Unlike myself ( ), the house that my finance and I bought in mid June dosn't seem to be well insulated to me (only has a 3 inch blanket in the attic). I'm pretty sure that this **** poor amount has lead to the ruin of the previous roof (evidence of delamination of the plywood in a few places, it has since had a new roof and proper venting) and I know home heating will be a bear this winter so I'm going to have some additional insulation blown in. I have an estimate from a local outfit that I trust and I was looking for some adive from those of you who might be knowledgeable about such things...

House background: 1100 square feet, one story, roof is ~3 years old, brand new high eff. furnace (gas). I live in western NY, which means it gets cold and we get a lot of snow. Ice daming can really be a b!tch.

The estimate
R-19 $825 for 8.75 inches
R-27 $1200 for 11.75 inches
R-30 $1315 for 14.25 inches

I'm sure that prices vary based on area and like I said I trust these people to work on my house so cost isn't too big a question (comments welcome as always) but I'm on the fence about how much a should have done? I was leaning towards the 11.75 inches but for another $125 is it worth it for more? I would like to get away with paying the $825, but I would rather pay more now, and save money on the heating and cooling later and take good care of the current roof. Thanks guys.

 

I bought the blown in stuff at Lowes and did it myself, the machine is free. Had a couple of freiends feed the hopper while I crawled around the attic. But do the math first, it just may well be cheaper to have a company to come in seeing how they get such a better price on insulation.
Here's a coverage chart. It's about $7 something a bag down here in GA

< http://www.cocooninsulation.com/Loos...art.asp?Type=H >

 

The r-27 is probably gonna give you the best results. The r-30 isn't that much different in price. I'd go with the r-30 if I was in COLD country. Once you get past a certain point though it's kinda overkill. You'd probably see a little bit of difference between 27 and 30 since you're in a more extreme climate. If it was a moderate climate 27 would be more than enough. My .02

Other issues are what kind of windows you have and how well the outside walls are insulated. Good windows make a big difference in efficiency, but they can be expensive and take quite a while to recoup the costs. Of course if you're heating with oil then it might not take that long

 

It all depends on the installer. One guy's 11" could be equal to another guy's 14". It isn't like they crawl around in the attic with a micrometer to make sure they have exactly the right amount in every spot. Besides, how much of your attic actually has 14" of clearance?

I'd get the 9" and be on hand to tip the installer an extra $50, you will most likely end up with close to 12" that way.

 

I have my doubts about the wall insulation but the windows are brand new quality double pane.

Thanks Rocky, I like the tipping idea, never hurts.

 

For the attic like that, you want at least and R30 total. Not sure what your 3" of existing insulation gives you, it depends on the material. Just make sure that after you are done you have at least R30 in the attic and R19 in the walls.

 

I have heard this same thing. Not sure why R30 in the ceiling and R19 in the walls. Seems like you are only as insulated as the weakest link. Yeah, Yeah, I know all that crap about heat rising, but sooner or later it has to get to the walls, doors, and windows.

 

I put 24 " of blowin insulation but I had special tall heel rafters built
r 60 in my shop roof
cost approx 80.00 a month to heat
mitch

 

Main reason, heat rises. By having R30 at the top, you cut down on the loss from the heat rising. Also the weakest link is windows. It is almost impossible to get better that about an R7 in windows, no matter how many glass layers you have. The only reason you can get 7 is because of having gases like argon between layers. Don't remember the exact number, but glass has an R value itself of about 1 or 2. It conducts heat like crazy.

 

Is this an open attic? If so, then your insulating will be easy; just blow in however much you want.

Ice damns are caused by only one thing: too much heat/moisture trapped in the attic from the living space below. Unless the heat/moisture is exchanged, the hot air contacts the bottom of the roof deck, thus melting the snow on the outside. The constant melting and refreezing causes ice to build up, and then it backs up under the shingles, builds up near the gutters, and then eventually gets inside the walls. In addition, the moisture generated by a typical household passes into the attic and builds up against the underside of the roof deck, where it freezes and thaws, and eventually drips into your insulation, and not only ruins it, but it loses its ability to insulate.

The secret is correct ventilation. In an open attic, the easiest way to accomplish it is to have louvers in the soffits, with tubes or some other device to keep the air passage open from the soffit vents, thru the insulation blanket, and then exhausted by some other method: either roof vents near the roof peak, or via turbine vents or a powered roof vent that comes on BOTH by temp and humidity. The goal, ideally, is to keep the attic as cold as the outside temperature.

I use soffit louvers, with tubes, and two 14" (throat size) ALUMINUM turbines. The galvanized turbines aren't worth *****, as they will rust and seize up. The turbines also are more effective in the summer at exhausting warm air and keeping A/C costs down. I have lived in my house for 28 yrs, and never had an ice dam.

Most houses, however, have too little ventillation. Soffit louvers are dirt cheap, as are ridge vents and turbines. If in doubt, add louvers and roof vents. If you are going to insulate the attic, make sure you install the soffit tubes (or plastic channels between the rafters; they all do the same thing) BEFORE you blow the insulation or you'll have to crawl thru the new stuff and insert the tubes, thus wrecking the insulation by compressing it.

Other attics require different methods of ventillation and are not so easy to do as an open attic.

Jim

 

Ditto on the ventilation post!

I inspect buildings for a living and most residential structures that I look at are WAY under-ventilated! If you blow-in additional insulation, make sure you install the plastic baffles out at the eaves to make sure you don't negate the performance of your soffit vents!

For what it is worth, you will get the best performance out of a ventilation system if the amount of "net free area" ventilation is evenly balanced between your soffit and ridge venting. This allows for "X-amount" of air to enter at the soffit and "X-amount" to exit at the ridge.

 

WHOA!!! time out...

First off what kind of insulation are they giving you? Blown in yeah but what? Cellulose or fiberglass. If it were me id go with a minimal of an R-40 of fiberglass.(the white stuff) Cellulose is much cheaper but it will settle over time. Fiberglass wont. Ventalation is also a big thing which every one has touched up on.

My dad owns a construction business and im his main guy. So if ya have any particular questions feel free to ask. Ill have to ask him what it usually takes price wise to insulate an attic. We just built a concrete house (Fold-Form brand) and its unbelievable how well it stays heated and cooled. Anyways good luck.

 

cellulose is also rodent (mice, squirrels) friendly.

 

You bet it is!

I have an earth contact home. 3 10" concrete walls holding the earth back with 4" bat insulation, 1 4" front wall with 4" bat insulation, 2x10" ceiling joist with 10" bat insulation, 12" slap floor. All electric, with fireplace for heating. With 4 people and two of those are kids that leave lights on. There are 4 computers running 24/7 plus then atleast 1 or more out of the 4 TV's is always on 24/7 too. Normal applicances, 3-4 loads of laundry a day. etc. etc. If my electric bill is over $100. Then I'm flipping out trying to figure out what is going on, why it's would be so high! Then only takes about 3 cords of fire wood to heat it throu a hard winter. You just cant beat it for effenciency. There are draw backs too though.

 

Bring that home up here and we'll see how long that 3 cords lasts during the winter!!!