# Is insulated vinyl siding worth the difference?



## joefrompa

Hi all,

So I'm in the process of getting 3 quotes for re-siding my 2-story colonial with vinyl siding. I've received 2 quotes so far and a ball-park 3rd quote which is being finalized right now. All 3 quotes have used foam-back vinyl siding from Crane, CertainTeed, or Mastic - so all top brands. The quotes also included new 5" aluminum gutters and 2x3 downspouts, soffits, etc.

Here's the quotes I've gotten:

$14,000 - The "low cost" guy
$13,000 - $18,000 - the ballpark I received this morning from a pro who is childhood friend of a nextdoor neighbor who's given me ~5 cords of free wood
$24,000 - The smooth talking super reputable company who had done work on a family members home 10 years ago and came back after 8 years to fix a flashing problem "they were ashamed had come from them". 

What I've been told is that the cost difference in materials from normal vinyl siding to foam-backed siding is between $2,500-$4,000 increase in job cost. However, the entire exterior siding of the home gets an r-4 value (instead of r-1), the siding has less seams in it because its more structurally rigid and therefore comes in longer pieces, and the siding is much less likely to experience any sort of bowing, cupping, breakage, or warping. It does eliminate the use of a beaded-vinyl siding, which I like the style of, but otherwise it's quite nice.

So my question is: What should I expect the increase in r-value to mean to me $$ wise each year? Any personal experience in these areas? 

I'm trying to determine if it's worth it to me. I plan on living here a minimum of 5 more years. 

Thanks all,

Joe

P.s. All jobs involve tyvek, tape & seal, which I'm sure will help as well.


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## dave11

To answer this question, you need to know two things:

1. The current R value of your exterior walls, and

2. The surface area of the walls that are going to be covered.

In general, insulation has "diminishing returns," meaning that the higher you go with R values, the less you're getting for your money. If your walls currently have a low R value, then you will save more over time by adding R value to the outside of the house. If your R value is already pretty good, as in greater than R20, the return on your money is much less.

In the same way, if the area to be covered is huge, you are likely to make more on your money. If small, you'll save much less. 

But even if the R value of your walls at present is low, you might be better served by increasing the R value directly, through blown-in fiberglass, than through adding insulation to the siding. 

Whether the insulated siding makes better siding than the uninsulated though, is a whole other matter.


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## joefrompa

Current siding = wood asbestos = .03 R-value

Surface Area = ~2400-4000 square feet (I actually don't know this, so I'm making an approximation, sorry it's so large)

I think the walls currently have batts in them that are worth R-9 or R-11. So I'd be going to roughly R13-R15 instead of R10-R12 (with standard vinyl siding and R-1 foam board). Additionally, the siding R-value is of course on top of the wood studs so it holds a bit more weight than the in-wall batts since it'll be slowing the conduction of heat through the studs as well.....not sure how that all pans out.


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## dave11

joefrompa said:
			
		

> Current siding = wood asbestos = .03 R-value
> 
> Surface Area = ~2400-4000 square feet (I actually don't know this, so I'm making an approximation, sorry it's so large)
> 
> I think the walls currently have batts in them that are worth R-9 or R-11. So I'd be going to roughly R13-R15 instead of R10-R12 (with standard vinyl siding and R-1 foam board). Additionally, the siding R-value is of course on top of the wood studs so it holds a bit more weight than the in-wall batts since it'll be slowing the conduction of heat through the studs as well.....not sure how that all pans out.



Assuming the wall is sheetrock (R=0.5) and the batts are R11 then, you're looking at a final wall R value of R12.5 vs R15.5. Not a big  difference. 

r12.5 reduces the rate of heat loss through the wall by 92%. 

r15.5 does so by 93.5%, a decrease of 1.5%. Pretty small. 

But--over the life of the siding, if the wall area is large, and the outside temps are really cold, this can be significant. From here, would need the exact wall area, and the average outside temp for winter in your area, to find your break-even point.

Might be better to make the decision based on any tangible improvement in the siding itself, when insulated, rather than on the little bit of heat saved, especially if you don't plan to stay for many years in that house.


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## joefrompa

Wow, using your metrics I'm surprised at how much heat loss is reduced by taking attics from r19 to r38, or even r38 to r60. 

I'll assume 3000 exterior square feet of wall space and average outside winter temp of 38 degrees.

I really appreciate this advice. I'm starting to think going with a really nice looking siding and a simple foam-board. I'm wondering what the cost of doing the job with Polyiso would be since it has a r value of ~3.5-4.0 for 1/2" thickness.


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## joefrompa

Doing some more research and saw a good point: vinyl siding has got to be able to flex over itself, so that insulated backed siding allows air underneath it and some modest airflow. So how insulating is it going to be compared to foamboard underneath?

I'm going to evaluate the difference it provides in the structure of the vinyl a bit - honestly, vinyl's old now and the standard stuff sold by Crane and CertainTeed is pretty damn good without the foam backing, so I'm not sure how much additional value I'd get out of increasing the cost of the job 15-20%.


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## Later

With "any" insulation in the walls, IMHO, most of your heat loss will be through the ceiling/roof and infiltration. Foam backed insulation's (IMHO) greatest feature is the rigidity it provides to the vinyl.


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## smokinj

My father had this installed a few years back the house was already very well insulated. He lives on a busy main st. now you can not hear traffic and gas bills under 100.00. They live by a small airport and a helicopter crashed in there back yard and they didn't know anything until the lights from the police cars where everywhere! 

You ask him and its was worth every penny! Wish I could afford it and installe it myself.


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## joefrompa

Gas Bill before this?

One comment i made to myself was: My heating bill is under $600 a year for oil, my electric in the summer is under $150 and about $100 in the winter - so maybe $50 max for air-conditioning 3 months a year.

Even if I saved $100 on oil and $100 on a/c use a year, that'd be $200 and it'd take be ~15 years to recoup the initial investment - and that's a pretty generous amount of energy savings from only an r-4 shingle. Further, I'm going to be getting ~r-1 to r-2 from a non-foam-backed siding simply through foam board sheets. And who knows how much of the benefit I'll get is simply from better air-sealing from the foam, tyvek, and taping.


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## smokinj

joefrompa said:
			
		

> Gas Bill before this?
> 
> One comment i made to myself was: My heating bill is under $600 a year for oil, my electric in the summer is under $150 and about $100 in the winter - so maybe $50 max for air-conditioning 3 months a year.
> 
> Even if I saved $100 on oil and $100 on a/c use a year, that'd be $200 and it'd take be ~15 years to recoup the initial investment - and that's a pretty generous amount of energy savings from only an r-4 shingle. Further, I'm going to be getting ~r-1 to r-2 from a non-foam-backed siding simply through foam board sheets. And who knows how much of the benefit I'll get is simply from better air-sealing from the foam, tyvek, and taping.





160.00 range. They also had the craw space foam in at the same time. There house was well above average prior to this as well.


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## PapaDave

If you're up to tackling this yourself, I was told at the HD pro desk that this stuff is about $2/sq. ft., but I didn't ask about the j-channel, f-channel, corner channel cost.
I have a ranch though.


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## woodsmaster

If it were me I'd put 1" foam on then some good uninsulated siding.


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## Hass

sorry to hijack, but since we're on the topic of siding...
I'm residing my house this year among many other things... Currently the outside has wood asbestos shingles, with 3/4 tongue and groove planks underneath it. Am I better off to tear off all of the Tongue and groove and put up 3/4 ply or just leave it?

Vinyl will be the finish, although I doubt that matters.


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## joefrompa

I'd say leave up the 3/4 t&g. As long as it's flat and a solid/stable underlayment, it'll even provide some additional sealing & insulation.


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## woodgeek

A handy mnemonic for computing conduction heat loss in my (and joes) climate (~5000 degday): 

1 sq ft insulated to R-1 will require 1 gallon of oil to heat for 1 season.  So, multiply by the area and divide by the R-value...

For example: I have double hung windows with storms, nominally R-2 and 10 sq ft.  Those puppies cost me 10/2 = 5 gallons = $16/year, each, if I heat with oil.

Compute the area of your siding less windows, and divide by R-11.  Then divide by R-15.  The difference is the number of oil gallons you should save due to the
R-4 insulated siding.  The number will not suggest a reasonable payback (<10 years), as your intuition suggests.  Airwash behind the insulated siding might cause 
it to perform less well than this calc suggests.

The airsealing benes of the housewrap, done correctly, are where will you save energy.  A yokel doing a crappy job on the wrap will not achieve good seal, and you 
will have missed an opportunity for a more eff home.


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## joefrompa

Using that calc, I use 272 gallons at r-11 and 200 at r-15. Estimated savings would be ~$350 a year in fuel and oil.  Assuming 3000 exterior square feet excluding windows, which is probably on the high side.

I evaluated a neighbor's job just done with vinyl in a beaded look (~6.5" shingle height, non-insulated). I was surprised at how non-rigid/flexible vinyl siding is - I've never owned it or really pushed up against it. It's pretty soft to the touch. The job was also not very clean looking - which is a shame, as I was getting a bid from that vendor. The lines, trim, j-channel, and such looked a little rough for a finished job.


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