Insulation in attic

[mass_burner]

Okay, I'm addressing some critters that got into our attic and I notice there is insulation (pink stuff) between the ceiling joists AND between the roof joists. Isn't this redundant?

Also, when we put on a new roof 7 years ago, we had ridge vents put in. Does this eliminate the need for gable end vents?

 

[Highbeam]

Okay, I'm addressing some critters that got into our attic and I notice there is insulation (pink stuff) between the ceiling joists AND between the roof joists. Isn't this redundant?

Also, when we put on a new roof 7 years ago, we had ridge vents put in. Does this eliminate the need for gable end vents?

Ridge vents at the top, that great. You need something at the bottom, usually soffit vents to allow cooler air in which will then flow along the roof and out through the ridge vent. Do you have soffit ventilation letting air in?

 

[kennyp2339]

Take the insulation out that runs along your roof joists, a roof should either be a warm roof (whole attic is insulated) or a cold roof (attic is not insulated) since you have a ridge vent your roof should be a cold roof. As highbeam indicated you should also have soffit vents, if the insulation along your ceiling joists is deep your going to have to install soffit sleeves (attic rafter vents) inside the roof so you get an unimpeded air flow along the roof, this will help prevent ice dams by keeping the plywood the same temp as the outside and allow the insulation to lay and cover the ceiling completely end to end.

 

[mass_burner]

Take the insulation out that runs along your roof joists, a roof should either be a warm roof (whole attic is insulated) or a cold roof (attic is not insulated) since you have a ridge vent your roof should be a cold roof. As highbeam indicated you should also have soffit vents, if the insulation along your ceiling joists is deep your going to have to install soffit sleeves (attic rafter vents) inside the roof so you get an unimpeded air flow along the roof, this will help prevent ice dams by keeping the plywood the same temp as the outside and allow the insulation to lay and cover the ceiling completely end to end.

Thanks, I'm not sure there are soffit vents, I'll check next time I'm there.

Ceiling insulation is an old, almost flat layer of yellow with foil and 6" of pink stuff. Ceiling joists are 6", it's a small room.

 

[jharkin]

Also, when we put on a new roof 7 years ago, we had ridge vents put in. Does this eliminate the need for gable end vents?

What you want is for the ventilation air to flow from the soffit up to the ridge. If you have ridge vents and gable end this airflow gets short circuited and you can have a stagnant airmass up there. Make sure soffit vents exist and if not add them. Once that's done eliminate the gable vents.

BTW, the roof framing members are called rafters. And yes you only want the roof deck OR the attic floor insulated, not both. Unless you want to finish it as living space keep the floor insulation and rip out the roof deck insulation. And make sure that attic floor is air sealed well.

 

[mass_burner]

What you want is for the ventilation air to flow from the soffit up to the ridge. If you have ridge vents and gable end this airflow gets short circuited and you can have a stagnant airmass up there. Make sure soffit vents exist and if not add them. Once that's done eliminate the gable vents.

BTW, the roof framing members are called rafters. And yes you only want the roof deck OR the attic floor insulated, not both. Unless you want to finish it as living space keep the floor insulation and rip out the roof deck insulation. And make sure that attic floor is air sealed well.

Thanks, that confirms what I thought. Are there guidelines for size/amount of soffit vents.

 

[jharkin]

I know the code has formulas for it, but dont know off the top of my head.

There is a good book that covers all aspects of insulation that's worth a read:

http://www.amazon.com/dp/1600854680/?tag=hearthamazon-20

 

[lml999]

Thanks, that confirms what I thought. Are there guidelines for size/amount of soffit vents.

As much as possible. Best approach is a continuous opening along the soffit...

BTW, check with Mass Save to see if they will do an energy audit for you (if you haven't done so already). We had ours done this morning, and have a long list of stuff to do, partially underwritten by the power company. Top plate sealing, blown in cellulose insulation (on top of existing fiberglass), ventilation fan rerouting, etc. $4K of work for $900...not bad...