Spray Foam Insulation Melting wires?

[Hari_Seldon]

My new home is under construction and I plan to wire for security, automation, audio and video before we seal up the walls. We are planning to use spray foam insulation (Icynene) in the walls and ceiling. I believe as spray foam cures and expands it can get very hot. I am concerned that this heat could melt the jackets of some of the wiring in the walls.

Does anyone have experience with spray foam insulation? Must I protect my wiring from the heat of the spray foam reaction?

I'd bet that security wiring is probably fine. RG6 and CAT6 may also be as they are mostly used in wall cavities. I am most worried about audio/video cabling (i.e. HDMI).

Thank you,
HS

 

[nightwalker]

My new home is under construction and I plan to wire for security, automation, audio and video before we seal up the walls. We are planning to use spray foam insulation (Icynene) in the walls and ceiling. I believe as spray foam cures and expands it can get very hot. I am concerned that this heat could melt the jackets of some of the wiring in the walls.

Does anyone have experience with spray foam insulation? Must I protect my wiring from the heat of the spray foam reaction?

I'd bet that security wiring is probably fine. RG6 and CAT6 may also be as they are mostly used in wall cavities. I am most worried about audio/video cabling (i.e. HDMI).

Thank you,
HS

Most new homes built these days require some type of seal, either spray foam, or fire caulk. I can't say i've noticed any ill effects with either, unless you are trying to add wires later.

 

[DavidL]

My home has a lot of spray foam for both structural and excellent thermal properties. There isn't any issue with heat affecting wires during spray or post.

It is a PITA to run wires later, so plan ahead.

Also, don't run spray foam to seal windows / doors due to the expansion affect and very little compression post install to compensate for house movement / shrinkage.

 

[pkoslow]

I've only done a couple jobs now where spray foam was used and haven't had any problem, but you do have a valid concern. The heat generated if the foam is not installed properly can melt the insulation on low voltage (and even high voltage romex). the guys I've worked with say the trick is to spray a quick thin layer over the wires and let it expand before shooting more over the top.

I guess if you spray a big, thick, heavy coat on all at once it can get too hot and cause a problem. I wasn't around when they shot the foam, but from my understanding, regular ceiling and wall cavities aren't applied thick enough to cause a problem. Trouble can happen when foaming in corners of unfinished attic space, in soffits, and other odd areas where an installer may tend to shoot thicker layers of foam. This also tend to be areas where a lot of wiring can be run.

I don't know about the temperature rating for HDMI cables. I'm sure they vary my manufacture and model. I don't have any experience with spray foam and HDMI yet...

Cheers,
Paul

 

[123]

When you look at how residential construction techniques have evolved over time you realize that there's more attention to little details, and far more "sub-systems" in place, than in the past. The goal nowadays is to build a "machine" whereas in the past it was a (drafty) piece of furniture. Today's home is more like a refrigerator than simply "four walls and a roof".

If you're going to build a machine you should consider making it serviceable. I'd give serious consideration to running cables through conduits as opposed to entombing them in dense foam ... if your local building code allows it. Just another little detail that sounds like a lot of trouble today but may become the norm tomorrow.

 

[BraveSirRobbin]

We had foam sprayed in every hole penetrated by a wire (high and low voltage) by our builder here. The goal was to make the home "energy star compliant". They even did a pressure test where they actually replaced the laundry room door to the garage with one that had a special attachment that went to some kind of blower on a truck and did a "leak" test (I don't know all the details as I was not present at the time). We got a lovely certificate suitable for framing stating that our home is energy star compliant!

 

[Sacedog]

I asked this question of our builder here in CA, as some sort of insulation in all holes is required for Title 24. Everyone uses foam, as did our builder's insulator sub. I actually went around and did a lot of the big holes myself, and haven't noticed any problems. My only suggestion would be that a little goes a long way!

 

[huggy59]

I think you'll find that there are different types of foam now that are used in different places. There's even a special type for around doors and windows that expands slowly and remains somewhat flexible to allow for settling and expansion/contraction of materials. Make sure you use a knowledgable, qualified, and quality-concious contractor.

 

[DavidL]

I think you'll find that there are different types of foam now that are used in different places. There's even a special type for around doors and windows that expands slowly and remains somewhat flexible to allow for settling and expansion/contraction of materials. Make sure you use a knowledgable, qualified, and quality-concious contractor.

My home has the slow expand around windows....mistake.

 

[Ranger Digital]

We ONLY build with spray insulation. Our first test resulting in PERFECT contectivity of EVERY wire. We were pleased with the results and expect zero problems from any type of heat transfer from spray foam.

What was our test? All security, audio, automation, sensor, etc. wires were installed. Spray foam installers completed their installation. Prior to drywall going up we re-tested all connection. All passed 100% as they continued to show the proper conectivity. These were OUR results. Does this mean YOUR install will net the same results? Who knows. I, in no way guarantee the same results for your test. That my legal disclaimer, LOL.

I would IMAGINE if spray foam resulted in unsatisfactory results for LV wiring, we would have heard, seen, read the warnings somewhere. Thus, I remain confident in the combination.

BTW, I dont think spray foam can be beat.

 

[Hari_Seldon]

Thank you all for your input. In talking with the insulation and low voltage wiring installers I learned there are 2 ways that spray foam can damage wires (which some of you brought up as well):

1 - If wiring is not secured, expanding foam can push it out past the studs/joists. When the insulation crew trims the excess foam (with a hot wire), they may cut/nick these wires as well.

2 - If too much liquid foam is applied then heat can build up and potentially exceed wire temperature ratings.

I'm told that #1 is far more likely than #2. An experienced installer knows to add liquid foam in layers to avoid #2. To avoid #1 I'm going to triple check every run to make sure it can't be pulled out too far.

Thanks for all of your help.
-HS

 

[thewireguy]

Thank you all for your input. In talking with the insulation and low voltage wiring installers I learned there are 2 ways that spray foam can damage wires (which some of you brought up as well):

1 - If wiring is not secured, expanding foam can push it out past the studs/joists. When the insulation crew trims the excess foam (with a hot wire), they may cut/nick these wires as well.

2 - If too much liquid foam is applied then heat can build up and potentially exceed wire temperature ratings.

I'm told that #1 is far more likely than #2. An experienced installer knows to add liquid foam in layers to avoid #2. To avoid #1 I'm going to triple check every run to make sure it can't be pulled out too far.

Thanks for all of your help.
-HS

I have done a couple of installs with the customer used spay foam. The most important step is securing the wiring. The foam expands with a tremendous force so what I did secure the wires about every foot. It takes a lot extra time but I have not had one bad wire when spray foam was used.

Run every wire you can think of now because once the walls are foamed you will destroy the foam if you try to fish wires later.

 

[86turbodsl]

I have done a couple of installs with the customer used spay foam. The most important step is securing the wiring. The foam expands with a tremendous force so what I did secure the wires about every foot. It takes a lot extra time but I have not had one bad wire when spray foam was used.

Run every wire you can think of now because once the walls are foamed you will destroy the foam if you try to fish wires later.

Our new house just got foamed today. The secret is to use closed cell foam and only 2-3 inches thick on a 2x6 wall. I have 3-4 inches
of dead air space between wallboard and insulation to run future wiring or whatever. My walls are about R19 or so with 2.5 ish inches.

That's more than enough. 80% of heat loss is through ceiling and about 15% through walls.

 

[politics123]

I have done a couple of installs with the customer used spay foam. The most important step is securing the wiring. The foam expands with a tremendous force so what I did secure the wires about every foot. It takes a lot extra time but I have not had one bad wire when spray foam was used.

Run every wire you can think of now because once the walls are foamed you will destroy the foam if you try to fish wires later.

Our new house just got foamed today. The secret is to use closed cell foam and only 2-3 inches thick on a 2x6 wall. I have 3-4 inches
of dead air space between wallboard and insulation to run future wiring or whatever. My walls are about R19 or so with 2.5 ish inches.

That's more than enough. 80% of heat loss is through ceiling and about 15% through walls.

True, you have space, but one of the distinct advantages of 2x6 walls is the ability to fit in more insulation. I'd rather have hyper-insulation. It seems like a way to protect yourself from future upgrades and expanding foam is to run conduit.

 

[thewireguy]

Our new house just got foamed today. The secret is to use closed cell foam and only 2-3 inches thick on a 2x6 wall. I have 3-4 inches
of dead air space between wallboard and insulation to run future wiring or whatever. My walls are about R19 or so with 2.5 ish inches.

That's more than enough. 80% of heat loss is through ceiling and about 15% through walls.

That defeats the purpose of spay foam.

You can use Carlon products for flexible raceways and low voltage rings.

Carlon products