccessible.. since the insulation will cover the floor..

The walls.. Unless you want to pull all the siding off the house.. or the inside walls off.. blowing in insulation is the only option for walls.

I would say that paying someone to do this is the most likely way to go.. It can be done by the homeowner.. but it involves drilling a hole in the siding.. or interior walls, and blowing in insulation between each stud. Fill the cavities.. call .. this is the sort of thing you will need an estimate from a local insulator for.

Basement .. Well you can insulate the basement ceiling.. but realize this will make the basement cold, since it is being kept warm by heat from the floor above. If you go this route.. you would use R-25... Batts installed vapor barrier up.

Or.. you can insulate the walls of the basement.. a variety of methods are available.. R-19 is the recommended levels.. see the article on recommended insulation values on this site.. Recommended R values

Vapor Barrier


I am finishing a new addition on my home and will be using tongue and groove knotty pine. The insulation contractor strongly recommended that I first install drywall over the sprayed cellulose due to moisture concerns.

I would rather have root canal than install drywall first, especially on the 16-foot cathedral ceiling.
Any ideas? will plastic be sufficient. is this necessary at all?

SOMEthing is DEFINITELY necessary. A vapor barrier. Drywall is NOT a vapor barrier. It may slow the moisture down.. but you need a vapor barrier. Install plastic....6 mil

Vapor barriers

When placing a vapor barrier in a warm basement on which side of the insulation does the barrier go? Is is ok to place unfaced fiberglass insulation directly up against a exterior basement wall?

The vapor barrier faces the warm more humid side. In a basement.. that is typically the inside. So yes.. the unfaced insulation side goes against the concrete.

That said.. if your basement walls get wet.. or damp, it is a good idea to seal them first with a concrete sealer.. (Like Thorough Seal, which is a cement based product.. you mix up sort of like cement.. and apply with a heavy brush).

It is good to seal it, since moisture coming through the concrete will be hidden from you inside the wall.. and trapped in the wall by your vapor barrier.

Another answer:

I'll be doing the same thing soon. I already picked up the five gals of Dryloc sealer, but haven't got to it yet. I've read several places that the way to be sure of no moisture problems is to seal the concrete, put a 6 mil plastic from the ceiling to the floor and under the sole plate, and then frame and insulate.

Keeps any moisture out of the insulation.

Radiant Heating

Proper insulation with Radiant heating

I am building a small 3-4 season sunroom in a northern climate. One of the options I am considering is electric floor heating. I have a concrete slab but want to lay some Pergo-like tile. Is this going to be expensive to heat?

Any experiences with electric radiant heating?
What kind of floor insulation should I lay to limit heat loss through the floor?

Is the slab already poured? Or is the whole thing in the planning stages. If you have not yet poured the slap consider putting a layer of blue poly insulation under the slab. The concrete can be poured right on top, and you won't lose the heat into the ground. If it is already poured, I am not sure how you can insulate that floor other than to build a wooden floor on top of it and insulate between the joists.. but I doubt that is the way you intended to go.


Insulating residential basement with fiberglass insulation

We insulated our basement two years ago, but recently we found out that it could give problems of condensation and mildew seeping through the dry wall and make the basement room feel mildew. Have we done anything wrong by putting the fiberglass insulation against the wall and paper against the dry wall?

No, you did right. However, basements have moisture problems because they have a high humidity level due to their cooler temperatures and moisture flow through the concrete. One of the best things you can do to combat the mildew is keep the humidity level down. Run a dehumidifier down there all summer.

Basement insulation

We have a chalet with 2 bedrooms in the lower level (basement) in the northeast. What is the best way to insulate and finish the walls without losing a lot of inches - can we use Styrofoam and is there an easier way to finish the walls instead of dry walling?

I'd like more info before REALLY answering . BUT, typically the BEST overall solution for finishing a basement is to frame the basement walls with 2x4s in front of block or poured concrete walls and insulate with Kraft faced fiberglass insulation.

Reason is that it allows 'normal' electrical and plumbing work if any as well as 'normal' insulation work.


Insulating a floor

My home is a ranch over a crawl space. The crawl space (foundation) walls are insulated with foam board. The floor is not insulated. Shouldn't the floor be insulated? And what do I do with the foundation vents - open or closed during the winter? Water pipes in the crawl space are not insulated. The house is located in Indiana.

Make sure, if the floor is dirt, you cover it with plastic then close the vents in the winter. The relative humidity is much lower in winter so you can get away with no ventilation. To make the house more energy efficient and the floors warmer, the floor should be insulated. But you will need to make sure the water pipes are between the insulation and the house so they stay warm. In Indiana, the floor would be insulated with R-25. (See the link below for recommended R values.)

If you can not keep, the pipes warm... then make sure you have R-19 at a minimum on the crawlspace walls.

Recommended R values

Cold floor and cabinets

My kitchen cantilevers 4 ft over my foundation. That area gets very cold in the winter including the floor and cabinets. I can get to the area from the basement, but what is the best way to insulate? Blown?

Ok.. so from the basement you can see in the length of the cantilever ... is there any insulation in there now? If not, buy paper faced insulation at a thickness just about the width of the joists. The joist are probably 2x10s.. so get 9-inch insulation. Slide it in to the cavities between the joists. If there is some insulation already in there, buy the unfaced insulation at a dimension to bring the total to 9 inches and slide that in.

I think that will be the easiest way to fill the cavities. The blown in would also work, but it will tend to want to pour out the ends back into the basement.


Compressing Insulation

I am in the process of building a refrigerated room for wine storage. I am wondering who to get the maximum insulation in a 2x4 framed space or about 3 1/2".

For example, would one get a higher R-value by taking R-21 bats designed for 5 1/2" space and compressing them into the 3 1/2" space or should you always stick with the 3 1/2" sized bats?

To answer your question, No don't compress insulation.
You're using Kraft bats to staple up in your framing cavities? Yes? If you want to use Kraft bafts before sheeting, use the proper size. Many insulation experts all say by compressing insulation in any way, you are doing a detriment to its performance. And hey, 3 1/2 bats are cheaper than 5 1/2, what a bonus!


Which pipes should I insulate in a new home?

I am in the process of building a two-story home and some people have recommended that I insulate my pipes to 1) retain heat better and 2) prevent noise (e.g. after toilet flushes). Does this really make a difference? If so, which pipes should I insulate and what is the best material to use to accomplish this ?

Pipe insulation on hot and cold water lines is always recommended. It stops condensation, heat loss and quiets the system considerably.

The best tip to a quiet system is to oversize the holes through which your pipes pass, this gives you room to stuff some insulation around pipes that pass through studs, joists, etc. On heating lines the expansion rate is severe on copper pipe. Make sure pipe is not rubbing on wood. Extra care when roughing house is key to a quiet system. Also, PVC waste stacks are noisy. Insulate with fiberglass insulation around waste stacks in interior walls.

Cold floor and cabinets

My kitchen cantilevers 4 ft over my foundation. That area gets very cold in the winter including the floor and cabinets. I can get to the area from the basement, but what is the best way to insulate? Blown?

Ok.. so from the basement you can see in the length of the cantilever ... is there any insulation in there now? If not, buy paper faced insulation at a thickness just about the width of the joists. The joist are probably 2x10s.. so get 9-inch insulation. Slide it in to the cavities between the joists. If there is some insulation already in there, buy the unfaced insulation at a dimension to bring the total to 9 inches and slide that in.

I think that will be the easiest way to fill the cavities. The blown in would also work, but it will tend to want to pour out the ends back into the basement.

Click here for our Vapor Barrier And Insulation Article
Click here for our Insulation Facts Article
Click here for our Keep Your Cool Article
Click here for our Electric Radiant Floors Article

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