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Limited Attic Space, no insulation, need help fast kellykungfu-deja 08-22-2005
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Posted by on August 22, 2005, 12:00 pm


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



Posted by abi on August 22, 2005, 1:03 pm


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



Posted by SQLit on August 22, 2005, 3:36 pm



> 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.

R-30 cellouse is 8.5 inches, just had it added to my home. 10 inches would
be fiberglass


> 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.

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


> 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?

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

> 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.

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.


> 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.

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......


> 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

Talk to some pros in your area. See what they offer and at what price.





Posted by on August 22, 2005, 5:42 pm


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



Posted by Chas Hurst on August 22, 2005, 8:51 pm



> 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

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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