Stains On Wooden Floor Caused By Underfloor Heating?

[stanmoor]

We recently moved into a newly refurbished property that has engineered oak wood flooring throughout the ground floor, along with wet underfloor heating in the kitchen area.

 

Within the kitchen, the flooring has some discoloration / staining, which, when we first moved in we assumed was from a window being left open when it was raining (as it was mostly directly under a skylight). Over the past week or so though, having been running the UFH, it seems as though the discoloration has gotten worse / spread to some other areas.

 

Could the staining be due to the UFH or something else? I checked the website from where the flooring was purchased and it says it's safe to be used with underfloor heating systems, so I'm not sure what exactly is causing the problem. No staining in the living room area (radiators are there), which is why I suspect it's an issue with the UFH. We've set the thermostat at 21 degrees over the past week in the evenings, and off otherwise. The room hasn't been colder than 20 degrees or so according to Nest despite heating off in the afternoon (well insulated, I guess..)

 

Attached are pictures - I'd be grateful for any advice that you can share on why this might be happening and how we can fix it / stop it getting worse (if that's possible!). It's probably clearer to see in the bottom picture - the darker area in the bottom third of the pic.

 

 

 

[JohnMo]

What flow temperature is the UFH set at?

[Nickfromwales]

If recently refurbished, do you know if they let the screed dry properly before the floor went down. A day per 1mm is the norm. Maybe they’ve put the floor down too soon and water is still evaporating. 
Either that or you’ve got a leak.
Is it a sealed and pressurised heating system? If so, there should be a pressure gauge ( on the boiler perhaps ) that will tell you if the system pressure is staying in the system.

[stanmoor]

12 hours ago, JohnMo said:

What flow temperature is the UFH set at?

 

I'm not sure on that, is there a way I can check? Sorry, I'm an absolute novice at this - I know where the manifold is, is there a way of checking on there? 

 

 

[stanmoor]

11 hours ago, Nickfromwales said:

If recently refurbished, do you know if they let the screed dry properly before the floor went down. A day per 1mm is the norm. Maybe they’ve put the floor down too soon and water is still evaporating. 
Either that or you’ve got a leak.
Is it a sealed and pressurised heating system? If so, there should be a pressure gauge ( on the boiler perhaps ) that will tell you if the system pressure is staying in the system.

 

I think you're possibly right with your first point (water still evaporating), as I can't imagine they would've let it dry.. do you think based on that it will disappear over time? 

I'm pretty confident there's no leak - it's all connected to the central heating (via zones controlled by Nest) - the pressure gauge on the boiler hasn't moved at all since we moved it. So on that basis, would you think it's the screed that didn't dry properly? There were marks when we moved in, and I think having the UFH on has made it most noticeable / worse.. so I suppose my options would be to replace the boards or allow it to dry over time (if that's even possible now?).

 

Thanks for your help.

[JohnMo]

12 minutes ago, stanmoor said:

 

I'm not sure on that, is there a way I can check? Sorry, I'm an absolute novice at this - I know where the manifold is, is there a way of checking on there? 

 

 

 

You should have a temperature setting knob on the UFH manifold with numbers in it, that is what your flow temp is set to.  You can also check the menu on your boiler and check the flow and return temperature.

[Temp]

My first reaction was.. has the oak been sealed/waxed? It almost looks like water damage from wet feet/shoes. 

 

 

[Radian]

20 hours ago, stanmoor said:

when we first moved in we assumed was from a window being left open when it was raining (as it was mostly directly under a skylight).

 

Could it be condensation? This is a kitchen and while the room may feel toasty, there'll be high humidity levels just waiting to condense out on a window. It's a mistake to think double glazed windows don't get condensation. If, say, your room was at 22^oC and RH was 75% (this is how my kitchen was while we cooked supper just now - lots of pasta boiling on the hob!) then the dew point would be 17.4^oC This isn't so low and could well be in range of the window glass. The giveaway would be some streaks at the bottom of the reveal.

[HelsbyW]

Hi all! I have this very problem. See photo attached. As it’s everywhere, based on what has been written on this thread, I can only assume that the builders did no leave enough time for the screed to dry. Is the colour change to wooden floo permanent, or does it ever revert back to original colour when fully dried out? Thank you! @Temp @JohnMo @stanmoor @Nickfromwales

 

[Temp]

Do you know anyone with a moisture meter? Would be interesting to compare the different colour areas to see if the wood gas a higher moisture content. 

 

Interesting that it looks drier under the rug? I might have expected it to be the other way around. Eg rug prevents moisture evaporating.

 

 

[Adsibob]

I agree with @Temp. You can get a moisture probe/meter from Amazon for about £15. That’s pre-inflation, so maybe £20 now. Mine has two fairly pointy probes sticking out of it, you pin these into the wood (a tiny amount, less than 0.5mm in and it gives you a moisture reading. 

Also worth turning the UFH heating temp down to minimum, and checking the UFH has no pressure loss.

[Tahir]

Hi @HelsbyW, hope you're well. Did you manage to resolve your problem. Did it dry out and become lighter or did you have to replace the floor? We have exactly the same issue and thing underfloor heating is responsible as well.

Edited December 23, 2023 by Nickfromwales
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