New construction insulation
1 - 9 of 9 Posts
Joined
·
3,483 Posts
blown in insulation has the same r-value as fibreglass batts. rigid foam typically has a r-5 value for every inch thick but can vary on what type of foam your using.. spray foam has a rating of r-7 and will fill all voids and get into all the odd spots when it expands however it is 3x more expensive..
locally open cell spray foam runs about $3.75/ sq ft installed, where closed cell foam which has the r-7 rating is 4.50/sq ft
locally open cell spray foam runs about $3.75/ sq ft installed, where closed cell foam which has the r-7 rating is 4.50/sq ft
Joined
·
53 Posts
yes but i think the spray foam is the best and will provide good result. yes it`s a bit costly but every thing good thing is costly.
If you can afford it, spray foam (closed cell) is the best. It closes all gaps, is a vapor barrier, and has higher r value. It costs an arm and a leg, and also can be applied sloppily. Open cell is cheaper but doesn't justify its cost.
For a diy, the most important thing to keep in mind is stopping the movement of air. Air disturbs the insulating quality and brings in moisture that may get trapped in the wall cavity.
(Air can dry out the materials, too, but it is better to compromise on the side of dead air movement and making sure there is no bulk moist vapor/water moving in. Rain and leak/condensation in the plumbing.)
Blown in cellulose is not really diy. Cellulose will settle in the wall, so it needs an experienced hand that can feel for the pressures in the hose for enough fibers in the wall that compensates for the settlement.
Fiberglass is only diy material in realistic sense. But it does nothing for the air movement. Stuffing it in is self defeating since you lose the r value. Since I am diy, what I do is this. I look at each stud bay and how the bay connects to ceiling and floor bays. Usually there are ceiling and floor plates that act as air barrier. But all lumber contact points, holes, cracks in lumber, etc, are open doors for the air movement. I use either cheaper caulk (Dap contractor pack) or spray can foam to close all joints in a given stud bay. I press in caulk along the sheathing joints. Then install fiberglass, vapor barrier and seal all opening in the sheetrock. In older houses with board sheathing, I'd use a sheet of 1/2 closed cell panel and seal the joint with spray can foam, then put in fiberglass.
For a diy, the most important thing to keep in mind is stopping the movement of air. Air disturbs the insulating quality and brings in moisture that may get trapped in the wall cavity.
(Air can dry out the materials, too, but it is better to compromise on the side of dead air movement and making sure there is no bulk moist vapor/water moving in. Rain and leak/condensation in the plumbing.)
Blown in cellulose is not really diy. Cellulose will settle in the wall, so it needs an experienced hand that can feel for the pressures in the hose for enough fibers in the wall that compensates for the settlement.
Fiberglass is only diy material in realistic sense. But it does nothing for the air movement. Stuffing it in is self defeating since you lose the r value. Since I am diy, what I do is this. I look at each stud bay and how the bay connects to ceiling and floor bays. Usually there are ceiling and floor plates that act as air barrier. But all lumber contact points, holes, cracks in lumber, etc, are open doors for the air movement. I use either cheaper caulk (Dap contractor pack) or spray can foam to close all joints in a given stud bay. I press in caulk along the sheathing joints. Then install fiberglass, vapor barrier and seal all opening in the sheetrock. In older houses with board sheathing, I'd use a sheet of 1/2 closed cell panel and seal the joint with spray can foam, then put in fiberglass.
Joined
·
43 Posts
It is more cost-effective to add insulation during construction. Know the R values properly before insulation.
Joined
·
3,483 Posts
if you read my post i basically state that without saying it by providing actual data
Joined
·
12 Posts
I do prefer to use blown in cellulose after sealing off top plates and penetrations, etc with spray foam and ensuring that the baffles are installed (correctly). However, I am also a big fan of spray foam and yes, it does cost more. However, if people could spend money on installing two new high efficiency units placed into an unconditioned attic (oven), with leaky duct connections, then they should be able to afford to have spray foam on the underside of the roof, moving the envelope.
1 - 9 of 9 Posts
