Dream garage is in sight

[GMJim]

well after applying for a variance for my 34X37 deep garage and jumping through a few hoops and giving the city a few bucks I got the ok to apply for a building permit and should have one in a couple of weeks. As usual a ton of questions are coming up.

I'm insulating under the concrete floor and the guy doing the floor says he uses fiberglass board instead of rigid 2 inch foam board. The foam board is very expensive but provides a R-10 value. He says the fiberglass is R-12 and is less expensive and he uses it because it doesn't break up when walking on it when putting the mesh on it. I'm also thinking of floor heat and it's necessary to walk on it quite a bit installing the tubing. I've been looking for fiberglass insulation board to see what I'm getting but can't find any. Is anyone on here familiar with this? Also I need to know if a vapor barrier is necessary with this product and does it go over or under the insulation board.
Any comments are appreciated.
Thanks

 

[matt_i]

I would look for engineering on the fiberglass board to show its compressive strength.

When building, an average soil has a bearing of ~2000 lbs/sqft (psf).

Two common grades of Foamular are F150 and F250 which have 15 psi and 25 psi compressive strengths. Multiply by 144 and you get 2160psf and 3600psf and you can see how these can be trusted.

If the fiberglass is less than 2000 psf/15psi then I think you are headed for trouble.

I would place the vapor barrier directly under the concrete. No sense in having your mix water saturate a possibly dry permeable board before it stops. Keep the hydration in the mix for max cured strength of the concrete.

 

[OptionalStop]

I would place the vapor barrier directly under the concrete. No sense in having your mix water saturate a possibly dry permeable board before it stops. Keep the hydration in the mix for max cured strength of the concrete.

That's an interesting point, I've never seen it done that way but it makes sense. Although I thought this type of beneath grade foam was moisture resistant.

 

[yeldogt]

I would do some research on the proposed insulation -- you don't want anything that can absorb water. Don't assume your concrete guy has any "real" knowledge of the products performance. Once it's covered -- it's covered ... he is on to the next job. When you look at a slab you can't tell what's going on under it.

You will find conflicting information on the proper floor "sandwich". I'm in an area with radon -- while not required by code ... I want a very strong barrier to protect from the radon. I also always do radiant floors. What people don't understand is the insulation is important with heated floors to make sure you don't drive the heat down into the soil as much as it is to protect from the cold outside. In my soil -- 4" of properly compacted stone base -- heavy VB and 2" of foam w/ taped seams ... mesh and the PEX tubes tied to it. 4" of slightly higher PSI concrete ..not too wet. Gets me good results.

I have set up mock samples of the VB and foam -- abused it for weeks. The VB stays intact and is not damaged (by the crushed stone). As long as you don't wait for weeks the tape holds to the foam and stops any excess water getting under it on top of the VB .. the proper concrete helps as well.

I get that having the PEX closer to the surface will provide faster response -- but I use constant recirculation anyway -- so this is really not a concern. I also build on top of the slab -- so I don't want any driven nails to hit the PEX. The mesh is really to hold the PEX .. stronger concrete helps a bit.

Many "experts" ... green building adviser and all associated with them want the VB on top of the foam and say that a few holes is not really a problem. I agree -- except when you have radon. They even say it's fine to staple the tubing to the foam through the VB ... in reality, moisture comes through many parts of a house ... so some tiny holes in a VB under a slab is not really a big problem .. again if radon is not in the mix. In parts of Canada and some areas of the USA the code is VB w/o any holes .... so the VB on top of foam crowd are going to have to change tunes.

My point in all the above is there is not one answer. Some people fixate on the tubing and want it on supports -- other want to use foam products with the built in tubing holders that place the tubing at the bottom. Many in the VB on top of the foam group swear that the foam is going to hold water and never dry .. never happened to me.

I always use the lest water permeable foam available at the time ... that's why your fiberglass jumps out ... better check it out.

 

[GMJim]

Thank you all for your comments. I'm going to check out the fiberglass (Foam with a fiberglass skin) to see if it's suitable. I also checked into DOW Expanded insulation (EPS) VS. Extruded insulation (XPS) and found that the EPS has the same R value per inch and better water repellent properties and similar PSI rating and is MUCH cheaper. I'm also going to check with other contractors to see what they do and get quotes.
Thanks
Jim

 

[Homerr]

There are regional recyclers of rigid insulation too, they usually get it off of commercial roofs and sell it cheap.

 

[GMJim]

I got some information on this product and it looks good. The company says they have been selling it for this purpose for 8 years with no issues. I have learned however that these panels come in fiberglass and steel and are the cut outs from steel or fiberglass entry doors. Look at the test specs.

http://www.instainsulation.com/

https://www.instapanels.ca/products/fibre-glass-smooth-panels/

Fibre Glass Smooth Panels
Description
INSTA-PANELS™ are insulated R-11 foam panels made of rigid polyurethane foam, covered in
steel or fiberglass on both sides. INSTA-PANELS™ are designed to be used as an affordable
and durable slab insulation and have all the benefits of regular sprayed-on polyurethane foam
but in a portable solution. Panels measure 1 ¾” thick and weigh 1.99 lb/ft2.

INSTA-PANELS™ are available in multiple dimensions; the most common are:

20 x 64 inches – Smooth (total area 8.9 ft2 / panel) CCMC #14016-R
22 x 64 inches – Smooth (total area 9.78ft2 /panel) CCMC #14016-R
22 x 36 inches – Embossed (total area 5.50ft2 /panel) Not CCMC evaluated
20 x 80 inches – Smooth (Total Area 11.11 ft2 / panel) CCMC #14016-R
22 x 80 inches – Smooth (Total Area 12.22 ft2 / panel) CCMC #14016-R
Uses
Intended for residential, commercial, and agricultural applications where insulation is required or
desired, under concrete, in radiant or non-heated floor systems. INSTA-PANELS™ can be used
in a variety of applications including: under concrete floors of houses; garages; commercial
workshops; warehouses; office buildings; cold storage and freezers; agricultural drive sheds;
poultry barns; and other specialized applications.

Features and Benefits
High R-value for minimal thickness – rated at R11, INSTA-PANELS™ offer among the
best R-value to cost ratio creating optimum energy efficiency, improved indoor air quality,
and affordability.
Easy and efficient to install – INSTA-PANELS™ offer the same benefits as polyurethane
spray foam, in a convenient, portable panel format that fits together quickly and easily.
Durable – rectangular panels are steel plated on both sides for ultimate strength and
durability. Unlike traditional foam insulation, INSTA-PANELS™will not break when walked on.
Best value on the market – in a recent CMHC research study, INSTA-PANELS™ were
found to have the best cost-benefit value of all comparable materials tested.
Eco-friendly – INSTA-PANELS™ are made from recycled and reclaimed products.
Approvals and Credentials
Conforms to CAN/ULC-S704-03, “Thermal Insulation, Polyurethane and Polyisocyanurate,
Boards, Faced.”as referenced in the National Building Code of Canada and provincial
codes.
INSTA-PANELS™ have been evaluated by the National Research Council’s Institute for Research
inConstruction (IRC) through the Canadian Construction Materials Centre (CCMC) and have been
issued a CCMC evaluation listing number. A third party evaluation has confirmed that INSTAPANELS
™ adhere to the requirements set forth in section 9.25.2.2 of the Ontario Building Code as an
under slab insulation.
Typical Physical Properties
The following test data is from an independent laboratory and is in compliance with the product
standard.

Property Value Metric (Imperial) Test Method
Density (core) 30.9 kg/m³ (1.93lb/ft³) ASTM D1622
Compressive strength kPa 152 kPa (22.1 psi) ASTM D1621
Water absorption 0.37% by volume ASTM D2842
Water vapour permeance 3 ng/Pa·s·m2 ASTM E96
*These physical property values are typical for this material as applied at our development facility under
controlled conditions.

Long-Term Thermal Resistance
Test method: ASTM C518-10

Thickness
mm (inches) R-value
ft2·hr·°F / BTU RSI
m2·K/W
43 (1.69) 11.4 2.0
*The Long-Term Thermal Resistance values are the design value used for INSTA-PANELS™ as per CAN/
ULC-S704-03.

Health, Safety and Handling Considerations
WARNING: INSTA-PANELS™ are not intended to be used as structural panels. Proper safety
equipment needs to be employed while handling polyurethane faced board insulation. Goggles,
a face mask, and protective body wear should be worn when cutting and handling INSTAPANELS
™. Product has sharp edges/corners and protective gloves should be worn when
handling. Always stack and store panels in a safe manner to prevent piled product from toppling
over. It is recommended that panels are piled neatly one on top of the other and are not stacked
higher than 5 feet.

Packaging
INSTA-PANELS™ are sold to the DIY (do-it-yourself) market and licensed contractors in bulk,
on skids.