They make 4 wide blanket sized insulation for this.
Insulation around brick chimney in attic.
Once you ve decided which type is best for you examine the material options and prices to home in on the right product.
Seal between the chimney and the framing with fireblock foam or caulk to prevent exterior air from coming in and then put 3 of roxul directly against the chimney brick.
Insulating your crawl space walls with at least an r 19 or r 21 will go a long way.
If there is a straight open space accessible from above you might consider polyisocyanurate foam insulation.
It is an effective barrier to the passage of heat.
You will probably have to look somewhere besides the big box stores for this.
It may be easier to use rigid foam insulation than.
Fiberglass is one of the most commonly used materials for insulating the home.
A 2 inch board has r 13 insulation.
Fiberglass insulation is commonly used in attics around the chimney stack.
Go with a full aluminum sheath right against the chimney to serve as the air barrier and then fill in behind it with roxul or 2.
In either cse it fills the required open air space around the b vent in the un conditioned attic space.
I think i ll either.
The opening around a furnace or water heater lue or chimney can be a major source of warm air moving in the attic.
Both can be added to uninsulated attics or layered over existing material.
Spun fiberglass insulation is like a sponge as far as its ability to collect and hold significant volume of water.
Loose fill or batt the common term for blanket insulation.
Because the pipe gets hot building codes usually require 1 inch of clearance from metal lues 2 inches from masonry chimneys to any combustible material including insulation.
The b vent system requires air space clearance as well as clearance from combustibles.
For diy attic insulation you ve got two choices.