How to Install Roofing Flashings


It's important that the flashings placed in the space between the wall and roof are installed correctly. Bad workmanship in this part of the job can lead to disastrous results. If the flashings are not installed properly, water from the rain will pass behind the flashing and will cause extensive aswell as expensive damage to your property. It is recommended to ask assistence from professionals like MSME Metalworkers for this kind of job, rather than attempt to do it yourself.


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However, if you are up to the task, let our metal experts guide you through the process of the flashing installation:

Step 1


Using a tape measure or similar measurement tool, measure the length of the intersection area between the roof and the wall. Then, use a saw to cut a two-by-six timber matching this length. Place the timber on the edge of the wall and use large nails and a hammer to nail it to the wall studs.

Step 2


Next, measure the length of the wall. Take tar paper and cut it to match this length. Attach the top edge of the two-by-six timber on the wall with a functional construction stapling machine. Place the paper in the corners between the roof and the wall and then staple it to the ceiling, making sure that it is sitting tight.

Step 3


Next, you should prepere a roofing cement mix. Place the correct cement tube into the caulking skeleton gun and make sure to trim the nozzle tip at a sharp angle. Now fit a 90' degree step-flashing into the wall and roof intersection.

Step 4


Now, remove the flashing. Press the roofing cement around the flashing in the space where it will join the roof an the wall. No place the flashing carefully into place and press it down gently but firm, so that it creates a perfect seal with the tar paper against the roof. Then fix the flashing into it's place with a nail and hammer in distances of 30 centimetres. It is important that this step is executed correctly.

Step 5

Now, fit a piece of Z-bar metal flashing over the flashing you just place and rest it on the timber. Make sure to place the flashing in such a way that the narrow lip is tilting away from the board. Check that at least 10 cm of flashing is on the wall above the placed board .

Step 6

Next, pull the z-bar flashing of the board and apply roofing cement around the area of the flashing. Carefully place the flashing on the board making sure it fits well, then secure it into place with a nail in equal distances of 30 cm relative to the flashing. You can slightly alter the distances depending on the length but make sure that you stick to one throughout.

Step 7


Now cut tar paper to the correct length and fix it to the wall so that it fits the z-bar flashing and overlaps it by about 5cm. Apply a thin layer of roofing cement with the caulk gun between the tar paper and the z-bar flashing. Make sure that the result is sealed.

Step 8


Now take a step back and check the installation. Do you see any visible joints? Seal them with an extra layer of protective roofing cement. If everything looks fine you may proceed with adding the roofing materials to the roof over the flashings. Well done! It's time for a coffee break :)

Here Are The Things You Will Need For Flashing Installation

Extra Flashings Advice

If your installation has a corner or a long edge, make sure you apply tar paper or flashing to the lower edge first before moving up to the rood, overlapping the previous sections. Make sure that you seal each overlapping join with extra layers of cement to make sure water cannot leak inside.

Fun Fact about Flashing

Long before there were sheet products for flashings available for builders. Creative methods were used to keep water out of the houses. Some of them are using angling roof shingles away from the joint, placing chimneys a the ridge, building steps intp the sides of the chimneys and covering the seams between the roofing material with mortar.

When manufactured flashing materials were introduced, the water penetration in the waek spots such as chimneys, windows and vent pipes, in houses decreased significantly. Houses have become more durable. This is a testament to how important it is to install flashings and secure houses against water damage.

The two different types of flashing that are in use today are either exposed or concealed. Exposed flashing are typically of a sheet metal and concealed flashing may be metal or a flexible, adhesive backed, material particularly around wall penetrations such as window and door openings. You can read more here.

Article tags: flashing, flashings, gutter, window flashing, chimney flashing, metal flashing, z flashing;


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We are located in Warkworth but serve our customers Auckland wide.

Disclaimer: These are trade best practices however MSME Ltd cannot be held accountable for any damage resulted from following this guide.

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