Looking for ideas for insulating craw duct work. - Contractor Talk - Professional Construction and Remodeling Forum

Veith@toast.net · 01-16-2009, 08:47 PM

Be gentle a painting contractor looking for some ideas. NW Ohio House is on a crawl. Typical 1950 ranch with metal duck work. Or am I pissing in the wind by doing this. As I said looking for idea. and the pros and cons
Thanks
David Veith
David Enterprises

neolitic · 01-16-2009, 09:06 PM

Insulate the crawl space,
not the duct work.
Vapor barrier on the floor,
2" styrofoam on the walls,
R-13 - R-19 in the joist
pockets and on the rim joist.
Keeps the plumbing and
floors warm.
The heat loss is.....
into the house!

Dr Heat · 01-16-2009, 11:29 PM

is the crawl ventilated?
Can you get to both sides of the duct?
what kind of floor is in the crawl?

Veith@toast.net · 01-17-2009, 04:07 PM

Dirt floor with vapor barrier 2x12 rafters and yes I can get around the main trunk line. Floor is mainly insulated.
David Veith

neolitic · 01-17-2009, 04:31 PM

Quote:

Originally Posted by Veith@toast.net

Dirt floor with vapor barrier 2x12 rafters and yes I can get around the main trunk line. Floor is mainly insulated.
David Veith

I told you what is best for
your climate, do what you will.

http://apps1.eere.energy.gov/consume.../mytopic=11480
http://forums.jlconline.com/forums/s...er+crawl+space
http://forums.jlconline.com/forums/s...te+crawl+space
http://forums.jlconline.com/forums/s...te+crawl+space
http://www.buildingscience.com/docum...s/?full_view=1

nap · 01-17-2009, 04:37 PM

neolitic has a good point but 2 things with that I can think of;

1. you have not stated if this is a vented crawlspace or not. If it isn't, have you taken a radon check to be sure you do not have a radon problem and if you are considering sealing the crawlspace, do not cause yourself a problem with radon buildup if it is there.

2. the crawlspace acts as a buffer. By making that buffer part of the heated/cooled area, you are increasing the temp differential between any 2 areas which results in a faster heat loss. Not sure of the overall result but something to think about.

If you want to insulate the ducts, use duct insulation or duct wrap. Here is a pic but I don;t know how to resize so I will only provide the link.

http://news.thomasnet.com/images/large/019/19284.jpg

neolitic · 01-17-2009, 04:50 PM

Vented crawls in our climate
are a nineteenth century idea.
This is the twenty first century!

Dr Heat · 01-17-2009, 04:59 PM

If the crawl is vented insulate the duct if it is not vented insulate and condition the crawl.

the best way to insulate duct is to wrap it national building code calls for a min R5.7 I use 2" fiberglass batts they come 47" wide and 50' long roll you can get other sizes but that is the standard.

Begin buy sealing all the connections with mastic or mastic tape code calls for 181 tape but you can get the same product without the label cheaper. Do not use duct tape or silicone as these will not stick.

Pre cut your insulation take the total top + sides + bottom then add 6 " for an overlap.

You will need to buy a stitcher (Aro p32 stapler) wrap the duct cutting around the takeoffs lapp to the corner and fold 2" under so you can stich the foil wrap together. Now tape the ends all the way around the duct.

This is an excelent diy project as it requiers time and lots of it but no particular danger of doing it wrong. Also you can save a butt load over having my crew do it. A recent job: 3' crawl wraped 50' of trunk and 200' of branch. Took 3 days $200 in matterial. Job cost $2,700 so if you can crawle around and do it you can save $$$

This is a two man job you really need one man on each side of the duct.
If you do not seal the duct you will endup with a balloon

Dr Heat · 01-17-2009, 05:03 PM

Quote:

Originally Posted by neolitic

Vented crawls in our climate
are a nineteenth century idea.
This is the twenty first century!

True; but do not make the mistake of turning a vented space into a non vented just by blocking the vents we do things for a reason even back in 19...

nap · 01-17-2009, 05:04 PM

Quote:

Originally Posted by neolitic

Vented crawls in our climate
are a nineteenth century idea.
This is the twenty first century!

but OP did state it is a 1950's vintage home. That makes it a 20th century home where some crawls are vented, some not

I would suggest sealing it but just be sure the radon is not a problem.

mrmike · 01-17-2009, 05:10 PM

Do not insulate the duct work as Neolitic said. Insulate the perimiter of the crawl space only. If anything install a diffused outlet from your duct work into the crawl space-keeping it & your floors & house warmer for the winter and your crawl space dryer. It will be more cost efficient... Ventilate it in warmer weather......... Mike

Veith@toast.net · 01-21-2009, 09:40 AM

The crawl is ventilated. What good the Half dozen or so vent do is a another ? that I don't plan to go after.
David Veith

neolitic · 01-21-2009, 06:59 PM

Quote:

Originally Posted by mrmike

Do not insulate the duct work as Neolitic said. Insulate the perimiter of the crawl space only. If anything install a diffused outlet from your duct work into the crawl space-keeping it & your floors & house warmer for the winter and your crawl space dryer. It will be more cost efficient... Ventilate it in warmer weather......... Mike

Where does any of this
say to insulate the duct work?

Quote:

Originally Posted by neolitic

Insulate the crawl space,
not the duct work.
Vapor barrier on the floor,
2" styrofoam on the walls,
R-13 - R-19 in the joist
pockets and on the rim joist.
Keeps the plumbing and
floors warm.
The heat loss is.....
into the house!

Quote:

Originally Posted by neolitic

I told you what is best for
your climate, do what you will.

http://apps1.eere.energy.gov/consume.../mytopic=11480
http://forums.jlconline.com/forums/s...er+crawl+space
http://forums.jlconline.com/forums/s...te+crawl+space
http://forums.jlconline.com/forums/s...te+crawl+space
http://www.buildingscience.com/docum...s/?full_view=1