Insulating ducts in crawl space

[czechsonofagun]

I need to insulate ducting in the crawl space. Some of the ducts (6" diameter) are laid in the 8" joist and it is impossible to wrap them with fiberglass insulation.

I figured I could use aluminum buble wrap and staple it to the joist, I am sure it will work for heating but what is it gonna do in summer when the same duct is used to cool the house. I am afraid it will not prevent condensation on the ducting.

What do you think?

here is the ecofoil application:

crawl space insulation, insulating a crawl space, insulate crawl space

 

[dave1949]

Is there good info on the effectiveness of reflective barriers? I put Slab Shield, a similar product, under my slab along with 2" of styro-foam. Of course, I have no way of quantifying the effectiveness of the Slab Shield. For the price, it seemed worth throwing it in just in case it actually worked.

How useful would it be to coat your ducts with spray foam? I don't know if the heat in winter would deteriorate the foam, but the ducts would be well insulated and sealed.

 

[LD1]

Its pricy, and I dont know about the application, but have you considered spray-foam?

 

[czechsonofagun]

That would be actualy neat, to encase the duct in foam. Kinda scary to go with spray foam gun in crwal space, it is hard the way it is.

 

[riptides]

I have to revisit my crawl space on the old part of my house. The insulation did not hold. I am thinking about this kit.

https://sprayfoamsys.com/store/do-i...-foam-systems/disposable-spray-foam-kits.html

 

[kenmac]

You probably don't want to do it,but the correct way would be to remove the duct and wrap it with insulation & re install. I've done it many times. Insulation will stay together with the proper staple gun

 

[newbury]

Have you calculated the cost of heat loss/cooling loss versus the cost of the project?

For example my house in Virginia has old style windows. Based on past energy consumption and giving a 5% rise annually in energy costs, if I replaced ALL the windows the estimated pay back for energy savings would be about eternity. That's assuming new Lowes energy efficient windows (about $150), my labor and tools and the cost of natural gas/electricity. We just don't spend that much on heating or cooling.

When I put in storm windows about 30 yrs ago at $10@ payback was soon.

 

[edlegault]

Can you cut rigid 2" foam board and lay up/glue onto the ductwork and then wrap the foil bubble wrap around that? The foam board is light weight. Staple and/or duct tape the bubble wrap around the foam board. There is almost no insulation value with the bubble wrap alone.
Or.... run completely new, properly insulated ducts through ceilings and walls.

 

[czechsonofagun]

newbury - I know what you mean. VA does not need that much for heating to pay off savings.

I am only concerned with condensation in summer, if there is a heat escaping to the crawl space, so be it, not a big deal. But I dont want the duct to rust because it is dripping wet 4 month a year.

 

[kenmac]

didn't you just have a unit installed ? If so, that should have been figured in with install price.Is the duct insulated inside ? Alot of older homes that were heat only weren't insulated inside (old code) when I add A/C or upgread I insulate outside. new code here is R 8 insulation

 

[Car Doc]

I am kind of wondering the same thing in the house I live in they are just galvanized tin ducts and they sweat all summer in a/c season and let cold air in all winter bad way to distribute air imho.

And I probably need to do something to a rental we just bought also its 40 yo or so. I cant get in the crawlspace in it yet the hole in the floor is too small for my carcass to get thru but I will be curious what is the best way for cramped areas etc.

 

[riptides]

And I probably need to do something to a rental we just bought also its 40 yo or so. I cant get in the crawlspace in it yet the hole in the floor is too small for my carcass to get thru but I will be curious what is the best way for cramped areas etc.

Smaller people. I had the same issue with my crawl space. I guess the ground swelled over a 120 year period. The last company we called in had a smaller guy crawl under the house. Unfortunate, but I need to revist the insulation again.

 

[Car Doc]

Smaller people.

:laughing: yeah I agree! I am looking for a real small person that would actually know what they were looking at once they get down there like where can I cut a bigger hole haha! I think my 105 lb wife could squeeze thru but all she would see is dirt and boards and spiders haha.

 

[kenmac]

Seal all the joints with mastic & insulate. That will stop the sweating

 

[Car Doc]

Seal all the joints with mastic & insulate. That will stop the sweating

Sounds easy when ya say it fast! :laughing: Nah I realize that would fix it just getting it done in a cramped space is a challenge in my house as well. That's why the spray foam someone mentioned is so intriguing but it must be a hazard to do in a crawlspace I can only imagine?

 

[dave1949]

Sounds easy when ya say it fast! :laughing: Nah I realize that would fix it just getting it done in a cramped space is a challenge in my house as well. That's why the spray foam someone mentioned is so intriguing but it must be a hazard to do in a crawlspace I can only imagine?

Mummified homeowner discovered in crawlspace? Spiders are suspected of being the cause of death.

 

[kenmac]

Sounds easy when ya say it fast! :laughing: Nah I realize that would fix it just getting it done in a cramped space is a challenge in my house as well. That's why the spray foam someone mentioned is so intriguing but it must be a hazard to do in a crawlspace I can only imagine?

We aren't allowed to do foam. Any material used on ducts has to be flame resistant

 

[Car Doc]

Makes sense and it would also have to be hard on lungs just imagining.

 

[yelbike]

I haven't seen pictures but it may be easier to insulate the stub wall(skirting) around the home, than lay a vapour barrier on the ground and add pea gravel(buck shot) over top of the poly to protect it. Sealing the "easy" joints on the duct work would help also. Then the crawl space becomes somewhat of a conditioned space. Just a thought.

 

[riptides]

I haven't seen pictures but it may be easier to insulate the stub wall(skirting) around the home, than lay a vapour barrier on the ground and add pea gravel(buck shot) over top of the poly to protect it. Sealing the "easy" joints on the duct work would help also. Then the crawl space becomes somewhat of a conditioned space. Just a thought.

Ding, ding! Winner. My other part of the foundations, (old house, old house, plus new house), the new house, done right, is conditioned. And we did the insulation right, and I can actually crawl in there!