Loose Gutter Nails and Gutter Screws
Loose gutter nails cause problems with your gutter. They allow your gutter to bulge out and sag. As the gutter sags, it accumulates more water in this low spot. Because of the increased water, more debris washed towards this area. This increases the weight in the gutter and perpetuates the problem. Gutter nails usually work loose at then ends and corners of the gutters. This allows the corner joint to work loose and leak. Also, as nails work loose on the ends, then the end sags and tries to pull the gutter off the house. This isn't too hard to do because the gutter nails typically used are less than seven (7) inches long. If the gutter does pull loose and bend, then it will make crease marks that are so difficult to be removed that it is cheaper to just replace the gutter.
Gutters are metal and they are fastened to wood. Wood expands when it gets wet. Gutter do not expand when wet. Both metal and wood expand at different rates according to temperatures. Because of these dissimilarities in expansion rates, gutter nails work loose from the wood that they are driven into.
The Ridiculous Facts
It appears that gutters are made and installed to fall off of buildings and to cause basements to flood in short order. Why do I say this? On a 5K gutter (typical) a seven inch gutter nail has less than 2 inches of bite and hardly any teeth in the fascia and rafter tail. A 5K gutter holds 1.5 gallons of water per foot. Since nails are installed from 2 to 4 feet apart, this comes out to (2 feet per nail x 1.5 gallons per feet x 7 pounds per gallon of water) 21 pounds of water plus the weight of the gutter and debris with almost 5 inches of leverage on the gutter nail. It's no wonder you see gutters trying to fall off older homes. Now add to this the nails getting worked back and forth as the gutters expand and contract in length with the temperature changes.
At Your Own Risk
Can you imagine if people built roofs and walls this way? Surely there must be some building codes to protect home-owners from such shoddy work. But nope. And what do you think is the biggest cause of basement flooding and damaged siding? So what are your conclusions? Since there are no building codes, your best bet is to hire people on Angie's list who have a reputation to lose if they do shoddy work. Good luck with the CCB. It won't happen in a timely manner. And businesses who do shoddy work are typically already broke so you have less chance of getting your money back from a bond. Angie's list is the way to go if you need new gutters. I don't have a gutter machine and don't install gutters. I help maintain them and educate people on how to make them last a long time.
Here is a visual comparison of gutter nails and a couple type of gutter screws. Also shown are some ferrules. The ferrules form a sleeve and spacer that keeps the back of the gutter the same distance from the front of the gutter for the length of the gutter so it looks nicer.
The Solution to Loose Gutter Nails and Sagging Gutters
Before your gutter pulls loose of the house, the loose gutter nails can be replaced with gutter screws. They are longer, have a larger diameter and have more and larger gripping teeth so they are very difficult to pull loose. This securely fastens your gutter to your house for many years. There are at least a couple varieties of gutter screws. There is the smaller shank screw that is 8 inches long that has a 1/4" drive head on it. There is also the more stout 8 inch gutter screw with a 3/8 inch hex head on it. It has more holding power and is good for where gutter nails have alread made a bigger hole as they worked loose. I mostly use the stouter 3/8" drive gutter screws. They are made of steel and are much stouter to prevent gutter sagging.