Limited Attic Space, no insulation, need help fast

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Hi Everyone,
Hopefully this makes sense and sorry for the long post.
I live in San Francisco, CA where the extreme temperatures are not that great, no frost and hardly anything above 80s.
My home was built in the late 30's. There is no insulation what so ever and no access to the attic.
I'm about to have my roof redone and wanted the roofers to pull up the wood planks so that I can insulate the home.
Here is where I get a lot of conflicting information, from the roofers/insulators/electricians that I spoke with.
Half the house has been transitioned to romex wiring. Since the house was built in the 30's there is also knob and tube wiring. Most of this serves the overhead lighting for the hallway, bathroom, bedrooms and dining room. So basically, the knob and tube wiring isn't used for any of the outlets and does not have a high load.
The house is single story that is roughly 25 feet wide by 60 feet long. The roof is flat, both ends slope towards the middle of the home for drainage. There is a four inch vent people that leads to this "attic space" and does some venting.
Hopefully, I have the right terminology right here. If I describe the cross section correctly, there are the roof rafters 2x4s (could be 2x6), then a space of about 4-8 inches (guess this might be considered the attaic space), then the ceiling joists 2x4s (could be 2x6). The knob and tube wiring is up here in the so called "attic space".
When I talked to the insulation people they said that they can blow in the celluse insulation to the very top of the roof rafters about 10 inches worth, to give a R-30 rating. The roofing people said that it was a bad idea to blow that much in because there may be a chance of condensation/moisture issues because its mostly dead space and will cause the wood to rot.
The electrical people didn't seem to care what the insulation people did but just need to certify that the knob and tubing was in good condition.
So my questions are:
1)Should I insulate to the very top of the roof and get the maximium R-Value and risk the chances of moisture? Remember there is no access to this area so once this is done, it'll be sealed up forever. Or until, I find out about some horrible mold or wood rot issues years down the line.
2)Should I just insulate the 4-5 inches worth so at least some of that "attic space" is retained so that moisture can be vented through that 4 inch vent pipe?
3)Should I just not insulate the home? Would 4-5 inches of insulation make any difference?
4)The roofers sugested a special foam/something or another sheet that they can add on the roof deck that gives a R-15 for 1/4 thickness. I thought this was exeragerated and was very costly to do, about 2400 just for that part of the job.
5)I have some recessed lighting (from Lowes), it says on the can that its thermal protected, but does not say if its IC rated or Non-IC rated. Should I just keep the insulation away from the can? If so how should I do it? I saw some websites that use metal flashing to create a cylindar shape to keep the instulation away. I think I even saw on the CertainTeed website, they had a cardboard box with the top removed to keep the insulation away.
6)To prevent any of the cellulose and or cellulose dust from getting into the home, can I use that spray foam to seal up (without getting a lot into the box) the area where the wires enter the boxes for the older existing lights? And also around the boxes too?
Please, if there are any home inspectors or knowledgeable folks in this area please let me know so I won't make a mistake.
Have a good day and God bless.
Thanks in advance, kelly
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Foam would probably be your best bet. Even an inch all over the ceiling would do what needs to be done. Your problem probably isn't conductive heat and cold transfer, as in through the ceiling drywall or plaster, given your stable climate.
That means you will probably get the most benefit from a good air seal. Foam is dustless. No worries there. I'd say you could get the whole attic floor covered with 3 of the foam kits at http://www.tigerfoam.com and they do have a way to get it in there through the roof if you remove a couple of slats here and there. You'd have to talk with them. Ask for Sam. He knows about the extension if you need it.
This will cost about $1,800-$2,000, but it'll do the job dustless (my favorite) and seal like nothing else can, but may be outside your budget.
Just an option. Personally, I like PU Foam for insulation and sealing. It doesn't settle, as any blown in insulation will. Cellulose is better than fiberglass, but I don't like the dust, eventhough it is just nuisance dust. I have enough problems trying to breathe in this world as it is! (asthma)
It's also E-84 fire rated, but you should definitely get covers on the lights. Safety first!
abi
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R-30 cellouse is 8.5 inches, just had it added to my home. 10 inches would be fiberglass

Have not a clue cant see it very well. The fog must have come in again.

Insulation does make a difference, how much is the issue.

1/4 thickness of what? inches? If it is inches please provide manufacture and model number.
Foam under the new roof might be your best bet. Probably more expensive. But less hassles. One guy does it all, with any luck.

Card board is flammable, should not be used for the recessed cans. A drywall hat would work. They are a pain in the ass to make and to install. Insulation should not be next to any recessed can that is not rated to be in direct contact with insulation. Some can manufactures say 6 inches of clearance. Wow that sorta puts a hole in the insulation......

Talk to some pros in your area. See what they offer and at what price.
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It seems to me that cellulose has two drawbacks- 1) It is flammable. 2) It is biodegradable and can support the growth of some micro-organisms. The manufacturer could add biocides to limit this second issue, but the underlying problem remains. Polyurethane foam OTOH is inert to most micro-organisms but is flammable. Flame retardants can be added but if the surrounding wood supports the flame, it will still burn but with a lot of toxic smoke. Could I suggest a small layer of fiberglass insulation on the attic floor? It is not as an efficient insulator as the others, but from your description of the temperature extremes you don't need that much. By the same token, it will not cause as much overheating of the wiring and will not by itself burst into flame if that were to happen. If access for laying an insulation matt is problematic, I believe fiberglass can be blown in the form of "chops" much like cellulose insulation. Perhaps another poster has details on this.-Jitney
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Cellulose is treated with flame retardant. That same flame retardant (boric acid) is a fine insecticide. I would be much more concerned about toxic smoke from drapes, upholstery and carpeting.
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Cellulose is treated with flame retardant. That same flame retardant (boric acid) is a fine insecticide(snip) That would work. I stand corrected.-Jitney
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Wow, thanks for all the responses everyone!
Here is a pic of the ceiling to the "attic space" to the roof rafter.
http://us.f3.yahoofs.com/users/41a50c03z69b19add/782f/__sr_/3533.jpg?ph3IrCDBOldFdIcO
The minimium amount of insulation could be the green arrow(about four inches). However, I would like to go to the red arrow (about 6-7 inches but below the knob and tube wiring). The insulation companies that I called said they would do a R-30 rating, so the knob and tube would be covered, as soon with the yellow arrow.
Also, I'm selecting celloluse because of the low cost, natural material and flame resistant. I'm thinking about the Cocoon brand that can be viewed online at http://www.cocooninsulation.com
Thanks again, kelly
snipped-for-privacy@yahoo.com wrote:

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Sorry everyone, here is a better link:
http://pg.photos.yahoo.com/ph/kelly_kung/my_photos
Any ideas or comments about the moisture or condensation? Or should I just fill up the entire cavity?
-kelly
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Who did the wiring job? It looks like a bunch of 4-year old Special Olympians were turned loose in your attic.
Better get the wiring corrected before you insulate.
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(boric
and
I have heard health warnings regarding loose glass fibre floating around, so I'd avoid "chop"! There may be roll-on matting of an alternative synthetic material available to you, but that requires access. Look at foam in-roof, or under sheeting, again.
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I beg to differ on a couple of points. Cellulose insulation isn't flammable. There are a lot of borates in the formula that make it impossible to ignite. Grab a handful at Home Depot and put a torch to it. I have. Won't burn. Foam is flammable, but there are formulas available today that aren't like they were 10-15 years ago. Foam burns, but the smoke, though colored differently than the smoke from the wood (less water vapor in the foam) the chemical make up of the foam is no more toxic than the smoke from the treated lumber. That is a fact.
Also, most foamers will build a drywall high hat and surround it with mineral wool and foam around that. Mineral wool doesn't burn at all.
But, this application seems more of an air sealing application than a insulating application given that the extremes in temp aren't a factor.
Of all the options, what is the best air seal choice? Not the fiberglass, that's for sure.
abi
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If it were my house I would replace the crappy old knob and tube wire with something good like armored cable and have foam put in so you can get good R value with enough space left open for venting (add vents if you need to). I would also be tempted to replace the in house light fixtures with new ones that could support some serious weight so that I could put in ceiling fans if I wanted to. You really need to get rid of that old wiring for insurance purposes.
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I don't know the answers to your questions, but make sure you do not put insulation on top of the knob and tube wiring. It is against code and it is a fire hazard to do so.
Dimitri
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D. Gerasimatos wrote:

I believe that is correct. Knob and tube by itself is very safe wiring. It will support more power than today's cables of the same size. However I seem to recall the prohibition against covering it.
--
Joseph Meehan

Dia duit
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Hi Everyone,
Wow, newsgroups are the best!!
In San Francisco, knob and tube wiring can be covered with insulation (fiberglass or cellulouse but not foam), just as long as a qualified electrician inspects it and qualifies it with a certificate. I'm also more curious to what everyone says about the humidity/condensation.
Thanks
-kelly
Joseph Meehan wrote:

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snipped-for-privacy@yahoo.com wrote:

That is more of a tough one, as local conditions come into play.

--
Joseph Meehan

Dia duit
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"It will support more power than today's cables of the same size."
Huh?
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I think what he means is that the wires that were used for, say 15 amp circuits before are a larger gauge than those used now. You could run 20 amps over K&t circuits designed to run 15 amps - at least in terms of the gauge of the wire.
Dimitri
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wrote:

I think it's reference to insulation or lack of. With no insulation the wire dissipates heat faster, hence the higher rating.
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"I think it's reference to insulation or lack of. With no insulation the wire dissipates heat faster, hence the higher rating. "
OK, I'm officially terrified now.
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