Concrete floors?

[iceman]

-a 4-season cottage (basically just a small 2-bedroom house). Coastal New England.
-1st floor, ~1100 sq. ft.
-would have radiant in them
-most likely on top of slab-on-grade (although it could be framed, with a crawl space, instead)
-the builder is very familiar with them, so we don't need to spend a lot of time on construction caveats (but knock yourself out)
-could be set up to have a different surface in the kitchen (maybe cork?) and/or bath (maybe tile?).
-I don't know the money difference (from hardwood) but I don't think it's huge. I will find out though.


What thinketh the collective?

[buttahflake]

friend of mine, ripper local skier. his stuff is impressive.
http://www.vermonthardscapes.com/

[skiballs]

Putting a cork floor on top of radiant defeats the purpose of radiant floor heating ( it's a good insulator ) .
I have radiant in my house ( slab on grade ) , the parts that are tile kick ass , the parts with wood floors are ok ( use quarter sawn wood flooring ) .
I used Wirsbo tubing and controls , with a weil-mclain boiler , going on 8 years trouble free ( knock on wood ).

[iceman]

Yeah the kitchen is small and we'd probably put a radiator in there and skip the radiant in it.

[RootSkier]

What does you interior decorator say?

[iceman]

We're interviewing. Interested?

[bushman]

My buddy put radiant concrete floors on all three floors of his log lake home (basement, main, and upstairs) and its very nice. Warm and quiet. He put assorted coverings, hardwood, carpet, and tile through the house. I think it was spendy but he is/was a commercial contractor, so he knows how to do it right. I think he uses it for cooling too.

[brice618]

Radiant is nice.

That said, concrete gathers dust like no other, even after they wax it. Probably not that big a deal in the North East but something to think about.

[Cruiser]

Doesn't radiant heat take a while to warm a room? If this is a weekend type place then would it be comfortable during the cooler months if you show up late on a chilly Friday night? Or can you run some sort of android enabled remote system to heat it when you leave your primary residence?

Not knocking it, just asking questions that come to mind cuz I've heard nothing but positive remarks about radiant heat. My in-laws used it in Santa Fe and absolutely loved it. Warm tootsies for that 2am piss are pretty much priceless.

[That was Pontus]

My 500sqft milkshed has radiant concrete in the bathroom. I'd say it's FKNA badass . All 32sqft of it.

[iceman]

Radiant cooling, the time it takes to warm up and dust are things I hadn't thought about, thanks.

What about hardness? I've heard that it's tough on your feet and legs after a while, but it's not like we'd be marching around in there.

[warthog]

Living in an area where tile floors are very common, I can tell you that it wears on you. Now, why is wood laid over concrete easier on you? I have no idea, but it is. I love the look of polished concrete. Polishing it can be labor and $ intensive, but you shouldn`t have to worry about it for a while.

[Alaskan Rover]

Radiant set in concrete is the cat's meow (what a silly expression....coz cats meow when they're perturbed and want to be let out or in...what's so good about that???). Very efficient in the long run...but it does take a bit to warm the house, so like it was said above, would it be best for a weekend getaway? I would ut in a decent Franklin-style wood stove for when the passive system is first starting up.

Polished concrete is truly high-end now...although I still prefer refurbished hardwood wide plank warehouse flooring...but that's not the best for radiant as the wood is less heat-absorbtive than concrete and more insulative...not what you want. Throw some orientals over the polished concyg

[GeoMatt]

Lowest level in my house is 6 rooms, 1200sqft, all stained/polished concrete with radiant. I have no complaints what so ever. I wish all the floors in the house were concrete. Want something a little soft, get some nice area rugs as needed.

Get the concrete floors, you'll love them.

[spindrift]

Work great.

Heating tube density & temps (per zone) can be adjusted for things like (correctly installed) wood or carpet on top.

More zones are better than too few...

We used a penetrating sealer. I like how it has worked out vs coatings that last rather well but then require a major stripping and redo. We just get a simple reapplication of the penetrating sealer in high use areas every few years.

Think about pigment vs staining concrete. Of course that probably means you need some design and sample work. But then you have the color you want in the concrete itself - so minor chips/scratches are more of a patina than looking like damage.

Bare concrete floors are very acoustically "live". Think about other wall, ceiling, furniture surfaces/treatments that might mitigate that.

I have no issues with walking/standing around on it barefoot.

[AlpiNord]

The higher the mass, the longer the time lag for heating the mass and also retention of the heat. One option if this is for periodic use is to control it via the internet so the time lag is accounted for and can be getting the house ready for when you get there. Generally, the mass provides efficiency after it's up to temp and the boiler just needs to keep it at temp. Much like driving at an even keel on the highway versus acceleration and deceleration. One other of many control options is an exterior temperature sensor to kick on the heat before it drops off at the end of the day and there may be a substantial temperature drop. Here we can see a 30 degree change in a short period of time.

A crawl space provides access for the future and also staging rough-ins for electrical plumbing and heating. With a framed floor you can install staple up (no mass and fast), 1 1/2" thin mass or 3" and more with a variety of finishes. If you know your finish flooring and it's conductive and insulative properties, the tube layout and temperatures in your zones can be designed to maximize efficiency. You can also add baseboards, radiators or fan coil units in some rooms/zones to reduce cost off the same boiler.

On typical radiant projects, we'd add an electric heater in bathrooms for supplemental, instant heat because often there was not enough area to get enough tubing in the floors. The warm tiles are always nice, however and a thicker mass might be worth considering in bathrooms. Conversely, bedrooms typically should be cooler than bathrooms and main living spaces so think about your zones and controls accordingly.

Definitely get wood flooring well acclimated before laying it down. On some reclaimed floors putting down a plywood underlayment was required to glue and nail to to minimize expansion and contraction due to seasonal changes. A floating wood floor can move as a whole.

[L7]

Ya, more on the mass of concrete. I'm a big in floor heating fan but if you have a lot of south windows the time lag can be an issue too. Slab warmed up to keep you warm, sun hits and it's too damn hot for some time. Sun goes down and takes it's warmth and long time to warm the slab for effective heating. Less of an issue on a framed floor but still solar warmth and floor heating may have issues.

[plugboots]

I don't see a downside. Especially since we have dogs. I've convinced 2 friends to do radiant concrete and they both love it. One is an infrequently used cabin and it's no biggie getting it going, (but so does a wood stove, which they and we also have). We also have a zone for each room, and leave the bathroom zones on all the time, and keep the door closed, otherwise the bathroom floor tries to heat the whole house. Also we have a whole house wrap around deck, so no sun beating down on it.

[frorider]

Agree with L7. Mother's house in Yurp had radiant concrete floors, and it drove me crazy. Always opening the windows in the middle of winter because the floor had so much thermal mass.

[spindrift]

You definitely want a programmable controller that has an outside sensor - and that can vary the temperature of the mix it is pushing through based on the difference between inside and outside temps. That said - there are definitely situations where things can slingshot...

[iceman]

Yeah the place is gonna have a woodstove but I can see a situation where you get there, fire up the stove and turn the heat up and then the stove is cranking and the floors start cranking and you have to open the windows in the middle of winter happening pretty easily. Hmm.

The point about the dogs is well-taken, the damage they've done to the floors here at home is crazy.

[AlpiNord]

If the stove is heating up the house the thermostat will not call for the heat system to kick on.

Regarding over heating with thermal mass and solar gain, even with good solar design and construction relative to seasonal norms and your typical local heating needs, you will get temperature swings by default. You need to provide for controls by either shading or venting, among other options.

Do you have CAD drawings of the cottage and orientation? A basic 3d model with solar animation can show you where the sun will hit relative to your lat/long or UTM and by day or time of year.

[jamesp]

All you people with radiant heat in slab-on-grade have the slab insulated yeah? Rigid foam under the slab? If the slab is not insulated won't the ground suck heat out of the floor?

With sun causing radiant heat... I thought this was a good thing if designed correctly? ie sun heats the floor, & the floor slowly releases its heat. As the floor cools gradually the boiler kicks in to maintain the designed temp. End result being warm floor with less input from the boiler. What am I missing?

[Foggy_Goggles]

Are you talking stamped/stained concrete floors w/radiant or gyp-crete w/ in floor radiant? The later can take any floor covering you want. Radiant heat systems can be sweet when done properly. They require much more design and engineering than the alternatives. Many second home owners don't like the slow response time for radiant. The thermal mass concept is not universally agreed on as the way to go. Look at Warm Floor. That is an alternative. If I were building a another house, I'd go high efficiency forced air. It's too bad Lennox screwed the pooch with Complete Heat because it was a really good concept.

[Rossymcg]

Don't put your dog bowls on the floor it heats the water and food up and the dog may not like it,
I'd also imagine it's nice to strip off and sit down on the floor gently settling your knacker sack in contact with the warm concrete, any chance of a TR on that please