Insulating Knee Walls | Making Finished Attics Energy Efficient in Cleveland
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- เผยแพร่เมื่อ 28 ก.ย. 2024
- www.drenergysav... | 1-888-225-6260
Knee walls are usually present in finished attics. The sloped roof creates a small space that can hardly be used for anything other than storage or, in some cases, to house air ducts.
So when finishing the attic, builders usually build a small, finished wall to close that space, many times with small doors to allow access for storage, sometimes with no access at all.
The problem with knee walls is that, for the most part, the space behind them remains unconditioned and the knee walls themselves are often poorly insulated.
The soffit vents, built to keep the roof cool, allow a lot of air in the space year round.
During the summer, that compartment can reach scorching temperatures, and because it is improperly insulated and air sealed, that heat will be transferred to the adjacent room through walls and floor and to the rooms below through the ceiling.
Larry Janesky from Dr. Energy Saver, proposes a different approach to knee wall insulation. The knee wall system developed by Dr. Energy Saver includes that small space into the building envelope, while preserving roof ventilation. SilverGlo, a special type of rigid foam board lined with radiant foil on both sides, is attached to the bottom of the rafters with special fasteners. The seams are then sealed with spray foam to prevent air leakages. The idea is to keep the temperature in the compartment behind the knee wall, as close as possible as the temperature in the adjacent rooms.
The SilverGlo foam is infused with graphite for higher R-Value, and the foil liner will reflect heat back into the room during the winter and back to the outside during the summer.
For more information on the SilverGlo attic and knee wall insulation system and for tips on how to save a lot of energy and money visit our website or call us for a comprehensive home energy audit!
Air is not hot air entering in the summer. The soffit vents are for the air to come in at the lower end, the soffits and should be guided with baffles up the underside of the roof decking to cool it off because it gets very hot from being in the sun.
Very informative but one question what about gable ends?
You guys mentioned the ventilation problem and how you get the mold. How do you ventilate with your insulation at the roofline? I have gable vents and I was planing on installing a gable fan and insulate on the knee walls
We would like to finish our attic but there are nails everywhere between the rafters. I can't see how I can add baffling to keep the air flow with how long the nails are...
How do you handle the knee wall when there are not any soffit vents. ? Thx
ken peffley. I knocked out several blocks down the side and installed vents. Also put in 2 roof turbine. Made it about 30 degrees cooler. There has to be airflow in the summer.
damn cape cod homes. as a kid, my bedroom was a room like that. froze in the winter.
Do you recommend creating an access door (DIY?) or sealing back up with drywall? Would I cut access before a Dr. Energy Saver inspection? I have a 5 1/2 ft 'knee' wall. I wish the wall was pushed back farther but it is probably defined by the roof truss structure.
While putting in shelf hangers, discovered wide area with 'missing' wall stud -- maybe a planned access point that was never realized.
So hot in summer I suspect builder blocked air flow to vent with insulation batts.
great camera work
What about your saffet vents?
where did they go? you have insulation from the foam to the roof? no air travels from saffett to ridge vent at the top? I have this exact problem and only asking question craving answers...thank you
They use baffles above the hard foam insulation. That way you have great airflow from the soffit to the peak vents.
Why newer homes not have sprayfoam insulation going green saves 🤑