Energy Efficiency: Insulation #3
Some notes on attics:
- When you’re working in the attic, be sure you have boards to walk on and an extension light to help you see what you’re doing. When walking on the floor joists, it only takes one slip to send you to the hospital, because that ceiling under you won’t support you and you’ll fall right through.
- Overhead, be careful at all times to steer clear of the roofing nails that are sticking through or you’ll get the hole in your head you’ve been hearing about all these years.
- The end walls can also be hazardous, because the nails that secure the outer siding are almost certainly sticking through. If your house has any years on it at all, those roofing and siding nails are dirty and rusty, and will give you a serious disease (tetanus or lockjaw) if you get punctured. If you do get a puncture wound, don’t mess around with it. Get to a doctor right away.
- Before you begin insulating, check the exposed roof areas for stains and discolorations on the wood. They indicate the presence of moisture. Be sure to find the source of moisture and assess its importance. For example, the moisture may originate from a bathroom fan that vents to the attic. It may be due to a leaky roof. You could have a mess on your hands if you don’t consider moisture as you weatherize your home. Wet insulation is ineffective and may damage your home by holding moisture and causing rot.
What about ventilation?
When you insulate your attic, you will want to make sure that any moisture which gets into your attic is whisked to the outdoors before it can condense in your insulation or on your roof. This is the purpose of ventilation. Usually a combination of high vents and low vents are best to insure that there is adequate air flow to move the moisture effectively. Vents can be installed in the gables, eaves or roof.
We know it seems strange to intentionally allow cold or hot air to come into your attic, but it’s better than the damage which moisture can cause. If you have a vapor barrier in place, then you will need about half as much ventilation as when there is no vapor barrier. The rule of thumb is that for every 150 square feet of attic space without a vapor barrier, or 300 square feet with a vapor barrier, you will need approximately one square foot of ventilation.
Taken in part from 547 Tips for $aving Energy in Your Home by Roger Albright