In the last two posts we discussed the importance of doing an energy audit. By using a blower door machine we can locate hard to find cold air infiltration points. I also mentioned using small spray foam cans to seal up those nasty little leaks. We also touched upon insulating foundations and beefing up the insulation level in your roof cap or attic.
In this issue I want to discuss the exciting science of infra red cameras and the issues of wall insulation.
Insulating a crawl space, cellar or attic is relatively straight forward .You can see what insulation is present or not. Walls are another matter. For older homes the question could be what is really in that wall cavity? When you bought your old & charming classic, the features section that listed insulation might have stated “Unknown”! Or perhaps you have a newer home that has fiberglass insulation. Yet, that was done 30 years ago and how effective is it really? Fiberglass has a predictable habit of settling and succumbing to nesting material for rodents. If fiberglass gets wet, it loses it “loft” and ability to restrict heat flow out of your home. I’ve seen countless opened wall systems where over the parade of years fiberglass insulation is reduced down to about a fourth of its original thickness due to improper installation and excessive airflow across it. This wall section ends up being a major energy leech and impacts on the comfort level of your home.
Enter the infra red camera. This little gem allows you to almost see into the walls by revealing apparent temperature differences on the wall surfaces. Images can be gleaned from the exterior and interior. Often times you can see framing members and even hidden fasteners. More importantly you can decipher insulation voids and even locate the sources of troublesome water leaks. The blower door machine identifies air infiltration. A wall could be tight but it could be poorly insulated! The infra red camera helps to dispense with the guess work. You can use this valuable information to tackle any insulation retrofit moves that your building might be seriously in need of.
Walls can receive blown in cellulose insulation with minimal impact on the structure. This is best done by a professional. Cellulose does not contain formaldehyde binders like fiberglass. It’s solid content is recycled newspapers and is treated with borate derivatives for fire retardation and pest control. It is also a great sound deadener and does very little settling when blown into wall sections when applied under the proper pressure. However, it can be a hit or miss venture because framing members like blocking or wind bracing can block the wall cavities from being properly filled. An infrared camera can assist with this application as well.
More radical moves would be to remove exterior wall siding, sheathing, or interior finishes and remove all existing insulation. At this point sprayed in closed-cell foam insulation could be your most cost effective solution. Again, done by a professional. This type of insulation has the highest R value on the market; controls vapor transmission and gives incredible structural stability to framing members.
Foil faced polyisocyanate boards can be used as well to effectively reduce thermal bridging. In other words heat loss by conduction through the wall studs. It also lends itself as a sound deadener and an effective vapor barrier. Do you put it on the interior or exterior? Depends, because you don’t want to create condensation problems inside your wall cavities by getting it wrong! Bad News!
If existing fiberglass or cellulose insulation is to be maintained, apply these foil faced boards on the interior under your interior finish. They will prevent vapor transmission into the wall and prevent internal condensation from developing inside the wall cavity. If there is latent moisture within the wall cavity it should be allowed to breathe out through the sheathing and siding. You can put this foil faced insulation on the exterior but you have to be very careful. There needs to be either a very tight vapor barrier on the interior or the insulation like closed cell foam does not allow vapor transmission through it anyway. The dew point, where moisture would condense, occurs within a material that has no moisture present anyway.
There are other issues to consider as well. Has there been any water damage to the buildings wall components? Have mice or squirrels set up their own tunneled transit system. Could the walls benefit from an electrical wiring upgrade. Is the exterior siding in need of replacement anyway! These last scenarios come more into the area of a major energy retro fit. The budget will get the final say but think of it this way. Pay now or pay more later.
Insulating your homes envelope to reduce the burdensome heating bill is a noble cause. It saves you money in the long run, has the immediate “Payback” of increased living comfort and not to forget, reduces our overall carbon footprint upon our precious planet.
Inevitably, when a conversation about insulation is underway, the arguments of creating the “Too Tight” home arise. Next issue we will discuss the complicated arena of the healthy home and controlled ventilation.