3" thick isocyanurate 4X8 foam boards

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I used these on the porch cieling and it works great - doesn't let any heat from the sun get through the roof to YOU sitting under it!! That combined with side breeze makes the front porch really komfy!!

QUESTION: The underbelly still isn't done...I've been putting it off and then when I get ready to do it another catastrophe happens. I want to DO the underbelly this winter. I would like to use the same pink boards I used for the porch under the home. The plan would be to use "extenders" off the floor joists and fasten the isocyanurate boards to this. THEN, I would block all the openings in the underskirting and begin to sleep through the night.

The home is a good 3-4' off the ground - plenty of room even for me to crawl / kneel around. Any reason why this would not work?....

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I can't see any reason why it wouldn't work. Just build it with enough support so that it will survive any strong winds that you may get, that job is not fun to do the first time. Greg

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Could I ask where you purchased these boards? I've been looking around for some. Thanks.

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Hi Nichodemus; I get them at Home Depot. Lowes only carries the thinner 1/2 stuff. This stuff has R values of 19++!!

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Hi Mark,

It should work just fine!

Just keep in mind that if you have any plumbing leaks or heating duct issues down the road, you'll need to cut into the foam board to find the problem. That's the main reason that fiberglass bat insulation and belly material is recommended. The insulation can be easily replaced and the belly material can be repaired easily!

Plenty of folks have used the rigid foam board down under. Maybe someone will chime in with the pros and negatives!

Personally, I prefer an easy access to the pipes and heating ducts.

Maureen

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Hi Maureen - yup, I was going to install access panels to the pipe area duct area. I was thinking of maybe 4-8 clips per panel; if access is needed swing the clips to one side, remove the 64oz (they're really LIGH weight) panel then re-install when servicing is through.

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Hi Mark,

Haven't heard of anyone trying this, but that doesn't mean that it won't work!

You're located in a mild climate (normally), so this might just work!

Give it a try, and report back to us!

Maureen

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Quoted From: loveoldtrux

Hi Nichodemus; I get them at Home Depot. Lowes only carries the thinner 1/2 stuff. This stuff has R values of 19++!!

I covered my whole crawl space with 1" blue Styrofoam Wallmate rated at R5. Light, easy to cut and fit and no fibreglass all over your face and arms.

I used 3" washered nails right into the joists. For the 3" I would use 4" screws with washers. Screws are easy to remove when needed.

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Hi Guys,

One very important aspect that I forgot to mention was, that your belly is meant to 'breath' to some point.

Using the foam panels, will lock in moisture under your home! This can cause mold on the subfloors.

If you live in a very dry area, you might be able to get away with it. I live in a very, very dry area and I wouldn't totally block airflow there.

Just one more thing to keep in mind guys!

Maureen