New house/garage build insulation question?

[2011laramie]

Were looking at building a new house next spring. 1820 sq ft, triple car garage, bungalow with blown in R60 roof, and triple pane windows. I told the builder to make it warm and he came back with 4.5" of closed high density spray foam. About R5.5/ inch. I think he said its like 6g less to do roxul mineral wool.

How much better is spray foam? Even if it saved 25 dollars a month in gas and AC, thats 20 years recovery, not to mention the extra interest on the mortgage.

 

[ItsNemo]

Spray Foam seals up air gaps better than anything else...but that's about where it's advantages end. It's more pricey, burns and off gasses terribly (fire hazard), and is impossible to do any work in the walls after.

You won't ever make back your money on it, a well built modern house is sealed up pretty good to begin with. You might just be a bit more comfortable in the house but honestly I'd rather spend 6 grand on a zoned HVAC system with variable/modulating furnace than the spray foam when worried about comfort.

 

[kbs2244]

ItsNemo has pretty much nailed it.

On a pure $ ROI basis it does not make sense.
On a comfort basis, maybe.

IMHO there enough kinds of draft prevention measures that can be used with conventional construction to make the extra dollars of spray a no go.

Just be sure your sub-contractors use them

 

[NUTTSGT]

I'd bet your $25/month savings is off. You guys have some cold Winters up there, I'd put good money into insulation, every time a heating or cooling dollar is spent, you reap the rewards of that extra insulation.

For us, I rolled some extra R13 in attic of the back of the house and then blanketed that with another layer perpendicular to the first. Our home is like 100 years old and not terribly well sealed up. Just adding that extra insulation (about $100 investment) made a huge difference that even the wife felt. I'm pretty sure that first year it paid for itself on fuel oil costs.

If anything, check out what it would cost to flash and batt. An inch or so of spray foam to seal everything up, followed by putting in Roxul.

 

[Lelandwelds]

Spray Foam seals up air gaps better than anything else...but that's about where it's advantages end. It's more pricey, burns and off gasses terribly (fire hazard), and is impossible to do any work in the walls after.

You won't ever make back your money on it, a well built modern house is sealed up pretty good to begin with. You might just be a bit more comfortable in the house but honestly I'd rather spend 6 grand on a zoned HVAC system with variable/modulating furnace than the spray foam when worried about comfort.

ItsNemo has pretty much nailed it.

On a pure $ ROI basis it does not make sense.
On a comfort basis, maybe.

IMHO there enough kinds of draft prevention measures that can be used with conventional construction to make the extra dollars of spray a no go.

Just be sure your sub-contractors use them

Insulation cost here are peanuts. My temperature difference between inside and outside is usually just 30°F. Cost differences between insulation types is not that much.

Foam can be great. Cellulose is great and the fire tests alone make it a great choice. Rockwool is even more fireproof it reduces sound even better than the others.

I think attention to execution is more important than insulation type. My guys did stuff for easier work instead of best performance. Nobody pays enough attention to air leaks and under insulated or under sealed places. My GC started rolling his eyes at stuff we spelled out and agreed to prior to the start. They did everything I insisted on but cut corners where I didnt notice. There is a lot going on at once.

 

[Lelandwelds]

I like the "Pretty Good House " movement. Matt Risenger makes good Youtube videos. Passive House scores some points too. Building Science Corp and " The Perfect Wall" make for excellent reading.

Most contractors, inspectors, and internet wannabes are ill informed or just idiotic stick in the mud dinosaurs. Wish you luck. Hope you nail it and come in under budget.

 

[ItsNemo]

I'd bet your $25/month savings is off. You guys have some cold Winters up there, I'd put good money into insulation, every time a heating or cooling dollar is spent, you reap the rewards of that extra insulation.

For us, I rolled some extra R13 in attic of the back of the house and then blanketed that with another layer perpendicular to the first. Our home is like 100 years old and not terribly well sealed up. Just adding that extra insulation (about $100 investment) made a huge difference that even the wife felt. I'm pretty sure that first year it paid for itself on fuel oil costs.

If anything, check out what it would cost to flash and batt. An inch or so of spray foam to seal everything up, followed by putting in Roxul.

Canadian building codes already do a lot for insulation...IIRC we're currently at R22 walls and R50 ceiling for minimum code and vapour barrier with acoustic caulking/tuck tape sealing it all up. So going up to spray foam isn't going to gain much in the way of R value, is going to help some with sealing but isn't that drastic. Plus there's a need for an HRV to keep air quality decent.

My house is a 2015 build in Ontario, 2500 sq ft upper levels + walk out basement, R22 walls, R60 attic, a 97% efficient variable modulating furnace, south facing, all brick clad...winter time total heat bill (natural gas) is around $40-50/month if you take out other usage for hot water tank, stove, and fire place (not used as primary heat, just occasional ambience). It would be nearly impossible to save even $10/month from insulation, let alone $25/month.

 

[NUTTSGT]

Canadian building codes already do a lot for insulation...IIRC we're currently at R22 walls and R50 ceiling for minimum code and vapour barrier with acoustic caulking/tuck tape sealing it all up. So going up to spray foam isn't going to gain much in the way of R value, is going to help some with sealing but isn't that drastic. Plus there's a need for an HRV to keep air quality decent.

My house is a 2015 build in Ontario, 2500 sq ft upper levels + walk out basement, R22 walls, R60 attic, a 97% efficient variable modulating furnace, south facing, all brick clad...winter time total heat bill (natural gas) is around $40-50/month if you take out other usage for hot water tank, stove, and fire place (not used as primary heat, just occasional ambience). It would be nearly impossible to save even $10/month from insulation, let alone $25/month.

I know you guys up there are hands down way ahead of us on the energy efficiency when it comes to building codes. Laugh all you want but that is one thing that I picked up from watching Holmes on Homes and some other tips on sealing up for the cold air. Points out why, as you know this, why we as older members constantly ask new members for their location before providing information.



R22 in the walls ? Is that sprayed in a 2x4 wall or does code require 2x6 for wall construction ?

$40-50 dollars a month is dirt cheap, even more so when you convert to US dollars. I've got say, I'm astonished, in awe, in disbelief or whatever whatever you want to call it. Wow.

 

[ItsNemo]

I know you guys up there are hands down way ahead of us on the energy efficiency when it comes to building codes. Laugh all you want but that is one thing that I picked up from watching Holmes on Homes and some other tips on sealing up for the cold air. Points out why, as you know this, why we as older members constantly ask new members for their location before providing information.



R22 in the walls ? Is that sprayed in a 2x4 wall or does code require 2x6 for wall construction ?

$40-50 dollars a month is dirt cheap, even more so when you convert to US dollars. I've got say, I'm astonished, in awe, in disbelief or whatever whatever you want to call it. Wow.

My house is 2x6 walls...wall is 3.5" brick, 1" air space, 7/16" osb, 2x6 studs with pink fiberglass R22 batts, 6 mil vapour barrier, 1/2" drywall, nearly 11" thick in total. Any gaps are spray foamed closed (shot from a can) such as windows/doors, acoustic caulking top bottom and between any studs for vapour barrier, tuck taped seams, sealed electrical boxes on outside walls, also tuck taped into vapour barrier.

Almost all of that is current minimum code in Ontario, I didn't have the builder do anything extra on insulating beyond their standards. I think code allows 2x4 walls and they use rigid foam on the outside to make up the R value though. Mind you this is a new build, so there are still TONS of homes with R24 attics and R12 walls out there.

My total utility bills (gas, water, electricity) are usually $175-225/month with two of us living in the house. Gas is $60-90 of that depending on the season but there's a fireplace, stove, bbq, hot water tank and furnace all included in that and we tend to use a lot of hot water (long showers, whirlpool tub, etc).

Really, any decent new build in Canada is going to end up fairly energy efficient. Hence why the spray foam doesn't really make it worth while. For comfort and savings a better HVAC system is money well spent.

 

[Lelandwelds]

would be nearly impossible to save even $10/month from insulation, let alone $25/month.

I think no version of phrases like" ROI" should ever come up when talking about a white hell which can have a difference of 100° or 125°F between inside and outside.

I have seen that cold white stuff fall from the sky twice. Nothing would be too much trouble to keep that junk outside. I vote for two of each kind of insulation. (Is vacuum jacketed insulation a common thing yet?)

 

[NUTTSGT]

My house is 2x6 walls...wall is 3.5" brick, 1" air space, 7/16" osb, 2x6 studs with pink fiberglass R22 batts, 6 mil vapour barrier, 1/2" drywall, nearly 11" thick in total. Any gaps are spray foamed closed (shot from a can) such as windows/doors, acoustic caulking top bottom and between any studs for vapour barrier, tuck taped seams, sealed electrical boxes on outside walls, also tuck taped into vapour barrier.

Almost all of that is current minimum code in Ontario, I didn't have the builder do anything extra on insulating beyond their standards. I think code allows 2x4 walls and they use rigid foam on the outside to make up the R value though. Mind you this is a new build, so there are still TONS of homes with R24 attics and R12 walls out there.

My total utility bills (gas, water, electricity) are usually $175-225/month with two of us living in the house. Gas is $60-90 of that depending on the season but there's a fireplace, stove, bbq, hot water tank and furnace all included in that and we tend to use a lot of hot water (long showers, whirlpool tub, etc).

Really, any decent new build in Canada is going to end up fairly energy efficient. Hence why the spray foam doesn't really make it worth while. For comfort and savings a better HVAC system is money well spent.

Thanks, that explains alot about your building codes up there.

Maybe the OP can chime in now and let us see what and how he is planning on building.

 

[terabitdan]

With a new house I’d ask the cost to add 2” of Polyiso to the exterior walls with roxul. You get a higher R-36 in the walls, limited thermal bridging for less money I’ll bet than foam.


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[yeldogt]

Spray Foam seals up air gaps better than anything else...but that's about where it's advantages end. It's more pricey, burns and off gasses terribly (fire hazard), and is impossible to do any work in the walls after.

You won't ever make back your money on it, a well built modern house is sealed up pretty good to begin with. You might just be a bit more comfortable in the house but honestly I'd rather spend 6 grand on a zoned HVAC system with variable/modulating furnace than the spray foam when worried about comfort.

Have you ever lived in a foam insulated house?

 

[yeldogt]

ItsNemo has pretty much nailed it.

On a pure $ ROI basis it does not make sense.
On a comfort basis, maybe.

IMHO there enough kinds of draft prevention measures that can be used with conventional construction to make the extra dollars of spray a no go.

Just be sure your sub-contractors use them

Don't agree ... you have not lived in a spray foamed house.

 

[yeldogt]

There is simply nothing that has changed the way buildings perform like spray foam insulation .. IMO .. nothing.

Unless you live in one .. you can't advise others on the comfort ... silent .. no drafts .. no heat gain .. no cold walls. I would never build a house w/o foam .. cut corners some place else. I ave fund very little difference with triple windows over high quality doubles .. unless a very modern design with all glass walls.

Be careful with exterior insulation in a cold climate.

 

[yeldogt]

I like the "Pretty Good House " movement. Matt Risenger makes good Youtube videos. Passive House scores some points too. Building Science Corp and " The Perfect Wall" make for excellent reading.

Most contractors, inspectors, and internet wannabes are ill informed or just idiotic stick in the mud dinosaurs. Wish you luck. Hope you nail it and come in under budget.

Did you see the most recent house with the Roxal on the outside -- and the crazy flashing he had to install... why? And it's ugly ?

Why design a wall that traps moisture -- .. don't get it .

 

[ard]

Boiling down the OPs question...

Is an R60 spray foam ceiling/roof better or that same as an R60 Roxul ceiling/roof

Correct?

All other things being equal, is the foam worth $6k extra?

This is a new build, so I assume they can do air ceiling, etc, etc, on the Roxul as needed.


Are there other attributes to spray foam? Sound? WIll it be quieter?

I dunno, just asking...


Having said that, I am not sure about OPs numbers...

4.5 inches of R5.5/inch is NOT R60... It's roughly r25.



Edit...I was editing when yel posted. Looks like some of this is addressed

 

[ItsNemo]

There is simply nothing that has changed the way buildings perform like spray foam insulation .. IMO .. nothing.

Unless you live in one .. you can't advise others on the comfort ... silent .. no drafts .. no heat gain .. no cold walls. I would never build a house w/o foam .. cut corners some place else. I ave fund very little difference with triple windows over high quality doubles .. unless a very modern design with all glass walls.

Be careful with exterior insulation in a cold climate.

My place is dead quiet (only noise comes from the windows), I've never felt a draft and none of my walls are cold. Normal construction techniques from a decent builder today aren't like houses 30 years ago.

I don't feel as though it's worth an EXTRA $6000 over a normally insulated house. When I look at upgrades that are worth $6000 there are better ways to spend it. All brick exterior rather than vinyl siding, sound insulation between the walls, 3/4" plywood subfloors (esp if builder does code 5/8" osb), higher efficiency appliances/furnace/hot water. Heck, spend 6 grand on quality window coverings that when closed provide some insulation, those alone will provide you with more energy savings and comfort than spray foam.

 

[2011laramie]

Hey guys, thanks for all the replies.

We were originally planning on a SIP wall house, but there may have been a miscommunication between the builder and SIP company. They claim they are having a meeting tomorrow to re-hash the details out over costs. So depending on the results will dictate which way we go forward.

Im willing to spend some extra on the mechanics of the house if i can justify it. Im doing standing seam metal roof to avoid shingle issues, good windows, HRV, etc...

 

[MushCreek]

I built our house from ICF, but SIP's were a strong consideration. In our mild climate, thermal mass of ICF works well, but I think in your climate it might not perform as well. There are two big issues with stick framing- one is sealing it up well, and I mean really well. The other is thermal transfer through the framing materials. You can lose up to 25% of your claimed R-value. That's why external rigid foam should be used.

Our small house is amazingly comfortable and efficient. We go months at a time without running the HVAC at all. Our total cooling load in hot SC is only 9K BTU- 3/4 of a ton. The maximum heating load maxes out at 11K BTU. We use mini-splits for both, and the energy usage is tiny.

 

[yeldogt]

My place is dead quiet (only noise comes from the windows), I've never felt a draft and none of my walls are cold. Normal construction techniques from a decent builder today aren't like houses 30 years ago.

I don't feel as though it's worth an EXTRA $6000 over a normally insulated house. When I look at upgrades that are worth $6000 there are better ways to spend it. All brick exterior rather than vinyl siding, sound insulation between the walls, 3/4" plywood subfloors (esp if builder does code 5/8" osb), higher efficiency appliances/furnace/hot water. Heck, spend 6 grand on quality window coverings that when closed provide some insulation, those alone will provide you with more energy savings and comfort than spray foam.

So the answer to my question .. I guess is ... no?

And .. your discussion about windows? how do you have any idea ?

As I said .. until you live in a foamed house you can't really understand it. It does cost more ... the benefits are not all in the energy savings ... they really are more comfortable structure. No conventional construction will be a tight when the building is finished -- or going forward like a foamed building.

I never use OSB. It's my main complaint about most of the new envelope products.products

 

[yeldogt]

Hey guys, thanks for all the replies.

We were originally planning on a SIP wall house, but there may have been a miscommunication between the builder and SIP company. They claim they are having a meeting tomorrow to re-hash the details out over costs. So depending on the results will dictate which way we go forward.

Im willing to spend some extra on the mechanics of the house if i can justify it. Im doing standing seam metal roof to avoid shingle issues, good windows, HRV, etc...

1/2 of my studio is SIP --- built about 20 years ago. My studio is a simple structure designed to look like a barn ... 10' walls and the roof is SIP as well. Few penetrations. This is for my property in rural PA. SIP's have a place ... they are great for barn reconstructions where the SIP become the exterior envelope for a rebuilt timber frame as an example .. and they make great building blocks for a modern type structure ... I don't think they are the answer for any traditional type building with lots of standard penetrations. In fact it's not uncommon for them to be used in conjunction with standard stick and spray foam -- around me.