insulating walls against roof line
dreadlock
| Posted in Energy, Heating & Insulation on
Insulating walls and ceiling against roofline and installing ventilation rafter mates on angled ceiling in attic and some parts of built ins. Rafters are odd size spacing, do the vents have to span from rafter to rafter being that our house was built in 1832 and the roof sheathing is strips of oak spaced at least 1 inch apart, perpindicular to the rafters? If i ran one single vent up the middle for ventilation will the spacing on the sheathing compensate from customizing 2 vents side by side to span between the rafters completley? Are the vents even neccessary and if so, is it overkill to go from rafter to rafter, hence doubling time and cost to install styrofoam vents?
Replies
Greetings d,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
94969.19
In the beginning there was Breaktime...
94969.1 Photo Gallery Table of Contents
The answer is
It Depends.
vent capacity soffit to ridge needs to be sized and balanced and provide enough venting to carry excess moisture from the space.
There are ways to do unvented insulation situations too. There are probably a couple dozen or more variables.
One option is instead of using those premade for 16" oc or 24" oc, make your own by ripping foam board and get some insulation value out of the effort
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Rafters are odd size spacing, do the vents have to span from rafter to rafter being that our house was built in 1832 and the roof sheathing is strips of oak spaced at least 1 inch apart, perpindicular to the rafters?
The space in between the sheathing boards does not account for much, if any, venting.
I'm Piffen here. 1/2" foam board is cheaper /sq.ft. thatn the styrofoam channels. It is easily cut and can be friction fit or foamed glued into place fairly easy.
If you are adding insulation to the attic be sure to get the vent chutes to the outer edge of the outside walls and fold it down to meet it if possible. If not add f/g batts or foam beneath the chutes to act as baffels and keep your blown in insulation from spilling into the outside soffets.
It is also a good time to air seal all penetrations from pipes, wires.light fixtures, etc. in the attic. That will improve you overall perfomance as much as the additional insulation.