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Discussion Forum

Drying out your building…

Waters | Posted in General Discussion on December 8, 2008 04:22am

What’s the preferred method for drying out your building after framing in the rain?  Framed with all kiln dried lumber–1/2″ cdx sheathed, osb subfloor up and slab down.

I’m dried in, windows and roofing–siding done.

I’ve been running a propane heater during the day.

I want to make sure the building is as dry as it should be b4 I move on to insulating and cover.

I’m now required to provide a moisture test b4 cover…

 

 

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  1. User avater
    McDesign | Dec 08, 2008 04:24am | #1

    Propane heater puts out tons of moisture - gallons.  Other than that, I don't know.

    Forrest

    1. Waters | Dec 08, 2008 04:28am | #2

      That's what I thought.  I just use a little one burner unit what mounts on top of a tank, rather than the bullet type.

      I would guess you want a forced air type of thing--electric that dries air rather than just heating things up.

      lessee what folks say... 

      1. User avater
        Ted W. | Dec 08, 2008 04:38am | #4

        I bet a few portable dehumdifiers would speed things up.See my work at TedsCarpentry.comBuy Cheap Tools! BuildersTools.net

        If you haven't already done so, please update your profile. Since many issues are dependant on the region in which you work, we often look at your profile to see where you are writing from.

  2. Pelipeth | Dec 08, 2008 04:37am | #3

    I'm a big fan of FANS, the oscillating type. Moving air dries things out, faster and cheaper than heat ever will. A combination thereof works great.

    1. MikeSmith | Dec 08, 2008 05:20am | #9

      we own a low-temp dehumidifier.... in slab jobs , with lots of moisture.. we turn it on as soon as the windows and doors are installed...

      if exterior conditions are low -humid... we open the doors and windowsMike Hussein Smith Rhode Island : Design / Build / Repair / Restore

    2. qtsam2 | Dec 08, 2008 07:16am | #10

      Fans work great at putting moisture in the air, but you need to remove the moisture out of the air or else it will just go back into the structure.

      1. Pelipeth | Dec 08, 2008 01:43pm | #11

        Sorry, but I can't get that at all, basements get flooded, the cleanup crews bring in FANS. Big rain storm, everything is wet, big breeze, everything gets dry.

        1. Piffin | Dec 08, 2008 02:19pm | #13

          It's simple physics. Not everything gets dry - the air gets wet. Like a sponge, it can only hold so much. you have to open the windows to change the air. if all you do is use fans to make the air pick up water, but leave the air in the house, it will deposit that water back on surfaces again. 

           

          Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          1. qtsam2 | Dec 09, 2008 01:12am | #15

            Exactly Piffin! Good illustration as well.

            Psychrometric's is key.

          2. Pelipeth | Dec 09, 2008 03:26am | #16

            Sorry I left out the "Open some windows and a door or two part", I'm just too used to common sense I guess.

  3. arcflash | Dec 08, 2008 05:01am | #5

    Dehumidifiers would work, yes, but it would take more than a few portable ones. I bought one at Walmart for $60 and the destructions said that it would be most effective on a small room, like a closet. Anything bigger would cost you big $$$. If you've got time, you could by a few of the little ones, and just dry several rooms at a time. If you do not have time, and you probably don't, I'd say big fans, and alot of them too!

  4. dovetail97128 | Dec 08, 2008 05:05am | #6

    Propane adds a lot of moisture to the air.
    Hit a rental yard for a large dehumidifier.

    I use then on occasion and they pay for themselves in time saved waiting for things to dry out.

    Large fans and salvaged electric baseboards if you have enough juice available to run them.

    They can't get your Goat if you don't tell them where it is hidden.
  5. sledgehammer | Dec 08, 2008 05:08am | #7

    Wouldn't worry too much about it till you get the insulation in. Then fire up the furnace and let'er sit a few days.

  6. User avater
    coonass | Dec 08, 2008 05:16am | #8

    Waters,

    I get the Heat&Air sub to power up his unit as soon as I black in. Yes they do pee and moan but I buy the best filters and put doubles on.
    Not only does it dry out the building but all the other subs are way happy to work in a conditioned space. Never had a problem with any kind of heat exchangers.

    KK

  7. Piffin | Dec 08, 2008 02:12pm | #12

    Running propane heat unvented is like turning on a hose to spray it down. It will kerep getting wetter instead of dryer.

    Open all the windows and doors and run fans on a dry day instead.

    Use electric heat to move the moisture.

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
    Excellence is its own reward!

    1. User avater
      talkingdog | Dec 08, 2008 06:38pm | #14

      However if you can get a propane or kerosene forced flue
      heater it will make your nose bleed right quick.

  8. Superbigstevie | Mar 31, 2009 03:01pm | #17

    Waters,

    Most of these posts are about 90% right.  Heat will add moisture to the air through evaporation of the bound water in the structure.  The air will then hold a amount of water relative to the temperature (relative humidity).  Warm air will hold more water than cold air.  In turn cold air will hold less water that warm air.  As air cools the relative humidity will rise while the amount of water in that air will stay the same.  Think of a 10 gallon bucket with one gallon of water (10% full).  Poor that same water in a one gallon bucket (100% full).  Now poor it in a 1/2 gallon bucket (rain).    

    So some have suggested using a propagne heater to dry thier home.  It is turned it on and will make a warm enviroment where water is rapidly evaporating, fans will intensify this effect.  This is run until the building looks dry.  When this type of system is turned off the building will cool and act like a dehimidifier.  Water will condence out of the air back onto the structure (rain).  All that this does is move the water from the structure to the air and back.  If you evaporate the water you have to get the wet air out of the house.  How do you do that and keep the house warm enough to keep evaporating?  If you open a window to let out the wet air, how do you keep the outside air out of your project?  The outside air may be holding more water than the inside air.  By opening the window.....you can add water to the project.  Your system must now be bigger than that of the Earth.

    Some have sugested to use a dehumidifier.  A dehumidifier will dry the air.  Dry air will absorb more water.  One important thing to remember: just because a dehumidifyer is filling a bucket with water does not mean that it is drying the building.  It is only drying the air in a the building.  Dehumifiers work very, very slowley.  Also they do not have the mechanical power to dry a building to less than the 16% moisture content that fosters mold and baterial growth.  Was that rental dehumidifyer decontaminated after it was used in its last flood?  Do you know what are you adding to the air in your project?

    The fastest way to dry a project is to replicate the enviroment that dryed the materals in the first place: a lumber kiln.  Hot air in, evaporation, get the wet air out.  Think about your clothes dryer.  It does not have a dehumidifier in it.  It has heat and airflow.  Look at a company called Water Out (http://www.waterout.com).  They have equipment that can dry a building in a couple of days.  They raise the temp to around 110 deg and exchange the air with the outside at around 2250 cf per min (135000 per hour).  The same way your clothes dryer works.  Hot air in plus wet air out equils a dry building.  Ever wonder how ABC's Extreame Home Makeover muds and tapes and paints a home in a few hours?  Lost of help and a Water Out unit.

    As a test: hang one wet shirt next to a dehumidifyer and put one in the dryer.  Which one will be dry faster? 

    Steve Brown

    Joplin, MO

           

     

     

     

     


    Edited 3/31/2009 8:06 am ET by Superbigstevie


    Edited 3/31/2009 8:08 am ET by Superbigstevie


    Edited 3/31/2009 8:09 am ET by Superbigstevie


    Edited 3/31/2009 8:10 am ET by Superbigstevie


    Edited 3/31/2009 8:10 am ET by Superbigstevie



    Edited 3/31/2009 8:11 am ET by Superbigstevie

    1. Waters | Apr 01, 2009 06:35pm | #18

      Hi Stevie,

      Thanks for your reply.

      I ended up getting two small 220v construction heaters and running them for about a week for a total electricity cost of less than 400$

      I used a moisture meter to test around the building and watched the moisture content gradually come down to less than 19% which is what the kiln dried studs came with.

      Interestingly, Taunton pulblished my question in their 'BT' portion of FHB but they 'edited' it considerably.  I knew that propane heat creates moisture, and so was asking what guys do to dry out.  They made me look pretty stupid!

      Cheers,

      pat 

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