New Build - Underfloor Upstairs?

[pdf27]

Has anybody done this, and if so how? Most of the suspended timber floor products look like they're aimed at retrofit rather than new build, and I get the feeling they might be quite badly optimised as a result.

I've not fully modelled it up yet, but the sort of design we think we want will probably be significantly bigger upstairs than down (over a double garage) and because the back of the house will face NW we may have overheating issues in summer. My suspicion is that this will mean we want a second UFH circuit upstairs for comfort reasons.

[Onoff]

Did you miss "Heating" from the thread title?

 

Grooved 22mm boards? For example:

 

https://www.theunderfloorheatingstore.com/profloor-boards?

[Redoctober]

@pdf27 have a look at this thread from my blog - may answer some of your questions.

 

 

[pdf27]

1 hour ago, Redoctober said:

@pdf27 have a look at this thread from my blog - may answer some of your questions.

Thanks, that's very helpful. It does raise more questions though!

• How come you used liquid screed downstairs and biscuit screed upstairs?
• What is the floor like to walk on, and how is sound transmission?
• What temperature do you run the flow from the ASHP at?

[Onoff]

On a retrofit with biscuit mix you need to make sure your joists will take the extra weight.

[Redoctober]

10 hours ago, pdf27 said:

Thanks, that's very helpful. It does raise more questions though!

• How come you used liquid screed downstairs and biscuit screed upstairs?
• What is the floor like to walk on, and how is sound transmission?
• What temperature do you run the flow from the ASHP at?

 

@pdf27 in answer to your questions - 

 

I honestly don't know why we did do liquid screed downstairs and biscuit mix upstairs as the rationale was never explained and I never asked. With most things on our build, I was happy to go with those who knew what they were doing. That said, I can only guess it was down to ease and possibly the structure of the base the coverings were going onto. I've never heard of a liquid screed being poured in an upstairs environment but that doesn't mean to say it can't.

 

The upstairs floor is as solid as anything. To explain better, I have attached a PDF showing the make up of our floor, which incorporates the UFH. We followed this and as I say, its solid and we suffer no creaking at all. For "Stirling boards" we used "eggerboards." As for sound transmission, that too is non existent as the ceiling downstairs has double plaster boards fitted and the gaps between the joists were stuffed with insulation.

 

Now the technical question! I do very little with the system - The main "unit" is set at 21 degrees. I have then set all the individual rooms at various temps, using their stand alone thermostats. The spare bedrooms upstairs are guest rooms so are not used very much during the colder months when the heating would be on. Their temps are adjusted accordingly.

For a more detailed explanation of temp flows etc, we might have to seek guidance from the collective as I don't fully understand it myself, I just know it works!!

 

 

Suspended timber - BUF.pdf

[ProDave]

We used the biscuit mix upstairs in our last house.

 

If floor loading is an issue, then aluminium spreader plates is a much lighter option.

[Temp]

We once lived in a house with a concrete first floor and liked it a lot, so when we built our own we opted for beam and block with UFH on both floors. Can't really tel you the cost hit as we used a builder as prim contractor.