I just purchased my home in August of 08 and need to correct the insulation in my attic. My house if roughly 3500sqft and my attic is a walk up attic and is roughly 1,200 sqft. There is about 3 inchs of blown in insulation  in the attic that was probably done about 60 years ago, the house was built in 1950. The center of the attic is floored leaving about 3 feet on each side open with blown in insulation. I do not have any soffit vents but I have 3 Gable vents, 2 fans( one in the ceiling and one next to the gable vent), 5 mushroom vents in the attic roof and 2 small windows. This winter I rolled R30 over the exposed sides of the attic to act as a blanket.

I have a brand new high end hvac system and this winter we had the temp set at 68 to 70 for the most part. The second floor always had a draft and was always around 60 degrees. When it was really cold the attic had icles hanging from the nails of the roof. Yesterday the outside temperture was 60 degrees, my thermastat was set on 65 and the attic was 91 degrees. I am assuming that I have an insulation promblem. I spoke to a contractor who reccomended removing all of the blown in insulation in my attic and spraying poly foam ( about 2 inchs ) He claims that my energy blls will drop a great deal and that my second floor will be allot warmer in the winter and cooler in the summer.

I would truly appreciate any comments
Many thanks
Mike

Mike,
Your contractor is probably right in that the temperature in the second floor would be more stable, however, I think you should go in a slightly different direction. His solution will not have any effect on the conditions in the attic itself. But if you were to spray foam insulation on the underside of your roof sheathing and any attic walls, then the attic itself would be insulated, eliminating the icicles in winter and oven in summer. Then the attic would become more usuable space, even if all you want it for is seasonal storage. This would also help stabilize the second floor temps as well.

By including the attic in the conditioned space, doesn't he increase the space that needs to be heated/cooled and increase the cost to do so? If he doesn't not need more living space wouldn't it be better to do a really good job of insulating the attic floor and sealing any access doors with weatherstriping?

Wes,
The contractor told me that if I sprayed the sheathing of the roof it would eventually cause wear and tear on the shingles, he believed that as long as I sprayed a strong base of poly in between the joists I would build a tight barrier from keeping the heat in the winter from escaping and from the heat entering in the house during the summer.
Thanks for your comments
Mike

Bingo!


Bingo Again! But then again, opinions vary!

Mike,
Panelcrafters is right that opinions vary, and on this subject, they vary a lot. This debate has taken place on this forum over several threads over the past few years. I happen to be of the opinion that an insulated attic space if preferable to an uninsulated attic. The shingle argument presented by your contractor is a common one, one that is mainly based on shingle mfg warrant warnings. Now most mfg are warranting their products the same for insulated roof decks as for any other installation. I, personnally, have seen no problems with shingles installed over insulated attics. Your description of the various vents in your attic indicate an ongoing heat and moisture problem in the attic space. The icicles hanging from the roof are an indication of serious moisture builtup. Insulating your ceiling will help increase the comfort levels in the second floor space, and it may reduce your moisture levels to some extent, but it will not eliminate all your attic problems.

Wes,
If I have the sheathing of the roof sprayed are you reccomending to spray over the vents as well and put a solid sheild on the attic roof
Thanks
Again
Mike

Mike,
Yes. Seal the attic space.

I'm sure he'd love to spray your house, he needs to pay for his spray rig.
My home was built in 1905 and was very leaky, I too do not have soffit vents and have just 2 gable vents. There was originally about 3 inches of blow in in my attic. What I did was install vent chutes to seperate insulation from the deck, located all my walls and ceiling penetrations and spray foamed all the old electrical holes, gaps, electrical boxes, bath fans and plumbing penetrations then blew in new cellulose over the old stuff to around 18". Sealed the scuttle with a high quality weatherstrip and a R38 batt stapled to it. Total cost was maybe $500 for materials, the cellulose blower was free with my purchase and it took around 3 hours of sealing and installing chutes by myself and maybe 4 hours including pickup and drop off to blow my attic with 1 helper.
What it resulted in was a R50 or better R value and dramatically reduced air leakage plus cellulose once settled does a decent job of denying air leakage (not like spray foam but the point I'm trying to make is the cost doesn't justify it)
I live in a 8800 climate by the way. I had an oil burner at the time and new windows and it cost maybe $1600 to heat the house each year with a programmable thermostat which was at 62 at night and during the day and 68 in the morning and evening. Last year I switched to 95% gas furnace, air sealed my basement, sealed my ducts and improved my duct work and the difference in comfort has been dramatic. Total cost was $1800 and will pay for itself in less than 2 years. My bill for the year will be around $600, and the house is much more comfortable and we've increased the temps to 70 on the thermostat for 2 more hours and maintain 62 at night and during the day. Air sealing my duct system in the basement lowered my basement temperature 10 degrees (its only used for storage) and gave more heat to the main and second floor rooms making them more comfortable and it seems easier to heat. I'm heating 1800 square feet plus a 3/4 basement for $600 with only around 50% of my walls insulated at this time.

In your situation the heat loss in your ceiling is condensing on your roof sheathing and creating little icicles which you can solve and it isn't necessary to have someone come in, suck up all your old blow in and use spray foam on the entire ceiling when you only need to foam a fraction of that square footage. Focus on foaming penetrations, gaps and holes and then install adequate insulation, ditch the ceiling fan. Seperate your roof deck from the insulation with vent chutes. For the drafts are your walls insulated, are your exterior outlet boxes sealed, is the space around your window and door frames insulated with sealant or foam behind the casing? Take a hard look at your duct system, you installed the new furnace, is it balanced and tuned for your ducts? Do you have adequate return volume from all floors? Are the duct joints sealed with mastic or foil tape? Go ijn the basement on a cold day with an incense stick and locate air leakage points and seal them. make sure your band joist and mudsill is sealed and insulated. Make sure you have and use bath vent fans and arent getting excess moisture from an old crawlspace or basment water issues, if you are address them.

All this stuff you could do yourself in a weekend or a competent contractor can address for less than just your spray foam attic bid in most cases. If you really like the idea of useable attic space and spray foam gives you a hard on like everyone else, then by all means pay the money to have your deck sprayed and feel good about that. If you have alot of the issues I've brought up your second floor will be a little warmer, your heat bill will be a little bit less but the house will still be drafty.

Alton,
I see your experiences with shingle warranties and shingle life are the same as mine.

I also see that my 30 years construction experience has been trumped by one man's short term experiences with his own home.

Wes,
Sorry to step on your toes with an example of some simple things anyone can do to reduce energy useage in their homes, God forbid people dont listen to you and spray foam everywhere.
So 30 years of construction experience has told you air sealing and cellulose dont work. That must be a tough pill to swallow.

Alton, Wes it might regional.  The op does not state his location.  Here in central WI,we have been seeing more problems with shingles.  Not due to improper install or venting,  just bad shingles right about  15 years old on a 25 year shingle.

[img]http://images47.fotki.com/v1484/photos/7/783033/4879255/Shingles-vi.jpg[/img]

Hmmm bbcode does not work picture attached to end of post.

13 years old This roof was was warrantied for a percentage.   It was not leaking. It was installed and vented correctly. 

As to the op's question. I would not spray foam on the underside of the roof without and air gap.  In this part of the country it can be a problem with ice dams in the winter.  With the different winters that we have been receiving,  more problems have been surfacing or dripping.  Seal the ceiling with spray foam.  Yes an old house will be drafty and is lots of locations that you can seal off your self over time. 

Well wadda you know, I was going through my inbox and came across this: http://www.cmhc-schl.gc.ca/en/co/maho/gemare/gemare_001.cfm from CMHC, sounded familiar.

Apparently they dont have the experience Wes does, because the only time they mention spray foam is at rafter or truss heels where you may not have sufficient depth for adequate insulation values.
The post is a great source of how to deal with attic issues from a CREDIBLE source that puts big money into studying these issues. It's dirty, dusty work up there but it works, my clients and myself personally can attest to the savings, doing what the newsletter says WILL pay for itself and save you money, even on new homes.

Mike: what was the quote to remove the blow-in and install spray foam?

Greentree,
I live in the suburbs of Philadelphia, I met with the installer earlier on in the week and I am waiting for a qoute. The installer had to go out of town to do a large commercial roof job.

Alton, Carlo and Wes thanks so much for your comments. I think I am inclined to spray the attic floor really well to see how it works. I can't see spraying the roof sheathing because to me I would be paying to heat or ac below the attic roof in the attic, I feel that if I spray the floor, I will stop the heat or ac from expanding in the attic.

I just want to thank everyone again for there input.
Mike

Hold up, that means you DON'T have an insulation problem. The attic is hot, and the house is not. That is what attic floor
insulation is supposed to do. If the house was 65 and the attic was also 65, they you would have an insulation problem.

Secondly, you had icycles on your nails. First, that means your insulation is working, because if it wasn't working, the icycles would have melted.  

Next, Icycles take more than just cold, the take cold and water. That means water is leaking into your attic from your roof somewhere and collecting on the nails. The absolute WORST thing you could possibly do is spray foam a leaky roof and let the water sit and rot out your rafters. (Everyone calm down, I'm not being anit-spray foam, I'm being anti spray foam+leak.)

He may not have water leaking in from the outside. It may be that water vapor is coming up from the living space and condensing on the cold nails, forming icicles.

If the roof seems sound, I'd seal the attic hatch and any other penetrations that could let warm moist air into the attic. Then see if you still get icicles. Of course, now that it's spring, you might have to wait some time.

He may need to inspect his roof from inside the attic during the next hard rain.

I am in the process of getting estimates for a new roof. The roof sheathing may be original 3/8 plyscord douglas fir, there are spongy spots on the roof , no leaks and the nails are exposed about a 1/2 inch inside the attic. In the winter the 1/2 inch exposed nails have frost on them when it gets really cold. I am going to have new sheathing put on with a new roof. Can anyone reccomend a type of sheating that would be the best to reflect heat?

Again many thanks to all

A light colored metal roof would reflect heat. I've seen drawings in some green building books of metal roofing installed on furring strips so there's an air gap between the metal and the sheathing.