October 12, 2021
Roof flashing prevents rainwater from splashing against walls and soaking them up. The water that is soaked up by the walls will lead to damp stops seen from inside the rooms of a home. Further dampening of the walls can also lead to water seeping into your homes. Leakage from the sides of the wall can also result in roofing timber rot. This could also end up with the roof deck collapsing.
So roof flashing is an important part of roofing and has to be done with great care to protect your home. We will take a look at how to install roof flashing against a wall in this article. There are various ways to do roof flashing depending on which part of the roof you are flashing. Step flashing is preferred over continuous flashing for roof flashing where the roof meets the wall.
Materials needed for roof flashing where roof meets wall
Step flashing is a piece of metal sheet bent square at 90 degrees. They come in various sizes from 5 5/8″ to 10″ width. Typically a 10-inch by 8-inch step flashing is chosen when flashing where a roof meets a vertical wall. This is because the flashing should always be a couple of inches longer than a roof shingle. Other than that you will need a sealant, galvanized roofing nails, and tin snips.
Step flashing needs to be patiently done because step flashing has to be completed before you undertake the siding. If step flashing has to be repaired or redone, you will have to remove the siding. Step flashing also has to extend 8 to 14 inches beyond the shingles as per the National Roofing Contractors Association (NRCA).
You will have to check if the wall that meets the roof has a corner. If it does, please follow the first method to install the step flashing. If there are no corners where the wall meets the roof, follow the second method to install the step flashing. Step flashing also has to be nailed on only one side, either the wall or the roof. They are generally nailed to the roof to allow the wall to expand and contract during the various seasons. If nailed on both sides, the step flashing will come loose when the building moves because of the changes in temperature.
How to install roof flashing against a wall with a corner
When there is a corner where the roof meets the wall you will need a corner flashing piece. A corner flashing piece can either be bought from the hardware store or it can be made using a regular step flashing piece. Here I will show you how you can make a corner flashing piece and install the roof flashing.
- Lay the underlayment and the shingles fully up till the wall. The first step flashing or the corner flashing should rest on a shingle. Take a tin snip and cut from one corner of the step flashing along 45 degrees to the centerfold.
- Next, cut from the other corner on the same side of the step flashing and along 45 degrees to the centerfold. Next, cut along the centerfold and remove the piece you have cut and bend the corner flashing square, so as to fit around the corner in the wall.If you don’t want to take the trouble making a corner flashing piece you can buy a ready-made one from the store and cut it to the size that you want.
- Place the bent corner flashing firmly against the wall. Make sure that the corner piece extends at least 8 inches above the shingles. Make sure it sits flat against the roof and the wall. Nail the corner flashing on the top side using two nails, one on each side.
- Take a piece of step flashing and bend it in place so that it overlaps the corner flashing by at least three inches. Apply sealant to cover the overlapping area of the step flashing and keep it in place. Make sure that it is flat against both the roof and the wall. Hammer a nail into the top of this flashing. The nail should be high enough to let the next row of shingles cover it.
- The next piece of step flashing should be placed where the next course of shingles will start. Place this piece of flashing so that it overlaps the previous flashing by at least three inches. Apply sealant where the two flashings overlap and nail the new shingle in place.
- Repeat the process alternating between the shingles and pieces of flashings till you reach of the top of the roof. For flashing the top of the roof you will have to make a custom piece out of a regular flashing piece.
- Take a piece of flashing and cut along its centerfold till about halfway. Leaving one of the cut pieces straight, bend the other piece so that it fits snugly along the peak of the roof. Secure this corner flashing piece with some roofing cement and a nail at the base. This corner flashing will later be covered by a ridge shingle.
How to install roof flashing against a wall without a corner
You don’t have to make custom corner flashing pieces when the roof connects to a wall without any corners in between. You will instead, need kick-out flashing to guide the water into the gutter. Kick flashing is difficult to make on-site when using galvanized steel. The best course of action will be to buy ready-made kick out flashings from a hardware store.
We will now go on to see how to install kick-out and step flashings.
Place a kick-out flashing at the base of the roof and flush against the wall. Remove the flashing and apply some roofing cement to fix the flashing into place.
Place the first piece of step flashing over the end of the tarter strip. Ensure that the step flashing will lead the water directly into the kick-out flashing.
Use roofing cement and nails to secure the step flashing to the deck. Make sure that the nails are high enough so that they will be covered by the next course of shingles.
Having fixed the first step flashing in place, apply sealant to the base of the flashing. Place a shingle so that it covers the nail of the first step flashing and nail the shingle in place.
Finish placing and fixing all the shingles.
Place the next piece of flashing so that it overlaps the previous flashing by at least three inches.
Apply sealant where the two flashings overlap and nail the new shingle in place.
Repeat the process alternating between shingles and pieces of flashings till you reach of the top of the roof.
Roof splashing, done properly will keep the walls of our homes safe from soaking up water during rains. Further rains will lead to water seepage into our homes and rotting of roof timber. Roof leakages and deck crashing are some of the consequences you will have to put up with if your roof flashing is wrongly done or deteriorates. We hope this article on how to install roof flashing against a wall will help you in roof flashing the roof of your home.