Underfloor heating and Engineered wood floor problem

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Hi Everyone :D

I've got a problem with some of my Engineered flooring planks swelling and turning dark brown. It looks like it's affecting planks that run lengthways above the plastic clip strips for my underfloor heating pipes.

I've added some pics in of the problem.

As part of a new extension and house refurb, I had a new concrete sub floor laid in September last year. I had underfloor heating installed on top of rigid insulation boards and then a floor screed poured at the end of October. The underfloor heating was then switched on at a low heat to dry the screed.

The engineered wood floor was laid on about the 8th of December. It is a click system that 'floats' on top of a very thin layer of white foam material, which I was informed was to stop the floor being noisey when walked on.

The affected boards stated to show swelling after we moved in mid January. They are now going dark brown as seen in the pictures. The area of discoluration is also pretty warm to the touch.

I've also included a pic of the underfloor heating installation. The plastic strip in the foreground is the one below the darkened area in the other pictures.

Any idea's what's going on here?

Many thanks, Andy

 
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Rather looks to me like your UF heating has developed a leak. This has come to the surface of the screed and is affecting your floor.
 
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Thanks for the reply.

Just for info, the same thing is happening in the kitchen adjacent to this room where the plastic strips lie beneath the boards longways. Although not as bad. There is always about 4 to 5 good boards between the affected ones.

The other 2 rooms and hall where the plastic strips go across the boards rather than longways are fine.

It's also worth pointing out that the concrete screed dried out ok with no sign of wetness before the floor was laid. The UFH was on continually during this time.

I'm not saying that isn't leaking, just trying to get my head around how it would leak in this pattern.

Cheers, Andy
 
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As John says it certainly looks as if this is being caused by a leak - possibly where the screed is thinnest along the line of the pipe clipping.

It won't improve and if it is a click system I would get it up asap to avoid any further damage to the floor. Presumably you or the installers (of the heating system) are insured for such as this?

On any concrete floor it is always advisable to incorporate a dpm in the underlay.
 
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I'm sorry that this comment is not in any way related to a solution of your problem - and you may also be aware - but floating floors are not recommended for UFH as they provide an additional unwanted insulation layer.

I only mention this , in case , during possible renovation you may wish to modify matters.
 
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I'm sorry that this comment is not in any way related to a solution of your problem - and you may also be aware - but floating floors are not recommended for UFH as they provide an additional unwanted insulation layer.

I only mention this , in case , during possible renovation you may wish to modify matters.

Thanks for the heads up on that! I'll do some research on that as well.

Cheers, Andy
 
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I'm no plumber but isn't there a test you can perform for leaks? Such as a pressure drop on your boiler when the heating is turned on?
 
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That's a fair point ref the pressure. There is a pressure gauge on the UFH manifiold, but there seems to be quite a bit of variation depending on how many zones are active and if the Radiator side of the system is on.

Not sure how 'sealed' the UFH side is either in terms of pressure, as the water gets heated by the boiler. I have a thermostatic mixer on the UFH system set to 50 degrees.
 
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how deep was the screed over the pipes?

Do you now what the moister reading of the concrete was before laying? (rh)

You say the concrete/screed was dry? how do you know? (1 month drying you will be lucky)

Was the underlay laid in the same direction as the lines in the floor? was the joins tapped with a dpm tape?

Are the boards cupped/crowned?

Take a measurment of the board width and compare this size to what the board specs say they are. Also see if the board with the line in is slightly wider or cupped worse than the others.
 
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Hi

The concrete screed is about 4 inches deep.

Don't know what the moisture reading of the concrete slab below the screed was before laying, if that's what you mean. There was no measurement taken that I am aware of, other than the 2 pronged meter maybe. The builder deemed it to be dry enough to proceed.

The screed was then left for about 6 weeks with the UFH switched on 24/7 and was tested with the normal 2 pronged meter. It gave a pretty dry reading on this before the floor went down.

Visually the screed looked uniformly dry throughout the whole house. I was looking out for any damp patches indicating a possible leak in the UFH.

The underlay was laid in the same direction as the floor and I do not believe that any DPM tape was used.

The affected boards are crowned, ie a bump in the middle of the board.

All the other flooring boards throughout the ground floor of the house are fine.
The two rooms affected are part of the new extension we had built. The rest of the house also had new concrete floor laid at the same time to replace the old suspended floor (1920's red brick semi).

The whole ground floor has basically the same layers of DPM, concrete slab, insulation and screed poured at the same time and has the same flooring laid.

The only thing I can think of that was different is that the new extension concrete subfloor was rained on for a bit after it was poured and was exposed to the elements until the roof went on. The concrete in the old part of the house was obviously in a dry environment after pouring.

As said, it is just the 2 new extension rooms that have the affected boards and these rooms are the only ones that have the UFH mounting strips running the same direction as the planks.
Just thinking though, there are a couple of areas that are affected also that don't match up to the UFH mouting strips. These would be about 2 consecutive boards long. I have a heap of photos and have been matching things up.

Thanks to everyone for taking the time to reply so far. Much appreciated :)
 
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o.k,

well first off concrete/screed needs approx 1mm per day to be dry enough to install most floorcoverings (below 75RH) However if wood is to be installed it needs longer to dry (below 65RH)

Moister of the concrete/screeded floor needs to be monitored witrh a Hygrometer and the test takes a minimum of 48-72hrs to get a accurate reading.

moister meters with the sticky out prongs are not sutible to take concrete/screed moister readings.


Have you also taken a surface temperature reading of the wood while the heating is on? or what was the surface temperature of the heating system before the wood was installed?



From what i can see it looks like its a mixture of moister and heat at the moment that has caused the problem.
 
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Thanks, all good info there on the damp readings and the screed. I should be able to get hold of a thermometer to check the temp of the flooring.

I pushed the prongs of the damp meter into the surface of the affected wood and it is giving me a high reading right on the discoloured wood. The adjacent wood is giving no reading at all.

Looks like it is due to moisture then and maybe heat as well as you say.

I have a scrap piece of the white underlay and it looks to be about 104 cm wide. If that is the correct width, the underlay fits very well between the areas of affected flooring. I've added some new pics of this!

Hopefully it's not the UFH leaking. I can't imagine how it would leak in so many places in this part of the house and not the other rooms, but who knows.

The builder had been waiting for a flooring rep to look at the problem but there is likely little point in waiting any longer if moisture is the issue.

Cheers, Andy :)
 
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It doesn't has to be a leak per see. It could also be condensation above the strips of the UFH system. If these strips are not fully level with the rest it could create an "air-gap" and cause condensation = moisture problems.
 
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looking at the fact that the underlay is about the same width as where the lines are i will go back to my theroy that the vapiour barrier underlay was not tapped at the joins and there is also to much moister in the concrete/screed (not dry)

however that underlay does not have a built in vapiour barrier. So did the installer lay plastic sheet down before the underlay ?


Im possitive that the problem is down to moister.

You say you stuck a damp meter into the wood? What was the reading in numbers? (Rh reading of concrete is different to wood reading, it should be around the 10-12ish number on the meter) Also what make of meter are you using? It is a wood moister meter i take it?
 

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