Insulating a/c ductwork on the roof
 

When my packaged a/c was installed on the roof they used ductwork that has
a thin layer on insulation inside. But then because of leaks they tarred
the outside. Of course the black absorbs the heat and warms the air
considerably.

How best to insulate? I see the various foam insulation boards. A neighbor
suggests going all out with 2" thick. I see you cut with a circular saw. I
see you tape the joints with 2-7/8" Weathermate Construction Tape. But the
Styrofoam sheathing can only take the UV for 90 days. I have to cover it
with something, either white or reflective. What do you all suggest?

I once got an estimate from a local roofer. He wanted $3500 for like 1/2"
thick insulation. No way should it cost that much. But I don't how he was
going to do the job.

Don. www.donwiss.com (e-mail link at home page bottom).

Insulating a/c ductwork on the roof
 

On Monday, August 15, 2016 at 12:15:46 PM UTC-5, Don Wiss wrote:
When my packaged a/c was installed on the roof they used ductwork that has
a thin layer on insulation inside. But then because of leaks they tarred
the outside. Of course the black absorbs the heat and warms the air
considerably.

How best to insulate? I see the various foam insulation boards. A neighbor
suggests going all out with 2" thick. I see you cut with a circular saw. I
see you tape the joints with 2-7/8" Weathermate Construction Tape. But the
Styrofoam sheathing can only take the UV for 90 days. I have to cover it
with something, either white or reflective. What do you all suggest?

I once got an estimate from a local roofer. He wanted $3500 for like 1/2"
thick insulation. No way should it cost that much. But I don't how he was
going to do the job.

Don. www.donwiss.com (e-mail link at home page bottom).

You could check with a roofing supply house to see if they have a white mastic sealer or that silver sealer you see on trailer roofs. ^_^

[8~{} Uncle Duct Monster

Insulating a/c ductwork on the roof
 

On Mon, 15 Aug 2016, Uncle Monster wrote:

On Monday, August 15, 2016 at 12:15:46 PM UTC-5, Don Wiss wrote:
How best to insulate? I see the various foam insulation boards. A neighbor
suggests going all out with 2" thick. I see you cut with a circular saw. I
see you tape the joints with 2-7/8" Weathermate Construction Tape. But the
Styrofoam sheathing can only take the UV for 90 days. I have to cover it
with something, either white or reflective. What do you all suggest?

You could check with a roofing supply house to see if they have a white mastic sealer or that silver sealer you see on trailer roofs. ^_^

I called Dow Chemical. Not unsurprisingly I was asking about an unusual
application. He emphasized that anything I put on it can't be solvent
based. It must be water based, like latex paint.

Looking at Home Depot I see they have a water based mastic that creates
air-tight seals on duct seams and joints.

He says sometimes it sticks out the bottom of walls and people put stucco
on it. But again, no solvents!

I supposed I could simply paint with white exterior latex paint.

Don. www.donwiss.com (e-mail link at home page bottom).

Insulating a/c ductwork on the roof
 

On 8/15/2016 4:38 PM, Don Wiss wrote:


I supposed I could simply paint with white exterior latex paint.

Don. www.donwiss.com (e-mail link at home page bottom).


I've been in the foam business for 46 years. I'd use latex paint. I
know of applications that are many years old and still in good
condition. Any color you desire will work.

Insulating a/c ductwork on the roof
 

On Mon, 15 Aug 2016 18:27:04 -0400, Ed Pawlowski wrote:

I've been in the foam business for 46 years. I'd use latex paint. I
know of applications that are many years old and still in good
condition. Any color you desire will work.

Do you use a circular saw or sabre/jig saw? I see there are special blades
for cutting foam: https://www.amazon.com/dp/B00KM0RLUU

I also see a mention of foil faced foam. Then I would use foil faced tape.

I would think Liquid Nails would attach the foam to the ductowrk.

Don. www.donwiss.com (e-mail link at home page bottom).

Insulating a/c ductwork on the roof
 

On 8/15/2016 8:47 PM, Don Wiss wrote:
On Mon, 15 Aug 2016 18:27:04 -0400, Ed Pawlowski wrote:

I've been in the foam business for 46 years. I'd use latex paint. I
know of applications that are many years old and still in good
condition. Any color you desire will work.

Do you use a circular saw or sabre/jig saw? I see there are special blades
for cutting foam: https://www.amazon.com/dp/B00KM0RLUU

I also see a mention of foil faced foam. Then I would use foil faced tape.

I would think Liquid Nails would attach the foam to the ductowrk.

Don. www.donwiss.com (e-mail link at home page bottom).



Hand saw makes for easy cutting with minimal mess. Electric knife works
well too. Not familiar with the blade you show but it looks like it
would work.

Pretty much any construction adhesive works well.

Insulating a/c ductwork on the roof
 

On Mon, 15 Aug 2016 21:34:15 -0400, Ed Pawlowski wrote:

Hand saw makes for easy cutting with minimal mess.

There will be a lot of cutting to cut all the pieces to fit around the
ductwork. No way would I use a hand saw.

Electric knife works
well too. Not familiar with the blade you show but it looks like it
would work.

The electric knife is an interesting suggestion that I had not thought of.
Thanks. (I've never owned or used an electric knife.)

If I do go all out and buy 2" insulation, will the electric knife still
work? It would be easier to handle than a much heavier sabre saw.

I see it would be hard to spend over $20 on a corded consumer electric
knife. And then afterwards I'd have a tool that I might use again.

I see I have a choice of a bread blade or carving blade. I would have no
use for a bread blade afterwards. I would think I would want a serrated
blade for the foam.

And I find a Heavy-Duty Electric Fillet Knife.

Don. www.donwiss.com (e-mail link at home page bottom).

Insulating a/c ductwork on the roof
 

Ed Pawlowski wrote:
On 8/15/2016 4:38 PM, Don Wiss wrote:


I supposed I could simply paint with white exterior latex
paint.

Don. www.donwiss.com (e-mail link at home page bottom).


I've been in the foam business for 46 years.

What type of foams? Packaging, furniture, industrial?
You don't sell any pincore latex, do you?

Insulating a/c ductwork on the roof
 

Don Wiss wrote:
On Mon, 15 Aug 2016 21:34:15 -0400, Ed Pawlowski
wrote:

Hand saw makes for easy cutting with minimal mess.

There will be a lot of cutting to cut all the pieces to
fit around the
ductwork. No way would I use a hand saw.

Electric knife works
well too. Not familiar with the blade you show but it
looks like it
would work.

The electric knife is an interesting suggestion that I had
not
thought of. Thanks. (I've never owned or used an electric
knife.)

If I do go all out and buy 2" insulation, will the
electric knife
still work? It would be easier to handle than a much
heavier sabre
saw.

I see it would be hard to spend over $20 on a corded
consumer electric
knife. And then afterwards I'd have a tool that I might
use again.

I see I have a choice of a bread blade or carving blade. I
would have
no use for a bread blade afterwards. I would think I would
want a
serrated blade for the foam.

And I find a Heavy-Duty Electric Fillet Knife.

Don. www.donwiss.com (e-mail link at home page bottom).

Are you using flexible / fiber silver/foil backed
insulation? If so. a razor knife and straight edge will do.
I'd use foil duct tape and wrap in radiant barrier
material(foil)

Insulating a/c ductwork on the roof
 

On Tue, 16 Aug 2016 00:11:26 -0500, "ChairMan"
wrote:

Ed Pawlowski wrote:
On 8/15/2016 4:38 PM, Don Wiss wrote:


I supposed I could simply paint with white exterior latex
paint.

Don. www.donwiss.com (e-mail link at home page bottom).


I've been in the foam business for 46 years.

What type of foams? Packaging, furniture, industrial?
You don't sell any pincore latex, do you?


EPS, expandable polystyrene. Packaging, fish boxes, ICFs. No latex.