[albertkao9]

I like to improve my basement insulation to qualify for the Enbridge Home Efficiency Rebate program.
Please see the attached photo for my current basement R12 insulation.
I am thinking of keeping current R12 insulation and insert R12, 24" on center insulation on lower half of wall,
then join upper vapour barrier to new vapour barrier being installed on lower half.
Is that a good idea?

Please review or suggest the materials and tools needed:
- Tuck Tape
e.g. https://www.canadiantire.ca/en/pdp/tuck-tape-construction-grade-sheathing-tape-0676000p.html

- Mastercraft Stapler Light Duty
e.g. https://www.canadiantire.ca/en/pdp/mastercraft-stapler-light-duty-0577936p.html#srp

- Vapor barrier
e.g. https://www.rona.ca/en/vapor-barrier-maxvapor-1000-sq-ft-0048125 ???

 

[Bud9051]

Hi Al, I was involved for awhile with an energy program here in Maine and my advice is to determine what the rules are. For example, here a home owner had to first get an energy audit to establish what was needed. Then, once complete a second audit would confirm the qualifying improvement. And in some cases those improvements had to be installed by certified ($) installers. Initially DIY wasn't allowed but the complaints forced them to change some of that.

But making the improvements is often only part of the process. Proving you saved energy may be the other half.

IMO it is the savings on your energy costs that are important and the improvements can add to the value of your home. Nice to get their incentives if the process doesn't add a lot to the overall cost. Not familiar with your program.

Bud

Note pulled up this link which I'm sure you have seen, but it mentions an Energy Advisor.
https://enbridgesmartsavings.com/home-efficiency-rebate/home-energy-upgrades

 

[Nealtw]

Looks like a 1980s house, out here now we would do just what you are suggesting.
The insulation at the rim joist should be covered with a barrier too. Behind the top of the wall the gap between the lower wall and the sill plate on the foundation should be covered (fire stop)

 

[albertkao9]

One contractor proposed:
1. Remove existing batting and vapour barrier
2. Install 3.33 inches (R20) CCMC approved 2lbs closed cell, spray foam all exterior foundation walls and rim joist.
Is that a good proposal?
My house is 21 years old in Ontario (zone 1), Canada.

 

[Nealtw]

I would finish the batt insulation and spend that extra money in the attic where you get more bang for the buck

 

[Bud9051]

You didn't reply to post #2 so I'll leave you alone, but with the energy program I worked with the before and after evaluation was mandatory, prevented people from removing existing insulation and installing new at their expense.

Good luck,
Bud

 

[CodeMatters]

Make sure insulating to bottom doesn't break current OBC (Ont
Building Code). I'm not an expert on the OBC, but I've spent
enough time wiring houses to pick up a few things.

There was a time in Ont when basement were insulated to the floor.
That was changed....maybe 20 years ago....to insulating to a certain
depth below grade and leaving the lower part open, as the op's is
done. I was told that this change was made after foundations were
damaged as a result of frost getting under footings.

IMO the op needs to know the pertinent OBC sections, and, as @Bud9051
pointed out, the details of the Enbridge program particularly around
audits, before starting.

EDIT: Also, every foundation wall I've seen has had tar paper attached
before insulation is added. An air space is also left between tar paper
and insulation. Think those are requirements. Is that tar paper
I see just below the insulation in the pic?

 

[albertkao9]

You didn't reply to post #2 so I'll leave you alone, but with the energy program I worked with the before and after evaluation was mandatory, prevented people from removing existing insulation and installing new at their expense.

Good luck,
Bud

Yes, I saw the same link you posted.

An Enbridge-approved Energy Advisor recommended not to remove existing insulation.

 

[albertkao9]

I would finish the batt insulation and spend that extra money in the attic where you get more bang for the buck

Do you mean spend more money with attic insulation than basement insulation?

 

[albertkao9]

Make sure insulating to bottom doesn't break current OBC (Ont
Building Code). I'm not an expert on the OBC, but I've spent
enough time wiring houses to pick up a few things.

There was a time in Ont when basement were insulated to the floor.
That was changed....maybe 20 years ago....to insulating to a certain
depth below grade and leaving the lower part open, as the op's is
done. I was told that this change was made after foundations were
damaged as a result of frost getting under footings.

IMO the op needs to know the pertinent OBC sections, and, as @Bud9051
pointed out, the details of the Enbridge program particularly around
audits, before starting.

EDIT: Also, every foundation wall I've seen has had tar paper attached
before insulation is added. An air space is also left between tar paper
and insulation. Think those are requirements. Is that tar paper
I see just below the insulation in the pic?

I depend on an Enbridge-approved Energy Advisor about OBC.
Please see zoom-in photo.

 

[Nealtw]

This in Ont. and he has some very good videos on different variations of this.

 

[user_12345a]

New homes in ontario come with full height R20 basement insulation.

That being said...

1. Spray foam has great properties for basements, but is flammable and toxic. Foam must be covered by something non-flammable.

I would only spray foam the rim joist area as it's near impossible to get that part well sealed with a barrier.

2. Vapor barrier with batts against the wall doesn't perform well in basements. The barrier traps the moisture in the wall assembly, reducing r-value and increasing risk of rot.

Vapor barriers only work well above grade due to drying potential to the outside.

If you have wall framing all around, remove the existing batt insulation.

Put 2" of rigid foam or roxul board directly on the wall to provide a thermal break. The thermal break stops thermal bridging to the studs and also stops condensation from forming.

Rigid foam has a higher r-value than roxul board. Both are unaffected by moisture.

Put roxul batt insulation between the studs, and only if required by the auditor/codes, put a vapor barrier on loosely.

The barrier is not needed when there's a thermal break.

Your gross r-value will be R-24 with foam and a bit lower with roxul board.

Insulate the rim joist area with rigid or spray foam. Cover that insulation with cut roxul batt to comply with codes re: exposed foam.

 

[Nealtw]

I find it interesting when people do a poor job of applying insulation and VB and see mold they quickly come to the conclusion that the VB was at fault.

Isn't it odd that when done properly there is no problem.



If you allow warm moist air to get to a cold surface it will deposit moisture and dirt and you have everything for mold.



If you allow cold to spread to the back of a drywall with a poor insulation job, it becomes a cold surface and will grow mold on the room side. With or without VB.

 

[user_12345a]

There is no such thing as a perfect plastic vapour barrier.

They work fine above-grade when you have drying potential.

Basements have moist soil so the wall doesn't dry out.

There's moisture both from the house and from the foundation.

A basement vapor barrier traps moisture in the wall assembly.

It's a fundamentally flawed way to insulate a foundation below grade and nothing can change that.

If the barrier is done very well and it's a newer house with good damp/water proofing, a wood wall may not rot out.

At best, r-value is reduced due to moisture trapped.

A continuous layer of rigid insulation right on the foundation works best. Eliminates the condensation risk as long as the r-value is high enough to keep the exposed surface above indoor dewpoint.

If batt insulation is used in addition to rigid, the greater the r-value of the batts is, the greater the r-value the layer of rigid insulation must be to stay above dewpoint.

To be clear, a thermal break is a must when using batts without a vapour barrier below grade in a basement.

An r-8 2" rigid roxul board wall in a basement without batts will out-perform R20 fiberglass/vapour barrier in the real world any day!

The batts are tested 100% dry in a lab with zero air movement.

Unfortunately there are out of date codes to work around.

 

[Nealtw]

There is no such thing as a perfect plastic vapour barrier.

They work fine above-grade when you have drying potential.

Basements have moist soil so the wall doesn't dry out.

There's moisture both from the house and from the foundation.

A basement vapor barrier traps moisture in the wall assembly.

It's a fundamentally flawed way to insulate a foundation below grade and nothing can change that.

If the barrier is done very well and it's a newer house with good damp/water proofing, a wood wall may not rot out.

At best, r-value is reduced due to moisture trapped.

A continuous layer of rigid insulation right on the foundation works best. Eliminates the condensation risk as long as the r-value is high enough to keep the exposed surface above indoor dewpoint.

If batt insulation is used in addition to rigid, the greater the r-value of the batts is, the greater the r-value the layer of rigid insulation must be to stay above dewpoint.

To be clear, a thermal break is a must when using batts without a vapour barrier below grade in a basement.

An r-8 2" rigid roxul board wall in a basement without batts will out-perform R20 fiberglass/vapour barrier in the real world any day!

The batts are tested 100% dry in a lab with zero air movement.

Unfortunately there are out of date codes to work around.

99% of the houses I have built have basement with some most all below grade, they are all built with a plan for living space in the basement.

I live in one without a problem

I have only seen a few done with out fiberglass insulation.

 

[albertkao9]

New homes in ontario come with full height R20 basement insulation.

That being said...

1. Spray foam has great properties for basements, but is flammable and toxic. Foam must be covered by something non-flammable.

I would only spray foam the rim joist area as it's near impossible to get that part well sealed with a barrier.

2. Vapor barrier with batts against the wall doesn't perform well in basements. The barrier traps the moisture in the wall assembly, reducing r-value and increasing risk of rot.

Vapor barriers only work well above grade due to drying potential to the outside.

If you have wall framing all around, remove the existing batt insulation.

Put 2" of rigid foam or roxul board directly on the wall to provide a thermal break. The thermal break stops thermal bridging to the studs and also stops condensation from forming.

Rigid foam has a higher r-value than roxul board. Both are unaffected by moisture.

Put roxul batt insulation between the studs, and only if required by the auditor/codes, put a vapor barrier on loosely.

The barrier is not needed when there's a thermal break.

Your gross r-value will be R-24 with foam and a bit lower with roxul board.

Insulate the rim joist area with rigid or spray foam. Cover that insulation with cut roxul batt to comply with codes re: exposed foam.

My wall is 2x4, so it will be R-12, not R-20, right?

 

[user_12345a]

The pictures show a gap between the framing and the foundation's wall.

If you can, get rigid insulation behind the framing and put batts between the studs to get the r-value up, create a thermal break to stop condensation and reduce thermal bridging.

It may be hard to slide insulation behind the framing.

Roxul 2x4 insulation R-14.

Combined that with R8 to R10 of rigid insulation and get R-22 to R-24 gross and outstanding thermal performance.

 

[user_12345a]

99% of the houses I have built have basement with some most all below grade, they are all built with a plan for living space in the basement.

I live in one without a problem

I have only seen a few done with out fiberglass insulation.

BC climate is different than ontario's. With the exception of the coast, BC is dry.

If a house is well built from scratch, it will have better than normal water/damp proofing, so moisture coming from the foundation won't be as much as a problem.

30+ year old subdivision mass produced homes in ontario can have a lot of moisture coming into the basement from the foundation. The older the house, the worse it is.

You can insulate in a way that is less than ideal and not have major issues, but the r-value is still diminished.

Fiberglass plus vapor barrier simply sucks for basements. You don't get anywhere near the stated r-value once moisture gets in the wall assembly.

You can have a thermal break with sufficient r-value to stop any condensation and use fiberglass or roxul batt without a vapor barrier.

I think building science courses should be mandatory for general contractors/carpenters/code enforcers/hvac guys to maintain certification - the way things are now people justify poor practices simply because they worked before and never learn.

 

[albertkao9]

The pictures show a gap between the framing and the foundation's wall.

If you can, get rigid insulation behind the framing and put batts between the studs to get the r-value up, create a thermal break to stop condensation and reduce thermal bridging.

It may be hard to slide insulation behind the framing.

Roxul 2x4 insulation R-14.

Combined that with R8 to R10 of rigid insulation and get R-22 to R-24 gross and outstanding thermal performance.

Would you mind suggesting a Youtube video to do this?

 

[user_12345a]

Won't be any videos of sliding rigid insulation under framing. You have to assess what you have and see if it's practical.

It won't be easy - may need to remove studs and reinstall, particularly if you use foam.

The gap between the frame and foundation may not even be large enough to provide a good thermal break.


Roxul board gets fastened:

The video shows installing a vapour barrier to comply with code. See my previous comments about that.

Foam gets glued with special adhesive.