Milling down particleboard in floor joists?

[catherineb]

Just need to add that we have hydronic underfloor heating in the house, so we can't avoid those pipes.

Thanks Mikael, will do.

 

[justusandersson]

It is perfectly possible to build wet rooms on top of sparse paneling. My objection to the sparse paneling in your case is solely due to the fact that it does not contribute to strengthening the joists. If it had been strong enough from the start, the sparse paneling would have worked well.

It is fine to install a radiator in the bathroom, even if the rest of the house has underfloor heating.

 

[Bernieberg]

The underfloor heating can be laid in grooved particle board and then adds no extra height (possibly a few tenths due to the distribution plates). You can self-level directly onto this. Typically, at least 15 mm of screed at the floor drain if you have electric heating, and then the slope determines the thickness at the thickest point. And then about 10 mm more for adhesive and tiles. I ignore the thickness of the foil-type waterproofing layer. So, the surface layer is approximately 22+15+10=47mm above the joists at the drain. A reasonable guess is that the slope adds 20 mm at the threshold, so 67 mm above the joists. In the adjoining space, you have 28 mm (?) lath and maybe 14 mm parquet, so 28+14=42 mm above the joists. Then there is a 25 mm height difference, which can be resolved with the threshold.

You can calculate the slope more accurately yourself if you check BKR's industry standards.

This is one of many solutions to provide a calculation example. Perhaps you should have 25 mm solid wood flooring outside the bathroom, which would make the difference more modest.

 

[catherineb]

It is perfectly fine to construct wet rooms on top of sparse paneling. My objection to the sparse paneling in your case is solely because it does not contribute to strengthening the joists. If it had been strong enough from the beginning, the sparse paneling would have worked well.

It's okay to install a radiator in the bathroom, even if the rest of the house has underfloor heating.

How nice.

 

[catherineb]

....

 

[catherineb]

The underfloor heating can be laid in a grooved particleboard flooring and then doesn't add any extra height (possibly a few tenths due to the distribution plates). You can pour self-leveling compound directly onto this. Typically min. 15 mm self-leveling compound at the floor drain if you have electric heating, and then the slope decides what it will be at the thickest point. And then about 10 mm more for adhesive and tiles. I disregard the thickness of the waterproofing of the foil type. So surface layer about 22+15+10=47mm above the joists at the drain. A reasonable guess is that the slope adds 20 mm at the threshold, i.e., 67 mm above the joists. In the adjacent space, you have 28 mm (?) slatted paneling and maybe 14 mm parquet, i.e., 28+14=42 mm above the joists. Then there's a 25 mm height difference that you need to solve with the threshold.

You can calculate the slope more accurately yourself if you check BKR’s industry regulations.

This was one of many solutions to provide a calculation example. Maybe you should have 25 mm solid wood flooring outside the bathroom, then the difference starts to become modest.

Thanks, great calculation example! I think the floor that will be laid is 10 mm, so that will be perfect!

 

[catherineb]

It is perfectly fine to build wet rooms on a spaced board. My objection to the spaced board in your case has exclusively to do with it not contributing to strengthening the floor structure. If it had been strong enough from the start, the spaced board would have worked fine.

It is fine to install a radiator in the bathroom, even if the rest of the house has underfloor heating.

How could the spaced battens have strengthened the floor structure? What is wrong?

 

[Bernieberg]

....

But 45x195 is not sufficient for your span, so you cannot use that solution in your case.

 

[justusandersson]

Sparse paneling can never reinforce a floor structure. It has the wrong direction. The floor structure must be sufficiently rigid on its own. This is achieved by ensuring the floor joists have sufficient dimensions, are placed close enough together, and do not have too large of a span.

 

[Bernieberg]

How could the sparse battens have reinforced the floor structure? What's wrong?

There is nothing wrong with how the sparse battens are positioned, but in that construction, they do not help to stiffen the floor structure.

 

[catherineb]

But 45x195 is not sufficient with your span, so you can't use that solution in your case.

How do you calculate that then?

 

[Mikael_L]

....

Mmm, here are some figures on the maximum span of the floor structure that highlight your problem.

Here is a link to the building ceramics handbook
https://www.bkr.se/fakta/byggkeramikhandboken/
And BBV https://www.bkr.se/fakta/branschregler/
But there is little information on the requirements for the floor structure in the beam's longitudinal direction, as far as I could see from a quick check. I might have missed it...
But otherwise, they assume it should be built according to the National Board of Housing, Building and Planning's building regulations or so, I think.

But in this document, I found some rules as well, on page 7 in the PDF (2 out of 4 in the report in the PDF).
https://www.sakervatten.se/download...lagets-uppbyggnad-i-vatrumskonstruktioner.pdf

 

[Bernieberg]

How do you calculate that then?

It says in the table you attached that the maximum span with 45x195 C24 is 3.0 m and you have 3.9 m. 45x220 C24 allows a maximum span of 3.4 m. And with a distributed load, the deflection increases by length to the power of 4, so it's not "almost ok".

 

[catherineb]

I've checked the drawing now, and the span is 2.9 meters, and there are double beams 45x220 under the larger part of the bathroom area.

 

[catherineb]

I might be thinking strangely, but what happens to the beams in a stairwell?