Blown in insulation roughing tips

[frogneck77]

I am starting my second house where the GC is using blown in insulation thruout the house-Anyone not familiar with this product its similar to Great Stuff-only doesnt expand as much. Its extremely efficient-The GC is a mechanical engineer and the 5000 fsq ft house has only one air handler with 7 zones. This insulation is becoming more popular in my area as part of the whole "GREEN" movement. The first house I wired with it we ran into a couple problems.(1) Wires are nearly impossible to snake after the fact-In bathrooms we typically leave a large loop above the vanity location with no rough in box-This allows the HO to decide on # of sconces and fixture placement based on mirror size/decorations on the finish stage of the project. With this insulaton my method didnt work too well.(2) The LV rings for all cable/data/phone locations were full of this insulation making the jacks difficult to install without chipping out alot. Has anyone else dealt with this insulation, and if so any tips for rough wiring with it.
Thanks,
Bill

[stickboy1375]

I dont bury wires (EVER) , and i just use deep low voltage rings and just remove some of the insulation at trim out.


One problem I am somewhat concerned with is derating of the cables encased in this stuff.

[electricalperson]

its always good to leave the wires poking out of the wall when they use this stuff. its possible to fish in this stuff but it can be a pain. i was speaking to the guy that installed this stuff the other day at a job and he says it costs 3 times as much as normal fiberglass but you will save that much money in 2 years of using it. its nice stuff but it can be a problem for us

if the foam is soft enough you can reach in and pull chunks of it out easily.

[nizak]

I used the "buried wire" method up until this type of insulation came along. Now I insist that the GC make a decsion on where the fixture will be and place an outlet box accordingly. I know of few homes that didn't sell because the perspective buyers din't like the vanity light that was already in place.

[stickboy1375]

i was speaking to the guy that installed this stuff the other day at a job and he says it costs 3 times as much as normal fiberglass but you will save that much money in 2 years of using it.


I would tell you that also if I was in the market of selling insulation. I'm a firm believer a house needs to breathe by the way.

[electricalperson]

I would tell you that also if I was in the market of selling insulation. I'm a firm believer a house needs to breath by the way.
it looks like it does a better job of insulating then fiberglass does. if i built my own house i would use it

[stickboy1375]

it looks like it does a better job of insulating then fiberglass does. if i built my own house i would use it

What about a house being able to breathe?

[electricalperson]

What about a house being able to breathe?
if the house told me it had to breathe id move out in a second :D

[stickboy1375]

if the house told me it had to breathe id move out in a second :D

:grin: Yeah, I'm just curious as to what harms they find out later on how bad it is to have a house that tight.

[brandon2177k]

FYI, open cell polyurethane foam(the soft spongy type) is breathable and is permiable, and technically is not a listed vapor barrier. Closed cell polyurethane, however, is the opposite and is a listed vapor barrier. Check out this website for more info: http://www.envirofoaminsulation.com/versus.html

[electricalperson]

:grin: Yeah, I'm just curious as to what harms they find out later on how bad it is to have a house that tight.
what could be a problem?

[c2500]

When you use the closed cell stuff, you normally add a fresh air intake system to swap out air. The neat thing is when it is 100+ degrees outside, the attic assembly is slightly above the set a/c temp.

c2500

[electricalperson]

When you use the closed cell stuff, you normally add a fresh air intake system to swap out air. The neat thing is when it is 100+ degrees outside, the attic assembly is slightly above the set a/c temp.

c2500
the houses around here that install the foam put in nice heating/ac systems that do that. i love the cool attics

[brantmacga]

What about a house being able to breathe?

Yeh they need to be able to breathe. Some of these guys are sealing them up way too tight. The lack of ventilation can cause condensation problems, which leads to mold in the house. I've done a few of these lately myself. Fortunately I stopped by after they did the insulation so I could find all of my cabinet lighting wires completely buried in the stuff. Insulation guy said I should have stapled them and left them poking out at the height I wanted them; the staples were there, just buried inside the foam. They do not care!

More info on this stuff.

Icynene Website (http://www.icynene.com/)

I will say it does keep the temp. down. We did a house for a guy who owns an insulation company and he did all of his exterior walls and rafters w/ this stuff; also, EVERY wall in the house was insulated. We were trimming the house in July; I had to go put up some light fixtures in the attic (completely floored). It was probably a good humid 100 deg. outside, and in the attic was just above 85. Usually this time of year attic temps down here reach 110+, and I've been in a couple that were over 120 which is almost impossible to function in.

[infinity]

Is this stuff really called blown in insulation or is it spray foam insulation? I only ask because the two are vastly different. Blown in insulation is chopped up fiberglass that is usually used to add a layer of insulation to attics. Spray foam insulation is like the expanding foam that comes in a can.

[ultramegabob]

there is also blown in "high density cellulose" they blow in wet ground up newspaper material, its a good idea to make sure someone uses duct tape on all your boxes when they blow the stuff in, saves alot of mess when you go back to install your devices on the finish.

[cschmid]

the spray on foam insulation is becoming popular and more cost effective here..I do have some long term questions on the health issues though..by the time most home owners notice the air exchangers are not working they have mold issues..

the air exchangers are required to be serviced every 30 days..filters cleaned anyone here ever do that how about the home owner think they do that..nope..air exchangers are even buried in the attic how cost effective is that..so I believe the health risks out way the benefits for both serviceman and home owner..

I know how hard it is to keep up with the ones we take care of..they are also expensive to maintain..filters, motors and parts are all custom and manufacturer specific..motor only last about 4 to 5 years and are 350 bucks a pop..up here in the frigid north country you even need to have fresh air preheaters to keep from pumping in cool moist air..

[goldstar]

The real fun comes when you have to cut in a remodel hi hat. That "poodle hair" insulation will be falling out of the ceiling for about 20 minutes. Bring plenty of drop cloths.:grin:

[frogneck77]

Thanks for the tips-This house is the closed cell insulation and hardens up alot from what the GC told me. Interesting tidbit- I heard the GC yelling at the framer for putting in too much wood-he said"I specifically told you to use the absolute minimum required by code/structural engineer specs- your extra wood is gonna waste energy" This guy is fanatical about R value and has thouroghly researched all the pros and cons of this installation. He is even using heat exchanging exhaust fans in all baths-by Panasonic. Should be an interesting project

[TwinCitySparky]

I used the "buried wire" method up until this type of insulation came along. Now I insist that the GC make a decsion on where the fixture will be and place an outlet box accordingly. I know of few homes that didn't sell because the perspective buyers din't like the vanity light that was already in place.

Wise advice to have the GC decide where the questionable boxes will go before the rock and closed cell foam gets applied. The closed cell foam is so strong it actually acts as a structural component to the building. It is simply a major pain to dig out when adding a rework box after the fact. Another thing. It gets HOT while it cures to a solid. Smurf tube is your friend if you are installing the low voltage wiring. (Cheap insurance!!) I learned the hard way... I had to dig out some garage opener low volt wires and some alarm zone wiring not long ago with a house foamed in the stuff. It actually melted the wires together in several different places, shorting them out. The insulating company said they would switch to the "open cell foam" (lower curing temp.) because of this possibility when they sprayed around the low voltage stuff. (ya right!:mad: ) that didn't happen.... I too would like to see some thourough, comprehensive testing with regard to derating wire i.e. buring romex wiring in the stuff... John

[George Stolz]

...we ran into a couple problems.(1) Wires are nearly impossible to snake after the fact-In bathrooms we typically leave a large loop above the vanity location with no rough in box-This allows the HO to decide on # of sconces and fixture placement based on mirror size/decorations on the finish stage of the project. With this insulaton my method didnt work too well.
If you look at the instructions for the fixtures, more than half of them require installation to a outlet box mounted to the structure. You should begin requiring specs on the intended fixtures before rough-in, or they can pay for the re-foam and drywall/paint repairs when they decide to make up their minds.

I used to do the same thing before I realized the code violation - 110.3(B) for the luminaire.

(2) The LV rings for all cable/data/phone locations were full of this insulation making the jacks difficult to install without chipping out alot.
Sure - use normal electrical boxes for the devices instead of open LV rings. You can go for metallic 4 squares and conduit if future expansion is desired.

[George Stolz]

I'm a firm believer a house needs to breathe by the way.
I dislike drafty houses. In my area, humidity is about 10% in a driving rain ( ;) ) so mold isn't really an issue for a well crafted house, IMO.

[rexowner]

(2) The LV rings for all cable/data/phone locations were full of this insulation making the jacks difficult to install without chipping out alot.



Sure - use normal electrical boxes for the devices instead of open LV rings. You can go for metallic 4 squares and conduit if future expansion is desired.

Wouldn't you have to run a separate ground wire to
the metallic box since it could be energized by a loose
LV wire? PoE is 48V. Not sure about satellite.

Smurf tube to an orange box or a blue plastic 4-square
that accepts conduit and a mudring would seem
easier than a metal box.

Here in earthquake country, there tends to be
so much metal bracing in the top plates that getting
any kind of conduit (usually smurf tube for LV) to
a box in an exterior wall can be near impossible.

I hate this stuff, but I agree that using a larger normal
box may be the best way to go.

[George Stolz]

Wouldn't you have to run a separate ground wire to
the metallic box since it could be energized by a loose
LV wire?
Code reference? :)

[wireman71]

I'd put my LV wire in to plastic boxes. Sounds like rings will be a PIA with this insulation.

[quogueelectric]

I always used the hot BB method where I heated a ball bearing at the top of the wall and dropped it down where it melted its way down to the bottom. This works well until you heat the BB too much and it sets the wall on fire. You had better have some water available when this happens and extra BB s because when you pour water on one melting its way down it will stop where the water hits it. If you think I am kidding just wait until you have to wire one of these nightmares.

[rexowner]

Code reference? :)

Good point. It's very likely my assumption was wrong.

In my tiny mind I was extrapolating from one manufacturer's
instructions to provide ground wire to their "structured
media center" to mean "metal low voltage boxes like
their smc should be get ground wires", which was probably
not a correct inference.

I looked through article 800 and didn't see anything.
I'm still thinking about where else I would look.

Thanks for making me think about it and disabusing
me of the mistaken assumption.

[George Stolz]

Good point. It's very likely my assumption was wrong.
I don't take it for granted that I'm right, I just never have and don't recall it ever coming up on the forum. As far as I know, no bonding is required.

Manufacturers specs calling for it are likely just belt-and-suspender moves.

[Pierre C Belarge]

Has anyone seen the change in the '05 NEC in regards to AC cables?

320.80 Ampacity.
(A) Thermal Insulation.
Armored cable installed in thermal insulation shall have conductors rated at 90C. The ampacity of cable installed in these applications shall be that of 60C conductors.

I do not see this requirement for MC-Art330, NM- Art 334 or for UF- Art340.
I wonder why this is a requirement for AC cables only???

[mdshunk]

I do not see this requirement for MC-Art330, NM- Art 334 or for UF- Art340.
I wonder why this is a requirement for AC cables only???
Because MC always had 90 degree conductors. The early type AC was just as bad (or worse) than the old braided romex or K&T. I see it every day. I don't have scientific facts, but it sure looks like the conductors in the old type AC were the same conductors formerly used in open wiring methods. Put two of them in a metal tube that holds in heat, and you have cooked wiring after 50 years. Insulate that same cable, and you're adding insult to injury. I think it's a righteous move.

[nakulak]

as for the tel/com/lv boxes,

smurf tube/plastic boxes sound like the ticket to me

[Pierre C Belarge]

Because MC always had 90 degree conductors. The early type AC was just as bad (or worse) than the old braided romex or K&T. I see it every day. I don't have scientific facts, but it sure looks like the conductors in the old type AC were the same conductors formerly used in open wiring methods. Put two of them in a metal tube that holds in heat, and you have cooked wiring after 50 years. Insulate that same cable, and you're adding insult to injury. I think it's a righteous move.


Marc
The conductors in AC and MC cable are the same conductors. Why is this requirement for AC cable only?

There really is very little difference between AC and MC cables.

[mdshunk]

Marc
The conductors in AC and MC cable are the same conductors. Why is this requirement for AC cable only?
Yeah, in modern type AC. I'm talking about old type AC. The only way to prevent old type AC from being insulated is to prevent all type AC from being insulated.

[Pierre C Belarge]

Yeah, in modern type AC. I'm talking about old type AC. The only way to prevent old type AC from being insulated is to prevent all type AC from being insulated.


that makes sense.

[LarryFine]

that makes sense.
Yeah.


Stop it.

[mdshunk]

I see this as a good back-door way to basically require replacement of vintage wiring methods. With the way building codes are written now, it doesn't take too much to trigger modern energy requirements for the structure (or at least the area involved). To meet these requirements, insulating needs done. To properly insulate, vintage wiring methods will need replaced with modern equivalents. That would then trigger much more electrical work than originally planned for, more than likely. From a business standpoint, you can't not be in favor of the change.

[Pierre C Belarge]

I see this as a good back-door way to basically require replacement of vintage wiring methods. With the way building codes are written now, it doesn't take too much to trigger modern energy requirements for the structure (or at least the area involved). To meet these requirements, insulating needs done. To properly insulate, vintage wiring methods will need replaced with modern equivalents. That would then trigger much more electrical work than originally planned for, more than likely. From a business standpoint, you can't not be in favor of the change.


A shorter way to say this is: CHA-CHING!!!

[electricmanscott]

Speaking of insulation and old wiring......Went on a call to repair a phone jack that I installed a month ago. They had the attic and crawlspace insulated and the guy must have snagged the wire and pulled it loose. Lot's of knob and tube in the house which is over 200 years old. They insulated it anyway.

After seeing what they did to the phone wire I can only imagine the damage they did to the knob and tube.

[peter d]

After seeing what they did to the phone wire I can only imagine the damage they did to the knob and tube.

That reminds me of a job I worked on where they ran the K&T right next to the scuttle hole in the attic. The K&T had the snot beaten out of it from people stepping on it over the years - many bare spots.

[mdshunk]

That reminds me of a job I worked on where they ran the K&T right next to the scuttle hole in the attic. The K&T had the snot beaten out of it from people stepping on it over the years - many bare spots.
That doesn't sound like wiring. That sounds more like a booby-trap.

[peter d]

That doesn't sound like wiring. That sounds more like a booby-trap.

Yeah, it pretty much was. You had to watch where you put your hands as you were climbing into the attic. :roll:

[jrannis]

I always used the hot BB method where I heated a ball bearing at the top of the wall and dropped it down where it melted its way down to the bottom. This works well until you heat the BB too much and it sets the wall on fire. You had better have some water available when this happens and extra BB s because when you pour water on one melting its way down it will stop where the water hits it. If you think I am kidding just wait until you have to wire one of these nightmares.

Dont leave us hanging,
What size bearing?
How did you heat it.
how far will it travel?

[cschmid]

So if the insulation heats when it dries and can damage insulation of conductors or even make smurf tube warp..why not use metal flex and metal boxes then your nightmare is only slight challange..Yet at modern day prices I am amazed that people can even afford to remodel..

Would it not make sense to just wire the house in metal flex? then add the wires after they blow in the insulation..

[TwinCitySparky]

Dont leave us hanging,
What size bearing?
How did you heat it.
how far will it travel?

"If you think I am kidding just wait until you have to wire one of these nightmares."

I have wired these nightmares and I think you must be kidding. Hot bearings dropped into the wall cavity?? That is FUNNY!! I can only imagine the ensuing chaos, possibly hidden/existing wires being shorted, and that wonderfull burning smell...

Then actually pour water into the wall cavity to stop it???
Ummm... OK. :D :D :rolleyes:

[TwinCitySparky]

Or another possible result:

Homeowner makes call to plumber saying they smell sewer gas...

Plumber finally opens wall up after pressure testing to find a romex cable running right thru a PVC vent line.

oooomigosh...