I've copied the message I left as a reply to linfairport's " gas furnace with HP or electric heat with hp" question. Hope it helps. Laying a radiant barrier over your existing insulation will act just like your 1-2" of snow, only it's always there!

I have a suggestion for you regarding insulation. Lay a radiant (foil) barrier over your existing attic insulation. We did it three years ago and it made an immediate difference. Our old and very noisy furnace did not cycle on anywhere near as many times during the evenings. We were able to watch something on TV without having to turn volume up and down as often as before because the heat was being held in (reflected) the house rather than float away through the attic. The hard result is that our natural gas use is way less also! I've included an link to one of the companies that produces such a product. This stuff really does work.

PS I do NOT work for any of the companies that produce or sell this stuff. It's just a great product.

Here is a link that might be useful: rFoil Insulation Products

Snow is actually a very good insulator because of the trapped dead air.

It could be that you do need more insulation.

How much do you have right now (depth) and what kind?

You would probably also benefit from more blown-in, these days they go a foot or more ABOVE the top of the ceiling joists (the horizontals at the bottom which is what I'm assuming you meant)

The other thing to look at is ventilation, believe it or not, you want that attic space above the insulation as cold as you can get it, which usually means a ridge vent or whirlybirds etc, plus adequate soffit ventilation, the most popular being the metal or vinyl perforated soffits, inside the roof space you want those cardboard or polystyrene baffles which run up between the rafters, this ensures air flow and that the additional insulation you get blown in doesn't block them.

A radiant barrier over that or stapled to the underside of the rafters (the underside of the actual roof framing) is a possibility too although I've heard some discussion that this can trap moisture underneath and cause rot.

I don't know what kind of blown-in stuff I have (I didn't build the house). I do have 360 degree soffit venting and I have styrofoam thingies that keep the insulation away from the soffit space. No ridge vent but 2 large vents at each end of the attic (? called eave vents or gable vents).

So visible ceiling joists = may benefit from more blown in insulation (thanks for teaching me the correct term).

Is it ok to lay a radiant barrier down on top of the joists? It worked for almac and it seems much less labor intensive than stapling it to the roof rafters (that's what a rafter is, right?).

You don't need to add any insulation if you lay down the radiant barrier I suggested, honest. Your heat energy is reflected back into your living space and the summer heat will be reflected away from the living space keeping it cooler. It's also used in some areas instead of building paper or Tyvek building wrap. Yes, just lay it over the top of the joists and the existing insulation, I called the company before I did mine and spoke for quite a while with one of the engineers. Sure my attic is still hot in the summer but I don't live in the attic, and I don't want to spend my $ heating it either. Applying it to the underside of the rafters is more difficult (easy on anew build or new roof install) and again, why heat the attic? We're so accustomed to speaking in terms of R-value that we think only thicker or deeper is better. This thin product is clean, easy and safe to install, and works! If you'd like to call and chat about it I'd be pleased to do that. I'm just a homeowner that wants high efficiency in my home. Hope this helps.

Our radiant barrier does not trap moisture. It has tiny perforations, kinda like Gore fabric. It breathes.

to understand a little bit more about radiant barriers you should go to sites not selling products as mfg's give very biased info.
sites like florida solar energy center and buildingscience.com will give you factual performance based info without the sales crap.

this is the time of year that I get a LOT of calls about the radiant barrier install of laying on top of insulation.
these companies come around and sell this install.
I refer these calls to fsec's question and answer section on radiant barriers. they don't have to believe me..I'm not selling any product..but get factual advice..not just someone selling products. that they pitch to retired people really gets me going..but I won't get into that now!

proper install of a radiant barrier adds R-10. not R-19 not R-23..R-10. with the proper install..on the roofline
(techshield for new construction) or installed to undersides of rafters, with foil facing into attic space.
will add R-10 to existing insulation value.

While radiant barriers work well in hot climates for the extended cooling season..they do not perform for heating climates..ok sorry bout that..minimal performance for heating climates.
They are not a fix all, and proper install is a bit more complicated than just rolling it out over existing insulation.

My radiant barrier has been in place for about 5 years.
my diy project. single sided foil on preforated denny foil guard paper. attached with button cap nails to undersides of rafters, foil facing into attic space. took me about 12 hours all totaled to install. (@ 10cents per sq ft material - my cost)
I had a little wind damage (gable end venting) and was
back in the attic once the hurricane had passed.
cynic that I am...when I did my install I laid one piece of radiant barrier on top of my insulation by the gable end. another piece was laid on insulation mid point of my attic. this was back in 04 when I did my install.
when I was doing my post hurricane repair last september..I took a look
at the radiant barrier on the attic floor. the piece nearest the gable end..very dusty. the piece midpoint of my attic..also very dusty. I was only measuring dust buildup. But then I had to take it a step further..
took part of both pieces out of the attic.
I laid both dusty pieces on top of a shed roof and went into the shed with my temp gun. the dusty radiant barrier
didn't reflect heat nearly as well as the clean radiant barrier. there was a 20 degree temp difference between clean radaint barrier and dusty (and only 4 years of dust).

So IMO those studies that say that in 5 years radiant barriers installed on the attic flooring loose 50% of their
reflectivity are right on target.

radiant barriers on walls..the problem is that you have to maintain at least a 3/4" air space between the foil and any other surface. it works behind bricks, but with hardi or vinyl,you would need to have furring strips between the foil and the siding. we do quite a bit of foam sheathing boards to the exterior..and most time use the foil faced sheating boards. the radiant barrier is useful (with the air space)on west walls, less so on east walls, and mininal on north south walls.
the sun hits the roof all day, it only hits one wall at a time. so it isn't as great of a performance as attic installs.

oh and fyi..all radiant barriers..single sided, double sided, foil bubble foil all perform the same. it is the foil that faces into the attic space that performs.
the difference is like mine....10 cents per sq ft for single sided..30 cents per sq ft for double sided and
45 to 50 cents per sq ft for foil bubble foil.
huge price difference (and just material..not labor)
same performance.

while I personally know the difference based on before and after in my own house, I use a software program that shows the benefits for houses with radiant barriers (again install install install).
As we put our heating systems and ductwork in the hottest part of the house (yep..attic)
the roofline install puts the mechanicals and ducts under insulation. this allows ductwork to perform better and extends life of mechanicals. not as well as locating both in the conditoned space..but there is a benefit.

rileysmom..you would benefit more from air sealing before adding insulation. areas like recessed lights, cuts at bath fans and stove vents, around fireplaces etc.
stopping warm air from escaping into the attic and cold air from entering the house from the attic.
this is an air barrier. the tighter the seal the better.
then insulate. insulation is the thermal barrier.
insulation does not perform when air moves through it
and insulationd does not stop air flow (unless it if foam insulation). stopping the air leakage before insulating is the best route.

best of luck.
we are a hot humid climate here..but we get some cold days.
when I first got into construction I remember giving a ride to a friend who sold insulation. he would make notes
of houses we passed that had no frost on the roof.
curious soul that I am..I asked why. he told me that if the frost melts that the house needed attic insulation.
I've found that to be true, but have also learned that house leakage and duct leakage cause frost to melt.
if you can see areas of the roof that the snow melts from first..check insulation level, air leakage and duct leakage at these areas.
houses tell us a lot..you just have to learn to listen and observe.

Very good post energy_rater_la, I got a lot out of it even though I'm not the OP.

When I lived in snow country I noticed some differences in light snow on roofs. Seeing less snow over the the rafters was indicative of sufficient insulation as the snow was being melted by residual heat from the rafter radiating through the roof deck and shingles. Other houses would have less snow on the deck and more on the rafter areas indicating insufficient insulation which allowed heat to pass more quickly through the deck/shingles with the rafters providing a little extra 'insulation' for the roof directly over them.

Thanks energy-rater I think you just saved me from an expensive mistake - if it seems too easy to be true, maybe it is.

Thinking of the space involved, it contains 2 bathroom ceiling fans, 3 bedroom fans, 6 ceiling mounted lights, 4 can lights, one set of attic steps (with attic tent) and one house fan (with homemade styrofoam insulation 'box').

Is one of these things more often the culprit than any other?

Also, what can I use to seal? I vaguely understand that you can burn your house down using the wrong stuff or not letting the light fixture cool itself off, somehow.

this is a good thread.

a few more tips

- the test designed to produce R values doesn't distinguish between radiant heat transfer and conductive(-convective). Seems to me it would be fun to devise a couple extreme examples of how this test could be performed to spec but under extreme conditions i.e. 1. that encourage radiative heat transfer and 2. that involve no significant radiative heat transfer. Then the results would be (I predict) vastly different, and replicable from one day to the next and when performed by anyone. Sounds like a scientifically valid way to show that R values are not valid units to base decisions on when dealing with insulation designed specifically to reflect radiant heat. p.s. in a roof, as mentioned above, a radiant barrier does not need to block air, i.e. be airtight.

- the reason why sheet metal (or metal foil) works well in house roofs in hot climates is that it prevents the world's greatest radiative heat source from sending heat into the building. The sun's heat. OTOH, in cold climates there is no equivalent (in radiative terms). Cold comes from all around, not from a source. Otherwise, if there were to be a cold source (or heat sink), radiant barriers facing it would work. And, radiant barriers do work in cold climates, but they have to be in the entire building, walls and all. In cold climate, rooms with exterior walls radiant-insulated are warm, if also airtight and insulated with trapped air (trapped air to slow down conductive heat transfer).

- the best radiant reflectors are also good conductors (when touching); this explains why you need air on one side. If they were touching solid material on both sides, they would be conductors of heat. ((Foil on Foam or on air bubbles is good, as the foam is 99% air , not solid material)). The idea is to separate them physically so that they reflecting heat instead of conducting it into the building.

- any metal will do, too. Steel roofs and steel buildings are good. You do not need aluminum or copper. Any metal will do fine. In your kitchen, your oven is made of layers of metal.

- how thick the sheet or foil, how much air space, etc-- this is a matter of increasing performance a little all the time. It's linear. It's a straight line, there is no curve, there is no specific number that is "good".

however, having said all this, i could be wrong about any particular thing so i'll be glad to study it more.

rileysmom17, in a new thread of your own you can post pictures taken from inside the attic showing the backside of the fixtures and holes. People will then get an idea of what you have both in the attic and in terms of fixtures. Then you will get valid input.

HTH
-david