After I completely gutted the attic, I had a blank slate. My primary concern was to ensure the attic had proper insulation and ventilation. Installing collar ties was a necessary step.
Basic Attic Structure
This diagram shows the basic structure of a finished attic in a 1½ story house.
The vertical studs are what is commonly referred to as the knee wall. The knee wall meets with the slope of the roof which creates a cathedral type sloped ceiling. The space on the other side of the knee wall is the side attic. The diagram also illustrates the use of styrofoam insulation which is an idea from Jon Eakes’ website which I incorporated into my own renovation. More on that later.
Installing Collar Ties
I installed some collar ties so I could insulate the ceiling while leaving an air space at the top of the attic for ventilation. The ties allow for a drywall ceiling and add strength to the roof structure.
I temporarily attached a couple of 2x4s to the rafters and made sure they were level to each other and along their lengths. Next, I cut 2x6s and installed them by resting them on the 2x4s and screwing them to the rafters. After that, I could remove the temporary supports.
The 2x6s allow for R-20 insulation. Extruded polystyrene boards sandwiched between the collars and drywall will provide an additional R-5 as well as a thermal break. I was advised against adding another layer of insulation above the collar ties as the resulting air space would be inadequate. While R-25 isn’t ideal, it far exceeds what was there before.
If I had to do it over again, I would install the collar ties lower to allow for the extra layer of ceiling insulation and I would use thicker foam board insulation. We have found the second floor temperatures in the summer to be about three degrees (Fahrenheit) warmer than the main floor.
Encapsulating minor fire damage
Before tackling the collar ties, I had to take care of a small surprise that came to light when I gutted the attic. At one time, there had been a fire in the side attic of the smaller bedroom. And while you might expect the previous owner to disclose this sort of thing, we have no disclosure laws here. The fire damage is obvious in these pictures, and fortunately was limited to only the surface of the timber.
I painted over the fire damage with Zinsser Bin spray primer which supposedly helps to encapsulate any odor. This step may not have been necessary since the damaged wood will be sealed behind vapour barrier (plus there was no detectable odor before) but this preventative measure required minimal investment of time or money.
- The Attic Tour
- Installing collar ties
- Removing the chimney
- Adding the dormer
- Wiring for the future
- Dryall and mud
- Lighting and heating
- The finished product