I wouldn t worry much about not having a square foot of insulation here and there.
Insulation around flue pipe.
Remove the insulation between the joists where the flue is located to clear an area about 18 inches away from the flue on each side.
Probably a less heat loss than a window.
It was covered with blown in insulation.
Compress the insulation around the rigid liner by hand until the two edges snap and lock together.
I have a fireplace insert in my basement.
Rigid insulation increases the outside diameter of the liner pipe by 1 75.
Always use fire resistant caulking.
Because the pipe gets hot building codes usually require 1 inch of clearance from metal flues 2 inches from masonry chimneys to any combustible material including insulation.
It had about a 5 rise from the furnace to the charred area in the attic.
I don t know about a dryer vent but for most heaters and woodstoves it is not allowed.
The pipe comes out of the wall into the garage and up to the roof.
Most code jurisdictions require the stove pipe be routed through a thimble to provide a safe distance from combustible materials.
The opening around a furnace or water heater flue or chimney can be a major source of warm air moving in the attic.
Air traveling over the surface of the flue pipe may be required to keep it safe and cool.
Cut enough aluminum flashing from the roll to wrap around the vent pipe with an extra 6 inches to spare.
In this case the b vent was also dented on the side so i know the airspace around the double wall pipe was compromised.
You worry for good reason.
The gas furnace was in a garage and the flue pipe went up through the above attic.
Apply a thick bead of high temperature caulk the flue on one side.
I have added a picture.
You should never have insulation in contact with a wood stove flue pipe.
Available in 24 lengths.
This makes it an ideal insulation material for use in areas that experience high temperatures.
As such it can be used to insulate a chimney.
I was thinking of doing some better framing around it and maybe use rigid foam insulation but i read that building code requires a 2 gap around.
Do not use spray foam for any of the joints near a vent pipe.
Now you must form an insulation dam to prevent insulation from contacting the flue pipe.
Unless the manufacturer says you can pack insulation around the pipe don t.
It is often installed in gaps around the chimney and flue to prevent airflow that can siphon the heat away from the interior of the building.
However the better method for filling voids in a chimney flue liner to the full height of the flue is to use vermiculite chips can be bought for insulation purposes or as soil treatment check around for best prices.
