New Slab in Basement

Heatmeister_2

I have decide to knock out in the basement floor and put in a new concrete floor over PEX instead of an over pour on the existing SLAB. For various reasons, i.e. hieght, insulation, drain tile etc... it seems to make sense since I don't plan on moving soon and it is part of an BIG basement remodel.

I live in Minnesota and have several questions. Keep in mind I am not doing this myself, I am hiring a pro. However I would like to know some answers for confirmation of standard protocol regarding this phase of my project:


1) Do I need a vapor barrier in addition to insulation. I live on a lake and even though the basement has never had a water issue it is set back about 80feet BUT it is only about 4 feet higher than the lake level.

2) Should I use 1" or 2" insulation. Is the pink DOW sufficient or should I consider an other brand or type.

3) My basement will have be 1200 sq. ft. and have a 1) TV Room,2) Office, 3)Game Room, 4) Laundry Room, 5)Bathroom and 6) Entrance. Is it standard practice to set up ONE Zone, ... 6 ZONES ...or other?

4) How deep should our pour be to get maximum efficiency and is Concrete all the same?

5) Should we use a special metal reinforcement over the PEX before the pour.

6)Is 1/2" PEX running 12" on center a standard approach or should I consider a different size pex running at a different distance?

7) What else should we take into consideration or factor????

Thanks

Ich Wundermich

new slab

1. Yes, at least one layer of six mil

2. In Minnesota 3-4"

3. A zone for each of the described areas

4. 4" is adequate, regular 24 mpa should do for interior floors

5. 7'x 10' remesh with 6" mesh grid UNDER the pex pipe.

6. 1/2" tube 6" on center will allow lower supply temperature.

7. real manufactured distribution manifolds.

Heatmeister_2

Vielen Danke!

Also, If I want to add drain tile, how far should the vertical insulation along the outside wall run into the ground? And should the drain tile be positioned realtive to the insluation?

1)Along the wall with the insulation insided

2)insulation on the outside with the draintile on the inside

3)or underneath.

Mike T., Swampeast MO

Great reply for a long-lived, quality, efficient installation.

My only embellishment is regarding the "zoning". Give HIGH consideration to FHVs (floor heat valves). Very similar to TRVs (thermostatic radiator valves) with a built-in balancing adjustment and available built-in bleeding ability (important in a below-the-boiler application).

Price should prove very competive compared to a thermostat and circulator or thermostat and zone valve for each zone. With such a large number of zones in a relatively small area with relatively low heat loss (basement below conditioned space) the FHVs should prove vastly superior to any other zoning strategy as the basement will become, in effect, a SINGLE zone of moderate size as compared to many zones of tiny size.

Heatmeister_2

Thanks

hr

Be sure

to run a strip of insulation along the wall where the slab pours to the foundation. This will act as a thermal break and an expansion joint. 1-1/2 or 2" should be fine. Bevel the top at a 45 to help hide the raw edge.

I would think 2" under slab would be enough if this basement is 8 feet below grade. But it's your money 4" under the slab will cost as much as the concrete

If you use foamboard you could skip the remesh and staple the tube to the foam. Remesh under the concrete pour does nothing for the strength of the slab, and becomes a big tripper

Be sure the subgrade is compacted for a good solid crack resistent slab.

Becareful not to "micro zone" a small square footage like that. If the rooms connect without a door I would zone them together. I would run separate loops to the defined rooms, should you partion off later.

Typically basement loads are low and 12" on center should meet the load with very low supply temperatures. The HDS program actually has a basement load heat loss calculator if you need to see the math first. Which is always a great first step.

hot rod

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Alex Giacomuzzi

drain tile etc........

Your drain tile should go below you horizontal sheet of insulation. It should sit adjacent to the side of your footing for a below grade basement wall. The side of slab insulation on a below grade basement will only be as thick (high) as the slab --- approx 4".

For a walk out basement, you could certainly install the edge insulation deeper if you would like to in that walk out area where the whole height of the basement might be exposed. Or you could install your tubing closer --- say 6" spacing for 2-3 feet along that outside exposed wall.
I do not know what type of basement you may have.

I do have a question or two for you, especially when thinking about how much work & $$ this will be.......

Have you possibly considered a radiant ceiling or even just good quality panel radiators on the walls along with some good insulation in the outside walls?

Good Luck...... Alex

ALH_4

Unibox

The Unibox from Oventrop is quite nice, though they are more money than a valved manifold and thermostats. Thanks to Mark E for posting about these in a previous thread.

-Andrew

Heatmeister_2

Thanks Again

My basement is somewhat unusual. Here is a picture. The the entrance door is now blocked with a small window on top( our new bathroom)and the garage door is getting converted to an main basement entrance.

ZONING: Only one room roughly 150sqft (aside from the bathroom) will have doors (double doors) and they will likely be open much of the time. Aside from that it is an open floor plan which about 1200 square ft.

FLOORING: I have considered an pour over called Thermafloor by Maxxon which is less expensive $3/sq. ft vs. $6.50/squ. ft for the removal and repour of concrete. If I repour I sacrafice nothing, plus it gives easy access to all my new below grade plumbing waste lines. I have a fair amount of plumbing changes.

If I pour over it is a lot easier but I give up some height(not a lot), no decent insulation below and would have to incur additional costs to breakout concrete in those area to change my plumbing which brings the cost up.

Also what about running treated 2X2 around perimeter before the pour for the CARPET GUYS?

PANEL RADS: I am sure that panel rads would heat this area just fine. Ceiling heat, I am not sure I can do if I intend to use Ultra fin for heating the second floor?

Given the scope of this project, I just figured that since the floor needs some TLC and leveling why not yank out and repour. My Heating pro says he can lay the PEX over styro in one day.

I have made enough mistakes with this house over the last 6 years. I should have done this project at the beginning not the end. I just figure I don't want to be sitting in the basement watching Bob Villa, next October, wishing I had spent the extra 10% to do it as it it were new construction.

HIGH VELOCITY A/C: Any comments, I have not A/C down here. I do have to units running the north and south side with Air handlers in the attic that service the first and second floor. Any guys here know of a site like this where I can get some information?