Need advice on insulation/ ducting

[ps2cho]

Got (3) insulation contractors out. I can feel the air leaking from the units in the attic, and was interested in getting more insulation to bring me up to R38 here in Arizona.

Contractor A ---- He inspected attic for 10mins up there, didnt say much other than they'd seal ducts at plenum that are clearly leaking (showed me photos) and add new blown insulation on top of existing 4" in attic. $2k

Contractor B --- He was up in the attic probably 30mins, spent a long time up there. Big sales pitch, insulation and duct sealing 6k

Contractor C --- refused job entirely, said the following:

1. theres so little space in the attic he's afraid of damaging the ducts that are 20-years old and may struggle to get into the corners to do the insulation
2. He said I need the ducts completely replaced and re-routed -- 18" return ducts vs 14" supply ducts means I am constricted and there are poorly done bends up there. (*** I dont notice any rooms in the house having large cooling/heating issues...so maybe thats true but doesnt seem to be massively problematic***)
3. He would only do insulation after I replace the entire duct system and routing and he referred me to a different HVAC company to do it (so it wasnt even an upsell, they dont do full replacement he wouldnt even do just the insulation).

What do you guys make of this and recommend I do? Let Contractor A have at it? Contractor B was a waste of time. Contractor C seemed genuine and I am sure the routing isnt ideal, but I dont plan to stay in this house forever and I am sure replacing everything from scratch is $$,000's ...

Need opinions here. thanks.

 

[PT Doc]

Call an insulation company and see how much the cost is to go from what you have to where you want to be. I would do R60. If not then R49. Sealing up ducts can be done by yourself with a tub or 2 of duct pooky.

 

[ps2cho]

Here in AZ R38/44 is plenty for my understanding since it’s not cold.

These were all insulation companies

 

[dscheidt]

Here in AZ R38/44 is plenty for my understanding since it’s not cold.

These were all insulation companies

It is, however, hot. Insulation blocks heat transfer into the house, too. If you have the space for it, going higher will pay for itself. Are you ducts not insulated? They should be. R8 is probably the code requirement, which you do not meet with a layer of magic bubble wrap.

 

[ps2cho]

It is, however, hot. Insulation blocks heat transfer into the house, too. If you have the space for it, going higher will pay for itself. Are you ducts not insulated? They should be. R8 is probably the code requirement, which you do not meet with a layer of magic bubble wrap.

Yes my ducts are R6 or R8…either way I posted my questions still - should I just insulate and move on and hope for the best or really consider replacing everything?

 

[danski0224]

Old flex duct is brittle and it can fall apart if you touch it. Especially the stuff with the grey or black plastic outer jacket.

Code has not allowed the non-metalized outer jacket on flex duct for a long time.

I'd be willing to bet that your existing ductwork is undersized and may not be sealed at the connections.

Far as I know, flex duct isn't supposed to be buried under more insulation because of the outer jacket acting as a vapor barrier.

The best solution is new ductwork and then foaming the attic to make it part of the conditioned space.

You can easily web search for your climate zone and recommend insulation amount.

This stuff is far better than anything you can buy at a box store or many supply houses:

Type 3

 

[Fabtechprerunner]

Call an insulation company and see how much the cost is to go from what you have to where you want to be. I would do R60. If not then R49. Sealing up ducts can be done by yourself with a tub or 2 of duct pooky.

Buy a tub of mastic and a paint brush, or tape mastic and squeegee and seal them yourself.

 

[Fabtechprerunner]

Yes my ducts are R6 or R8…either way I posted my questions still - should I just insulate and move on and hope for the best or really consider replacing everything?

Messing around too much with old fiberglass ductwork can just cause more

Old flex duct is brittle and it can fall apart if you touch it. Especially the stuff with the grey or black plastic outer jacket.

Code has not allowed the non-metalized outer jacket on flex duct for a long time.

I'd be willing to bet that your existing ductwork is undersized and may not be sealed at the connections.

Far as I know, flex duct isn't supposed to be buried under more insulation because of the outer jacket acting as a vapor barrier.

The best solution is new ductwork and then foaming the attic to make it part of the conditioned space.

You can easily web search for your climate zone and recommend insulation amount.

This stuff is far better than anything you can buy at a box store or many supply houses:

Type 3

If he foams the attic then he needs to do a ERV due to the fumes that the foam insulation puts off. Second, there's another issue with spray foam insulation, if you happen to ever have a roof leak good luck finding it in 6in of foam filled insulation. Roofers hate spray foam insulation, it's hard as hell find roof leaks. Not to mention by the time you find the roof leak you have mold and mildew problems


He is better off doing foam board insulation.

 

[ps2cho]

Messing around too much with old fiberglass ductwork can just cause more

If he foams the attic then he needs to do a ERV due to the fumes that the foam insulation puts off. Second, there's another issue with spray foam insulation, if you happen to ever have a roof leak good luck finding it in 6in of foam filled insulation. Roofers hate spray foam insulation, it's hard as hell find roof leaks. Not to mention by the time you find the roof leak you have mold and mildew problems


He is better off doing foam board insulation.

Not possible to do foam board. There is such minimal space up there, it would be nearly impossible. Blown fiberglass is the only real option.

Still original question applies.
If this isnt our forever home and I dont see major heating/cooling problems room-to-room, can I get away with just blowing fiberglass insulation on top of the existing ~4" to get some additional efficiency, duct seal as best as is accessible and move on without I'm assuming dropping $10k+ on all new ducts?

 

[danski0224]

If this isnt our forever home

It is never anyone's "forever home".

Just **** it in and be done with it.

That's the answer you are looking for.

Good luck.

 

[Fabtechprerunner]

Not possible to do foam board. There is such minimal space up there, it would be nearly impossible. Blown fiberglass is the only real option.

Still original question applies.
If this isnt our forever home and I dont see major heating/cooling problems room-to-room, can I get away with just blowing fiberglass insulation on top of the existing ~4" to get some additional efficiency, duct seal as best as is accessible and move on without I'm assuming dropping $10k+ on all new ducts?

Just buy mastic in a tub, a roll of Neshua 324 foil tape, a paint brush for applying mastic and be done with it, if it's not your forever home. Due the minimal until you're ready to move to.your forever home.

 

[ps2cho]

Fair enough - the larger holes tape first then mastic brushed over the top?
I might go this route for now until I decide if it’s worth it.

Either way I can’t do ducting now because it’s too late in the year already, attic is already near 100F, it’ll hit 150F in the next month by time I get quotes and guys will die up there, it’s a winter job here in Phoenix.

Just buy mastic in a tub, a roll of Neshua 324 foil tape, a paint brush for applying mastic and be done with it, if it's not your forever home. Due the minimal until you're ready to move to.your forever home.

 

[e015475]

There's a duct sealing process called 'Aeroseal' where they pump an aerosolized mastic into your ductwork and it will seal the leakage down to a few percent of the CFM in the ductwork (they say that a typrical starting point is about 20-30% leakage)

I don't have any experience with it but there's lots of Youtube video about it including one from "This Old House". I may consider using it.

There's a butload of contractors in AZ offering the Aeroseal process, just search 'Arizona aeroseal' Some of the websites say there's a $1200 tax credit from the Feds which might be worth investigating

My recommendation is that you start with an energy audit and take the results and find a contractor to execute them. The answer you'll get from any insullation company will always be "you need more insulation of the type I sell"

SRP, the local utility here in Mesa/Phoenix will come to your house and assess your energy usage including the condition of your ducts for $50 if you're a customer. APS, the other utility here, probably has a similar program.

ReIS also offers an energy audit for about $200 which I think is a little more comprehensive. The last one I had done by ReIS made a list of energy improvements to the house in rank order of payback. (the only one of which I acted on was to buy a higher SEER AC when mine came to the end of its economic life)

I recently bought a 'winter' house in Phoenix, built in 1979 by a tract builder. The original square sheet metal ducts in the house ran in drop-downs and soffets and had about a foot of blown-in celulose insulation over them, about the same as the ceiling. I think it'd be fair to say the old ductwork was nearly in the air conditioned space, but it is leaky.

I took the dropdowns/soffets out of my kitchen to put a modern kitchen in my house and removed about 10' of the old sheet metal duct and replaced it with insulated flex tube. The HVAC contractor warned me that a lot of Arizona houses had evaporative cooling and they ofen encounter rusted ducts in older homes and they sometimes end up replacing the entire duct system (fortunatly mine were fine)

The 10' of old metal ductwork I removed was sealed with duct-tape that had mumified and wasn't sealing anything. There wasn't any seal at all on the slip and drive connections. After seeing what came out of the house, the 20-30% leakage seems to have a degree of credibility. On the plus side it had about 10-12" of insulation over it and the new flex duct is just R8 by code. In the flex-duct's favor is that all the joints are pookied with mastic and can't really leak much. (I'm considering having the insulation removed from the remaining old duct and having it foamed in place or Aerosealing the old duct, but since I only live there in the winter, I might not do anything)

If the audit ends up telling you that the ductwork needs replacing/modified, I've used Central Supply and Metal in Phoenix for about the last 35 years and 4-5 AC installations.

Having said all that, I've owned quite a few homes in the Phoenix area over the last 45 years, my general experience is that most energy improvements beyond builder-grade don't have a significant enough payback to justify them. A 14-16 SEER AC, any dual pane windows, 82F thermostat setting in the summer and your utilities' time-of-use plan is about the best bang for your buck. I'd get an energy audit, and if there's something really wrong, I'd fix it, but in general 'if it ain't broke, don't fix it.

 

[Fabtechprerunner]

Fair enough - the larger holes tape first then mastic brushed over the top?
I might go this route for now until I decide if it’s worth it.

Either way I can’t do ducting now because it’s too late in the year already, attic is already near 100F, it’ll hit 150F in the next month by time I get quotes and guys will die up there, it’s a winter job here in Phoenix.

When you say large holes, what are you referring to? Holes in the flex? Is it a hole in the outer layer (vapor barrier) or the inner liner, or both?


If you have holes in the ductwork (ductboad) then tape over them if they are small and squeegee the hell out of them.

If you absolutely want to fix this system so it works properly and you will have to fix it or take a substantial loss when you go to sell the house. Look into rebates through your utility companies to help offset your cost.

 

[danski0224]

or take a substantial loss when you go to sell the house.

Home inspector #1 credo:

"Don't break the deal".

 

[AC-WC]

If you don't do it yourself with the tape and mastic then Contractor A seems to be fair.
I checked into the 'aeroseal' on my ductwork and it was around $3-4k like 3 yrs ago when I had the furnace replaced. I was so disappointed with the refit of the new furnace to the existing plenum I got PO'd and did a bunch of sealing with the tape and mastic. Less than $100 in materials but all mine is in the basement and reasonably easy to access.
What kind of ductwork do you have that would be brittle in 20yrs? All the houses around here have metal.

 

[Fabtechprerunner]

If you don't do it yourself with the tape and mastic then Contractor A seems to be fair.
I checked into the 'aeroseal' on my ductwork and it was around $3-4k like 3 yrs ago when I had the furnace replaced. I was so disappointed with the refit of the new furnace to the existing plenum I got PO'd and did a bunch of sealing with the tape and mastic. Less than $100 in materials but all mine is in the basement and reasonably easy to access.
What kind of ductwork do you have that would be brittle in 20yrs? All the houses around here have metal.

If its metal and has leakage the buy silver bubble wrap, a roll of Neshua 324 foil tape, squeegee and mastic and paint brush.

Metal ductwork is extremely rare to find in residential hvac nowadays. Everything has been updated to **** ductboard which start deteriorating within 2 years.

 

[danski0224]

Metal ductwork is extremely rare to find in residential hvac nowadays.

Depends on your location.

Everything has been updated to **** ductboard which start deteriorating within 2 years.

I have only seen one house with ductboard, and it was built over 30 years ago.

Last time I worked on it, the ductboard was fine. Poorly installed and not sealed, but I fixed the sealing part.

As a product, it's better than metal ductwork + external insulation because external insulation is usually installed poorly.

There's a foam product that works just like ductboard, but it's crazy expensive.

I wouldn't want it, but a home buyer probably won't know what they are getting for HVAC, unless that buyer is either the GC or very deeply involved in the decision processes.