Insulating skirting

[Krunch]

My skirting is Hardipanel. The skirting frame is built of a lower horizontal board of 2x6 pressure treated wood and upright 2x4s every 4 feet for nailing surface of the skirting. I want to install rigid foam insulation to the back side of the skirting. Does it make a difference in the insulating value whether I install the foam board between the upright 2x4s where it would be in direct contact with the Hardipanel skirting or can I just attach it to the back of the 2x4 framing, leaving a 1 ½” space between the skirting and the foam board. By doing that each foam board would span 8 feet and could also come down over the lower 2x6 which would eliminate several cracks where air could get through. It also seems it would be easier to just attach it to the framing than trying to cut each section to fit between the uprights but I’m not sure if there is a downside to installing it that way. I only want to do this once and so would like to get it right and was advised by one neighbor that it should be installed between the uprights. Is he right?

[SpongeBob]

HI there, I think I'm with your neighbor on this one. I believe the 1.5" would be a welcome breeding ground for some lil' critters. Also if you do put it between the uprights, I think it will be stronger and last longer. Hope this helped.

-Bob

[Greg]

Bob is right to a point, but the flip side is that it would create a dead air space if you span the 2x4. Either way you go I would doubt that you would notice any difference in insulation value. Greg

[JD]

As Bob and Greg said, there are points to be made either way. What I see is an easy installation going to the back of the 2x4s. Cutting the insulation in the 4' direction would allow you to use sheetrock type screws and some type of batten on each of the 2x4s to hold in the insulation. The batten could be 1x4 redwood, strips of fence boards or maybe no batten at all. You may be able to just use 1-1/4" fender washers on the screws, maybe 3 per upright.

I have never done this before as there is not much need for it in my area. JMO

I would recommend uprights every 16" though, or at least 24", to keep the skirting from warping.

JD

[Demolition]

I don't think the skirting has to be totally air tight.
Just having it there will help some. It ain't like you are living under the house.
The heat from the ground, about 58*F will help some. Also you want to make sure there ain't no Propane furnaces that might build up under there.
Be sure to put a little door in case you want to crawl under the house... like anybody WANTS to crawl under there.

The main thing is so it don't blow off during high winds.

[Krunch]

Thanks to all four of you for the responses. I think I will go with installing it between the uprights - never gave critters nesting in the 1 1/2" space a thought, but don't want to give them any encouragement. I had planned on attaching the insulation directly to my access doors for easy entry no matter which method I used to install the rest of the insulation. When we bought this house (1986) we ordered upgraded insulation but each year it seems the floors are colder and colder. The insulation in the belly area is the blown in insulation and I wonder, does that stuff eventually pack down and become ineffective? Or, maybe as we get older we are just less tolerant of the cold. Thanks again for you help.

[Manitoba Bill]

Not knowing where you live but up here I had installed insulation on my skirting but took it all off after I learned it did little good unless the crawl space was heated. I then installed it against the underside of the belly where it added to the ins. of my ducting and pipes.

As long as the skirting is intact it's like adding insulation to an unheated shed.

The park where I live, in cold country, also advises to pile snow against the skirting. I have never done this as all it does is rot the wood during the spring and you would have to pile it at least a foot above the average 3' skirting. JMO

[SpongeBob]

Honestly, when an unheated space is insulated, it is basically the same theory as creating a refrigerator. An unheated shed for instance that is insulated will be colder than if it was not insulated.

-Bob

[Krunch]

We live in Northern California so we don't have really severe weather but the floors seems sooooo cold that I was hoping the insulation would help with that. What I don't want to do, though, is create a refrigeration-like area under the house. I may just junk this project or go with insulating the belly area. I suppose large area rugs over the existing carpet would also add a layer of warmth. Thanks all for you help.

[Yanita]

Hi,

I just checked for a profile on your home...you have not created one. What year home do you have. Have you recently checked your underbelly and made sure that the insulation is there.

If this is an older home it is possible that thru the years repairs have been done and the insulation was put back properly or the underbelly material replaced correctly.

You said your floors are real cold and you have carpeting. Are there any significant drafts in your home. Check areas like the outlets on exterior walls, you'd be amazed at how much air can come thru these.

Since you say you do not have severe winters I would think that if your skirting is tight and the vents closed you should be fine in that area...check the underbelly and let us know what you see.

Also completing a profile on your home will help us as well.

Thanks,
Yanita

[Dean2]

I thought of insulating My skirting here in NE IA(can be bitter cold) but decided against it and just wrapped the framing in heavy plastic and then screwed the steel to the 2x2s..Cut/formed some corner caps and walked away basically. My neighbor built and insulated(pink foam board) His around the same time,now 2 1/2 years later He wants the same as I have.He's lucky cause I think I can get more of the same steel.

I would think the belly is far more benefit to have insulated correctly..

Something I'll never do is use fiberglass insulation in the stud cavities of skirting! When I took the old skirting(bad disrepair) apart under this place before moving it the fiberglass was NASTY! Years of dust,mouse trails,probably Shrew trails and one big fat nest of big fat Bumble
Bees! Ticked-off bees to say the least! My helper sprayed them and I batted them from the air with a shovel..They all died or vacated the area real quick and We got back to work! No time to call the Bumble Bee relocaters!! LOL.

Dean