I'm not the resident expert around here but let me take a stab at giving you an answer.
For me at least, I will clean a fence or deck as long as it's above freezing. The obvious problem is that the surface (particularly horizontal deck boards) will take longer to reach the required 12% or less moisture level. Most penetrating stain Manufactures suggest an air temp of at least 50 degrees. Ready Seal boasts that you can apply their stain in virtually any temp. The colder temps are going to create to problems though. 1) The wood will not accept the stain as readily or deeply since the pores will be tighter and 2) It will take longer than usual for the stain to dry.
Brick restoration. Again, you can do this in cold weather but you have to be careful when dealing with porous brick, as it will absorb a lot of water. If the air temp falls below freezing, that water can freeze causing all sorts of problems like blowing out the mortar.
House washing- this is one of the few jobs I will do in cold weather. I won't do it below freezing, primarily because I don't like the cold! But, I don't want an issue of creating ice dams in or on a gutter or hazardous conditions along walkways. Also, I've found that a lot of the chemicals that we use are not as effective at colder temps.
Again, I'm not the expert.... If anyone sees me in error please correct me for the thread originator and my sakes.
Good luck this year!
-Tom
