Cold Concrete Floors

[MasterPlumbersKeymaster]

We have just purchased a large manufacturing building built in the 60’s and early 70’s. We plan to build about 4000 sqft of offices (40 100′) in an area that was formerly an unheated loading dock. The floor is an uninsulated concrete slab.
– 100′ feet of the office will be on an outside wall and we can add insulation on the outside before backfilling.
– The two 40′ sides will be adjacent to semi-heated loading docks.
– The remaining 100′ side is adjacent to heated manufacturing space.

Everyone tells me that unless we go to the expense of installing in-floor hot water heat we will have uncomfortably cold floors. It seems such a waste to pour a new concrete floor over a perfectly good concrete floor.

It seems to me that by heating the perimeter (with radiant baseboard heat?) we can keep the cold out, but they insist that the heat won’t go into the floor.

What do you think?

Thanks,
Terry

[SylvanLMPParticipant]

Well, this is news to me about having to install underground piping that can never be serviced or inspected.

All the big buildings I work in have either cast Iron radiators or Cast Iron baseboard or scorched heating (heating ducts)

To pour concrete over a perfectly sound floor sounds like an engineer who has trouble sleeping at night and looking to think up things so the boredom will help him sleep.

I wonder what folks did in the OLD DAY like the early 60’s in Bowling allies to keep warm?

OH well why not just E mail me and ILL let you meet my team of experts on my list to answer you

[GuestParticipant]

SNIP> We have just purchased a large manufacturing building built in the 60’s and early 70’s …The remaining 100′ side is adjacent to heated manufacturing space.Everyone tells me that unless we go to the expense of installing in-floor hot water heat we will have uncomfortably cold floors The building has been in use since the 1960’s. According to the ‘Everyone’s’, the occupants were never warm because they did not have radiant floors installed. In fact, except for some residential experiments, noone at that time had radiant floors, so according to ‘Everyone’s ‘ logic no person ever has been warm or comfortable before. This is obviously untrue.

Unless you insulate the 4000 square foot area so the heat loss will be less than 25 btuh per square foot (100,000 btuh) you will need supplementary baseboard heat to make up for the fact that the floor radiant heat will not be able to give sufficient heat to the space, as there is a limit to how hot you can make the floor. The underside of the floor is uninsulated to isolate the slab from the ground so 15% of the slab heat will be lost into the ground below, raising the fuel bill.

In addition, a thick concrete slab has a large heat absorption and release time because of the weight of the concrete. Rapid changes in weather will cause a lag in heating, so as the weather becomes colder the room will be too cool until the slab absorbs enough heat. As the weather grows warmer, the room will be too warm until the slab gives up enough heat. Most radiant installers are unaware of mass heat storage capacity and control timing to successfully provide comfort, so they make the mistake of thinking there is no difference in approaches for wood floors over spaces and heavy concrete over 2-inch thick. The ideal solution for a large heavy slab is to warm the slab enough to provide half the heat requirement and provide the remainder of the heat by baseboard element, as baseboard rapidly cools to ‘get ahead or behind’ the heat demand. This means you need perimeter heating either way.

It is common practice to install rugs in offices for quiet, comfort, and maintenance ease. A good rug and pad will isolate occupants from a cool slab as it does for thousands of homes built on slabs. Insulate the perimeter and install commercial hot water heating around the perimeter. Everyone will be quite happy with the heat.

[SylvanLMPParticipant]

There you go Harold giving away information that a P&H guy was going to say.

Of course the P&H experts (self taught) not one of your IBR trained guys would have guessed by the rule of hand approach.

Harold for what it is worth I ageee with you on the Marble chips RE boiler discharge (Shhhhhh dont spread it around)

[Author]

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