QC Radiant Heat plan with couple specific questions

Sukhoi29SU

Hello, FNG here with gut remodel project in north central Illinois where I plan on radiant heat throughout. I found this forum last night and figured I might ask you experts to QC my plan and possibly answer a couple specific questions. Thank you in advance.

1971 home north of Rockford, IL just south of Wisconsin border. 2 - story with walkout lower level. Big picture plan: I'm taking the existing attached garage and taking down the wall between it and the living room on the other side and turning the garage into living space - creating a large living room with vaulted ceilings. I'm then building an attached garage addition (1700 square foot) with a span-crete floor with additional 1700 square foot beneath the garage as work shop. Main level square footage: 2500. Lower level walk-out square footage: 1700. Main level garage: 1700. Lower level garage / workshop: 1700. Total sq. ft.: 7600.

Before I recently gutted the existing house, I heated it with two wood burning Avalon Olympic stoves. Natural Gas is unavailable, as the property is very rural. As a result, I had to rely on propane forced air as my 'backup'. The house was very poorly insulated and I plan to really prioritize insulation during the remodel and addition construction.

I'm interested in removing the forced air propane system completely and installing a Switzer wood gasification boiler in the lower level shop under the garage. (Also considering a Heatmaster G400, but leaning towards Switzer). I will need a propane boiler as a backup system for when I'm gone and can't feed the wood boiler. Hoping for domestic hot water with this system, too.

Looking to install pex tubing in concrete in both lower level workshop and main garage. Only plan on heating these areas to 50 degrees or so. In the main upper level of the house I plan on pouring concrete over the existing garage floor / concrete slab (new living space) and putting pex tubing / radiant heat in that. Then a floating floor. Where weight is a concern, I'm considering gyp-crete with matching floating floor - most likely engineered hardwood.

Downstairs lower level I'm stuck. I'm removing the forced air system in the ceilings to free up some ceiling height. But, if i install radiant down there - I need to insulate the concrete slab and then pour concrete or gyp-crete on top of that. Ideally, I'd like concrete and then put a nice acid stain or polish on the concrete for a finished floor. My other thought was to install radiant ceiling heat in the lower level. So, I'd have lower level ceiling radiant and main level floor radiant. I imagine the pex tubing would be separated by insulation between.

Couple questions: What is the minimum amount of insulation and concrete thickness I can get away with to have an effective radiant floor heat on the lower level. I imagine busting up the existing concrete floor and then insulating and pouring more concrete is probably not be feasible. I am also unable to insulate around the entire perimeter of the lower level because of the existing garage slab on the south, and a walkout concrete patio to the north. Is insulation just on top of the concrete sufficient? I'm really looking at what the minimum amount of ceiling height i will lose to get floor radiant. And if too much, whether the ceiling option is feasible for a lower level with concrete slab?

Finally I'm looking for an expert in the area to design the system. Someone who is ideally familiar with wood boilers and can help with a propane backup. Calculate heat loss / BTUs required, etc etc.

Anyone from northern illinois or southern wisconsin know someone?

Thanks for your time and thanks in advance for any info.

Gordy

http://www.roth-usa.com/products_radiant_panelsystem.cfm

https://www.sunboardpanel.com/sunboard-panel-design.php

https://www.warmboard.com/faq

Gordy

Sounds like quite a project!

I’ll start off by saying insulation is your friend in the slab areas you want to add radiant. It comes down to where you want the energy, and your dollars to go. To heat the space, or the ground. It’s not that it won’t heat the space, but a lot of the energy will be lost to the ground.

Also that ceiling radiant is a nice option, and you will lose less head room verses an over the top insulation radiant over pour detail.

The above links may give you better options in some of your areas.

Sukhoi29SU

Thanks, Gordy

I actually have a sample of the warm board and was considering it as an option for the lower level. I’ll check out your other links.

Being content with polished concrete as the actual floor, however, I thought maybe I’d be able to lose less ceiling height with insulation and a concrete pour over the pex tubing. I’m not sure what the minumum thickness of the concrete and insulation would be, however.

I figured I’ll lose ceiling height regardless, whether it’s insulation, a pad, and floating floor. Or, insulation and concrete. Just don’t know what the difference in lost ceiling height would be if I went with the bare minimum but still kept it effective.

Perhaps putting a floor over the existing concrete in the lower level is the best (with no radiant), and putting the radiant heat in the ceiling. That way I preserve the ceiling height and still take advantage of the hydronic heat?

Gordy

The Roth panel is a great option for the ceiling.

I don’t know the shape of existing concrete floor, but if you did ceiling you could polish, and acid etch the existing floor. Or maybe an epoxy type of finish. There are exotic concrete floor finishes that use the existing concrete.

Gordy

ANother link for creative juices.

https://www.concretenetwork.com/

Gordy

Roth on ceiling.

https://goo.gl/images/G2iWbY

Sukhoi29SU

That’s a great idea but I think I’d at least need to put a thin self-leveler layer over the existing concrete.

I just checked out your sunboardpanel link. Are they telling the truth when they say their product is a more efficient form of radiant heat than installing the pex tubing in concrete? I was always under the impression that concrete was the best form because of the thermal mass properties of concrete?

Some guys also talked me onto the European style radiator panels, which might work down there- but if I can prevent having a cold uninsulated concrete floor down there - that’d be ideal.

Thanks again

Sukhoi29SU

I love the look of those finished concrete floors and my wife has picked out a couple options of those. I figure a floor like that has pex tubing within it, it’d be a great way to heat ; but some of these other products ; warmboard, etc make it seem like their way is better than radiant involving concrete

Gordy

Panel systems are quicker to respond, and a bit easier to control.

Nothing wrong with concrete if controlled properly.

Panel rads with trvs are a nice option. Size them to use lower water temps. Since you are using an outdoor boiler not a huge concern until you go to backup if a condensing boiler will be your choice.

Sukhoi29SU

Actually planning on an a Switzer boiler indoors, in the lower level workshop.

It’ll take up a bit of real estate, but I figure my wife will be more inclined to start a fire if she doesn’t have to trek through 2 ft of snow in 0 degree weather, when I’m away from home.

http://switzerswoodburning.weebly.com

Gordy

I’ll reiterate there is nothing wrong with concrete, or gypcrete radiant when properly controlled, and INSULATED.

However with your situation that is a bit of a nut to crack. These options are a work around, and cost of course would need to be compared among different options.

I’m not a big fan of thin overpours especially when it will be a finished product with an expensive finish. The results over time may be undesirable.

Gordy

I also recommend reviewing over pours on the concrete network site. That way you have in your head a recommended thickness, and then add at least 1/2” XPS, and vapor barrier under that. My thought would be a 2 1/2” minimum build up.

Paul Pollets

Our code requires R10 under slabs and perimeter insulation. Embedded tubing is the easiest to install and slab thickness should be at least 31/2". If thinner, expect lots of cracking. If your system design requires multiple temperatures, you'll need a mixing valve with motor actuator (or Smart zone valves) to keep setpoints accurate.

Gordy

This isn’t a new construction slab. Ideally He wants to overpour an existing slab, and have a stained finish with minimum build up.

Sukhoi29SU

Thanks again for comments. Could I get away with a higher psi concrete with less thickness and avoid the cracking? I think I might be able to get away with 4 inches. The lowest part of the ceiling of lower level is a support beam that is 81in from the floor. I’d be at 77 in ceiling height (at the lowest portion) after losing 4 inches. Could I get away with 1/2 in insulation and 3.5 in pour over the pex?

Gordy

Yes that would work. So long as you are okay with 6’5” of head room.

Sukhoi29SU

Not ideal, but it would work.

How feasible do you think it’d be to bust out the existing concrete floor, insulate, and re-pour?

Crazy thought?

It’d definitely solve my ceiling height problem, but I’m not sure how costly or practical it is to bust out the existing floor.

Gordy

Well anything can be done. I’ve seen it done many times. It is laborious, and few wish to do that for the soul purpose to install radiant with an existing floor. However I think the fruits of your money, and labor would produce a far better product. Especially since you want a final finished concrete floor as you noted, and a workable space for head room.

I’m quite sure some excavation would also need to be done to allow for 2” of insulation since you are going to be going through all that to give you ample head room.

ratio

You should cypher up the floor surface temperature at various outdoor temperatures, it may too low to feel warm, especially at higher outdoor temps.

Voyager

Sukhoi29SU said:

Not ideal, but it would work.



How feasible do you think it’d be to bust out the existing concrete floor, insulate, and re-pour?



Crazy thought?



It’d definitely solve my ceiling height problem, but I’m not sure how costly or practical it is to bust out the existing floor.

Busting up concrete is feasible and is done all of the time. It is hard, noisy and dusty work though, especially if you have to do it by hand. I think you said your had a walk out basement. If you can remove a large door and get a small skid steer in with a concrete chisel attachment, they will go through a slab pretty fast.

Sukhoi29SU

This would definitely be the time to do it... not worried about dust right now and I think I could actually get a small skid steer in there once I take down a couple walls ..

I’ll look into this , thank you

Sukhoi29SU

What would support my floor joists if I’m busting out the lower level floor?

Voyager

Sukhoi29SU said:

What would support my floor joists if I’m busting out the lower level floor?

Can’t say without pictures and engineering drawings of the footing system. A well built house should have footings under the outside walls and all interior load bearing walls and columns. I have no idea what the structure of your house is. You may need to have a local engineer or a very experienced builder look at it.

pecmsg

You dont know if there supported properly for this elevation or the new elevation.

For this you need an engineer

Gordy

Depending on age of your home. Typically there is an 8” thick x 16” wide footing under 8” thick concrete walls. footings under load bearing framed walls should be same. Floors being poured over top of footings.

Footings under beams using jack posts for support should be 2’x2’x 8” thick footing under each post with floor poured over top of footings.

You could bust out the floor at locations, and do some investigating as to what you might have. If concrete walls are size stated above measure in from the wall 5” pop a hole big enough to dig down, and find footing. Same for load bearing jack posts for beams.

If you proceed be sure not to over excavate for the floor, and insulation so you don’t lose the key for the footing in undisterbed earth. You have side force on the wall and footing now that foundation is back filled.

This would also be an opportunity to tile the foundation if it is not already.

Zman

Sukhoi29SU said:

What would support my floor joists if I’m busting out the lower level floor?

You would need to work out a temp support plan.

Sukhoi29SU

Never really considered this as a practical option before... seems a bit complicated.

Any estimates or educated guesses on what this would cost for approx 1700 sq ft? The good thing is that it’s a walk out lower level with some large doors, so carrying concrete up the stairs would not be required.

I definitely see the benefits of doing this - but depending on complexity and cost, it might not make sense. I’d like to do it right, though.

Most of this lower level consists of bedrooms. Is it worth it to get radiant floor heat in bedrooms? I figured having the entire lower level slab heated would be a benefit overall, but I might be wrong.

Gordy

It's really not that complicated. Labor intensive yes. You know what good labor costs. I won't throw finite figures to it but 5 figures is definite. Not including staining, and radiant portion.

Gordy

I think your costs would be more finite in all aspects if you let go of the stained concrete thought, and just overlay existing with an insulated prefab panel system like Roth, and a finish floor on that.

Gordy

Also remember you will have to determine which walls are bearing which will have to be shored, and removed, and any interior non bearing partitions will have to be demoed to do the removal, and replace.

Sukhoi29SU

Thanks Gordy, you’ve been a big help. I’ll explore the options you recommended and come up with a good plan.

Sukhoi29SU

If I were to use Roth or warmboard, etc , would those panels in the lower level be compatible with regular pex tubing laid in concrete in other portions of the home? From what I’ve read, it sounds like water temps utilizing Roth are much lower than other applications such as pex in concrete or gyp Crete. I imagine I’d have to control the water temps through the Roth boards differently than the concrete pex?

Brewbeer

It's a good strategy to design the various emitters to operate at the same supply temp, but isn't necessary. Will you be using a large storage tank with the wood gas boiler?

Zman

You can run the math on the output of the different assembly's and compare that to the heatloss of the spaces. TheRoth system will not run at a significantly different temp than concrete for the same output. They are both very good systems for heat transfer.

Sukhoi29SU

@Brewbeer
As of now I plan on utilizing a Switzer Wood gasification boiler with 1750 gal internal storage.

Sukhoi29SU

@Gordy , I put an ad out on Facebook in my area just to get an idea on cost. One guy quoted $/sq ft. Which would put it right around $ for removal of slab. I just need to make sure they’re licensed and insured and we take the necessary precautions before busting out walls or digging down too deep next to the perimeter, as you mentioned, if I decide to go this route.

The warmboard or Roth will be a decent option so long as that system is compatible with the standard pex tubing I plan in using in other portions of the remodel- but I do like the idea of polished concrete down there, which I can always install a floating floor over down the road if I want to. But I’ll have a nice thermal mass in the lower level of the home.

I need a good general contractor, I think. I’d like to be able to do all of this on my own and hire out the work myself- but I think I lack the necessary knowledge to do it myself. The help / advice found on this site is great, though

Gordy

We don’t discuss pricing.

Does the sf price include removing partition walls if existing, temp shoring of beams, and or bearing walls? Excavation of the additional 2” of earth to allow for xps insulation?

Sukhoi29SU

Probably not, no. That price is probably just for the concrete removal.

Sukhoi29SU

@Gordy I ended up going with the advice to bust out the lower level slab. It was surprisingly much more affordable than I had imagined, and includes temporary beams, etc. They start this Friday.

Couple more questions if you have a minute:

I plan on putting down a vapor barrier and insulation under the entire new slab to be poured. I’ll dig out enough dirt under existing slab to allow this. I’m curious as to how I’d insulate the perimeter, though. Can I dig down along the inside of perimeter wall / foundation to put insulation down along there? I don’t want to dig too deep to disrupt the ground that the footing sits on...

I’ve convinced the guy who did drawings for my house that beefing up the floor joists in order to support a suspended concrete slab for the upstairs (main level) will be worth it. Not gypcrete, but actual concrete. (I’m still trying to determine if I’m correct). I have 2x10 floor joists and where the span exceeds about 13’ I will secure two 2x8’s on either side of the 2x10s.

Up top, I plan on keeping the majority of the existing subfloor. I’ll have to replace some where there are current holes from the floor vents that will no longer be needed. I plan on a vapor barrier over the subfloor. And then a concrete pour over pex. I’m trying to determine what the minimum amount of concrete I can get away with here would be? I am thinking I don’t want more than 2” from the pex to top of slab. Would a 2” slab of high psi concrete suffice ? I don’t want it to crack all over the place as this will be a stained / polished and finished floor. 2.5 inches?

Also, for insulation under this- I’m hoping I can place the insulation within the floor joists below so that I don’t lose the heat into the basement. Would this insulation below the sub floor work or would I need insulation directly underneath the slab?

Learning a lot throughout this process, hopefully it will pay off when this project is complete.

Gordy