Concrete floors

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Concrete floors

Post by PNB GUEST »

FLLW often used stained concrete floors in his Usonians. I have always liked the idea and looks of these. However, I am wondering just how comfortable they are in a house setting? Any insight from those who live with concrete floors would be appreciated.


Post by Richard »

Are you going to have radiant heat? Will you be using area rugs? Do you have very young children? Are there going to be large southern window exposures? What type of climate is the house in? . . .

For example, if you live in a cold climate and you don't have good size windows facing south, concrete floors will be cold and may appear dark. If you do have windows facing south, concrete floors can be very enjoyable.

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Post by flwright »

As a youngster, I never thought twice about growing up with concrete floors; they never bothered me. In fact, they were quite useful in shooting toy cars across the room and sliding around in sock feet (but I did have my fair share of tumbles and near concussions!).

As I age, however, it is a completly different story. Concrete is very hard on the feet and especially the knees. My parents are very anxious to build a new house and do away with their concrete floors -- it is very high on their priority list. My suggestion, if you intend to go down this road, would be to temper the concrete floors with a lot of fluffy rugs.

And, as Richard eludes to, there are many ways to make concrete floors even better. Lots of south facing windows and radiant heat (as my childhood home had) go a long way. The floors can also act as a solar mass and give off slow even heat making for a real comfortable home climate while lowering your energy bills.

One must remember that there are pros and cons to everything and each person must weigh these against their own priorities. As for me, (even with my ridiculously bad knees) I would still select concrete floors because they are beautiful, functional and are cost efficient. Besides, it gives me an excuse to not have a basement!


Post by Guest »

I have investigated solid concrete flooring options for the Jacobs #1-based home I am building in Christchurch New Zealand. This is a temperate Island climate with a year round average of 12 degrees C. Winter temperatures seldom drop below -5C and summer temperatures seldom get above 30C.

Apart from the issues raised above...

There are numerous issues with concrete floors:

1) Cracking. Concrete is, quite literally "born to crack" the only issue being, will it crack in 2 weeks, 2 years or 20 years. There are numerous anti-crack technologies, but they aren't worth a hill of beans unless the concrete slab is immediately placed under sealed plastic to set. The evaporation rate is critical, as is the ambient temperature.

"Concrete Placers" - the people who lay the concrete are a VERY VERY important part of the equation. They must be very familiar with creating concrete floors, and youmust inspect some of their work before retaining them.

2) Staining? Or Dying? My preferred option is to dye the concrete before it is placed, rather than attempting to stain concrete already in place. It is easier to get a consistent colour with all the concrete dyed. This is another area the Concrete Placer must have well under control.

3) Concrete floors must be left for an absolute minimum of 28 days after pouring before any work can be acrried out on the concrete surface. THERE ARE NO EXCEPTIONS TO THIS RULE WHATSOEVER.

4) The "construction cuts" must be made within 12 hours of the slab being poured. These cuts are designed to induce cracking along the bottom of the cuts. They are quite deep: at least 25% the depth of the slab. Here it is critical that the placement of reinforcing, underfloor water pipes and underfloor electric elements is critical. If you cut either pipes or elements, you are stuck with a floor that does not work, a region that does not heat, or you are having huge arguments with 2 or three different contractors, all of which are blaming each other.

5) Concrete floors simply MUST be heated in anything other than a very benign climate. In New Zealand, a 223 square metre (2300 square feet?) home with 200 square metres of heated floor is around $15,000 for the hardware and installation of the various control systems. Heating of the water is recommended by use of a pool heater, in the heat-exchanger form-factor, usually of at least 2.5KW draw. (10KW at the hot end under ideal conditions).

A heated concrete floor will require at LEAST 100 mm of polystyrene insulating it from the ground. 200mm is preferable. This is expensive also.

A slab so-insulated will begin to noticeably lose heat after 12 hours of not being heated. This measn that generally you can not use ONLY "night rate" power to heat the floor - although this will be your main way to reduce running costs.

Consider: 8 hours @ 2.5KW @ 17cents/KWh x 30 days. That's at least $100 in heating for the month, plus top-up electricity, which will vary from 0 to double. I know of heated floors which cost in excess of $300 a month to heat.

6) Exposed aggregate flooring is even more difficult to do, as the placers must NOT even stand in the concrete after it is poured. To ensure that the aggregate stays just below the surface and produces a perfect floor is almost impossible. No one will give you a guarantee. A house I visited recently had footprints all down the hallway. The wife cried when she saw them. So she spent $2000 on a long rug to hide them.

7) "flag-stone" concrete is heavily "worked" when it is poured, and decorative cuts are designed to give the floor the look of coloured flagstones. This is possibly the safest and easiest option, as the look is excellent, and cracks make the floor look even better, rather than worse.

To my way of thinking, a floor which sucks an extra $25,000 to start with, has no guarantee and then costs between $100 and $300 a month to run is not an option.

My home will have, instead, "stonecarpet" which is a dutch thing, brought to NZ about 20 years ago. It is river gravel (or glass, or whatever you want), held in a totally open matrix, with non-toxic epoxy resin. (Please don't ask "How do you keep it clean?" as I am sick of explaining it!) Because it is a matrix, only abour 25% of your feet touch the floor, and because the room air circulates through the floor, it acquires the room temperature rapidly. It is therefore much preferable to stone, concrete or tile, as it does not feel cold to stand on with bare feet - even in winter.

I spent months agonising over a floor.

Good luck with your owns agonizations!

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Post by Mobius »

That was me BTW.

How many escape pods are there? "NONE, SIR!" You counted them? "TWICE, SIR!"

*Plotting to take over the world since 1965

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Post by Reidy »

Millie Ablin, a Wright client, once noted that eveything breaks on a concrete floor, even supposedely unbreakable plastics.



Post by Richard »

Mobius, in a Wright house with radiant floors, the radiant floor is the main source of heat. Sometimes, supplemental radiation above ground is sometimes used as well. Also, a furnace would be used and not a pool pump to heat the water. Floors run at about 130 degrees whereas the copper or steel radiation can run as high as 190+. So, you need zone valves, mixing valves etc. to distribute correctly heated water if you have more than one type of radiation... Temperatures in the Chicago area can vary quite a bit from 10-15 below O to 95 and above F.


Post by Richard »

Mobius, BTW, was it Dr. Mobius or Morbius from the movie Forbidden Planet? Great sci fi movie based on the Shakespeare story about a shipwreck - The Tempest.


Post by rgrant »

Close, Richard, but no cigar. Walter Pidgeon played Dr. Morbius. His daughter, Altaira, was played by Anne Francis and Leslie Neilsen played Commander John J. Adams. The robot, Robby, was inhabited by small actor Michael Carpenter, one of the finest drama coaches around. "Forbidden Planet" was among the first of the seemingly endless adaptations of Shakespeare's "The Tempest."

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Post by flwright »

Mobius -- A few additional points to ponder on your last post:

Anonymous wrote:There are numerous issues with concrete floors:

1) Cracking. Concrete is, quite literally "born to crack" the only issue being, will it crack in 2 weeks, 2 years or 20 years. There are numerous anti-crack technologies, but they aren't worth a hill of beans unless the concrete slab is immediately placed under sealed plastic to set. The evaporation rate is critical, as is the ambient temperature.

Yes, concrete will crack but let us not take this to any extreme. Many common reasons for cracking include: lack of reinforcing, proper curing, weak concrete mixes, lack of a sand layer directly under the slab (which assists curing), lack of a slip sheet (2 layers of polyethylene sheets laid 90 degrees to each other to assist movement) and settling of under-slab soils due to poorly compacted backfill


Concerete Staining

Post by WrightEnthusiast »

Given the choice between staining or dyeing, I agree that better control and finished product effect achieved can be attained through staining. Can someone state the specific materials (where they can be purchased) and the steps to perform?

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Location: New York

Post by lgranowe »

I love the way the concrete floors in my Henken house look- but they are indeed hard on one's knees as you age. And we are having a hard time finding someone to do some restoration/repair work

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