I plan to lay a Pergo laminate floor on a concrete slab with underfloor heating. However, their instructions state that the moisture content must be below 60% RH.
The slab for the house was poured in mid-May 2022, and the underfloor heating and FTX have been running since mid-November. A week ago, we did a moisture measurement that resulted in 83% RH. This means it has dried enough to apply a moisture barrier but not for laying the Pergo floor. When I asked how long it would take to get below 60%, the response was "several years."
I have emailed Pergo, and they say, "We base this on industry requirements from Golvbranschen- GBR, EPLF - Association of European Producers if Laminate Flooring and also hus AMA."
In hus AMA, it states:
"When laying, the relative humidity (RH) in the substrate must not exceed 60%. However, laying may be performed at 60–90% RH in the substrate if the substrate is covered with a moisture barrier of plastic film according to JSF.5. When covering on YHB.221."
I will be laying Pergo’s Silent Walk, which has a vapor barrier/moisture protection, so it should be OK to lay the floor at 83% RH. But Pergo’s response is that I would waive my right to the warranty because I am deviating from their instructions.
My thoughts:
The slab for the house was poured in mid-May 2022, and the underfloor heating and FTX have been running since mid-November. A week ago, we did a moisture measurement that resulted in 83% RH. This means it has dried enough to apply a moisture barrier but not for laying the Pergo floor. When I asked how long it would take to get below 60%, the response was "several years."
I have emailed Pergo, and they say, "We base this on industry requirements from Golvbranschen- GBR, EPLF - Association of European Producers if Laminate Flooring and also hus AMA."
In hus AMA, it states:
"When laying, the relative humidity (RH) in the substrate must not exceed 60%. However, laying may be performed at 60–90% RH in the substrate if the substrate is covered with a moisture barrier of plastic film according to JSF.5. When covering on YHB.221."
I will be laying Pergo’s Silent Walk, which has a vapor barrier/moisture protection, so it should be OK to lay the floor at 83% RH. But Pergo’s response is that I would waive my right to the warranty because I am deviating from their instructions.
My thoughts:
- Are their requirements for 60% entirely unreasonable?
- It is about 3 weeks away from when I plan to lay the floor, which means a 4-week drying time from the measurement that said 83%. How much can it theoretically dry? The supply temperature on the underfloor heating is about 23 degrees, the air temperature is about 19-20 degrees, and the humidity is around 40-45%. Unfortunately, I don’t know what the W/C ratio of the concrete is, but I can try to find out.
- Should I ignore their requirement and lay the floor in 3 weeks? Or what could be the consequences?
Is the underfloor heating on today? If you turn it up, the RH will decrease significantly. If you have 85% today with a surface temp of, say, 18 degrees, you have a moisture content of 12.32g water vapor. If you turn the heating up to 25 degrees, RH will be around 50-55% somewhere. If you already have the underfloor heating on, that’s another matter.I Intershade said:
The underfloor heating has been on since the end of November, so a little over 2 months...I Installation said:
Temperature? It shouldn't be a problem with under 85%rh, especially if you have aged-resistant plastic between the concrete and the laminate. They are a bit neurotic. How many square meters are we talking about?I Intershade said:
Supply temperature for underfloor heating is about 23 degrees, air temperature is around 19-20 degrees, and humidity is around 40-45%. Is it worth increasing the supply temperature?I Installation said:
The slab is 128 sqm, and I will lay the Pergo flooring on about 75 sqm of this.
I also find them somewhat neurotic. But I lack experience and knowledge of how one should act in this situation. I've already bought the floor and would prefer to avoid the hassle of trying to return it and buy another floor. How do others building new homes and laying Pergo floors handle this is a question I'd like answered.
Turn the temp up to 27 degrees. Place the packages with Pergo in the room and lay in 3 weeks. If you are worried, measure again in 2 weeks. Do you have a good measurement hole? Or do you surface measure? It's perfect for a while longer with high RH outside with low temperatures and low RH inside with higher temperatures. Since you've reached below 85%, you can bring in a dehumidifier if you want. But increasing the temperature in the slab should be enough.I Intershade said:
I hired a firm that did the measurement, and they drilled two 4 cm deep holes at two places and had a meter there for a few days.I Installation said:
It was the guy from that company who said it would take several years to get down to 60%rh.
I'm more or less inclined to ignore the moisture content and just go ahead and lay the floor in 3 weeks. I don't feel like I have a more reasonable alternative; I want to move into the house. Initially, I wanted to check here to ensure it's not completely crazy. But sure, I can do another measurement when I install the floor to see if it's dropped further.
I admit I am very ignorant about this. I mean that I am prepared to ignore their requirement to be under 60%RH even if it means waiving my right to a warranty..Matti_75 said:
The following is a recommendation from Pergo:
The moisture content of the subfloor must be less than 2.5% CM/75% RH (cement) or less than 0.5% CM/50% RH (anhydrite – subfloor). If there is underfloor heating, the values must be 1.5% CM/60% RH and 0.3% CM/40% RH respectively.
The following are the results from the measurement:
How should this be interpreted? Is it reasonable to meet their requirements then?