Insulation in unfinished basement ceiling?

[PT Doc]

Here are the details of the home in question:

1750 sq ft unfinished walkout basement with structural concrete floor with ~3 ft of crawlspace under the concrete floor. Rim joist will be spray foamed to achieve somewhere in neighborhood of r28. Some of the walls as the foundation steps down the hill will be 10" thick. All walls are insulated.

What are the thoughts on insulating the ceiling of the basement? There will obviously be plumbing and electrical and ducts run in the joist spaces.

What type of insulation (batt, blown in) and what R value would you recommend? The point is to make a difference in the ground floor comfort and home efficiency without busting the bank.

What is a best guess on the cost of your recommendation?

Thanks in advance.

 

[Elginz]

So, you have a basement with a crawl space under it? As for insulating the ceiling of the basement, I wouldn't think much heat is lost on the floor above, but if your basement is that cold it may help. I would go with batts so I could remove it to add, change, reroute things and not make a huge mess in the future. As for cost I have no idea how things are in your area. I insulated part of my basement ceiling in the pantry to be able to keep it cooler (window open in winter).

 

[PT Doc]

Our current house has a structural wood floor with crawl space under it. About 1600 sq ft. I don't think anyone currently builds anything without concrete structural floors due to moisture and potential of mold growth in the crawl space when using wood. The wood struc floors are typical engineered joists painted and the whole space has mechanically fixed vapor barrier, etc. The concrete struc floors have steel I beams and concrete poured over some kind of corrugated steel panels. I haven't seen it up close but it seems like a sound plan. It would be interested to see what is done in other parts of the country.

Just as an FYI, the Denver metro area has a history of expansive soils that were very devastating to homes and ultimately builders. The structural engineers have come up with all kinds of solutions based on percent of expansive soils. I believe under 2% can be a slab on grade concrete basement floor. If you finish your basement, the builders spec a concrete structural concrete floor. Some just spec the concrete struc floor and be done with it. If the soils are expansive, excavation of soil to 3 floors down and wetting of soil has been done. How that worked out, who knows. After prepping land for redi entail building, .9% expansive soil is not unusual.

 

[rancherbill]

I have just two thoughts.

1) your floors will be quieter.
2) very carefully check for other stuff in your crawl space. I am thinking of water pipes. Perhaps the heat 'leaking' through the floor is keeping them from freezing. If you insulate pipe might freeze.

 

[PT Doc]

I have just two thoughts.

1) your floors will be quieter.
2) very carefully check for other stuff in your crawl space. I am thinking of water pipes. Perhaps the heat 'leaking' through the floor is keeping them from freezing. If you insulate pipe might freeze.

Good points. Under the structural floor is pvc plumbing only. All hot and cold water is run in basement ceiling or on insulated basement walls. I was told the foundation walls are approx 56F degrees. I wonder what the crawl space temps would be since the walls of the space are all below ground at the ceiling to this space is the concrete floor of the basement. Even though it's unfinished is has ducting to provide heating and cooling.

 

[Elginz]

Yes, different parts of the country do things very different as the needs of the area dictate. Interesting. thanks

 

[DC73]

What are the thoughts on insulating the ceiling of the basement? There will obviously be plumbing and electrical and ducts run in the joist spaces.

It's hard to find good info on insulating basement ceilings because the consensus appears to be that you treat it like a first floor room in a 2 story house. That is, you properly insulate the walls and don't worry about the ceiling.

But, mineral wool would be a good choice for a basement ceiling. It is one of the highest fire rated insulating materials and is also an excellent sound proofing material.

DC

 

[kbs2244]

FA gas furnace with exposed ducts in the unfinished walkout basement ?
Somewhat common around here and I have never seen a insulated basement celing.
The temp difference just isn't enough to be worth it.

 

[CNGsaves]

It's hard to find good info on insulating basement ceilings because the consensus appears to be that you treat it like a first floor room in a 2 story house. That is, you properly insulate the walls and don't worry about the ceiling.

But, mineral wool would be a good choice for a basement ceiling. It is one of the highest fire rated insulating materials and is also an excellent sound proofing material. DC

+1 to insulate (at minimum) ceiling in basement where Sound Proofing would be beneficial. No one likes getting woke up when furnace/AC kicks on at night or hear the washing machine/dryer running downstairs.

Did this when finished basement at last house. Utility/mechanical rooms had both insulated ceiling, along with insulated walls, just for purpose of sound proofing.

OP you might consider suspended ceiling that would hold the insulation.

 

[Crfdell]

Roxul sound and fire give insulation, fire and sound protection.. Used in all of my homes no noises from the basement.

 

[PT Doc]

R19 Batt insulation cost to me is about $625. Install by insulation guy brought price to $1225. Guy recommended covering with something so that fiberglass would not fall to the floor. Joists are TGI joists so the lip should hold the insulation. Spring steel lightening rods could be used. Other company quoted $2000.

Could always be done at a later date if noise from mechanical area is an issue. It will be directly under great room.

 

[PT Doc]

Roxul sound and fire give insulation, fire and sound protection.. Used in all of my homes no noises from the basement.

Any guess on Roxul pricing per sq ft?

 

[hockey88fan]

My unfinished basement ceiling is insulated, unfaced fiberglass was used. All of my interior walls in living space of our home are insulated as well, really helps cut down on the noise from room to room, I did not build the house.

 

[DC73]

Any guess on Roxul pricing per sq ft?

R15 - 16" batts of Roxul (which is mineral wool) are available at Lowe's for about $40 per 60 sq. ft. They also sell the Safe & Sound batts for fire/sound protection but the package doesn't list the R value. It's probably less than the R15 batts because it's 3" vs 3.5". But I'm betting the regular insulation and the Safe & Sound are about the same thing, only different thicknesses. Mineral wool is mineral wool. Lowe's can order other R values and sizes of Roxul if what's on hand doesn't meet your needs.

Here's the link to the R15 batts: http://www.lowes.com/pd_138683-1278-RXCB351525_0__?productId=3388304&Ntt=roxul&pl=1¤tURL=%3FNtt%3Droxul&facetInfo=

You could use insulation netting for holding up the insulation. Something like this: http://www.amazon.com/dp/B00HAM24WI/?tag=atomicindus08-20

Fiberglass is not nearly as good for sound proofing as mineral wool and other dense insulation materials.

DC

 

[Tader82]

Insulation in today's world is a hard one to read with everything from Fiberglass, Blow-in Cellulose, Spray foams and their different type, to wool rock. Now that said lets look at them and there trade off.

To start fiberglass baits are the old and well known type of insulation. Their cheap and require little to no formal installation training to do your self and really no special tools. Just a good sharp knife and a staple gun if using backed insulation. But their not that good at stopping drafts in the wall(70-80% of all heat lose or gain in a closed space is do to the movement of air) and have a poor R-value per inch for todays standards.

Blow-in Cellulose is the next in the line of known and well used in the industry. But it requires special tools and equipment to install but no real training other than learning to control the spray gun used to blow it in. One can rent the equipment from Home Depot and Lowes pretty cheap. The drawbacks are that it makes a HUGE mess and if you have to dig it out of the wall cavity to fix something you MUST BLOW IT back in or it will not have to same R-value as the reset of the wall. This type of insulation does have a much better ability to stop the flow of air in the wall cavity, however it doesn't stop it completely.

Wool Rock is one of the oldest forms of insulation we have(besides old newspapers and hay stuff in the wall cavities lol) and is a by-product of the steel industry. It installs the same as Fiberglass insulation and uses the same tools for installation and has the same properties for air movement and R-values. But it does do a good job at stopping fires and sound, this is why it is used in most apartments and working building to separate spaces . Most time you will find Wool Rock in a Fire rate wall or wall separating two apartments.

Now lets talk about the "New" kids in the game, this guys are miles ahead in R-value and in Draft control. As I stayed somewhere above 70-80% of all heat loss/gain is do to air moving freely in and out of the wall or space. R-value is meaningless if you can fell a breeze in the space. This is why nowadays we are building homes as airtight as we can make them. Think of the lowly old styrofoam coffee cup, it only has an R-value of 0.5 but we all know that it keeps a ton of that heat in the coffee from burning your hand off. Why is that, well its because the heat in the coffee is trying to Radiate the heat out of the coffee through conduction and not convection.

So Spray Foams are great at both stopping conduction(radiant) and convection(movement of air) because of their make-up. Spray Foams are made-up of two type Open Cells and Closed Cells, as the names entails each has a good place for its use. Now to install this type of insulation you need to have very special tools and safety gear and no one rents any of the tools for this. You also need to have been trained in the proper mixing of this two part systems, if you mess up the ratios you can have adverse effects(like a really and I mean REALLY bad smell of rotting fish).
But don't let that scare you away from this just make sure the people installing it know what their doing. And yes there are do it yourself kits but they're REALLY expensive, believe it or not its cheaper to have someone do it than buy one of this kits and do it yourself most of the time.

Lastly is Denim insulation, it has some really great properties and is very health friendly(hell you don't even need to wear a mask to install it). It installs just like fiberglass using the same tools, and has the same fire rating as wool rock but is much higher in sound control than wool rock. It also has a very good air movement control right on par with blow-in cellulose. And its got a good price.

So that being said here are some links to stuff i have worked with for building theaters for people

Denim insulation
http://www.homedepot.com/p/UltraTou...15/204082527?N=5yc1vZbvev#product_description

Wool Rock
http://www.homedepot.com/p/Roxul-Co...e-Wool-Insulation-8-Roll-RXCB551525/202531867

Fiberglass
http://www.homedepot.com/p/Owens-Co...n-10-Bags-BF60/205470953?N=5yc1vZbay7Z1z0z6g2

 

[csp]

Your basement should be a conditioned space if it's new construction. The only reason for insulating one conditioned space from another is for sound.

By code they are going to require the exterior walls of the basement to be insulated.

I don't really see the point unless you're trying to isolate noise between floors.