The Difference Between Nominal Insulation And Effective Insulation

For as long as I can remember we have talked about the R value of the walls and ceiling inside residential homes. Decades later we still discuss R value with people because that's what they understand when you are talking about the insulation that goes in the walls and ceilings of homes. Even the building code in Ontario only talked about R value when making the minimum limits for insulation in homes.

Well as the building code is going through an ever changing climb with regard to the rules that govern insulation levels and the air tightness of homes everyone needs to start talking a different way.

Contractors who understand this are now starting to talk to people in a different way, instead of talking about R value of the walls we are now trying to talk to people about effective R value. The old way of talking about R value in walls is considered Nominal R value. Nominal R value refers to the labels or rates that are given to the insulation that you install in the walls or ceilings.

Effective R values are different they take into consideration the thermal bridging that is in the walls, thermal bridging in walls and ceilings are usually the wood framing that creates paths were the air can move through the wall because there is no insulation to stop it.

Now you know the difference but as the homeowner how does this actually affect you and your home? Well if we take the 2016 Ontario building code it stats that your exterior wood framed walls are to have a nominal R value of R-24. That can be achieved by simply installing a r-24 fibreglass batt inside the 2x6 wall cavity. But it you look at that same walls effective R value it is actually down around R-17, that's because of all the thermal bridging that is in the wall cavity from the wood studs.

The 2017 Ontario building code has the same R-value for the exterior walls but they have made one big change and that is that you must have continuous insulation placed on the outside of the wall that is made of polystyrene insulation if you are looking to install the minimum building code. This continuous insulation layer covers all the thermal bridging in the wall effectively insulating the entire wall. You can expect that the R-value of the wall should be what you want it to be, if you are trying to achieve R-24 then with a continuous insulation layer that's what you would end up with an effective R value of R-24.

Effective R values are a more effective way to achieve homes that are sealed against the outside elements, helping reduce the heating and cooling costs and stop wind wash from affecting the inside temperature of the home.

So the next time you talk about R values with your contractor or if you are a contractor then you should be talking about the effective R value and not just the nominal R value. It might take a little educating on your part but it will be worth it in the end.

Rob Abbott
Village Builders Inc.

Insulation should be upgraded when planning your custom home

When you are planning to build a custom home there will be many questions you will need to answer about what kind of home you want to build, one of those questions is how much insulation do you want to install in the walls of your new home?

To answer that question you need to figure out some numbers, those numbers will have to come from your general contractor.

When you raise the amount of insulation in the walls of the home it raises the cost of the overall insulation in the home. The more insulation the higher the R-value in the home.

When insulation is increased in the home the amount of energy it requires to heat and cool the home decreases. The less energy it requires the more money that you save on your heating and cooling bills for the lifetime of the home.

When you are planning to add insulation to your home to the point that it will be constructed above the minimum insulation code requirements you then will have the ability to decrease the size of your heating and cooling system. Doing this will save you money on the cost of the overall heating system upon installation.

The calculation that you have to work out with your general contractor is the point where the adding of insulation stops saving you enough money to be cost effective.

To help figure that point out you take the cost of the extra insulation and deduct the costs that you believe it will save you in energy and then add the cost savings of the reduced size of the heating system.

The point toward where you want to get too is where you have $1.00 to $1.00 insulation installation to overall savings.

You don’t have to stop when you reach that threshold, you can add more insulation over that point if you take into consideration that energy in the future will only be going up, this will increase the amount of savings the farther into the future you calculate the numbers.

The great thing about insulation is that it never wears out; it never goes away and will always be in the walls. That means that in the future when you decide to sell the home the extra insulation becomes a bonus to any perspective homebuyer and should help the resale value of your home.

The optimum wall insulation for a highly insulated home is R-40, if you want to super insulate your homes walls you should be aiming for R-60. These values are double or triple the minimum code requirements in the building codes that are currently enforced today.

Remember when planning to build a new home you should be spending more time thinking about the insulation then you ever did before. These choices could end up costing you money well into your future if you don’t decide on the proper level of insulation, but choose appropriately and it could save you a lot more money than the extra added monies to your mortgage.

Rob Abbott
Village Builders Inc.