Floating Engineered Wood Flooring over Underfloor Heating UFH

[revelation]

Hi all

 

We have ab uncertain situation with our flooring.   We have UFH on our first floor (wet system, aluminium plates under chipboard flooring).

 

We bought all our flooring at the start of the year from a company called Woodpecker.  We have noticed that their instruction say this can not be floated and glued (on the tongue and grove joints).  If it is being floated they only recommend their own Solitec self-adhesive underlay  (£95 for 10 sq m, I would need 8 of these)

 

I have called and spoken to Woodpecker, they said it can't be glued on the joints and placed on a standard UFH underlay.  However, my fitter doesn't see an issue with doing it this way but is reluctant to go against the manufacturers' instructions.  

 

I was wondering if anyone else can shed some light on this.  (we can not glue this to the floor, it onset an option)

 

Thanks in advance.

[markc]

Sounds like a bit of bullsh1t. If you glue flooring together it becomes a big piece, nothing weird, magical or sinister. Now if the flooring is very thin or brittle then anything underneath would need to be flat and rigid so soft underlay would cause problems. What is the flooring material, thickness and make up? Some pics would help

[revelation]

5 hours ago, markc said:

Sounds like a bit of bullsh1t. If you glue flooring together it becomes a big piece, nothing weird, magical or sinister. Now if the flooring is very thin or brittle then anything underneath would need to be flat and rigid so soft underlay would cause problems. What is the flooring material, thickness and make up? Some pics would help

the flooring is 20mm thick engineered oak wood.   Woodpecker said due to the temp changes because of the UFH it can cause cracking.  I don’t know if this is genuine or just to sell their super expensive underlay. 

[ProDave]

It is important when buying flooring that the manufacturer says it is okay with UFH.  We have 20mm engineered Oak over UFH (fixed not floating) without issue, but we confirmed before buying it, that it was okay with UFH.

[markc]

19 minutes ago, revelation said:

the flooring is 20mm thick engineered oak wood.   Woodpecker said due to the temp changes because of the UFH it can cause cracking.  I don’t know if this is genuine or just to sell their super expensive underlay. 

Electric UFH can can see some big changes in temperature (one left a towel on my bathroom floor and burned my foot when I stood where the towel had just been) but wet rarely gets above 35 deg C, and cannot create hot spots. Plus the laminating process is done at around 50 deg c to cure the adhesive. 
 

[AliG]

I have never seen engineered flooring that could not be fitted over UFH.

 

Looking at their website, that underlay seems to be used instead of gluing the floor together. There might be some advantages to this, but standard underlay and gluing would be fine. I have hundreds of square metres of floor installed floating on a basic foam underlay.

 

What kind of flow temperature will you be running? I would be worried that laying 43mm (chipboard+underlay+wood) of floor over the UFH spreader plates seriously limits the transfer of heat.

[revelation]

1 hour ago, ProDave said:

It is important when buying flooring that the manufacturer says it is okay with UFH.  We have 20mm engineered Oak over UFH (fixed not floating) without issue, but we confirmed before buying it, that it was okay with UFH.

woodpecker say their engineering wood floor is suitable for UFH.  But not if the joints are glued.  As I said my fitter can’t see why. Also the UFH temperature will not be run higher than 27 C. 

[markc]

Still sounds like Bullsh1t. I know what I would get on and lay it, glued and on a decent non insulating underlay but only you can make your decision

[AliG]

The floor will be fine if it is glued. Mine is just glued and laid over normal underlay, not fixed to the floor.

 

I am surprised to see you quote a flow temp of 27C. I tried finding your insulation values in previous posts but couldn't. Basically that would put out so little heat using spreader plates and through two layers of wood that it would only work if you didn't actually need any heating.

 

I find I need to run the flow temp in my house 3-4C higher where the floors are covered in wood than tiles and that is just 15mm engineered flooring on screed. In my previous house where we retrofitted UFH on spreader plates in the kitchen we had to run the flow temp at 60C. Admittedly it was a lot less well insulated.

 

[Gus Potter]

6 hours ago, AliG said:

I have hundreds of square metres of floor installed floating on a basic foam underlay.

We too, but not hundreds of sq m, that said we have one room that is big and a U shape. 

 

The U shaped room has a concrete slab under part of it, the bottom part of the U.. the rear house extension part and a chipboard suspended floor which forms the legs of the U which is where we knocked out the back of the house to make a big open plan space. Flooring is 15mm fairly high end engineered flooring. The flooring interlocks with some clever plastic bits to join the butt ends. You can also glue it if you want and fix down with adhesive.

 

In the end I used the basic foam underlay to create a bit of a slip plane as the concrete and timber floor will move by different amounts. Yes, the basic foam underlay acts as an insulating layer but when you look at it it's not much of an insulator. My though process was partly.. if it gets damaged / wet can I easily lift some and replace, what if we want to change it later (hope this never happens), if it's glued down will be a nightmare to lift. If we did want to lift it then we could use the unworn bits in other rooms maybe.

 

In summary it's all been down a nearly 18 months so full year of UFH cycle.. heating on and off different humidity levels and all still looks tight. What I would do is if you have some really heavy furniture then maybe just move it from time to time to let the floor move / de stress? We faced a dilemma in that we have an island unit in the kitchen with waterfall sides. Conflicting advice was offered. Do you put the floor down first and then the water fall sides on top or do you do the water fall and butt the floor up to it.

 

In the end we put the floor down first and put a bit of plastic under the bottom of the waterfall sides to make a slip plane and then trimmed off. So far no signs of overstressing on the island unit and the flooring. All looks good.

 

 

 

 

[Temp]

4 hours ago, AliG said:

The floor will be fine if it is glued. Mine is just glued and laid over normal underlay, not fixed to the floor.

 

I am surprised to see you quote a flow temp of 27C. I tried finding your insulation values in previous posts but couldn't. Basically that would put out so little heat using spreader plates and through two layers of wood that it would only work if you didn't actually need any heating.

 

I find I need to run the flow temp in my house 3-4C higher where the floors are covered in wood than tiles and that is just 15mm engineered flooring on screed. In my previous house where we retrofitted UFH on spreader plates in the kitchen we had to run the flow temp at 60C. Admittedly it was a lot less well insulated.

 

 

We have 21mm Engineered Oak fixed to battens with UFH and spreader plates, no chipboard. We have had to turn flow rates up to 50C.  House built to the regs in 2007. 

 

If we had ASHP (eg lower flow temps)  I wouldn't want 20+18 = 38mm of wood over the pipes. 

 

 

[Andehh]

We have family with Ufh, spread plates, 22mm hardie floor, then 15mm engineer wood and they also need to run at 50 degrees for an effective heating solution. Over 80mm PIR. Renovation property so insulation is only 'good'. 

[revelation]

16 hours ago, Andehh said:

We have family with Ufh, spread plates, 22mm hardie floor, then 15mm engineer wood and they also need to run at 50 degrees for an effective heating solution. Over 80mm PIR. Renovation property so insulation is only 'good'. 

 

Thank you for that information, we have run the pipes using aluminium plates but have used 50mm PIR and 50mm of rockwool.  We were advised that the temp that we would have to run this would be higher than that of the UFH in the screed, but not as high as 50C, I don't mind longer warm-up times just as long as the temp is not super high.

[revelation]

On 13/09/2022 at 21:09, Temp said:

 

We have 21mm Engineered Oak fixed to battens with UFH and spreader plates, no chipboard. We have had to turn flow rates up to 50C.  House built to the regs in 2007. 

 

If we had ASHP (eg lower flow temps)  I wouldn't want 20+18 = 38mm of wood over the pipes. 

 

 

 

We have 100mm of insulation below the spreader plates (50mm kingpin, 50mm rock wool).  Also what was the space between your pipes?

 

Regards

[Temp]

Our system is pipe in foiled insulation with spreader plates. We have 80mm of PIR insulation under the UFH system so I guess equivalent to 85mm?  That's over a beam and block floor. Pipe spacing around 150mm. 

 

We turned the flow temperature up because the first winter was very cold and the heating couldn't quite keep those rooms to the set temperature.  Not helped by no curtains in those rooms.

 

Our engineered wood floor has coped with the highish temperatures ok.