Overlay board UFH

[bissoejosh]

When people use overlay board instead of screed what is the best method of heat distribution for an UFH system assuming a build up of approximately 200mm insulation, 22mm Chipboard all bonded together? I'm considering this for our upper ground floor which is on beam and block and has an available depth of 240mm. Site access makes screeding quite challenging and a pumped option isn't within the budget. 

 

Further advantages are more depth for insulation and zero drying time but I need to get my head around the UFH components before deciding.

 

Many thanks

[Nickfromwales]

Check out the Wunda Overlay system, link. You'll need to bond this system all down, so the issue will be, exactly how level is the B&B floor ? You may need to get some sharp sand and slid the B&B first to get it like a mill pond, because whatever you lay modular material on ( like 8x4's of insulation ) will be the floor you end up with. Check out their YT videos  

 

The heat is diffused by aluminium 'foil' facing on the upper side of the overlay panels, and its pretty damn efficient at emitting heat upwards. A~s you'll be asked to bond the floor down to this in most cases you'll end up with a floor that feels rock solid too. 

 

You'll need either more pipe or two manifolds if you have two differing types of emitters, eg slab and overlay mixed in the same dwelling, as the overlay will typically require a higher flow temp to get the same w/m2.   

[Dudda]

If using overlay board or floating floor you can use overfloor underfloor heating boards. example: 

https://www.wundatrade.co.uk/product-category/home/overfloor/

 

 

I've used it on a renovation project where we weren't digging out the sub floor and had very limited height to work with. We therefore used as much PIR insulation as we could and then the overfloor UFH boards which work out thinner than a screed. A good cost saving is possible if you're willing to put down the additional insulation and UFH yourself.

 

EDIT: you just beat me to the post Nick

Edited November 14, 2018 by Dudda

[Nickfromwales]

4 minutes ago, Dudda said:

EDIT: you just beat me to the post Nick

Ninja !

 

4 minutes ago, Dudda said:

If using overlay board or floating floor you can use overfloor underfloor heating boards. example: 

https://www.wundatrade.co.uk/product-category/home/overfloor/

 

 

I've used it on a renovation project where we weren't digging out the sub floor and had very limited height to work with. We therefore used as much PIR insulation as we could and then the overfloor UFH boards which work out thinner than a screed. A good cost saving is possible if you're willing to put down the additional insulation and UFH yourself.

 

 

Did you get any issues with 'squeaking' or 'creaking' at all ? What m2 areas were they if you dont mind me asking? Ive only done smaller spaces with that, as all of the others have been in spreader plates.  

[HerbJ]

I used  a system using Fermacell for the overlay board for the 1st Floor UFH. I didn't need the amount of insulation you're contemplating and laid my system directly onto the OSB floor.

i attach the data sheet for the system I used but I think that other similar systems are available.

Flooring_Installation_Guide_11.09f.pdf

ECO-10U Pt E.pdf

[Dudda]

 

Just now, Nickfromwales said:

Did you get any issues with 'squeaking' or 'creaking' at all ? What m2 areas were they if you dont mind me asking? Ive only done smaller spaces with that, as all of the others have been in spreader plates.  

It was only about 60 sqm. The existing buildup was 60-70mm screed on 25mm eps insulation on a concrete sub floor. We removed the screed and old eps insulation which gave us about 85mm to work with to get as insulated as we could. First we put down sand in areas to level the subfloor, new radon membrane, then 50mm pir insulation. A 50x50mm timber batten was used at the perimeter and under internal walls fixed to the sub floor. Then the 18mm T&G OSB3 on on top. The supports to the perimeter and under internal walls (which continued through door opes) supported the OSB preventing creaking or squeaking and making it feel solid. On top of this the Wunda boards were fitted with the UFH, then laminate timber.

 

Now I know putting UFH on such a small amount of insulation (50mm PIR) isn't ideal or very efficient and wouldn't generally recommend it but we couldn't use radiators and wanted to get as much insulation in as possible.

[bissoejosh]

Many thanks everyone, certainly looks like a viable option if the beam and block can be levelled with sharp sand - I'll get the level out in a bit and see how bad it is. It's likely that the finished flooring could take a while so how would these sort of panels work if they were then covered with something like T&G OSB or Chipboard? Another option would be to do as @dudda did and build to the OSB level then wait until we're ready for the final covering before fitting the UFH sheets.  

 

I'm thinking of potential damage whilst construction continues to either the EPS or the piping as realistically the final floor is at the bottom of quite a long list! 

 

 

Edited November 14, 2018 by bissoejosh

[scottishjohn]

self levelling compound ?same as you use for tiling a floor