attic insulation question

Home repair ignoramus here.
My boyfriend wants to insulate the attic. We don't intend to turn it into living quarters. We just want to help keep the heating bills down. He says he wants to insulate both the roof and attic floor. I say just to do the attic floor. By the way, there is no ventilation in the attic...no soffits, no ridge vents, no attic fan. This is something we will be dealing with eventually, but my thoughts about insulating just the attic floor have to do with allowing the attic to breathe a bit.
What do you folks think?
TIA for your opinions, bonnie in Oklahoma
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Bonnie Jean wrote:

Well the conclusion is definitely the correct one albeit slightly wrong in reasoning. If were to do both, would end up w/ high probability of a condensation problem and that is almost always an issue against a roof.
You definitely need some attic ventilation and it really ought to come sooner rather than later (the "eventually" prompted me to say that)...
--
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Venting is not the only answer. Take a look at The Building Science Corporation web site. It includes work by building reasearchers. This is a link to a series of pieces on vented and unvented roofs. http://www.buildingscienceconsulting.com/resources/roofs/default.htm T
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wrote:

Great website. Thanks. The house was originally built in 1961. The attic is kind of divided up in compartments. The second floor has gables with small attic/storage spaces between and on the sides of the gables. Over the second story room is another attic space, about 4 feet tall. There is an A/C unit up there which is just for the second floor. It was put in many years after the home was built.
We also need to insulate the walls. We don't think there is any thing in there. I guess you'd have to shoot that foam stuff in there. Is that a job for a professional? We have aluminum siding which I hate. (White stuff rubs off from it. Oxidation???)
bonnie in OK
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Venting and insulating the floor is the best practice. Remember Venting is #1 adding insulation is #2.
--
Joseph Meehan

Dia \'s Muire duit
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wrote Re attic insulation question:

I would do just the floor, and vent the attic also.

Where in OK? I graduated from OU many years ago. I loved it there :-)
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Ponca City/Osage County. I was born and raised in NYC but came here via South Jersey and Pennsylvania. BIG change but I like it more than I expected. Very pretty countryside.
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wrote:

Somewhat unusual not to have any attic ventilation. You are correct, just insulate the floor.
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no vents is not normal, but unless there is mold on the attic ceiling that was its design, it worked. Only the floor should be insulated , and at maybe R 40-50, but then you must get sufficient venting to keep the attic temp near to outside temp or condensation, mold and rot happen quickly.
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There is no mold or mustiness. The attic spaces are all dry. If (emphasis on If) the attic is presently functioning with even flow of moisture/air and heat/cold...and I put insulation on the floor, I can see how that would change the "balance" since air wouldn't be rising through it. Is it possible it would reach a different equilibrium...just base on changed circumstances? Am I making any sense?
b in OK
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Unless there is clearly already a vapor barrier, be sure to install one or use insulation with one. The vapor barrier goes between the heated area and the insulation. This will at least decrease the moisture getting into the attic to cause problems. Venting should still be done ASAP.
Bob
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BTW in certain instances the use of ' certain oil' based (non-latex) paint on 'interior' surfaces will act somewhat as a non permeable vapour barrier. A certain house here that the owner couldn't keep paint on. Problem, outside husband was painting with non breathable (non- permeable) marine paint. Inside wife was painting with latex paint (easy to clean up with water etc.) No vapor barrier on warm side of the walls and ceiling, lots of cooking etc. moisture trapped in walls, outside paint blistering. The owner never did figure it out. Eventually put vinyl siding on and now has some rot problems inside his walls!
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Insulate ceiling only. Ventilate the attic. It's not a matter of 'allowing an attic to breathe a bit' a rotted roof is expensive to replace. For example; Canada standard IIRC is 0.3% minimum percent venting 'distributed in such a way as to allow cross-ventilation. (That's a 'minimum' of three square feet for every 1000 sq. feet of attic area. We have added soffit vents a couple of times to our approx 2000 sq. foot attic, over the years to ensure adequate ventilation and in summer we also open a screened hatch in one gable. Potential rot and mould up there without venting is likely, depending in part on your climate and life style. Also check the vapor barrier of your ceilings to minimize warm and therefore damp air reaching the attic. You are completely on the right track. It's amazing how many people do not understand the importance of NOT having moisture condensing up there. Do some more reading on vapour barriers. On a regular basis we even have people asking 'Is it Ok to vent a bathroom or a dryer into the attic"! Not realizing apparently that all those pounds of water in warm damp air will condense somewhere up there!!!!! Mushrooms/fungus anyone?
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i think youll be ok insulating the attic floor .
http://www.minibite.com/america/malone.htm
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