"Force-drying" a floor

24 Aug 2009
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@ WoodYoulike

In a previous topic entitled "when to lay wood-floor", you said not to do this. Does that include all situations in your opinion ?

I ask because i will shortly be having a self-levelling screed laid for UFH and the manufacturer of the screed says on its site - and also talking directly to the Tech Dept - that they recommend that you start using the UFH to a prescribed heating plan after 3 weeks on a 50/60 mm depth.
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Depends on the depth of the concrete IMHO. 50/60mm normally would take 2 - 2.5 months for all the moist to come up from below to the surface. Doing this too quickly can mean the concrete will not bond together completely (cracks) which can affect the efficiency of your UFH.

The start up procedure does mean increasing the water temperature with only 5 degrees C per day, not going full tilt at once.

From our (Duoplank) manufacturer's guide:

If you install a wood-engineered floor on a under floor heated sub floor, there are some conditions you
should respect:
- Tubes should be located minimal 3cm below the surface of the screed.
- The screed must dry naturally to below 1,8% moisture content (anhydrite: 0,3%). Do not turn the under-floor heating on before the correct moisture level is achieved
- The maximum temperature of the surface of the screed should be 28 ° C and steady.
- Relative atmospheric humidity should be maintained between 50-65%, adjust by ventilate or using a humidifier.
Heath up the water of the system to 20° C
- Raise the temperature every day with 5° C until a maximum of 45° C
- Maintain this temperature for 5 days.
- In the following days, lower the temperature with 5° C every day until you reached the temperature of 20° C
- Than turn off the system.

So in total 15 days = 5 weeks after a concrete layer of 50/60mm is poured if you follow your screed manufacturer's advice. Not sure about this, IMHO too quickly and could result in a failing underfloor.

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