Insulation, Radiant and Vapor Barriers - Attic Insulation

I have an old home built in 1932. I have recently had the roof replaced. I am wondering if I need to insulate the actual roof itself or just the top layer of the crawl space which has existing sawdust (yes, that old!) and a layer of insulation from about 25 years ago.

I insulated my garage this summer. I had some insulation left over from this project (R-19) and place these rolls of batted insulation (6 of them) in the attic. I stapled them on the attic roof inside the home and have noticed that the snow melted everywhere on the roof except where I had insulated.

Maybe this is a dumb question, but is it a good sign that the snow has not melted where I placed the insulation or is the insulation supposed to be on the floor of the roof (the ceiling of the main home) and heat is supposed to heat the roof enough to melt the snow? I live in Wenatchee, Washington state where we get 1-2 feet of snow per year. Am I better off insulating the ceiling of the home but not the roof of the house and placing heating cables on the roof to melt the snow and ice or is it a good thing that the insulation on the roof is preventing the snow from melting? Am I saving money here or should I allow the house to heat the roof enough to melt the snow?

What is the right choice: insulate the roof or insulate the ceiling?

thanks!

I think there are two options here. First if you have a heating system up in the attic, then I would insulate the bottom of the roof. I would make sure there are soffit and a peak vent and absolutetly make sure the insulation does not compress up against the sheathing. You want to maintain a path for air to flow from the eves to the peak along the sheathing.

If you do not have a heating system in the attic, then insulate the ceiling. The attic will be cold in the winter, but then it should not matter since the ceiling insulation is keeping the heat downstairs and not allowing to get into the attic.

In my house, my furnace for the 2nd floor is in the attic. All the insulation is in the ceiling (attic floor). When the heating system turns on, some of the heat is lost from the duct work into the attic. This heats up the attic some and I also notice that the snow on my roof melts very quickly. I am going to insulate the bottom of the roof to maintain some of this heat in the attic and keep it from rising up through the roofing sheathing.

In unfinished attic spaces, insulate between and over the floor joists to seal off living spaces below. This will keep the heat in the area below where you want it. Go to www.doityourself.com/insulate on this website to learn more about attic insulation and to calculate the R-value for your ZIP.

Greetings,

Sure fire way to rot out the sheathing, insuate it with FG.

Any suggestions since you don't think fiberglass insulation is a wise idea in this situation? Comments are great but without a possible idea for a solution this dialogue is useless.

Greetings,

My apologies for the cryptic answer. I saw the comments and was in a hurry, so, I felt some advice was better than none at all.

Your discription of the constuction was not detailed enough to give a good short answer, as, indicated by previous answers. Common problem. Most home owners are not aware that 6" FG is about maximum for savings vs costs. In fact, too much FG could incresae your a/c costs.

Your're right about not liking FG. It's one of the biggest rip offs going. Check out radiant barriers on the web and if you see the benefits there over FG. I'll give you detailed answer about what type to use and how to install based on more construction info.

Also check on the web, FG litigation, FG cancer, FG chemicals, FG mold problems.

I have been installing RB for 29 years.

Thank you for considering my opinion.

It s old! so lets start over and do it right. I would get all of that saw dust out of there by hand or vac it has the moisture in it from how many years. Then put down R-19 FG batts with the paper side down to the ceiling to act as a vapor retarder. Then get a 4" FG blow on top of this. Make sure you have enough vents up there for the attic. Dont put any insulation up on the roof. Use heater tape for the snow on the roof if its that bad. With the new roof they did put that new full like liner you put on the lower part of the roof to stop leaks from ice damsI hope;) ED

Greetings,

The paper on FG batts is useless as a VB. Not only that, the paper is glued to the FG with very flammable pitch. If you notice the FG mfrs do not list the perm rate because it is so high. Another FG deception.

Adding blown to batt is a waste of time and money.

Thank you for considering my opinion.

Then why does our Gov. say in there test of RB all it has to do is get some dust or dirt on it and its no good And why do some power companys stay away from it?????;)

I personally dont trust any tests our government does. They are way too persuadable, all it takes is a little money!!;)

Greetings,

Sorry for the terdy reply.

Your'e being too kind.

I have occasion to talk to engineers and scientists that are involved in testing for the government.
One of the interesting things is that they test but don't publsh the results. You think they don't know about the serious problems with FG. DOE has been ignoring the elavuation of the $1 per year roof pond heat'g/cool'g system for about 25 years.

They manipulate the date for RB and don't mention the problems with FG or that it gets up to 50% less "R" value than what is advertised.

I here from enviromental product mfgrs all the time about how the government manipulates.

And people get ticked off when I try to explain that these are facist procedures.

Look at this way. If gov/industry can keet you at the base of the Maslow pyramid by controlling energy, are we really free?

Thank you for considering my opinion.