Treating concrete floor with underfloor heating - AVS Forum
Dedicated Theater Design & Construction > Treating concrete floor with underfloor heating
kinw3's Avatar kinw3 05:05 AM 07-04-2013

My cinema is planned to have underfloor (water in pex) heating.

From the Soundproofing site I can see that to isolate the floor a layer of Serenity Mat, or whatever I can get in the UK together with two green-glued layers of ply is the way to go.

However with all of that, and carpet underlay (pad), and carpet, it will seriously affect the performance of the heating.

Here in the UK heating is a bigger issue than ac, even though I do plan some modest cooling/ventilation.

There is an option to forego the underfloor heating and install radiators, but running at low temperature will require unsightly radiator sizes.

Does anyone have underfloor heating under an isolated floor who can. comment?

Are there any. other thoughts?

Thank you

BIGmouthinDC's Avatar BIGmouthinDC 11:26 AM 07-04-2013
Isolated floors are nice but not an absolute necessity. It would help to understand the construction of the floor and this rooms relative position to other rooms. For instance is this a concrete slab directly on the ground?
kinw3's Avatar kinw3 12:27 PM 07-04-2013
Originally Posted by BIGmouthinDC 
Isolated floors are nice but not an absolute necessity. It would help to understand the construction of the floor and this rooms relative position to other rooms. For instance is this a concrete slab directly on the ground?


I have a thirty day trial of AutoCAD.

I`m going to draw you a picture and photograph it.

Nuff said about AutoCAD for the time being, but I will produce fully dimensioned drawings at some point.

As far as construction is concerned the area where the theatre is going is a 90ish extension to 1905 house.

Some of the walls are 9inch solid, and the morerecent ones are 11inch cavity construction.

Thr theatre is next to the kitchen/family/dining room, on the other side it joins the garage, the third side is next to a 6 foot corridor which joins the boot room to the garage and will have a loo and loads of storage, I will steal some. space for a rack, a rear sub, an a box for the projector.

The forrh side is an external wall. The nearest neighbour is fairly close, and I want to be able to play at near reference level and not heard outside or in the house.

The 4xtension. Is built on strip foundations, between the foundations is filled with hardcore and then concreted. The whole structure is solid, and I suspect ideal for reverberating along with the subs.

Picture to follow, hope this helps and is not too long-winded.
BIGmouthinDC's Avatar BIGmouthinDC 01:26 PM 07-04-2013
First person I would talk to is Ted White at fire off a PM. They sell the serenity mat system. If you don't get a response let me know. In the years I've been dealing with Ted I've never heard him once recommend a product just to make a sale. If he thinks it will cause problems or interfere with your heating system he will tell you.
kinw3's Avatar kinw3 02:13 PM 07-04-2013

Ted White's Avatar Ted White 02:46 PM 07-04-2013
What is the proposed floor assembly? Are you using a subflooring that has channels for the Pex?

Depending on the system you're using, you can install an isolation mat under the Pex / subfloor layer, but never on top.

The Serenity's resistance to heat transfer (Insulation) is actually a benefit under the Pex layer, as it helps direct the heat up through the finished floor.

If you are using a concrete slab as a thermal mass, then that mass will take longer to "charge" and take longer to "discharge" / radiate the stored heat.

If you are embedding the Pex in the cement, then I would not use the Isolation mat. Again, The Pex needs to be above the Serenity or you will suffer performance loss as you've described.
kinw3's Avatar kinw3 03:20 PM 07-04-2013
Thank you for a very prompt reply.

You have confirmed what I was worrying about.

I want to isolate the floor so will forego the underfloor heating in this part of the house remodel.

I think I will specify radiators and try to keep them as unobtrusive as possible.

Thanks again - this theatre building project has taken me in directions which I never even cnonidered before I started researching.

Nexrt step is to work out how to build the internal walls on the isolated floor - there wil only be 1.5 inches to fasten the sole plate to.

More research.
petew's Avatar petew 06:01 PM 07-04-2013
Originally Posted by kinw3 View Post

I have a thirty day trial of AutoCAD.

Check out

This is an AutoCAD LT clone. Totally free, even for commercial use. From Dassault Systems, publisher of SolidWorks, Catia and other really high end stuff. Did I mention Free?
rabident's Avatar rabident 06:53 PM 07-04-2013
Warmlyyours has electric heating elements if you wanted to go that route. radiant-basement

I use the 240v version in our 20 x 20 bathroom and it works great. That's on 2nd floor, wood subfloor, with travertine on top. I love it. It heats up to 85F in about 15 - 20 min. Guest bath with ceramic tile heats up much faster even on 120v. I'm not sure what the time would be in a basement. I think a lot is based on the the type of flooring you put down. But they have systems specifically for basements and others can even de-ice your driveway. Lots of options. You could float the floor with SM, put in a wood subfloor which I think you need anyway, and then the wire mesh. Check their site for details and run it by Ted. It's a lot cheaper & easier to install than the hot water system, and no risk of leaks.
BIGmouthinDC's Avatar BIGmouthinDC 08:32 PM 07-04-2013
Kinw3, just another random idea. If you have enough adjacent areas with their own heating and cooling you could set up an air exchange system with those areas. Using an inline fan for both the supply and return you could heat and cool the theater by drawing conditioned air from other areas and still maintain sound containment if you used dead vents. Of course the theater might smell like the kitchen.
kinw3's Avatar kinw3 12:30 AM 07-05-2013
Thank you all for the replies.

@petew - its downloading on my laptop as I type this on my pad

@rabident - thanks for the suggestion, I have a deep seated aversion to using electricity for any heating. It is vey expensive, and I intend to extract heat and cold from the ground and heat/cool via a heat pump which I wll power as much as possible from solar panels

@Big - thank you for interrupting your busy schedule to help me. Perhaps in Damelon`s theatre the smell of sizzling fat might be. more appropriate!

Thanks again

PS - @petew - it has scrollbars - awesome!
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