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Discussion Forum

Crackle & pops – wood floor over radiant

willNeuhauser | Posted in General Discussion on April 2, 2002 07:37am

A recently installed cherry floor over radiant heat crackles every morning when we walk on it the first time. And in the middle of the night, we hear some very loud pops throughout the house. House has been occupied, with these symptoms on-going for 60 days.

Looking for help understanding what is making these noises and if there is anything to do to stop them and whether we’ll have to live with them forever.

The floor looks fine, no cracks, cupping, etc. It has a swedish polyurathane finish. Looks great in spite of the noises it makes.

The 3/4″ (sustainably-harvested) cherry floor boards are nailed directly to sleepers which are ring-nailed to the building-paper covered subfloor. The radiant heat tubes are in gypcrete poured to just-below the top of the sleepers (1/8″ air gap). The floor was dried in place before installation and measured for moisture before installation.

Radiant heat is keeping the rooms 68 – 73 degrees. Water temperature in the tank is set to 115 degrees with 10 degree offset. The water tank temperature is maintained by a water-to-water heat pump to in-ground loop. Seems to be running fine.

Any ideas what is making these two types of noises (crackling, pops). And if there is anything to be done to make them go away?

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Replies

  1. Splintie | Apr 02, 2002 07:49pm | #1

    Will, this is a common problem. Here is a link to some folks who've been discussing the problems of finishes over radiant heat for a l-o-n-g time. In some areas, the idea is to use an oil-based penetrative finish and let the floor move as it wishes. The oppposing idea seems to be to run a humidifier to keep a constant MC if you desire a film-forming finish. The guy who runs the forum, Bill, is a flooring wizard and there are lots of knowledgeable lay-peole (*groan*) there. Good luck! 

    http://floormasters.com/wwwboard/wwwboard.html

  2. User avater
    BossHog | Apr 02, 2002 08:19pm | #2

    I got called out on a complaint in a house with similar problems a short time ago. The house wasn't occupied yet, but they were in the process of installing floor coverings.

    The cause of the pops/noises hasn't been determined yet (Lots of accusations and finger pointing, though) Do you know what's making the noises in your floor? Is it the hardwood floors, or is the exact source unclear?

    This particular house has an I-joist floor, and the tubes are under the subfloor. It also pops louder in the morning than any other time.

    1. IanDGilham | Apr 02, 2002 08:28pm | #3

      Ron,

      Splinter has a handle on it -- the noise is caused by expansion/contraction in the floor and the consensus seems to be that the movement is caused by humidity changes in the timber over the day.

      With an impervious surface coating on the floor, the solution seems to be humidification to keep the moisture content constant.

      In Australia the recommendation was that the coating should allow moisture to pass through so that the timber could breathe -- polyurethane finishes were considered totally unsuitable for use in these situations

      Check the link that Splinter gave, Bill Price is really helpful.

      1. User avater
        BossHog | Apr 02, 2002 08:54pm | #5

        Ian -

        I did look at Splinter's link - But it seems to be dealing mostly with hardwood floors. The house I mentioned was making noise long before they thought about putting in floors.

        The builder thinks the I-joists are defective and are making the noises. I think it's the radiant tubes under the subfloor.

        They had a factory rep from LP come out and look at the I-joists and 3/4 T&G, but he couldn't find anything wrong. (Both were LP brand) The only thing he mentioned (which I wasn't aware of) was that they recommend that glue be put in the T&G joint. I've never seen that done before.

        1. User avater
          CloudHidden | Apr 02, 2002 09:07pm | #6

          Was the subfloor glued to the I-joists?

          1. User avater
            BossHog | Apr 02, 2002 09:47pm | #10

            Yo Cloud -

            Or should I call you MR Hidden ???.............(-:

            The subfloor was glued down. Don't remember the adhesive brand.

            One thing I thought was kinda odd - The subfloor was installed last August. When the LP rep was there they cut up a section of subfloor that was 32" by 48" and sent it off to their lab for testing. The LP rep said the adhesive was still gummy, and hadn't cured fully. I didn't see it, so I don't know exactly what he meant or how "gummy" it was. But I would think it would be fully cured after 6 or 7 months.

        2. IanDGilham | Apr 02, 2002 09:46pm | #9

          Ron,

          The flooring gurus seem to be saying that the cure for movement -- and creaking, cracking, etc., --- is to maintain a constant humidity so that the timber doesn't keep expanding and contracting.

          I don't think any of the timber elements are defective -- in fact I think if you replaced them you'd have just as much trouble with the replacements.

          If you read the threads on flooring over radiant heat you'll see that some contractors are even specifying an humidity level to be maintained in the house and stating that failure to do this will negate their guarantee!!

          The solution to your problem may come when the house is occupied and the humidity stabilises.

  3. dthodal | Apr 02, 2002 08:44pm | #4

    I have noticed that the cracking/ popping noise is more prevalent on rfh floors that use sleeper installation rather than the double sheet od cdx for fastening. It may be the movement in all components of the floor system compounds the problem of expansion and contraction during the heat cycle. Maybe even more than the floor finish.

    I have not had achance to explore that link yet, but thank you SG for posting it

    david

    walk good
    1. IanDGilham | Apr 02, 2002 09:25pm | #7

      David,

      There is a discussion going on behind the scenes on Floormasters regarding finish for floors on radiant heat.

      A polyurethane (or any film) finish can cause panellisation, edge bonding and cupping -- the recommended finish in Australia is a penetrative oil finish.

      In America the recommended solution is to maintain a constant humidity 24/365 so the timber doesn't move, --- in Oz the recommended solution is to allow the timber to move as the humidity changes.

      1. dthodal | Apr 02, 2002 09:44pm | #8

        Ian, As you may be aware from past posyings, I am a strong proponent of penetrating oil finishs for wood, including floors for reasons including the panelisation, you mention. However the reality in today's market here in the states is the look and durability of poly.

        Be that as it may, I have installed and finished a number of wood floors up to 12" over RFH. Only two floors did I use sleepers with gypcrete between. The remaining 1/2 doxzen or so were all double sheet of cdx floating free over gypcrete.

        My observations, while no way quantitative, suggests that the problem of cracking appears to be more noticable in the sleeper application rather than the cdx method. Either method I can detect no seperation or cracking in the wood or poly finish. ( I use DURASEAL oil-modified poly). I have heard the creaking/ cracking sound in floors though and it seemed to be more prevalent, like I said in the sleeper floor system.

        Maybe the double cdx method insulates the sound better, but I am more inclined to believe it moderates the temperature in the floor and disperses it more uniformly over the entire area being a similar material unlike gypcrete/ wood sleepers.

        However, I also live in SW Montana which is arid and take precaution that both my sub floor and flooring are dry and acclimatized.

        It makes for interesting discussion and I will definitely check out the Floormasters site.

        Maybe using red rosin paper as a floor underlay paper has something to do with it.

        david

        walk good

        1. IanDGilham | Apr 02, 2002 10:09pm | #11

          David,

          I am only contrasting the different approaches to the problem -- you would not find an Oz floorlayer to coat a radiant heated floor with poly -- here you do so.

          Floormasters board regularly deals with posters experiencing problems with panellisation, cupping, splitting and cracking of film finishes on timber over radiant heat and Bill Price, for one, is starting to question whether there may not be a better way of dealing with the problem than expecting the client to maintain a constant humidity 24/365.

          As to the sleeper-vs-cdx, I would also expect the diffusion of heat to the underside of the flooring to be more gradual with cdx.

          Concerning pentrative oil finishes, there is a general misconception regarding the amount of maintenance required -- in fact it is less than any other type of floor finish.

          Edited 4/2/2002 3:12:19 PM ET by IanG

          1. dthodal | Apr 03, 2002 01:57am | #12

            Ian,

            I agree it is perceived here that oiled floors require more maintainence. I was not very clear in what I was saying. The vast majority of my clients and people in general here like the floor to look shiny and new regardless of the traffic and wear and tear or respect of the wood. Not just in flooring, I might add. So we paint a plastic on top of the wood.

            I use DURASEAL, because to date I have had very liitle problems with it as a poly finish goes.

            Thanks for the info

            davidwalk good

          2. Czarnowski | Apr 11, 2002 12:50am | #14

            Hello IanG,

            I'm new at all of this. Could really use some guidance and info regarding oiling indoor flooring. Would like to use ipe in living and dining rooms. What are the long term maintenance requirements and pros and cons.

            (Don't know how my name got to be n/a. I tried to make it Czarnowski. Go figure.)

          3. IanDGilham | Apr 11, 2002 02:18am | #15

            Mr CzarnowskiThe oil I use I mix myself -- it is equal parts of boiled linseed oil, tung oil and turpentine.Cons first.It should only be used in areas that are suitable for fitted carpet, since it will stain if liquids are left on it.The sanding of the floor has to be much better than for varnish because, unlike varnish, it won't fill the scratchesAny rags used to apply it are liable to self-combust so they should be spread out until dry before throwing them in the trash.ProsIt is non-toxicEasy to apply -- you don't even have to vacuum the floor first and you could even apply it with a soft yard broom! I use a strip of carpet nailed to a wood 'T' shape applicatorIt allows the timber to breathe so that moisture from say, a damp crawl space will pass right through whereas varnish will hold the moisture in the timber and you'll get cupping and swelling. That's why it works so well over a heated floor.It is the very best finish to bring out the color and figure of the timberIt is almost maintenance free. Instead of using a broom or vacuum on the floor, you clean the floor with a flat-mop on which has been sprinkled a few drops of cedar oil or teak oil. That's it! -- no re-sanding, no re-coating, nothing!An oiled floor will just look better and better as it develops a patina of wear from use.

            Here is a parquet floor that I laid over a heated concrete slab and finished with oil some 8 years or so ago.

            If you need precise instructions on how to apply and finish the oil, then just send me an e-mail.

            IDGIDG.

            Edited 4/10/2002 7:22:43 PM ET by IanG

  4. archyII | Apr 03, 2002 03:17am | #13

    I recently had a wood floor installed in my attic.  The materail was delivered one week before it was installed.  I have hot water heat on the main floor and forced air on second floor.  The floor had three coats of satin poly applied and crackle and pops (more like bangs) began about 3 days after the finish was applied.  The noise was quite loud and frequent for the first week.  Now it only pops about once a day.  I live in Chicago and it is winter time. Our house is pretty dry and I realized why all of the noise.  The poly glued the boards together and as they dryed the bond was broken.  I now have gaps (minor) between the boards just like the floor on the main level that was installed in 1931.  I am assuming that the gaps will be gone in the summer.

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