Sonic Gold Underlay too soft, causing laminate to sink? (used for electric underfloor heating under laminate)

[Issy Burke]

Hi all,

 

I have installed underfloor heating in 3 rooms in my flat so far. I opted to use 5mm Sonic Gold Underlay, but am experiencing an issue and am curious to know whether anyone else has experienced this. In effect the underlay is so soft, that it is warping some of my laminate. The floor itself is effectively concrete, with noggins and a tongue and groove chipboard on-top (plenty of foam so lots of insulation in there which is a plus). However the lazy builders of the 90's did not bother to level the floor at all, and pinned it to noggins, resulting in a pretty uneven chipboard floor, we suspect the concrete beams are also not level and seem to sort of rise at either end of the building. Yes, in the ideal world you might rip it all out and start again - sure. However, I needed a heating solution and hoped that decent underlay would deal with this to some degree..... I opted for the 5mm sonic gold, in part because I had some to hand, but it also came pretty highly rated for UF heating/laminate etc.

 

However, I have found that heavy furniture (wardrobe / bed) is causing the laminate to warp, i.e. sink. The positives of Sonic Gold that I can report, is that it is definitely soft underfoot, definitely very effective at insulating (it literally takes minutes to notice that the electric floor is on) and the room heats up very effectively and quickly. 

 

The downside is - that I think the softness of the underlay is unfortunately not brilliant unless your floor is 99.9% level and presumably your laminate is of german engineering quality and can withstand a degree unequal loading without any sink or split... I just wanted to know if anyone else has used this underlay, experienced similar issues - and before I do floor number 4 (the living room) - I would just like to check in and see whether I should be using a different underlay? Or if anyone has any recommendations I guess? In time I may look to re-do the floors, but its a pretty big job to rip it all out again as you can imagine.

 

As I said, the Sonic Gold is definitely very soft, quiet and insulating - but equally its soft and doesn't seem to be brilliant when exposed to unequal loading - and yes, I hear you - this is because of my floor - but at the time screeing the whole floor was not on the cards!!!

 

Thanks!

 

p.s. sorry floor looks so dirty!! ha

[saveasteading]

The t and g of the laminate doesn't seem to be spreading the load far enough .

Can you place furniture leg cups under the feet? 

As an immediate remedy, any piece of timber say 15cm x 10cm or more will possibly sort it. Especially if if sits on more than one floor plank.

[Issy Burke]

I agree, its a Wickes Laminate - in theory it should be better then this. This isn't even close to the worst of it.... In one area a wardrobe with quite a large supporting base I might add (not little feet) has split the tongue and groove about 20cm along its length - this section will need full remedial work. Interestingly the bathroom has a higher quality laminate in it (due to waterproofing requirement), same UF electric heating installed and despite the uneven floor issue - it doesn't seem to be reacting in the same way - it's just more stable. Me and my tradeperson friend/neighbour, did not anticipate that the floor was unlevel enough in this case to cause this problem.

 

I think other people must experience the same issue using soft underlays.... hence me thinking I might use a harder foam underlay for the living room, due to the amount of heavy furniture that you tend to have. There isn't really alot of info out there on installation of UFH with laminate, neither problem solving - even though I have to say, it really works amazingly well and efficiently. Totally recommend it, albiet with a slightly denser underlay... I have had it installed for 2 years so far.

Edited June 28, 2023 by Issy Burke

[Conor]

We used 5mm wood fibre underlay, has a noticeable softness, but no sinking or bounce. And it's cheap.

 

As you've underfloor heating, the last thing you want is an insulating underlay. 

[ProDave]

I think the issue in not the use of a particular underlay, but the use of a particularly thing particularly weak laminate flooring.

 

I am not a fan of laminate flooring, preferring proper engineered wood flooring, but I have used a good laminate in our sun room without such issues. the tongue and groove joint in yours appears too weak to be fit for purpose.

[Issy Burke]

Hey Conor, the insulation is underneath the underfloor heating which is important because I want all the heat to rise up, through the laminate and to loose no heat to the floor below (which is a concrete ceiling, underneath is a garage). It actually works extremely well, is very quick to heat, all on carefully positioned thermostats to maintain consistent temperatures. Other then the laminate issue, its cheap to install and cheap to run and provides a wonderful dry, ambient heat. I would have been recluctant to use a wood wool/fibre underlay as these flats are north facing, next to a canal and prone to damp issues; therefore the use of a moisture-resistant type of underlay is important in this case.

 

@ProDave I appreciate your assessment, its a shame. It wasn't the cheapest laminate, it was just the standard grade which Wickes supply. I did honestly think it would do the trick in bedrooms/living room etc. It's not like its an old building on exposed wooden, uneven floor boards or anything. In the hallway area, which had a signficiant recess due to the installation of services, I did infact scree the floor with a latex compound and I haven't had any sinking issues in this area, but its really a sort of spot-fix solution. Ah well, I suppose this is a 10-year floor and not a 20-30 year floor which is a shame....

[Conor]

Ah, so you have an electric system sitting on top of the the underlay? Trying to picture the build-up. What thickness is laminate?

[Issy Burke]

Yes, so its like this from below to top:

 

1. Garage - nice warm air space, its massive could park 6 medium sized cars in there but quite warm and dry

2. Concrete Slab Reinforced Ceiling (1990's pretty thick, not so even, can't quite remember (6-8 inches at least)

3. Noggins screwed to concrete + polystyrene foam block + tongue and groove floorboards - pretty uneven as the noggins were not levelled - they even pinned it over ventilation flues for the kitchen and bathroom which left really unusual carpet speed bumps (😂)... we sorted all of these.

4. 5mm Sonic Gold underlay with foil moisture barrier and quite soft foam top

5. 2mm Electric underfloor heating for laminate which is installed like a reptile heat mat....

6. 8mm wood laminate flooring (Wickes brand)

7. my toasty warm feet....

 

This is pretty nice and warm, since it basically benefits from a nice warm air space, followed by perhaps 2 inches of foam block, followed by wood (an air space), a barrier and 5mm of soft foam - so all the heat has to penetrate through is 8mm of cheaply constructed laminate flooring.... I would think almost no heat is lost to the ground/subfloor.

 

I even have it installed under waterproof laminate in the bathroom which so far has worked extremely well. As long as you are kind to the laminate floor and don't let it stew in water (i.e. have the floor on low twice a day for an hour say)... to dry it all up, its wonderful. But sure, if you let it stay wet for long periods of time I think you might get issues with warping etc. It's a decent quality jet black laminate.

 

If I installed it all again, I would spend more time leveling the existing floor using a levelling scree compound, probably opt for a mid strength underlay something like Aquastop which is firm but soft (but expensive as) and perhaps invest in a higher quality vinyl or waterproof laminate - but its way more expensive OR maybe rip out the entire floor and literally do a scree in underfloor heating system - but I don't think it would be quite as heat efficient or fast to react as what I have installed now. What I did works very well, except for the soft spot issue and was actually really cheap to install. Electric UF heating for the ~20m2 living room for example was £350 which is signficantly less then the cost of a single storage heater.

 

If I get a chance this weekend, i'll upload some photos as a reference 👍

Edited June 30, 2023 by Issy Burke