About 54 percent of St. Albert homes were built before 1991 - the highest share of any city on this list. A mature stock is a genuine retrofit market, and retrofit work has an order to it. Doing the steps out of sequence is how people spend a lot and feel very little. Residential spray foam insulation in St. Albert is a genuine retrofit market, and retrofit has an order to it.
Step one: find out what the assembly actually is
Houses of this age rarely match their drawings. Before anything is specified, somebody should open a small area and look - at whether there is a polyethylene vapour barrier and what condition it is in, at what the rim joist has in it, and at how the attic ceiling plane was built. A quote produced without that is a starting position rather than a price.
Step two: deal with the vapour barrier question
This is the decision that distinguishes a considered retrofit from a sprayed one. Older assemblies were built around a poly sheet doing the vapour control. Closed-cell becomes a vapour retarder in its own right at about 38 mm under Alberta section 9.25, so there is a real choice about whether the poly is removed, left, or worked around - and getting it wrong can trap moisture inside the assembly instead of keeping it out. Ask any contractor what they intend to do with it. The answer tells you how much thought has gone in.
Step three: seal before you deepen
Rim joist first, attic ceiling plane second. Both are small areas that leak continuously, both are cheap relative to their effect, and both must be done before extra attic depth is worth buying.
Step four: below grade
Basement walls, against the concrete, closed-cell - two inches for roughly R-12 to R-14, three to four inches for R-18 to R-28 where the framing allows. Moisture resistance is the reason, not the R-value.
Step five: depth, and now the cheaper product usually wins
Once the air path is closed, R-38 in the attic is about six inches of closed-cell or eleven of open-cell. Where headroom exists the cheaper material reaching the same number is the better buy.
The thing that will not wait
Foam facing occupied space needs a thermal barrier over it - 12.7 mm drywall or an approved intumescent coating. On a basement that will be finished later, build that into the plan now.
What a retrofit disturbs
Work in an occupied older house is more intrusive than in an empty new one, and it is better to know that in advance. Removing old batts and a failed vapour barrier makes dust, the work area has to be cleared and ventilated while the foam cures, and the installer will give a re-occupancy time before leaving. On a phased retrofit, doing one zone at a time keeps the house usable throughout, which is usually worth more to people living there than finishing a week sooner.
Residential Spray Foam Insulation St. Albert: Common Questions
What order should a retrofit go in? Find out what the assembly actually is, decide what happens to the existing vapour barrier, seal the rim joist and ceiling plane, then below grade, and depth last.
Why is the vapour barrier decision so important? Because getting it wrong traps moisture inside the assembly instead of keeping it out. Closed cell is a vapour retarder in its own right at about 38 mm, so there is a real choice to make.
Is the disruption manageable? Phasing it one zone at a time keeps the house usable, which is usually worth more to people living there than finishing a week sooner.
Sequence it with the spray foam calculator, see how prep drives the price, or get a free St. Albert quote.