Radiant heat insulation

[nhraracer90]

Hello,
I am in the process of building my 40x50 building and I am installing radiant heat. I already bought the kit from Blue Ridge Company. From what I have been researching, I would need 2 inch insulation under the slab. I was looking at the 2 inch x 4ftx8ft pieces at Lowes and it's going to cost be around $2300 for what I need. Is there anywhere else I can get the foam board? Can I go with 1 inch or is 2 inch best?

Thanks!

 

[toyotadriver]

The less insulation you have the more of your heat dollars will be absorbed into the ground.

1 inch be better than none but go 2 inches if at all possible.

Check a bunch of places. Lowe's usually isn't the cheapest for foam sheets. Not sure if you have a Menards nearby but awhile back I needed some and they beat everyone else's prices on foam sheets.

 

[corrie]

I'm not sure about foam sheets, but insulation is one job that can sometimes be subbed out for less than or equal to the cost of doing it yourself.

 

[Randy in Maine]

Talk to you concrete guy and he can tell you where to buy it. A 4x8 foot sheet of 2" foam cost me about $32 delivered. It was already marked for installing the pex tubing on.

I had them also bring me some 6"x 6" sheets (4x10') of woven wire mesh at the same time for securing the pex to the wire. That was cheap like $6 a sheet. Get some of those wire twist ties to secure the wire sheets to the next one. Get a bag of zip ties to secure the pex to the wires.

 

[Firebrick43]

Talk to you concrete guy and he can tell you where to buy it. A 4x8 foot sheet of 2" foam cost me about $32 delivered. It was already marked for installing the pex tubing on.

I had them also bring me some 6"x 6" sheets (4x10') of woven wire mesh at the same time for securing the pex to the wire. That was cheap like $6 a sheet. Get some of those wire twist ties to secure the wire sheets to the next one. Get a bag of zip ties to secure the pex to the wires.

The wire "bag ties" are fine to attach the pex as long as you don't tighten them to much. They should be a little loose. The are 4 or 5 times faster than zip ties and you don't have to clip all the ends off

 

[kabinenroller]

Look for the best deal on comparable products and spend the money on insulation now instead of energy and wear and tear on your boiler later.
Don't forget the vapor barrier!
You cannot over insulate, when you think you have enough add some extra.

 

[Aquamoose]

Google "insulation" and click the maps tab.


Sent from my iPhone using Tapatalk

 

[NotOrganized]

I was able to get a good deal on foam from a company that makes signs and wall plaques. The type where they spray stucco or concrete over the formed foam. We put 2" under our house slab and heating via floor loops is quite economical.

 

[toyotadriver]

EPS will be the cheapest if you can find the dense version that's rated to be used under concrete. XPS will be my preference but probably a bit more expensive.

 

[tdkkart]

If you're going to spend money spend it on insulation now, not on heat later. If I had it to do again in my 30x40, I'd put in 2 layers of 2".

Current price at my Menards is $29.90/sheet.

 

[nhraracer90]

I was looking at the Foamular 250 from Home Depot possibly. Will that be able to withstand everything (concrete, pressure, etc..)?

 

[theoldwizard1]

There are places on the internet that sell reclaimed/seconds of rigid foam board. Typically you have to pick up up yourself. A friend of a friend saved over 50%.

 

[toyotadriver]

I was looking at the Foamular 250 from Home Depot possibly. Will that be able to withstand everything (concrete, pressure, etc..)?

That should work fine. The 150 isn't dense enough to put under concrete as I understand.

 

[4cyclic]

Look for Greenguard 2 inch 4x8 sheets. The tongue & groove is deeper than 250 Formular. This was recommended by my concrete guy. More flexible when you walk on it and deeper mating groove. I agreed with him and ordered the better boards. No regrets , 42x72 slab.

 

[BadgerBoilerMN]

There are places on the internet that sell reclaimed/seconds of rigid foam board. Typically you have to pick up up yourself. A friend of a friend saved over 50%.

15 psi minimum.

We use 2" XPS here in Minneapolis. In your relatively mild climate 2" is more than enough.
The same goes for EPS, coffee cup white, but you will need twice as much to get the same R-value as XPS.

 

[nhraracer90]

Will this insulation from Home Depot work? Its 2 inches thick.

http://www.homedepot.com/p/Thermash...-Rigid-Foam-Insulation-Board-613010/100573703

 

[Firebrick43]

No, you don't want poly isocyanate foam in contact with the ground as it can absorb more water than extruded polystyrene (XPS) or expanded polystyrene (EPS)

It's also much more brittle than other foams.

 

[nhraracer90]

Okay. The Home Depot around here has to order the foamular 250 (takes about 1 1/2-2 weeks to get) @ $30 sheet. Lowes has the greenboard in stock but @ $36 a sheet.

 

[Aquamoose]

Did you ever search for insulation companies near you?


Sent from my iPhone using Tapatalk

 

[nhraracer90]

Yeah I did and I believe our local lumber company 84 Lumber can it for $32.80/sheet. It's the DOW blue foam board. Home Depot can get it but it will take about 2 weeks to get.

 

[Randy in Maine]

Do any concrete supply places have it down there? They all do up here.

 

[Northislander]

Not sure if you have time to do this but. When i built my last shop i collected window cut outs from exterior doors at my local door store it is Polyisocyanurate so can absorb water but with the ground seal under and my dry ground conditions its not a problem. It took me a year to collect enough to do two layers covering 1000 sq.ft. Each layer of doors gives an r value of 9.8 for a 1-3/4" thick door giving me an r value of almost 20 for free. Bonus was i got a lot of full doors once the guys new what i was doing they saved all the scratched and damaged full doors also.
In the process of building my new shop in the spring this time ill be buying the insulation as i didn't plan ahead.
Kevin