Greetings RPA members and others,

My associate with the Jefferson County Building department here in Colorado would like to view your opinions on his proposed code changes regarding the requirement of thermal insulation in radiant heating systems. His proposed changes area as follows:

Proposal: Add new text as follows.

1209.5 Thermal barrier required. Radiant floor heating systems shall be provided with a thermal barrier in accordance with 1209.5.1, through 1209.5.4

1209.5.1 Radiant piping utilized in slab on grade applications shall be provided with insulating materials installed beneath the piping having a minimum r-value of 5.

1209.5.2 In suspended floor applications, insulation shall be installed in the joist bay cavity serving the heating space above and shall consist of materials having a minimum r-value of 19.

1209.5.3 A thermal break shall be provided consisting of asphalt expansion joint materials or similar insulating materials at a point where a heated slab meets a stem wall or other conductive slab.

1209.5.4 Insulating materials utilized in thermal barriers shall be identified in accordance with section 102.5.1 of the International Energy Conservation Code.

Note: Show the proposal using strikeout, underline format. At the beginning of each section, one of the following instruction lines are also needed: •Revise as follows •Add new text as follows •Delete and substitute as follows •Delete without substitution

Supporting Information (3.3.4 & 3.4): Many tens of thousands can be spent on radiant heat systems that do not work properly due to the lack of thermal barriers. There’s not much inspectors can do when they see piping laying in the dirt with no insulation beneath it. Radiant systems cannot operate as intended without a thermal barrier. In the case of a slab on grade application, the ground will require a substantial charging of energy in order to hit a point of equilibrium where the thermal energy starts coming upwards instead of going downwards. Thermal energy flows from hot to cold, always and continuously. It substantially effects the over-all energy requirements and can seriously affect the performance of the system negatively and waste precious resources. In the case of a suspended floor application, if the insulation is not properly applied, the lower floor (basement) will have a tendency to overheat and the floor that is trying to be heated will be under-heated. Once the system is installed without insulation its’ too late and balancing is virtually impossible. The end result is that energy bills are high, comfort levels are low due to the lack of insulation, which in most cases can not be retrofitted to appease the situation. The lack of insulation can drive the operating costs as high as 25% depending upon the application and exposure. The paybacks for the consumer are huge considering the minimal cost of insulating materials such as 1-inch foam, which costs approximately .48/sq. ft. The energy code does not provide guidance in this situation. It is appropriate for this text to be included in this document as this is what is used by installers for the installation.

Note: The following items are required to be included: Purpose: The proponent shall clearly state the purpose of the proposed code change (e.g., clarify the Code; revise outdated material; substitute new or revised material for current provision of the Code; add new requirements to the Code; delete current requirements, etc.) Reasons: The proponent shall justify changing the current code provisions, stating why the proposal is superior to the current provisions of the Code. Proposals that add or delete requirements shall be supported by a logical explanation which clearly shows why the current Code provisions are inadequate or overly restrictive, specifies the shortcomings of the current Code provisions and explains how such proposals will improve the Code. Substantiation: The proponent shall substantiate the proposed code change based on technical information and substantiation. Substantiation provided which is reviewed in accordance with Section 4.2 and determined as not germane to the technical issues addressed in the proposed code change shall be identified as such. The proponent shall be notified that the proposal is considered an incomplete proposal in accordance with Section 4.3, and the proposal shall be held until the deficiencies are corrected. The proponent shall have the right to appeal this action in accordance with the policy of the ICC Board. The burden of providing substantiating material lies with the proponent of the code change proposal. A minimum of two copies of all substantiating information shall be submitted. (3.4) Bibliography: The proponent shall submit a bibliography of any substantiating material submitted with the code change proposal. The bibliography shall be published with the code change and the proponent shall make the substantiating materials available for review at the appropriate ICC office and during the public hearing. Referenced Standards (3.4 & 3.6):

List any new referenced standards that are proposed to be referenced in the code and provide a minimum of two copies. For ICC rules on referenced standards, see Section 3.6 of CP #28. Cost Impact (3.3.4.6): Will increase cost.

Note: The proponent shall indicate one of the following regarding the cost impact of the code change proposal: 1) The code change proposal will increase the cost of construction; or 2) The code change proposal will increase the cost of construction. This information will be included in the published code change proposal.

END OF PROPOSED CHANGES.

What thinks ye Groupees? Any and all comments are appreciated. He has a very short time in which to prepare his final recommendations and wants to make sure that it is right the first time before submittal.

Thank you in advance for your comments, pro or con.

Bear in mind for our friends to the FAR north in Alaska, that these are MINIMUM insulation standards. As the code usually dictates, local code enforcement can be equal to or greater than, but not less than the precriptive code.

Thanks in advance. I am going to invite Mr McMann to visit this site frequently to view your comments.

Mark Eatherton
Mark Eatherton and Associates

Hi Mark,

I think 1209.5.1 is excellent.

I think 1209.5.2 is a bit extreme in a lot of cases. I think I would differentiate between joist heating and top-of-subfloor systems. Also, there needs to be some clarification for floor systems in which insulation is not possible (such as when the 1st floor ceiling IS the floor for the 2nd floor). Personally I would call for an R30 over unheated space in any circumstance, as many energy codes already do.

Although I believe this is a very necessary step,I would question how the code would deal with variances, such as:

1. A design that uses the ground as a heat sink for off-peak energy rates or solar storage, etc.

2. Large footprint designs over dry soil and a deep water table where heatloss to the ground in the interior is minimal. Test and calculations prove that inuslation under the interior is not necessary in these circumstances.

3. Joist bay installations where the design calls for bi-radiant heating. In other words, the system is designed to provide a heated floor above and a heated ceiling below. This can be very effective and efficient when properly designed. It certainly isn't any worse than a forced air system in a multi-level building with a single thermostat.

Once a code is established, it is very difficult to change. We need to make sure that all our bases are covered.

quote:

1209.5.2 In suspended floor applications, insulation shall be installed in the joist bay cavity serving the heating space above and shall consist of materials having a minimum r-value of 19.

I was just at an existing jobsite where they used R-13, the flooring was tile, and the space below was conditioned. Works great. I think R-19 is a little extreme in this case. Unconditioned space, sure.

Different amounts of insulation are beneficial for different systems. For example, Warmboards under tile doesn't need nearly as much insulation as one of the "bare tube between the joists" systems below carpet. The latter runs at much higher water temperatures, and there is less intrinsic insulation (as in none) below the tubing.

Rob, Larry et al...

The basic problem is that none of these inspectors knows the difference between a staple up job and a plate job, stapled down in gypcrete or lightweight concrete or engineered (WarmBoard) system. It's not their job to make that difference. They're looking at a RFH system. Regardless of the floor finish at time of construction, there is nothing that precludes the new owners from throwing down high R value pad and carpet and causing "issues" with the heating system later, hence the need for a higher R value. Been there, seen that and couldn't do a thing about it. The cost differential of the higher R value (R19) is insignificant in the scheme of things. Remember also that these are "MINIMUM" standards. If you want to specify 2" XPS foam everywhere, then so be it.

Larry, your exemptions would only tend to dillute the intent of the code changes, and if someone is such a forward thinking person so as to be able to control ALL of the parameters relating to heat gains and heat losses of a given multifloored structure, then their "system" will most likely be a totally engineered system in the first place, and they would simply file for engineered exemption to the rules.

As for "earth linked" systems, in my 33 years of doing this, I have never heard of such an animal. Writing exemptions for "potential" applications is not waranted IMPO. We need to stop the bleeding now, and if we find the tourniquet is too tight, we can adjust it later.

The lack of an insulation standard has raised its ugly head after the fact WAY to many times to ignore this issue and debate it to death prior to getting a minimum standard in place. We're already fighting an uphill battle against the HBA who are continuously fighting increased thermal energy standards as "unnecessary costs". We don't need suppression from within the industry based on the potential of some way off the beaten path designs.

I think we need to get behind this and have some representation at the hearings to promote its use. I for one would be willing to go testify if the organization will pay the freight.

ME

well mark, I do applaud raising thermal energy standards, but if it's ONLY being raised for radiant systems, then the more added costs you throw in the less attractive you make radiant.

Now, I haven't priced insulation recently, but I'll tell you, I haven't seen a radiant system in between two heated floors that R19 was really needed for. If someone comes by and throws down a high R carpet, lowering your backloss is only a small adjustment to output relative to what you have to do to water temps force the heat through the carpet at an acceptable rate.

I may be wrong, for sure. But that's what I think.

Have you actually ran the numbers in a conditioned space scenerio, between R-13 and R-19? I'm guessing that there really isn't a significant difference. Or, does R-19 just sound like a good number? I'd like to know just for personal knowledge.

Of course the buildind dept could just mind their own gd business. I don't think the insulation is much of a safety issue.

I think Mark has it spot on. We have these guidelines to Follow in California that many installers in my area have no idea about.

2005 Building Energy Efficency Standards
RESIDENTIAL COMPLIANCE MANUAL states:


Radiant floor systems in concrete slabs must have insulation between the
heated portion of the slab and the outdoors.
When space heating hot water pipes or heating elements are set into a concrete
slab-on-grade floor, slab-edge insulation from the level of the top of the slab,
down 16 in. or to the frost line, whichever is greater (insulation may stop at the
top of the footing, where this is less than the required depth), or insulation
installed down from the top of the slab and wrapping under the slab for a
minimum of 4 ft toward the middle of the slab, is required. The required
insulation value for each of these insulating methods is either R-5 or R-10
depending on climate zone.

I like the idea *~/:]

like i say Insulate Ventilate Heatilate and not too late!

1209.5.2 (In suspended floor applications ... minimum r-value of 19)

Does indeed seem extreme. I have R13 in an extruded plate application over a unheated basement with R-10 on the concrete foundation walls. "Leaks" just enough to be take the edge off in the basement. Otherwise I'd have to think about adding heat emitters to serve this unfinished space.

"Deep Heat" is a big thing in Minnesota where people can get great off-peak rates (something you don't see much of in Colorado).

Using a large ground-coupled thermal mass, with radiant floor heating cannot only save money by taking advantage of off-peak rates, it is great with solar and other renewable energy applications.

Anybody thinking "green" in our future? A code designed for tomorrow should not shut the door on developing technology today.

The code should address common problems, but not rule out exceptions.

I have R-30 between my floors simply because more is better, insulation is relatively cheap in the grand scheme of things, my floor joists were 2x12's so there was plenty of room and it made the house quieter, by which I mean I barely hear my kids downstairs when they are jumping around upstairs.

I agree wiht Mark that we are better off leading rather than fighting this sort of code change. And I believe Mark is right, that any engineered system, of the sort that Larry envisions, can be exempted with adequate calcs being presented.

I don't think anyone is fighting a standard code, but make it based on tests and facts, not based on "I can't hear my kids through the floor". Hell, if it's sooo cheap, put it in all your inside walls to cut down on sound and make zoning better too. Anyone who knows anything about the law of diminishing returns knows you don't need an R-30 between conditioned floors.

Codes should be written based on facts and figures, not based on what an insulation salesman would like to see.