Lori S

I made a quilt for my niece going off the college a few years ago . I used a wool batting , she loved it , said it was just what she needed to stay warm in the dorm at night( near buffalo, NY). The weight was perfect.
If you are looking for wamth , but not wool, consider a double batt, one cotton and one low loft poly. The poly will give the added warmth with out the weight. I have done a few quilts this way and really really like the results. That little bit extra poly give just enough loft to show off the quilting a bit more , and it is extra warm.

BKrenning

My hubby complained that our king size quilt with 1 layer of Hobbs Heirloom 80/20 and regular cotton front & back isn't heavy enough so I made him his own personal throw size quilt with old denim for the backing and his old work shirts for the front--faux cathedral windows style. He uses it every night.

Yes, you can quilt or tie multiple layers of batting or fleece. You can also an acrylic blanket or old quilt for batting in a new quilt to make a heavy quilt.

Fiber Artist

Wool

meemersmom

I have used wool and two layers of cotton with great results. But, the best (warmest) combination I have come up with is Thinsulate batting (same as used for winter coats; not sure if still available --- bought several when they were on clearance at JoAnn's) along with anti-pill fleece for the backing. I know Hobb's makes a batt called Thermore which handles just like Thinsulate. You have to remember not to use any kind of fabric softener (liquid or sheets), though, as it flattens out the loft which is what makes it so warm. I live near Buffalo, NY, and the fleece/Thinsulate combo is warm enough that it is the only blanket I need to use, and I tend to sleep with a window open a crack on all but the coldest nights.

Holice

I believe the question to ask your brother is does he want heavier or warmer. The answer will guide you on what to use. He may be confusing heavy with warm when a wool batting may serve the intended purpose.