Informal Quiz on Radiant Slab Insulation

marc

Dow EPS 2" insulation typically in the 250 board (25 psi) It is the only one that has R-10 stamped on it for labeling. Also, our state requires R-10 as a minimum for insulation under a heated slab.

Marc

Supply House Rick

What Products Do You Use?

Please list features & benefits. R-Factors etc. Thank you for your time...

Rick

Supply House Rick

Thanks...

Anybody else?

Jeff Lawrence_25

I use

Slab Sheild. It may not be the best there is, but we have termite problems around here and they just LOVE the blueboard.

It's tested to R-2 under the slab weight.

One local inspector looked at a radiant job locally that had the Blue Board under it and turned it down.

Ragu_5

Slab Insulation...

Dow 2 inches@R10 for under the ENTIRE slab and around the perimeter. No ant problems to date in Coastal Maine.


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Unknown

put sand under the insulation. termites hate that.

In georgia, though, I won't yell at you too much . Just make sure to do a real insulation for those slab on grade vertical edges!

hr

I've dabbled with a few

of the thin roll products, but have gone back to Dow or Corning 250 boards. 1" under the slab 2" edge.

I've been on two jobs in the last month that didn't insulate the slabs at all! $800 monthly energy costs and one fellow blew the power company transformere off the pole running the electric boiler and two heat pumps with strip heat. And still a 60F space!

I still struggle with a neat way to detail that edge insulation, however. On metal buildings we get a Z trim built. Much tougher on residential home slabs and garage door edge insulation.

I'm not sure what to do about termites. I know they live, and eat, around here

hot rod

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Jeff Lawrence_25

Did anyone tell the termites?

Rob, As much as I appreciate your comment about the sand, it's up to the AHJ to approve or reject it. What do you think they'd do? Especially without hard evidence to support sand under the insulation?

There's not too much we can do around here regarding the edge insulation at all. Slab Shield isn't linear in it's insulating ability (2 layers will NOT double the insulating value).

Unknown

Of course it will. The same nearly nothing will double to double nearly nothing. Or, go from a 1.5 to a 3, roughly. Because you are getting no reflective benefit from the insulation at all, so what you actually get is linear. I'm being a little flip there, but the numbers are real enough.

Let me get this straight.. they can't get through slab shield? Then I have your answer. Put down your slab shield, and put foam insulation on top of it.

Otherwise, I fail to see any benefit to the slab shield at all.

Ken_40

Ants?

We don't got no problems wit no freakin' ants anymore.

We set one 55-gallon drum of chlordane in the middle of da floor before the pour, pop a few hollow points below the grade into da barrel and lock da doors overnight.

By morning, we jerk da barrel out, lay the tube and wire out and pour.

After the job's done, we take the barrel and burn all the PEX scraps in it. We had one job, it burned for tree months.

My father taught me all dis. Too bad. He died when he was 23.

But I'll tell you dis: We never had no freakin' ants.

Never. Not even one.

Wayco Wayne_2

I like BARRIER

insulation under the slab and 1 inch of blue board around the perimeter. BARRIER is 1/2 inch foam, is flexible and comes in rolls. R 2.5. As you get away from the edge theres not a lot of heat loss under the slab, so you don't need a lot of R value. Most folks use 2 inch blueboard because it won't break when you walk on it. R 10 is over kill for under slabs here in MD. WW

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Ron Gillen

Type 2 Expanded polystyrene

I use 2" Type 2 EPS under the entire slab. That's about R8.8 and less than half the price of extruded polystyrene. We don't have termites in Alberta but I read about a termite resistant EPS that is now available. Don't know if it's approved everywhere.http://www.r-control.com/performguard.asp

Jeff Lawrence_25

Too bad

Chlordane isn't sold any more...

Of course, the ants would need fur coats up there, both in Joisey and Vermont.

I was telling someone today about your 4 feet of snow that the locals called 'flurries'. Brrrrrrrrrrrrr....

Ken_40

It may not be sold anymore...

But you can still get it.

I have friends that have friends, that know people, that might be able to hook you up.

We could always scope out The Mighty Passaic River! Many unlabelled barrels along the banks. Who knows what we might find.

Jimmy Hoffa perhaps? A little chlordane? Maybe Jimmy Hoffa IN a barrel of chlordane?

Jeff Lawrence_25

You're so far gone

From Joisey that the Chlordane may have dissolved Jimmy by now.

We are under a threat of snow now. Linda's at the store buying bread and milk. I hope she gets home tonight....

Weezbo

Ken, i like this answer *~/:)

my thought is, lay in the two inch foam, by an anteater from one of the white house staff,call it good:)

ANDREW_12

Hey

I use to live by the great passic river. Haha
And Hoffa is under Giant Stadium.

Ken_40

We started that rumor...

Just so guys like you would never think to look in The Mighty Passaic River, its numerous chlordane filled barrels strewn about the banks, or look inside for "remains."

Thankfully, you bought it.

Guest_7

hot rod, i know what your sayin. saw a job that the guy was wasting 100s a month then when the snow came he melted it 5 feet around the house. He insulated the side and the problem was solved.

1" (R5) 5-10 ft around the edges and 2"(R10) on the side

Guest_7

hot rod, i know what your sayin. saw a job that the guy was wasting 100s a month then when the snow came he melted it 5 feet around the house. He insulated the side and the problem was solved.

1" (R5) 5-10 ft around the edges and 2"(R10) on the side

Dave_4

Thank you

For your input...

Jeff Lawrence_25

I've heard of

A similar product that had some kind of termite prevention in it from the factory. The manufacturer said that the product in it was good for 5 (?) years and after that, there was no guaranteed protection. What good is that? There are a lot of people around here that don't have any kind of termite protection at all, but (supposedly) know of the problem with termites around here.

I'll look into the product, it may be what I need.

Thanks.

Constantin

Used XPS... Dowfoam, IIRC.

We had termites here... a lot of them. The house gave them everything they needed: wood, heat, and water. We tore that part of the house off, it could not be saved. I doubt that termites could live here now, considering that there is no nearby water supply anymore. All the roof runoff goes into the cistern, for example.

There are other insulation products for areas where pests are expected. Some of the glass-based insulation "wools" have sufficient compressive strength, IIRC. Also, the Canadian home mortatge study that debunked the barrier foils also mentioned encapsulated urethane panels. Such encapsulation (steel, I think) should do the trick as long as the foundation stays dry.

Ron Gillen

encapsulated polyurethane

I think those panels were the window cut-outs from steel doors.Great way to recycle.If a guy could find a source, they might even be free.Wouldn't the edges still be subject to termites?

Constantin

I think the idea was...

... that the metal would encapsulate the foam 100%. How all that is to be sealed, I leave to others. I happen to think that XPS with borates in it will likely last a very long time as long as water is not allowed to leach off the borates. Another water management and siting issue.

In this area, land has become so scarce that people build in places that historically have not been occupied... floodplains, steep slopes, etc. As a result, I believe we will see more "outlier" like failures because the sites that houses are built on have also become more extreme.