How To Insulate A Skylight | Do It Yourself

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How To Insulate Skylights

Oscar P. from Provo, UT wrote:

Hey Itchy,

I was in my attic yesterday and I noticed that both of my skylights don't have any insulation. Isn't this required? How do I go about insulating a skylight?

I've seen this many times, even with new construction where the insulators didn't bother insulating the skylight. This is a little tricky as you're going to have to insulate it without disturbing the existing insulation. You'll need a ladder, tape measure, drop light, utility knife, staple gun, staples, 23" wide R-19 kraft (paper) faced insulation batts and some twine.

Skylights come in many sizes. You'll need to measure the skylight for insulation. Measure the width and height of one side and multiply both figures to obtain the square footage.

Do the same for each side and add the square footages to come up with the total amount of insulation needed. You don't have to get into that attic to do this. Get on the ladder and measure it from inside your home.

Grab a dust mask and put on protective clothing and get on into the attic. You want to start at the bottom of the skylight. If it already has insulation, such as loose fill around it don't worry about it - that portion of the skylight is already insulated.

Start on one side of the skylight and staple the batt to it, with the kraft paper faced side towards the drywall. This is done by stapling it through the paper flanges directly to the skylight wood framing and wrapping it around the skylight, stapling as you go. Don't try stapling directly to the drywall! I've done that and well, let's not talk about that one... Anyway, you will have to make some cuts at the studs in areas where the fiberglass batt won't wrap completely around the skylight. Unfortunately, insulation manufacturers don't make insulation batts in custom sizes for skylights. It's kind of a mix and match situation. Just make sure each piece of insulation is secured at both ends by stapling it into the wood framing. Continue with this process until all of the sides of the skylight are insulated.

Make sure there aren't any gaps by stuffing scrap pieces of insulation into those areas.

Hint: I've said this before but I'll say it again. The easiest way to make a cut in a kraft faced fiberglass batt is through the insulation with the paper side against a 2X4 or plywood... if you try cutting it through the paper side you will just end up tearing it. Make sure your utility knife has a fresh blade before you begin.

Okay, you have the insulation installed to the skylight. The next step is to secure it with the twine as through the years those staples won't do the trick. Simply start at the top and start wrapping the twine around the skylight in a downward spiral fashion every six to eight inches and secure it to the bottom. Make sure you don't wrap it too tight - just snug or otherwise the insulation will lose some of it's r-value if compressed too much.

Related Tips and Advice:

How to Insulate an attic with blown in insulation.
How much insulation do I need?
How to soundproof a wall with fiberglass insulation.
How to insulate ducts.
How to seal air leaks in your home.

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