Comparing Thermals of Laminate Flooring Underlays

[MortarThePoint]

We have some rooms with laminate (8mm or 10mm I think) over concrete screed with UFH pipes in so we want to have as little insulating effect from the underlay as possible. I found a useful table of underlay options [1] and have crunched the numbers to look for outliers that have below the trend tog values for their thickness. Graph below. The winners (QA TimberTech2 Gold 3.3mm x 0.53tog and QA TimberTech2 Acoustic Plus 5mm x 0.7tog) are both rubber. For those interested, the highest insulating outlier was unsurprisingly the Polystyrene one (QA FineFloor TechniBoard 5mm x 2.2tog). Not in the table, but Vitex Premium is commonly available (e.g. Toolstation) and pretty insulating at 5mm x 2tog so not good for me unfortunately.

 

I'm nervous of something too thin as then it won't take out any small lumps and bumps in my screed which is pretty flat but does have the odd lump (max about 2mm high). Feels like 5mm would be a good option (thoughts?).

 

For reference, the laminate itself is 0.73tog and 0.83tog for 8mm and 10mm respectively.

 

This data obviously isn't complete so if anyone has a good suggestion I'd be grateful.

 

  

 

 

[1] https://flooringwarehousedirect.co.uk/info-guides-advice/underlay-comparison-guide/

[LiamJones]

Self level and glue? Minimum buildup and maximum heat transfer? 

[MortarThePoint]

1 minute ago, LiamJones said:

Self level and glue? Minimum buildup and maximum heat transfer? 

 

Laminate doesn't feel to me like a permanent enough surface to glue. Good though about the thermals though

[Nickfromwales]

25 minutes ago, MortarThePoint said:

I'm nervous of something too thin as then it won't take out any small lumps and bumps in my screed which is pretty flat but does have the odd lump (max about 2mm high). Feels like 5mm would be a good option (thoughts?).

Use a primer and a feathering compound. Shouldn't be a floating floor at all, so look for one that can be bonded.

[MortarThePoint]

9 minutes ago, Nickfromwales said:

Use a primer and a feathering compound. Shouldn't be a floating floor at all, so look for one that can be bonded.

 

There are barely any lumps and they surprise me whenever I find them. Could sanding / grinding be an option?

[Nickfromwales]

1 minute ago, MortarThePoint said:

 

There are barely any lumps and they surprise me whenever I find them. Could sanding / grinding be an option?

Yup, but how is your back?

 

To be honest, grinding can often result in making the floor worse than when you started if you're not proficient with said grinder.

[MortarThePoint]

3 minutes ago, Nickfromwales said:

Yup, but how is your back?

 

To be honest, grinding can often result in making the floor worse than when you started if you're not proficient with said grinder.

The painter is on site with his long handle wall sander. I wonder if he'd be game to give it a try?

[MortarThePoint]

This option is in the table but without a tog value. Looking at its datasheet it is a very good outlier (3mm, 0.1tog):

    https://flooringwarehousedirect.co.uk/product/timbertech-elite-silver-plus-foil-wood-underlay-10m-x-1m-x-3mm-10m2/

 

[Nickfromwales]

59 minutes ago, MortarThePoint said:

The painter is on site with his long handle wall sander. I wonder if he'd be game to give it a try?

Expect a punch in the face....followed by 2 - 3 more. He may also go for a swifty to the nut-sack.

 

I'd just shoot you for suggesting it.

 

But yes, go ask him, I am keen to hear his response  

[Nickfromwales]

1 hour ago, MortarThePoint said:

This option is in the table but without a tog value. Looking at its datasheet it is a very good outlier (3mm, 0.1tog):

    https://flooringwarehousedirect.co.uk/product/timbertech-elite-silver-plus-foil-wood-underlay-10m-x-1m-x-3mm-10m2/

 

No. No. And thrice, No.

 

 

Just NO. You have UFH!!

[MortarThePoint]

7 hours ago, Nickfromwales said:

No. No. And thrice, No.

 

 

Just NO. You have UFH!!

 

Oh, are you suggesting I have no underlay and use something that can be glued straight to the screed (or feathered) surface?

 

If it's to be believed, 0.1 tog is the difference between 8mm and 10mm laminate, so wouldn't rob much heat. Anything that could be bonded is likely to be thicker. As an example, 14mm engineered oak is 1.13tog. that's the same as 10mm laminate plus 0.3tog underlay.

 

Or are you suggesting something like glue down LVT would be a better choice?

[Andehh]

How much insulation have you got below the UFH? And in the house in general? 

 

Tog slow the heat transfer , but don't stop it. Providing you have a good amount of insulation below you might not need to be too over zealous with the underlay, if there is a risk of compromising actual usability.

 

(Ironic as we spent a couple grand on low tog carpet underlay, likely with a ROI beyond my own life span... But hey ho...  ) 

[JohnMo]

I have an oak floor glued down to concrete, with UFH, it works well.

 

Thing with laminate is, and any floating floor covering, you have the underlay, plus air pockets, which add to the tog rating. They also fight against you, especially so with a well insulated house, which has a low flow temperature.

 

Hold your hand a couple of mm away from the kettle surface which has just boiled, it's warm to hot, touch the kettle you are likely to burn yourself. Air is a rubbish heat transfer medium. So you need to eliminated it in the surface build up for low temp UFH to work.

[saveasteading]

9 hours ago, MortarThePoint said:

Could sanding / grinding be an option?

For caution, just use a brick. It will grind off the tiny high spots to the surrounding level with no risk.

Or buy an abrasive stone....but usually a brick is better I think.

[Nick Laslett]

@MortarThePoint, seems like a tricky topic. It was never on my radar as being an area that needed special consideration, oh well.

 

I bought the concrete grinding/polishing discs for my grinder and smoothed all the bumps. I used Ardex Feather Finish Rapid Drying Patching And Smoothing Compound to address the dips. (I took it so seriously, I bought a 4m aluminium straight level)
 

Good disc selection and advice here. 

https://rightlines.co.uk/?syclid=110c7de9-f13f-409c-803f-0bdfabe44a46
 

We used Parador Akustik 500 underlay, with Quickstep 14mm Engineered wood flooring. the Parador is 2.6mm thick with a thermal resistance of 0.01 m²K/W. Google is telling me that 1 TOG is equal to 0.1 m²K/W, so Parador has very low thermal resistance on the Tog scale, unless I’m confused, which does often happen. The Quickstep engineered wood has a thermal resistance of 0.14 m²K/W. 

 

https://parador.de/en/accessories-underlay-akustik-protect-500-1744869?srsltid=AfmBOooaFaFrjJSMVF_Wc4ClyHZbqSLTl4WEjgl9t-tVqKvkH6494yvB

 

The heat transfer from the UFH seems fine. I think off the top of my head that the weather compensation curve has a max water temp of 32°c at -2°c outside, but I will have to check. We have 300mm EPS under the concrete. It is an MBC insulated foundation. 
 

We still have cheap foam underlay and protecto mats on top of the wood flooring, so hard to really get a read on the heat transfer. Still have bare concrete upstairs. Even though we have had the ASHP in cooling mode, I might grab the thermal imaging tool and get a reading. 
 

We had glued down oak flooring in a previous property, wanted to go with floating at this one. Will be interested to see how I feel about the difference once we are actually living there. 

Edited Wednesday at 08:23 by Nick Laslett

[MortarThePoint]

17 minutes ago, Nick Laslett said:

We used Parador Akustik 500 underlay, with Quickstep 14mm Engineered wood flooring. 

 

Looks like good stuff. It says it has a thermal resistance of 0,01 m²K/W which is 0.1tog. Thin though (2.6mm) so makes the levelling more important. I like the certifications 

 

17 minutes ago, Nick Laslett said:

I bought the concrete grinding/polishing discs for my grinder and smoothed all the bumps. I used Ardex Feather Finish Rapid Drying Patching And Smoothing Compound to address the dips. (I took it so seriously, I bought a 4m aluminium straight level)

 

Impressive effort, must have ended up perfect.

 

 

Edited Wednesday at 08:25 by MortarThePoint

[Nick Laslett]

2 minutes ago, MortarThePoint said:

Impressive effort, must have ended up perfect.

🤣, I wish it was so!
 

My wife always says it is our perfect, imperfect house. 
 

At least most of the bodges are of my own making.  I find after a day or two of scrutinising a cockup, the pain fades, or you have to do the work again. 

 

[MortarThePoint]

8 minutes ago, Nick Laslett said:

I find after a day or two of scrutinising a cockup, the pain fades,

There's definitely a mourning process

[Nick Laslett]

Just a point about the grinder. 
 

I have the dust attachment, which greatly increases its stability. There are brushes and a spring, so the disc does not touch the concrete until you apply some pressure. 
 

[Nickfromwales]

5 hours ago, MortarThePoint said:

 

Oh, are you suggesting I have no underlay and use something that can be glued straight to the screed (or feathered) surface?

 

If it's to be believed, 0.1 tog is the difference between 8mm and 10mm laminate, so wouldn't rob much heat. Anything that could be bonded is likely to be thicker. As an example, 14mm engineered oak is 1.13tog. that's the same as 10mm laminate plus 0.3tog underlay.

 

Or are you suggesting something like glue down LVT would be a better choice?

Yup, defo. Putting that thicker 'undulation-absorbing' underlay down is just going to cause you to have to run the UFH flow temp a bit higher, and that would then be quite notable on areas where there are tiles etc, not so problematic if you have one floor covering product throughout.