Foil backed plywood is the more efficient than spray. Here is one site but many use the same figures. http://www.atticfoil.com/install-questions/paint-vs-foil.html
Christofer, There is a lot written about your particular condition. What I would do would be to install a spray polyurethane insulation (closed cell insulation) into the attic ceiling and down to and including the eaves. this installed over a 1/4" plywood that would be "cleated" down at a minimum of 1" below the bottom of the roof sheathing, thus eliminating the "hot roof" situation. As far as moisture... if you understand that warm air rises and carries the moisture up (another reason i would use a closed cell product) then it makes sense to foam any walls or kneewalls as well. The venting on the top side would not be to eliminate any interior moisture, but to make your shingles last longer (keep them from overheating). Quite a few asphalt companies have disclaimers on warrantees because of this issue. You would need to check with your steel roof manufacturer how they respond to a hot roof application.
Ok so you don't really want all that moisture collecting on your windows and or finished wall substrates in the attic. So an ERV/HRV or even the furnace fan run continuously would help distrubute or evacute the excess moisture if this is your main house furnace (air handler). FYI- change filters monthly in these systems to help mitigate possible mold issues. I recommend the 6" combustion air (bringing in dry outside air) code required in IRC. I am not sure if this furnace unit in your attic is the primary furnace (air handler) for the home. If so that would help distribute attic moisture to the lower parts of the home. If separate attic unit only, I'm not thinking it will ever distribute moist warm air to the lower level like you suggest.
Remember this... once you start changing the function of your home's ventilation/conditioned or unconditioning of a space you will be changing the whole dynamics of how the house used to function. Henceforth do your homework. All this said...I run my company business in the extreme temperature zone of Minnesota. Your local heating guys should have a better handle on providing a safe living environment for your family. Mold can be a serious issue.
We've done this application numerous times in southeastern PA with one subtle change, we use closed cell foam insulation directly against the underside of the roof sheathing. Open cell will continue to let air/humidity through, closed cell will not. Since air can't move through the closed cell foam there isn't any need for air flow under the roof sheathing because there won't be any humidity there to potentially condensate. Air already moves through the fiberglass insulation and that won't change when the Attic becomes conditioned space. I believe it would be best to remove ALL of the existing fiberglass ceiling insulation so that the Attic space becomes 'one' with the rest of the House. Fresh air intake to the fossil fuel furnace is necessary. It should be set up with a power damper that opens when the furnace turns on to allow combustion air directly to the heat chamber. When the furnace isn't running the damper is closed to keep unconditioned air out of the Attic.
Dennis D. Gehman, CR, MSA, CLC, CKBR, GAC, CAPS
President
Gehman Design Remodeling
NARI = National Association of the Remodeling Industry
CR = NARI Certified Remodeler
MSA = CertainTeed Master Shingle Applicator
CLC = NARI Certifled Lead Carpenter
CKBR = NARI Certified Kitchen & Bath Remodeler
GAC = Green Advantage Certified
CAPS = Certified Aging in Place Specialist
As a Denver roofing and siding company, we would suggest using a hardie board product. This would ultimately come down to your project budget, as insulated vinyl siding will be about 50% cheeper than a hardie board product.
Go to Everlastsiding.com
Make sure that your attic is properly insulated. Make sure the seals around all windows and doors are in good shape. If you can see daylight air is entering and leaving as well.
All of the answers given were great options. There are many, many ways to improve a home's energy efficiency. As we are a siding and window company, my focus will be on those areas. Windows are a huge energy loss/gain. Did you know that windows and doors account for approximately 50% of your heating/cooling loss? Air leaks around a window or door due to a crack of 1/16" of an inch is like having a hole in your wall the size of a brick. In the average home, that is equal to about 15 bricks. Consider how large that "hole" is in your home. The glass package is the most important thing to consider when replacing windows. Most folks just look at the cost of the window and install, and some smoke and mirrors some companies like to drag on about. A smart homeowner knows what Low-E is, what a good U-Factor rating is, whether or not it's single, double or triple pane glass, etc. etc. Same features apply to most doors. Lastly, siding is another area where a homeowner can save money. Check into insulated siding. Check to see what kind of underlayment is being applied to your home. Many companies don't even put a housewrap on to save cost and the average homeowner never knows. Make sure you only hire someone who is appropriately licensed and insured. Ask to see those documents. Hope this helps folks looking to replace siding, windows or doors! Happy remodeling!
The most cost effective things that you can do to improve your homes energy efficiency will depend on the existing condition of your building envelope, the efficiency of your equipment, and humiditiy control.
Addressing the condition overhead and tightening the building envelope are basic principles involved in maintaining efficient temperture control in the home. Thermal imaging will clearly indicate areas of major heat loss.
There are many types of structures and styles of thermal barriers. Therefore, you are best advised to have an energy consultant from a Home Energy Rating Service HERS evaluate of your particular home and assist in identifying the weakness of your home envelope and machanical equipment. Such a report can provide you with a roadmap to begin taking steps to improve the overall efficiency of the home.
Hello Alex,
One alternative that most homeowners are not aware yet is reviewing your Roofing System. Along with the attic insulation, the type of roof you have can make a huge difference on how energy efficient your home is.
Most roofing materials (especially asphalt composite roofs) absorb solar energy and transfer heat to your home (requiring more air-conditioning during summer). On the other hand, energy efficient Metal Roofs are reflective and emissive. They bounce most of the sun's visible and UV light - meaning less heat transferred to your home. Independent studies show energy savings of up to 25%.
The Interlock Metal Roofing System is Energy Star certified (US only). More than energy efficient, our roofs are truly sustainable, being made of up to 95% recycled material, reducing the dependence of asphalt and stopping the cycle of old roofing material going to landfills. It is a lifelong solution that is better for your home, your pocket and the planet.
Are your heating & cooling bills going through the roof? Did you know that up to 40% of a home’s conditioned air escapes through the attic? Adding attic insulation is the most effective thing you can do to reduce greenhouse gas emissions.
Is your garage attached to the house or is it on its own? If it is attached is there living space above the garage? Are you looking to insulate the walls and ceiling? Are you going to drywall the garage? I would suggest using batt insulation, with a vapor barrier. I would then drywall everything. Before you drywall I would make sure that you have all the electrical and anything else that you want in the walls installed.
I really noticed a difference in my electric bill when I put in a programable thermostat for my HVAC. I tend to keep the air down low and would forget to turn it up when I went to work. The new thermostat does that for me.
James Hardie Fiber cement siding would be the best option for the new siding on your home. Hardie House Wrap will help to create a thermal envelope for the exterior of your home. Foam sheathing can be installed on the exterior walls to increase the insulation R-Factor of your walls. The insulation issues you are having might also be related to problems with your windows in the addition. We recommend that you have the windows inspected as well. The James Hardie materials have an excellent return on investment as well as beauty. It will give your siding the look of real wood without the maintenance. Vinyl siding has serious issues with fading and doesn't provide the long term beauty that James Hardie products will give you.
Please feel free to contact us for additional information.
www.MDSidingPro.com
Insulation is insulation regardless of type. Whatever the R-Value per inch of the specific material is, times the number of inches, will equal the total R-Value. We are looking for R-49 to be Energy Star.
If the roof is not vented or we are talking about a hot roof deck, that is another consideration.
The floors in your home, while insulation will certainly mitigate this delta, will be different temperatures as the laws of thermodynamics are universal.
Get the insulation in the attic to R-49, seal the ductwork, seal the top plates, etc. and you will be good.