# Routing chipboard



## moneymark (Sep 3, 2015)

Hi, I have a pretty straightforward question. How easy would it be to route a 13mm channel into chipboard to accept a 12mm pipe for underfloor heating?

The catch is I would need to cut an overall length of 100M plus. Is this plausible? Is there a bit that would be able to handle it?

Many thanks

Mark


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## MAFoElffen (Jun 8, 2012)

For 100 meters???

If it were me and we were talking for underfloor radiant heating lines... I would mark it out > Set your depth of cut on your circular saw. Cut the outline with a circular saw. Cut bend outlines with a kick saw. Cut a few between those boundaries and chip it out with a pry bar. (usually cuts spaced about 1/8"-1/4" apart and all that just pried out)

Why? Chipboard particles and glue are hard on tooling. 100 meters is a ways. For installation of tubing for heating, it is not rocket science. You do not need a precision channel. For an installer, you are paid for the job, not by the hour. The precision of the channel profile does not affect the transfer of heat and it is not something that is seen.

But from what you are describing and the way you are describing it... don't you need to re-look at your design and how radiant systems are installed? I'm no expert on these, but...

You're filling the channels for your PEX tubing for your radiant heat system with screed right? (so a channel for a 12mm PEX is usually bigger than just 13mm...) And above that probably some thin screed board? It's the screed that helps transfer the heat from the tubing and spread that heat transfer out to a full surface... Instead of just where your coils are (directly). The heat transfer of wood or particle board is not as efficient as screed.

Most installers just use tubing guides on top the base (sort of looks like a comb) , the tube laid in the guides to hold them in place, the screed layer (that then surrounds the tubes), then cover that with the floor... not even fooling with cutting channels (where channels are going to weaken an existing structures subfloor).. Do you have a height requirement/limitation where you need to have channels cut into the subfloor?


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## hawkeye10 (Jul 28, 2015)

I don't know a whole lot and could be very wrong, but isn't it a bad idea to have chip board in a floor? If water ever got to it the chip board would swell and buckle bad.


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## MAFoElffen (Jun 8, 2012)

Fairly standard in the last 20 years. Even for roof decking and outside sheathing (OSB). OSB is not "particle" board. OSB stands for Oriented Strand Board. The strands are oriented, glued and compressed into shaped. The glue used makes it a good choice for exterior work. (Within reason.)

You have to remember that even ply products are glued laminates. A lot has to do with the layers and the glues used. TJI trus joists are the same OSB material in the web with laminate ribs.


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## hawkeye10 (Jul 28, 2015)

MAFoElffen said:


> Fairly standard in the last 20 years. Even for roof decking and outside sheathing (OSB). OSB is not "particle" board. OSB stands for Oriented Strand Board. The strands are oriented, glued and compressed into shaped. The glue used makes it a good choice for exterior work. (Within reason.)
> 
> You have to remember that even ply products are glued laminates. A lot has to do with the layers and the glues used. TJI trus joists are the same OSB material in the web with laminate ribs.


Thanks Mike I didn't understand it was OSB.


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## MT Stringer (Aug 15, 2012)

100 meters?
I'd like to see pics of this house.


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## moneymark (Sep 3, 2015)

Thanks for the replies. I've been reading more into it and I think I'm probably over complicating things.

I'm going to go the more traditional route and put the pipe over the insulation and lay the floor above.

Not sure if I'm going to screed yet. I've heard that if you seal the insulation with expanding foam to get everything air tight it can eliminate the need to screed.


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## MAFoElffen (Jun 8, 2012)

MT Stringer said:


> 100 meters?
> I'd like to see pics of this house.


Answer to Mike (MT):








If you look at a normal layout (above), 100 meters is around 328 feet... You can see by a layout diagram that it would be easy to layout that much PEX, in a zone in a normal sized house right? 

But planning a radiant heat heating zone, 12mm Pex (or 1/2" PEX here), has a min run length of 100 feet and Max length run of 300 feet (in one zone). Longer than that and your heat starts dropping off too much. At 1/2" PEX, you have a radius/spacing of 6"-8".

So 100 meters is just over the limit length of 1/2" PEX... (For a single zone.) That would be where above they split a living room into 2 zones, because it was too much length for just one.

If you plan a larger zone with a longer run (200-400 feet) then you can go 7/8" PEX with a radius/spacing of 12"-16". If you have 150" total or less, you can go 3/8 PEX.


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## Cherryville Chuck (Sep 28, 2010)

moneymark said:


> Thanks for the replies. I've been reading more into it and I think I'm probably over complicating things.
> 
> I'm going to go the more traditional route and put the pipe over the insulation and lay the floor above.
> 
> Not sure if I'm going to screed yet. I've heard that if you seal the insulation with expanding foam to get everything air tight it can eliminate the need to screed.


I'm not sure what you mean by insulating to eliminate screed but the idea of in floor hydronic heating is to transfer the heat to a large thermal mass. The large mass retains heat for a long period of time once it is warmed up and is also slow to change temperature which makes it more comfortable than forced air systems for example where it cycles from low to high and back again. The last thing you would want to do is insulate the piping from the thermal mass.


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## MT Stringer (Aug 15, 2012)

MAFoElffen said:


> Answer to Mike (MT):
> 
> 
> 
> ...


Ah ha! I see the light said the blind man.  Never thought about it like that. Don't see much of that where I live. :no: Thanks for 'splainin' it.


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## moneymark (Sep 3, 2015)

Cherryville Chuck said:


> moneymark said:
> 
> 
> > Thanks for the replies. I've been reading more into it and I think I'm probably over complicating things.
> ...


I get your point, and you're right. I'm talking about insulating under the pipe between the joist, the fitting the pipe snugly between the top of the insulation and the flooring. The foam would then be used to make sure this gap was completely airtight: I.e. A 20mm space where the pipe is. 

You'd usually screed this, but as my system won't have to work particularly hard I was going to leave it. It would also be more of an instant heat.

On reflection though, I think I'll throw in a 8:1 dry sand/ cement mix.


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