Embracing insulating concrete forms

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This article was published 21/03/2015 (3825 days ago), so information in it may no longer be current.

Home renovations often include large additions or finished basements. Many people are telling their contractor to build their basement, and even the upstairs walls, with insulating concrete forms (ICF), which exceed R-values recommended by the Manitoba Building Code.

“The present code requires a minimum R-20 insulation in a finished concrete basement. ICF walls can more than double that value,” said Conrad Hoeppner, territory manager with Logix ICF Technologies.

Abe Warkentin lives in a house in southern Manitoba with basement walls built of ICF.

“The difference between ICF walls and traditional concrete ones insulated with fibreglass is remarkable,” said Warketin, who has lived in homes with both types of basements.

He said fibreglass or rock wool (Roxul) are inappropriate for insulating concrete because warm air that leaks behind the insulation condenses on the cold concrete wall, forming moisture that freezes in winter and melts in warmer months. The result is water that runs down the walls and puddles at the bottom.

“Wherever you have moisture, you have a problem with rot and mould, which feeds on wood structural members,” said Warkentin.

Because of air leaks, the basement never feels comfortable, remaining cool and drafty with a musty smell that increases as moisture continues to form on the walls, he said.

When he moved into a new home with an ICF basement, Warkentin said he couldn’t believe the difference.

“It was dry, comfortable, and the walls felt warm to the touch. It didn’t have a musty smell and was very easy to heat,” he said.

He became a huge fan of ICF construction, and has plans to build a smaller home (the kids have grown up) built of ICF from basement to roof.

“It’s surprising how many houses in areas like Morden, Winkler, Brandon and Steinbach have ICF basements,” said Hoeppner. “People living south of the Trans-Canada seem to be ahead of the rest of us when it comes to embracing foam technology.”

ICF products available in Manitoba include Smart Block, Logix, Fox Blocks and Integra Spec Canada.

The Home Depot in Winnipeg sells Smart Block, and Home Hardware stores in Manitoba sell Fox Blocks.

Most ICFs are similar in that they consist of expanded polystyrene (EPS) blocks that can be fitted together by anyone who has built something out of Lego. The basic idea is to create outside and inside walls, with the stackable blocks held together by ties. A gap between the EPS walls is filled with concrete.

The rigid blocks are available in a number of lengths and heights, depending on the manufacturer. A common size is 16 inches high by 48 inches long and 23/4 inches thick. As the blocks are assembled, engineered polymer ties with an open truss design to allow for proper concrete consolidation are placed approximately every eight inches. The ties hold the walls together, and rebar is added as required by code. The width of the concrete core can be adjusted in two-inch increments, from four inches to 12 inches.

Form configurations include straight walls, 45- and 90-degree corners, T-blocks, radius, taper and corbel ledge. Furring strips on inside and outside blocks allow drywall to be attached to interior walls and stucco or other exterior finishes to be added to above-grade outside elevations.

Below-grade exterior walls are wrapped with a waterproof membrane to prevent moisture moving through the concrete core. A standard six-mm vapour barrier covers the interior walls.

An advantage to EPS block systems is wood concrete forms do not have to be removed when the concrete is set, creating an undesirable mess at the building site.

Another advantage is curing concrete in a conventional basement in winter costs about $1,500 in gas or propane heat, compared with nothing for a similar ICF structure.

Though the price of installing a basement or constructing an entire addition out of ICF may seem expensive in relation to framed renovations, savings of up to 50 per cent on heating and cooling costs may actually reduce monthly payments.

“By choosing a better-insulated home, the monthly savings on utilities may match or exceed the added mortgage payment cost. In most cases, there is no payback period at all; you are simply diverting your financial responsibilities,” said Ted Cullen of QuickTherm. “For example, if you invest an additional $7,000 in insulating your building and the investment saves you $40 per month on utility bills, then based on a 25-year mortgage at three per cent, the additional monthly mortgage payment would be $33.19, a saving of $6.81 per month on overall costs.”

Another consideration is normal basements cost a lot of money to insulate and finish with studs, fibreglass, vapour barriers and drywall or other suitable materials. Even then, homeowners are faced with the likelihood their grottos will be damp, uncomfortable and perfect incubators for mould.

“People have lived in this northern climate for centuries. Heating has always been a challenge,” Warkentin said. “Why have our governments not helped people to build energy-efficient buildings? In the 1950s, every community was busy building California-style bungalows with two by four-inch walls and inadequate insulation. Today, we are building huge houses with 12-foot ceilings and heated garages. Why? Aren’t we aware of climate change yet? We could scrap Bipole III and a few other dams if the government would encourage energy-efficient buildings with ICF basements.”

It’s not too late to renovate with ICF products, which are becoming popular throughout the Great White North.

 

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