6 Tips for Insulating an Attic

Insulating the attic, or above the ceiling, is a bit more difficult than insulating walls but done right everything will go smoothly. Here are a few hard learned tips...

1) Cover up - Protect Yourself
Be safe! We covered this in a previous post (see it here).

2) Use Lots of Staples
The weight of the insulation is supported by the vapour barrier until the drywall is installed. The weight can be substantial PLUS there is added pressure as you are moving and placing each batt of insulation. Before the drywall is in place the only thing holding the vapour barrier to the ceiling joists are the staples. Use lots of staples. We found that one every 3 inches seems to work really well. Anything further apart than 6 inches just wasn't secure enough. Trust me I learned the hard way...

3) Overlap Vapour Barrier by one Stud
Another trick was to overlap the vapour barrier by one ceiling joist pair. This means that every 6 feet or so there is a double thickness of vapour barrier. This provides extra holding strength for the insulation -- mostly because you are doubling the number of staples in that section.

4) Lots of Tuck Tape
Tuck tape is the red stuff in the picture above. It is used to seal the joints between the sections of vapour barrier and around the holes for the electrical openings. Not only does this ensure a complete vapor seal, it adds additional holding strength. Use lots of tape! It is not that expensive and an extra roll or two is not going to kill the budget.

5) Use a Bread Knife
With mineral wool, the brand we used is called Roxul, the best way to cut it is with a bread knife. And I recommend using a real bread knife. You can recognize a bread knife by its unusual shape. A bread knife has the tip pointing down, and has a serrated blade. Cutting Roxul is really just like cutting a loaf of bread! Other knifes which are better for cutting glass wool insulation just do not work well with mineral wool.

I actually keep two knifes when working with Roxul a bread knife plus a standard box cutter which I use to open the bags of insulation.

6) Change Directions
It is generally recommended that you approach an R40 value when insulating an attic. This will mean using two layers of insulation. To get the best coverage place one layer between the ceiling joists, and then one across this layer perpendicular to the direction of the joists. Because the ceiling joists are mostly 2 x 4's in our attic we used R14 for the first layer, as it fit perfectly. We covered this with a layer of R22 across the joists. In total we have R36.

It is worth the effort...
With the above tricks and tips you can save yourself a lot of grief. It takes a marginal amount of extra time but in the face of the consequences a great insurance policy.

3 Reasons Why I Love Roxul (Mineral Wool) Insulation

Last weekend we started putting in some of the insulation after the electrician finished his work on the main floor. The little bit of insulation we did confirmed my previous experiences with Roxul, and why I like using the material so much:

1. Roxul Doesn't cause a rash
With fibreglass insulation you have to take all kinds of precautions to cover yourself up. With Roxul the only thing I do is wear gloves.

2. Roxul is more fire & water resistant
...and they have the stats to prove it (www.roxul.com). Roxul melts at over 1000 degrees C which is almost twice the temperature that fibreglass wool melts at. Water just runs off Roxul, whereas the glass wool stuff seem to wick up water.

3. Roxul is simply easier to install
Roxul is a firmer material, thus it fills the walls much nicer - it just feels like it isn't going to compress or fall in the cavity like the glass wool products always seem to prefer to do. It cuts easily with a bread knife. It installs nicely - it has a side that compresses nicely to assist installing it - and this side is clearly marked.

An added bonus reason:

4. Roxul has great soundproofing properties
Roxul is the stuff most sound rooms are insulted with.

Roxul is marginally more expensive but well worth the extra cost in my estimation...

4 Reasons I picked Roxul over Pink Insulation

There are basically two brands of insulation on the market:

Fiberglass:
This is the insulation that we commonly known as pink insulation. It is made of fiberglass. The biggest manufacturer of pink fiberglass insulation is Owens Corning. Owens Corning has also created a second website that helps you weave your way through the various government programs to subsidize the purchase of insulation. Incidentally these programs apply to any type/manufacturer of insulation.

Mineral Wool:
This is a less common type of material but increasing in use because of some superior attributes to the 'pink' stuff. Mineral wool is made from basalt rock and slag, and this combination results in a non-combustible product. There are no added flame retardants in mineral wool products. Combustible insulations often need to have chemicals added to make them less flammable. The biggest manufacture of mineral wool insulation is Roxul, Inc.

Roxul really plays up the fire resistance of their mineral wool insulation product. But I invite you to their website for the details.
BTW Glass wool is fiberglass. So you can see Roxul beats the pink insulation, and total blows away the spray foam insulation (polyurethane and polystyrene foam).

The five reasons I picked Roxul (rock wool) over the pick (fiberglass) insulation:

1. Roxul does not give me a rash - With fiberglass insulation you have to cover complete up - gloves, long sleeves, etc... The primary reason is that fiberglass gets on your skin and and becomes very irritable. With the sweating it just makes it worse. Using Roxul the only precautions I take is a mask and I wear gloves.
2. Roxul is easier to use: Cutting and shaping it only requires a bread knife. It is really easy to cut out little bits to shape around outlet boxes, etc.
3. Roxul is much more water resistant: Water seems to run off rock wool. I am sure you have seen what happens to fiberglass insulation when water is nearby - it acts like a sponge.
   
4. Roxul is much more fire resistant: Act the analysis given above demonstrated rock wool is much more fire resistant than any of the other popular insulations materials.
   

Caveats:
There are a few things about rock wool you should know about:

• It is more expensive -- I have found it to be 5% to 10% more expensive
• It is harder to get -- Not everyone keeps it in stock, although that seems to be changing. You can always order it from most building supply stores.
• It crumbles - When moving it around be careful not to break open the bag as the material tends to chunk and break off easier.