ladders on house

From the diagram above
Upper Left  
The ladder on the porch roof is tied into the building at the bottom rung to prevent kick-back .This can often be done by setting a screw eye into solid wood to tie the rope to. This is a shallow pitch roof .A roof with a steeper pitch or a slippery roof would need a solid support fixed to the porch roof to hold the ladder from sliding back.
 Using this method the ladder treads should have good traction against the roof surface.
The rope should have tension on it, so that the ladder will not slide. The idea is to prevent a slide, not to stop one in progress
The rope may be angled upward, but should not be angled latterly (side to side). So each time the ladder is moved along the roof, the rope will have to be tied to a point on the building.

From the diagram above
 Lower Left 
 The ladder setting on the ground that leans against the porch roof is tied to a horizontal rope attached to a post closer to the top of the ladder. This helps support the ladder from side to side motion and keeps the ladder from tipping back. If this rope had been tide tied at the next rung up, and run horizontally to the higher position on the post ,it would give better even support. It's usually best to keep this rope as horizontal as possible .The rope should be not be angled latterly, keeping it about 90 degrees (side to side ).

From The Diagram Above
Center Right
 The Yellow ladder leaning against the wall of the house has ladder mitts. The mitts not only protect the building, they also create traction between the ladder and the building, helping to prevent the side to side sliding action. These mitts fit on over most any ladder and reasonably priced at hardware or paint stores.
The ladder is on uneven ground , so that it is necessary to block or shim under one side to keep the ladder latterly plumb.

Keep several size boards available to use as blocking or shims.
From a piece of
( 2 by 4 or 2 by 6 )
to a piece of 1" board
a piece of 1/2" plywood
a piece of 1/4" plywood
Use these in combination where necessary.
Shim underneath with the wood shingles to make blocking level, but do not try block to high as so that the blocking could tip. Don't block higher than about half the width blocking. On side hills It is some times necessary to dig a place in the ground to place the ladder

From The Diagram Above
Left Roof
A roof hook is used to hold a ladder in place so that the end wall of the house can be accessed.
Also See Roof Ladder Safety

From The Diagram Above
Left Deck
 To prevent the ladder from sliding back where the traction may not be adequate, a (1" by 3") board is nailed down to the deck. It is placed so that is directly against the back of the ladder shoes. Small common nails can be used for this purpose, but be sure they penetrate at lest a half inch into the decking. Larger common nails or screws should be used on a surface that is quite slippery.