I am building an CEB (like adobe) home and would like to buy a laser level to help make sure the top course is level. There is no roof yet, and this will be outside, and in the sun. The house is only ~20' x 20', so the furthest the laser will have to travel if we put it in the center is something like 14'. Will most rotating laser level points be visible at this distance? I've seen multiple different mw power levels for lasers. How far is each visible outside in the sun?
The laser beam itself will barely be dissipated by the sunlight, check the specs on each device for their range. The difficulty seeing the laser can be attributed to the sunlight flooding all* light spectra/frequencies as well as sensitizing your eyes (or camera white balance) to light. Creating a shadow with your hand near the laser point on the wall should easily reveal it. If you can find/afford it, a green laser would work better for outdoor applications, the light frequency is further away from infrared as well as they are typically stronger.
* "All" is relative to visible frequencies (and a few invisible ones) but for cases of visible light by human eyes, the near red frequencies are visibly flooded heavier due to infrared being so close.
I would agree with most of the above comments with a few additions. One being that when in doubt of the distance the laser can be visibly seen then opt for a laser that comes with a hand held laser detector/receiver. This extends the lasers usable distance much greater than what is visible to your eyes. You would only use the laser detector as a back up when the beam cannot be visibly seen.
Most good lasers have the distance specification spelled out in two areas.
1.) Visible and 2.) Distance with Laser Detector/Receiver.
There was also a mention of Green Beam lasers above. They are brighter but they are typically only used in an indoor setting. Green Beam lasers can be used outdoor with a receiver but it is not recommended and not a popular option.
Laser Goggles or Glasses help some but not much. The laser with a receiver/detector would insure that you are buying a laser product that can be used in various light conditions for both indoor and out.