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  1. #1
    Join Date
    Dec 2012
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    4

    Question Insulating ductwork?

    My wife & I purchased our first "real" house after living in a manufactured home during all of our married life.
    The house is a small, ranch-style house on a concrete block foundation. We were told it was built in the '40's, but if so it's built suprisingly well.
    My question is about the ductwork for the central heat & air. We recently put in a new gas heater & it seemed that when it first kicks on, cold air comes out of the registers. It eventually warms up, but it's not real hot. I contacted the company we purchased it from & they came right over & checked it out. He told me that the registers weren't insulated & that was the reason I was feeling the cold air initially. He stated that they need to be foil wrapped at the joints & foil "bubble wrap" around the ductwork. He stated that fiberglass insulation wouldn't last long. He gave me a quote of "about $1000" to do the job & that it would take a good days work to complete. I called to get a second opinion & he told me the same thing except that he wanted to use the fiberglass & that it holds up well. He climbed into the crawlspace & checked everything & said the ductwork was in good condition. He gave me a quote of $1290.
    The house is about 32'L x 28"W. I looked at insulation at Home Depot...the foil "bubble wrap" type. If I figured right, the insulation & foil tape would run about $400-500. Is this a job I could do myself or should I leave it to a pro?
    Also, while the crawlspace does have plastic sheathing on the ground, there is no insulation between the floor joists. Should there be some type of insulation there?
    Thanks for any help.

  2. #2
    Join Date
    Jul 2010
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    6,509

    Default Re: Insulating ductwork?

    Replacing ducts is not easy, mainly due to space restrictions, so it's hard for us to tell you whether you can do it or not.

    The bids you got are right on the money.

  3. #3
    Join Date
    Dec 2012
    Posts
    4

    Default Re: Insulating ductwork?

    Quote Originally Posted by dj1 View Post
    Replacing ducts is not easy, mainly due to space restrictions, so it's hard for us to tell you whether you can do it or not.

    The bids you got are right on the money.
    I'm not wanting to replace the ducts, i'm wanting to insulate them by wrapping them with whatever they need to be wrapped with.
    I'm also needing to know if the floors need to be insulated underneath.

  4. #4
    Join Date
    Dec 2007
    Location
    Tennessee
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    1,737

    Default Re: Insulating ductwork?

    If you think you can do it, then I think you can do it. Its not rocket science, but crawling around on your hands and knees in a very confined space it is very unpleasant work that not a lot of people are willing to do. The fiberglass is durable and probably less expensive but is even more unpleasant to work with than the foil bubble wrap. You should consider the R values of each as part of your decision.

    Be sure to use a foil tape for sealing as "duct tape" will not hold up. As for insulating your floors, that depends on your climate and the foundation construction. In moderate climates, it really doesn't save any where near as much energy as people believe.

  5. #5
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,509

    Default Re: Insulating ductwork?

    Actually, replacing ducts with insulated ones will be easier than wrapping existing ducts with insulation...

    Do this:
    Go under the house, crawl around and stay there for 5-10 minutes. Then tell us how it felt.

  6. #6
    Join Date
    Dec 2012
    Posts
    4

    Default Re: Insulating ductwork?

    Quote Originally Posted by dj1 View Post
    Actually, replacing ducts with insulated ones will be easier than wrapping existing ducts with insulation...

    Do this:
    Go under the house, crawl around and stay there for 5-10 minutes. Then tell us how it felt.
    The price difference for replacing the ductwork vs. insulating was $1700.
    I know i'm not going to like crawling around under the house, but i'm just trying to save some money. I was just hoping an "expert" here could tell me if it was something that had to be done by a professional.
    As far as the insulation underneath the floors, the house is sitting on a block foundation & there's plenty of venting. There's a moisture barrier on the ground under the house. I live in So. IL so it's not like i'm going to experience too harsh of a winter (knock on wood). I do know that the floors are awfully cold (& I don't plan on installing carpet) so I didn't know if some type of insulation underneath would help or not.

  7. #7
    Join Date
    Mar 2010
    Location
    Canada
    Posts
    86

    Default Re: Insulating ductwork?

    Quote Originally Posted by JGKC9AYC View Post
    My wife & I purchased our first "real" house after living in a manufactured home during all of our married life.
    The house is a small, ranch-style house on a concrete block foundation. We were told it was built in the '40's, but if so it's built suprisingly well.
    My question is about the ductwork for the central heat & air. We recently put in a new gas heater & it seemed that when it first kicks on, cold air comes out of the registers. It eventually warms up, but it's not real hot. I contacted the company we purchased it from & they came right over & checked it out. He told me that the registers weren't insulated & that was the reason I was feeling the cold air initially. He stated that they need to be foil wrapped at the joints & foil "bubble wrap" around the ductwork. He stated that fiberglass insulation wouldn't last long. He gave me a quote of "about $1000" to do the job & that it would take a good days work to complete. I called to get a second opinion & he told me the same thing except that he wanted to use the fiberglass & that it holds up well. He climbed into the crawlspace & checked everything & said the ductwork was in good condition. He gave me a quote of $1290.
    The house is about 32'L x 28"W. I looked at insulation at Home Depot...the foil "bubble wrap" type. If I figured right, the insulation & foil tape would run about $400-500. Is this a job I could do myself or should I leave it to a pro?
    Also, while the crawlspace does have plastic sheathing on the ground, there is no insulation between the floor joists. Should there be some type of insulation there?
    Thanks for any help.
    Yes,the ducting should be insulated and all joints sealed. The air sealof all joints with foil tape is very important ,don't rely of the duct wrap for this.
    Which type , bubble wrap or foil/fiberglass , is your choice. I can say from personal experience the foil/fiberglass wrap works well.

    One thing one has to wonder. Is this duct work old?
    If it has been in the crawl space unsealed and uninsulated for quite some time then you might consider having the ducting cleaned , perferably with a powered brush/vacumm system. There might be a fair amount of gunk inside those ducts if they are leaky being inside a crawl space. The other consideration is mould/mildew buildup being inside an unconditioned space , leaky and uninsulated.

    Insulating the floor joists will be a wise thing to help keep your floor warmer and increase your comfort. Also, with insulating the floor joists will add more insulation to those ducts within those spaces. Attaching housewrap to the underside of the floor joists will keep colder moving air reaching the ducting and floor improving the insulation performance.
    Seal the wall / floor junction at the baseboards to prevent cold infiltration helping to keep the floor warmer also increasing comfort.

    Can you do it yourself ?
    Sure you can , just take your time and do a good job and it will pay off in comfort.
    Perhaps the money you save on doing this yourself could go toward the duct cleaning.

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