Comparing Thermals of Laminate Flooring Underlays

[Nickfromwales]

1 hour ago, Conor said:

No, on our ground floor it's 70% laminate, one other room is carpet. Seven loops but operates as one zone. But no same loop under different flooring types, so just had to adjust flow rates and all works well.

Thanks for the feedback, good to know. So you just fettled with the flow rates and that was suffice? One stat?

[Conor]

27 minutes ago, Nickfromwales said:

Thanks for the feedback, good to know. So you just fettled with the flow rates and that was suffice? One stat?

Yes. But it's made easier by the fact that our ground floor is effectively just two living spaces and a bathroom. Doors are rarely closed, if ever. 

[Gus Potter]

On 24/06/2025 at 21:59, MortarThePoint said:

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.

Hiya.

 

It's the unreconstructed philistine here in terms of UFH! So this may not help.. but a few comments.

 

Maybe one way of looking at this is how the floor is going to be laid. Often I get asked to make houses open plan and maybe marry that in with an extension with a big glazed opening looking out into the garden. Imagine you have built a rear extension, you walk in from say the hall and look into this big space with glazing that lights it all up. Now if you lay the say laminate flooring perpendicular to the direction of view into the garden say it will do two things. 

 

1/ Any bumps and undulations often show up due the dominant light direction, it cast shaddows. People are sensitive to changes in level when walking over longer distances and any shaddows alert them to these slight changes in level. If the flooring is laid perpendicular to your direction of travel it shaddows more. 

 

2/ It makes the the room look smaller in perspective when looking outwards into say the garden. 

 

Summary: If you lay the flooring parallel to the main view direction it not only makes the room look bigger it also mitigates any bumps in your floor slab as folk walk into the room. Once they change direction say to sit on a sofa the mind is interested in getting seated / what food is on the table say and you are much less aware of any change in floor level as you may be having to navigate around a coffee table and thinking about where you are going to sit.. try it and see for your self. 

 

Now I've experimented with UFH over the years..I like to design my own systems from a practical and maintainable view point. My approach is.. let's see if I can make the UFH pipes last for say 50 years and make it cost effective to say maintain, even if folk want to connect fancy controls to the loops at least it give the next owner of the home a fighting chance to change the set up. 

 

On my current house I have a ground bearing concrete slab in the extension part of it with a good clay soil dumpling under the insulation which transitions to a suspended timber floor, it's one open plan space so lots of things are moving about. I also looked a tog values of underlay vs glueing the floor directly to the concrete. The dumpling size does influence the performance of UFH.. which is a story for another day.. but often ignored in standard calculations as it sits under the layer of insulation.

 

At the end of the day I floated my parquet style oak flooring over a 2.0 mm thick poly underlay. I took the view that as the flooring is expensive I wanted to be able to fix it locally if it got damaged. Case in point.. a plant pot leaked and has stained the floor. If I get round to fixing it then the job should be easier as it floats rather than being glued down.

 

Probably the main thing is that we have rugs on the floor and some big furniture that traps the heat. That said the furniture is always warm when you sit down. In the round I reckon that all this reduces the rate of heat emission by at least 20%. so this well outlays the tog value of the flooring and makes any detailed technical heat calculations and excercise in futility. But I know this as have done it before and it's partly a dark art coupled with basic engineering principle. 

 

@MortarThePoint that's my first go at responding to your post, do you fancy posting a floor plan so we can see the room size and so on? Can you tells us what your floor slab is sitting on.. clay or gravel and where the water table is and if you have a mobile water table? Or if not got the will to live on this.. just cart on and sleep well!

 

@MortarThePoint "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?)."

 

Maybe think about some of your friends houses that are old and look at their floors, take a bottle of wine, visit and walk about, get a feel for what 25mm of change in level feels like. Also remember that your SE might have designed your house to cope with 25mm of settlement over a 50 year period which is standard. It could be that you are over thinking this?

 

As always all the best!

[Gus Potter]

As I'm on a roll here is a question for @Nickfromwales as I want to tap into his boots on the ground experience.

 

Nick. Ok say say we are setting out UF pipes. The manufacture gives us a minimum bend radius as we put in the loops. My own experience tells me that even with flexible pipes the centres are tight when we get to less than 175mm. The pipes start to oval if disturbed.

 

I know that when we want to bend the pipe we smooth out the radius on site.. like driving a racing car.. we anticipate the bend. 

 

But for all.. you get a UF design, play about with loop cad and then the concrete workers turn up (100kg a man+  with big wellie boots).. they just might crimp a pipe? and then it all goes wrong. UFH pipes need to be designed for buildability and unless you do this then you are on a hiding to nothing. 

 

 

 

 

[Nickfromwales]

58 minutes ago, Gus Potter said:

As I'm on a roll here is a question for @Nickfromwales as I want to tap into his boots on the ground experience.

 

Nick. Ok say say we are setting out UF pipes. The manufacture gives us a minimum bend radius as we put in the loops. My own experience tells me that even with flexible pipes the centres are tight when we get to less than 175mm. The pipes start to oval if disturbed.

 

I know that when we want to bend the pipe we smooth out the radius on site.. like driving a racing car.. we anticipate the bend. 

 

But for all.. you get a UF design, play about with loop cad and then the concrete workers turn up (100kg a man+  with big wellie boots).. they just might crimp a pipe? and then it all goes wrong. UFH pipes need to be designed for buildability and unless you do this then you are on a hiding to nothing. 

 

 

 

 

I have had 'orangutans' up-end a full wheelbarrow load of screed on a single pipe, and still just a bit of a dent but nothing more. With Pert-al you have to have a vendetta against the pipe to damage it tbh. Unless they're all concrete laying trannies who have turned up in stilettoes you're pretty safe, as most site boots are flat bottomed and the 100+kg is not delivered in a point load.

 

QQ: are we still allowed to say trannies, or is there a new standard? I'm really struggling to keep up with it all tbh. 

 

Bending raduis's (just googled it, hold on.....................) radii, are managed by not reversing by 180 degrees, but instead laying serpentine and only turning 90 degrees until two looser radii bends are required in the middle, to turn at 180's.

 

 

I've been sinking pipes into screeds etc for north of 25 years, and not ONCE has a pert-al pipe let me down, EVER. I imagine the flexible non al stuff may be more forgiving, but prob easier to strong-arm past it's 'point of no return', so that would then be a possible ticking time bomb that the bendee would be blissfully unaware of.

 

 

[Nickfromwales]

Radii.....

[Gus Potter]

47 minutes ago, Nickfromwales said:

and still just a bit of a dent but nothing more.

And folks it's that little dent that can compromise the whole loop!

 

 

 

[MortarThePoint]

9 hours ago, Gus Potter said:

If you lay the flooring parallel to the main view direction it not only makes the room look bigger it also mitigates any bumps in your floor slab as folk walk into the room.

 

Good point and in one room that gets me thinking. I had intended to lay the laminate (10mm Egger EHL175) in the direction of the long axis of the study which also leads to the predominant light source. That does however leave it perpendicular to the direction of room entry. The red zigzag is the direction of the herringbone in the hallway.

 

   

 

I have a similar situation in the sitting room, but there is a bay window at the end and it will also run through into the dining room with patio doors at the end so I think it only makes sense to have it going parallel to the long axis in there. That's likely to be 14 or 15mm engineered oak flooring so a different consideration to the laminate.

 

Upstairs, we are having Herringbone 8 laminate (8mm) in the main bedroom and also I expect in the dressing room, though that may end up carpet to better cope with the possibility of wet feet.

 

  

 

9 hours ago, Gus Potter said:

Can you tells us what your floor slab is sitting on

 

Ground floor is Thermabeam insulated precast concrete planks over 300mm void and first floor is 150mm HCF planks. I particularly liked the idea of the Thermabeam as it keeps the concrete inside the insulated envelope unlike standard beam and block. HCF was good for speed of installation and again thermal mass inside the insulated envelope. I'd be concerned if either had any mid-span settling. They've been down for 5 years and covered in screed (50 - 60mm Cemfloor cement-based liquid screed) for almost 4 years. We've only had one screed crack in a position I partly expected it on a long narrow run where I proposed a break anyway.

   

 

The screed is extremely flat, with the odd bubble crater or piece of aggregate sticking up about 1mm. I think I'm over thinking it and a 3mm underlay would be fine, though I'll still hunt down and grind any pimples with a brick as @saveasteading suggests and a grinder if anything more significant, but I'd be surprised if I needed that.

[Spinny]

On 24/06/2025 at 23:43, 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?

A painter with a wall sander ? How does that work ? Is he sanding imperfections in the plaster ?

How do you find a painter and decorator that diligent ?

[MortarThePoint]

7 minutes ago, Spinny said:

A painter with a wall sander ? How does that work ? Is he sanding imperfections in the plaster ?

How do you find a painter and decorator that diligent ?

He's seems really good. He's knocking back any imperfections in the plaster. His method is light sand, primer/mist, proper sand, spot prime/mist and then the finish coats (which we haven't got to yet). The first sand mainly gets rid of plaster splashes and dust etc as it's got extract. The uniformity of the white primer coat allows him to pick up imperfections with his low angle light. The spot priming is adding back primer to any significant patches that have been sanded off.

Edited Saturday at 08:06 by MortarThePoint

[Nickfromwales]

11 hours ago, Gus Potter said:

And folks it's that little dent that can compromise the whole loop!

 

 

 

Nah. Done too many, and the pipe flow rates can be much higher through a pipe which is not compromised, so when sending water at ~2 lpm in the same size pipe that could deliver 20 lpm, you have headroom.

 

Any pipes ‘seriously’ damaged had a section cut out or were lifted, binned, and replaced. I had a practice of always making sure there was at least 1x 100m coil excess on each install for such an eventuality. Not so much of a problem these days as a lot of places now carry UFH pipe in stock. 

[Nickfromwales]

3 hours ago, Spinny said:

A painter with a wall sander ? How does that work ? Is he sanding imperfections in the plaster ?

How do you find a painter and decorator that diligent ?

By choosing well  

 

The correct methodology should be a mist coat (preferably sprayed) on to new plaster which is left to dry completely. 
 

Then your chap pole sands where the joints are, plus the general wall area to highlight high spots / dings. The idea being that the paint is removed almost instantly on high points, and gets left in any dings, making spot filling a doddle.

 

The painter I saw on our previous project was doing this very diligently, and I kept watching him. He asked why and I told him there’s only a few good ones out there they won’t just turn up to a private job (therefore nobody looking/watching/checking) and blast the paint on and leave. 
 

On a job in Oxford the painter was just horrific. I told him, in these exact words, that a drunk could paint straighter lines than you. 
 

He then used a loose WC pan as a hop up, fell off it and smashed it to pieces, then screamed at everyone because that was ‘all their faults’ and stormed off the job.

 

”Bye”. 👋.

 

If you get a decent painter (decorator) then all the hard work getting to the point of painting will be worth it, because if you put a cheap suit on it doesn’t matter how many days you spent in the gym  

[Spinny]

4 hours ago, Nickfromwales said:

if you put a cheap suit on it doesn’t matter how many days you spent in the gym  

That has always been my worry, but I cannot for the life of me find any way to find a good tradesperson. Internet reviews are meaningless and often fixed and fictitious. Recommendations are dodgy because often the customer just doesn't know the difference between good and bad - or else they are doing a favour recommending their cousins boyfriend. I have tried highly rated on checkatrade and they say they will come but never do. I have had 7 plumbers, 3 have done incompetent things, 2 never quoted, and 1 buggered off for 3 months immediately after starting work, and 1 blocked my mobile because I called him twice in 3 weeks enquiring after my quote.

 

 

 

[JohnMo]

19 minutes ago, Spinny said:

cannot for the life of me find any way to find a good tradesperson

For me I have always asked other trades for their recommendation. It filters out the wan#ers that are a pain to work with, or don't do a good job.

[saveasteading]

12 minutes ago, JohnMo said:

always asked other trades for their recommendation. 

Plus, assuming you've been a good customer, that also gets through to the new trade party.

Bad customers will be a constant worry. 

Will they pay and promptly? 

Are they nagging? Chatting?

Do they want free extras along the way?

Recommendations work both ways.

 

[Gus Potter]

On 28/06/2025 at 12:15, Nickfromwales said:

Nah. Done too many, and the pipe flow rates can be much higher through a pipe which is not compromised, so when sending water at ~2 lpm in the same size pipe that could deliver 20 lpm, you have headroom.

 

Any pipes ‘seriously’ damaged had a section cut out or were lifted, binned, and replaced. I had a practice of always making sure there was at least 1x 100m coil excess on each install for such an eventuality. Not so much of a problem these days as a lot of places now carry UFH pipe in stock. 

Hi Nick.

 

Me being old school and all have this idea that UF pipes where buried in screed and inaccessible should be installed without joints. Make all your joints, ideally above the floor where you can get to them. If you are making joints during concreting it's sods law these will be the ones that fail as everyone is under pressure. 

 

I then think.. say twenty years down the road, various plumbers come and go but one lets some gunk get into the UF and that slowly makes its way along the loop until it catches on the spliced bit with the joint. Then you could end up chasing you tail diagnosing the problem. You might be able to blow it back with compressed air.. but that may over stress the splice joint. Just a thought!

[Nickfromwales]

1 hour ago, Gus Potter said:

Hi Nick.

 

Me being old school and all have this idea that UF pipes where buried in screed and inaccessible should be installed without joints. Make all your joints, ideally above the floor where you can get to them. If you are making joints during concreting it's sods law these will be the ones that fail as everyone is under pressure. 

 

I then think.. say twenty years down the road, various plumbers come and go but one lets some gunk get into the UF and that slowly makes its way along the loop until it catches on the spliced bit with the joint. Then you could end up chasing you tail diagnosing the problem. You might be able to blow it back with compressed air.. but that may over stress the splice joint. Just a thought!

A non-issue.

 

To be 1000% clear, I have only had to introduce a joint and bury it when the shit has hit the fan and there is zero other option. One example, on a PH raft concrete pour down in Doooorrrrrset the concrete pump truck failed, then did it's replacement. The willing machine driver then took the concrete from the trucks into the biggest bucket he had, and proceeded to lob it in vs admit defeat; legendary bit of GAF there for sure.

 

Said tracked machine swung out, lost balance, and then punched the bucket down hard damaging 4 UFH pipes.

 

Solution was to make a timber box to shutter 1m2 area around the damaged pipes and continue with the 'pour'. I then repaired the 4 pipes (so 8 straight coupling joints in total) and it's been there ever since (pressure tested on the day of the repair with cold mains pressure at4bar).

 

There will be no "gunk", there would be no issue, just a pipe with a joint in it carrying fluid from one end to 'tother.

 

These joints will cope with 10 bar and are WRAS approved; the only issue would be if a dick fitted them badly, the same with everything, everywhere.......