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Hardwood Right On Top Of Pex - Problem ?
JudeNY
Member Posts: 50
For my above the floor radiant installation with Thermofin U on sleepers, some of the ply sleeper edges were not eased enough. In some places the oak finish floor will be pressed tight against the pex in the U-channel. It doesn't compress the pex, but it's pressed tight. It's probably not great for the oak, but is this going to create a problem with the pex in the future ?
0
Comments
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Nah...
As long as there are no sharp metal objects in contact with the pex it shouldn't be a problem. PEX is some TUFF stuff.
ME0 -
Thanks Mark. I wrapped the pex with pipe insulation where it passes through the floor and was going to put more where it is pressing against brick. Is that not necessary ?0 -
It depends...
If it is going to see a substantial amount of lateral movement due to expansion, and can come into contact with an abrasive surface, you'd be smart to protect it. If it's held captive and has no chance of seeing any sawing action, it's probably OK. Better safe than sorry, and it's expensive to go back and fix it...
ME0 -
Watch your maximum temperatures
Long time lurker...check and make sure that your maximum surface temperature is compatible with the type of wood that you're using; some woods can warp if the temperature is too high.0 -
A word on maximum temperature...
Jason, you are correct in your statement to some degree. Radiant surfaces that are commonly in human contact should be limited to 85 degree F. This is a FACT. And it doesn't matter whether the emmiting surface is slate or hardwood.
However, and this is a BIG however, if hardwood floors were limited to an 85 degree F surface temperature, it should be ILLEGAL to allow them to be installed in rooms with south facing glass. I have personally witnessed hardwood flooring in south facing rooms in direct contact with sun at temperatures over 130 degrees F, and the floors were fine! Somewhat yellowed from the effects of the sun, but none the less, just fine...
The major problem with hardwood floors comes from people putting the wood down before it is optimally dried to the normal back ground Relative Humidity.
If the wood is NOT dried before you put it down, and you turn on the radiant floor, it WILL dry the wood out, and the wood NEVER dries evenly, and WARPS!
Conversely, if the wood is dry, but the floor has not given up all its free moisture, the wood WILL absorb the moisture and warp and cup.
The key to succesful hardwood over radiant floors is this.
First, the wood should be uniformly dried to the ambient humidity levels in the area that they are being applied.
Secondly, the floor to which the wood is being applied should ALSO be dried to ambient humidity.
After the fact, RH should be controlled in the space or you CAN expect the wood to change dimensionally, one way or the other.
Now, you know more about hardwood floors and radiant heating than you ever thought you should!
Congratulations!
ME0 -
equilubrium moisture content
> Jason, you are correct in your statement to some
> degree. Radiant surfaces that are commonly in
> human contact should be limited to 85 degree F.
> This is a FACT. And it doesn't matter whether the
> emmiting surface is slate or hardwood.
> However, and this is a BIG however, if hardwood
> floors were limited to an 85 degree F surface
> temperature, it should be ILLEGAL to allow them
> to be installed in rooms with south facing glass.
> I have personally witnessed hardwood flooring in
> south facing rooms in direct contact with sun at
> temperatures over 130 degrees F, and the floors
> were fine! Somewhat yellowed from the effects of
> the sun, but none the less, just fine...
>
> The
> major problem with hardwood floors comes from
> people putting the wood down before it is
> optimally dried to the normal back ground
> Relative Humidity.
>
> If the wood is NOT dried
> before you put it down, and you turn on the
> radiant floor, it WILL dry the wood out, and the
> wood NEVER dries evenly, and
> WARPS!
>
> Conversely, if the wood is dry, but the
> floor has not given up all its free moisture, the
> wood WILL absorb the moisture and warp and
> cup.
>
> The key to succesful hardwood over
> radiant floors is this.
>
> First, the wood
> should be uniformly dried to the ambient humidity
> levels in the area that they are being
> applied.
>
> Secondly, the floor to which the wood
> is being applied should ALSO be dried to ambient
> humidity.
>
> After the fact, RH should be
> controlled in the space or you CAN expect the
> wood to change dimensionally, one way or the
> other.
>
> Now, you know more about hardwood
> floors and radiant heating than you ever thought
> you should!
>
> Congratulations!
>
> ME
0 -
equilubrium moisture content
> Jason, you are correct in your statement to some
> degree. Radiant surfaces that are commonly in
> human contact should be limited to 85 degree F.
> This is a FACT. And it doesn't matter whether the
> emmiting surface is slate or hardwood.
> However, and this is a BIG however, if hardwood
> floors were limited to an 85 degree F surface
> temperature, it should be ILLEGAL to allow them
> to be installed in rooms with south facing glass.
> I have personally witnessed hardwood flooring in
> south facing rooms in direct contact with sun at
> temperatures over 130 degrees F, and the floors
> were fine! Somewhat yellowed from the effects of
> the sun, but none the less, just fine...
>
> The
> major problem with hardwood floors comes from
> people putting the wood down before it is
> optimally dried to the normal back ground
> Relative Humidity.
>
> If the wood is NOT dried
> before you put it down, and you turn on the
> radiant floor, it WILL dry the wood out, and the
> wood NEVER dries evenly, and
> WARPS!
>
> Conversely, if the wood is dry, but the
> floor has not given up all its free moisture, the
> wood WILL absorb the moisture and warp and
> cup.
>
> The key to succesful hardwood over
> radiant floors is this.
>
> First, the wood
> should be uniformly dried to the ambient humidity
> levels in the area that they are being
> applied.
>
> Secondly, the floor to which the wood
> is being applied should ALSO be dried to ambient
> humidity.
>
> After the fact, RH should be
> controlled in the space or you CAN expect the
> wood to change dimensionally, one way or the
> other.
>
> Now, you know more about hardwood
> floors and radiant heating than you ever thought
> you should!
>
> Congratulations!
>
> ME
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equilibrium moisture content of wood floor
The moisture content of your flooring should reach equilibrium with the ambient conditions that will be present during the occupation of the space.If the space has recently been under construction these conditions may not exist as of yet. As Mark mentioned you need to provide the means to get the ambient conditions to match what they will are going to be so that every thing will reach EMC.The U.S. Department of Agriculture Forest Products Laboratory has a chart that shows what the EMC will be for a given temperature and relative humidity. For example at 75 degrees and 31 per cent humidity the EMC will be 6.2 per cent moisture, at the same temperature and 44 per cent humidity the EMC will be 8.2 per cent moisture. The latter is probably close to what most wood is dryed too, because that is a very typical EMC for a lot of the country. Because wood is very hydroscopic it will always seek to balance itself with its ambient conditions.From the two examples I just gave you can see why wood moves so much, the key is to keep the ambient conditions controlled closely.
It is always good to check the moisture content of something as important as your floor. This can be done with a moisture meter or by weighing a sample and oven drying and reweighing (for the technically proficient)using a little math tells you what per cent was water.The chart I quoted from is in the Agriculture Handbook No. 72 Forest Products Laboratory.
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Thanks for all the feedback. Mark, after managing the construction of an addition to the back of a row house I now know more about a lot of things that I never cared about. The ply sleepers have been down for 6 weeks, taping is happening now and the addition is mostly open to the rest of the house which has been heated (ancient hot water cast iron radiators). The radiant has been pressure tested but will not be operational for a couple of months (don't ask) but the floor has to go down soon. I planned on having the flooring in the adjacent heated room 7-10 days before installation.
Conditioning the wood to ambient conditions has always confused me - January and July in NYC may as well be different planets. This room is in a rental apartment where there is no central air and I have no control over ac. What am I conditioning it to ? Logically, it seems like it might be better not to have it too dry at installation and have spaces in the winter than to dry it well and have it heave in the summer. Any thoughts ?0 -
I concur...
Gaps are easier to live with than humps. It seems that regardless of how much dilligence you do, unless you are in total control of the RH, the floors going to do what IT wants to do anyway. I've seen my own HW floors gap in the winter, and fill in the spring, and they don't even have RFH under them!
So long as they aren't large enough to swallow a small child, I think you're OK.
ME
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Some of the gaps in the old wide plank fir in the rest of the house without rhf easily swallow coins, screws and puzzle pieces (thanks to the small children who don't get swallowed). I guess the narrow plank oak over the rh won't be much worse. Thanks.0 -
HEADS UP !
Jude, if I'm understanding your post correctly, you're saying the hardwood flooring will be IN DIRECT CONTACT with the PEX tubing?
I hope not.
Pex can expand and contract a great deal with temperature change, and believe me, if it's in direct contact with wood, the resulting ticks, pops and creaks from expansion rubbing noises will drive you mad within a week.
I've used extruded track and had no noise problems, but PEX against wood is a big no-no! I learned this from others who stapled PEX directly to wood subfloors.
If there is some clearance between the PEX and the wood and the PEX is allowed to expand and contract within the track without touching the wood, ignore this post.0 -
I think
you are using ThermoFin U style transfer plates? If so, yes the hardwood can touch the top of the pex without problems. Those fins lock the tube tightly.
I still prefer PAP for this install as it does not have that sticky and noisey EVOH barrier on the outside.
Usually hardwood installers have, or should have, a rosin paper between the subfloor and hardwood install, also.
hot rod
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Which ambient??
I've always told customers to make sure the hardwood is acclimated to the ambient conditions and I've had no real problems so far. Trouble is, I feel a bit dishonest about it because there is no one ambient. Consider warm humid summer days where the humidity is 70% or more and the floor temperature may reach say 70 degrees. Seems to me that floor would soak up a good deal of moisture. Contrast that to a winter day when the heat is on and the humidity is maybe 20 % and the floor is 80 degrees: Seems to me the floor would dump all its moisture.
So: which ambient do we choose??
Bill
Thinking about it some more, it may be that what is at work here is the need to get wood structure (subfloor and framing) and finish floor acclimated to the SAME conditions so they can move together as conditions change. They wouldn't move exactly the same amount because the materials are different, but they would at least move in the same direction so the differential would be minimised. Does this sound correct?
Bill0 -
Yes, the pex is in Thermofin U and yes the oak finish floor will be in direct contact with the pex. I've seen hardwood installed directly over old wide plank fir and never with rosin paper. Is the rosin paper specific to installation over ply ? What is it's function ? I don't like the idea of it; I want them to SEE the pex and the ply as they're nailing - and I'll be there with a shotgun.0
This discussion has been closed.
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