Flashing question

Thanks to all who provide their time and expertise to this roofing forum. It is very informative.

I have a flashing question. I am getting ready for a re-roof. It has the original roof plus one on top that will be taken off down to the decking. I have an overhanging front porch. Of course it has sidewalls on each side and the porch does cover these sidewalls probably about 12"-18" out. Here is the question. Obviously these sidewalls are flashed(have no idea about the flashing method). What should be done about this area as far as flashing? Just reuse what’s there which is what the roofer indicates he will do? There has never been any known roof leak to this area. I would like to hear advice as I want to get this right and I know nothing about flashing or various flashing methods. House was built in late 60s-Southeast location.

Thanks for your help.

The most common method is reusing the flashing (not trying to ruffle any of the roofers here who are in the top 3% and always replace flashing…just saying what is normal to the other 97% :wink: ).

It all depends what kind of condition its in.

thank you for your reply.

Could you tell me what to look for that would indicate replacement of flashing is the best course of action? I have confidence in my roofer as he comes highly recommended. as stated in my OP, I just want to get this right.


chances are, especially with a 2 layer roof, that the existing flashing is somehow buried in a sandwiched layer of asphalt, most likely somewhere in the original roof area. Picking that flashing apart and pulling nails is a slow and tedious job, and quite often, trying to hurry with the thin aluminum that most
builders used and still use today can slow down things even more. Regardless of that, assuming that you have cleaned out all of the asphalt and mastic cements that might be used to secure this flashing detail, then you have to deal with lifting it back to nail the top edge of the newer roofing, then fold it back down, and secure it again, over the new roof. One thing that I do in this application is to add an additional slip sheet of flashing, under the existing flashing, and weave that into the installation. In the end, it will be hidden, but
knowing that a nail punctured wall flashing is counter flashed is an inexpensive insurance against
water intrusion thru an existing flashing that has endured the nails and holes of two previous roof jobs. Also, it is possible that the original siding has been installed fairly tight on top of the first roof, and the second roof was just set in cement, against the old siding. This is a horrible application, but
generally acceptable by most installers. Taking it apart can be a real headache either way.

hope this helps


ditto marshall,
i will add:
clean off top of metal before your pry up under it.
try to do when cold.
do not bend up metal to much for it will be harder to
nail back down.


WHy risk a reused busted or bent up flashing? They are really cheap and are faster to install than jacking around with the old.

Save a penny to spend a buck? Doesnt make sense to me.

Tear out the old and install new. It is better AND less costly.

Thank you for your replies.

This flashing issue is really the last piece of the roofing puzzle for me.

Why wouldn’t you want to replace the flashing? Existing by whatever flashing method is probably about 40 yrs old. Is this a big deal to replace? Expensive? I estimate each sidewall is about 20 ft in length.

As stated roofer intends to just reuse. Is it the best recommendation to just go ahead and replace? And should there be special leak barrier felt/film under the flashing as an extra precaution?

thanks for everyone’s help/advice.

If it causes damage to the siding to get the old flashing out you might want to examine the existing flashing and re-use it. You might also be able to leave the old as counter flashing and just cut it off short then slide new step flashings up behind it, I did this recently on a small wall when I re-roofed my house, it had cedar shingles which I didn’t want to disturb…DaveB

If it is fastened into the wall, behind the siding, you have potential siding issues to consider.

Will the customer be wiling to pay additional time for the slow careful time required to move the siding out of the way?

Is it wood siding or aluminum siding? Different answers for the type.

For some wood clap-board sidings, we use a 4 1/2" saw to cut the bottom edge away and slide the old out or slide a new one in, on top of the old if the old one will not come out.

For others, we sometimes cut away the bottom 4"which is enough room to remove the old flashing, then install a “Z” flashing directly under the cut edge of the siding and then install the proper sheet metal flashing and then install a 1" x 4" of cedar, stained to a similar color as the siding or the roofing material.

If it was only a 1 layer tear-off, the flashing can usually be re-used without bending it, as long as you are careful.

I’m one of the 3 per-center’s I guess. LOL.


After re-reading my original post and all the replies, I am absolutely confused on the best course of action. As stated I have no idea of the existing flashing method. I don’t like the idea of not replacing 40 yr old flashing but I don’t like the idea of removing the sidewalls.

Am I to understand that it is not necessary to remove sidewall if the step flashing method is used?

If this was your re-roof, then give me the best course of action to take. I may call roofer over today to review this issue. New roof tentatively scheduled post Thanksgiving.

Thank you again for reading this thread as well as your help/advice.


What type of siding do you have?

painted wood

Depending on the type of wood and condition pulling up the wood siding to replace the step flashing may damage a lot of the siding. Quite often when trying to pry on wood siding it cracks.

The best course of action may be what Ed has mentioned. That is to cut the siding 4 inches to allow underlayments and new flashing on up the side wall. Put a 4 inch board in the cavity with some good sealant on the top leading edge and your as good as gold.

To offer the 5 star Certainteed Integrity warranty one must replace all metal flashings including step and base (dormer) flashing.

If the siding was brick or stucho it would be a piece of case to just cut in riglet.

How about a photo so we can be more on target.

When you say wood.

Well, is it T-111, Cedar Beveled Siding, 3" clapboard, etc…

Each has to be looked at and solved uniquely.

The “Z” Flashing is critical on top of the 1" x 4" instead of just depending on caulk.

An alternative is to cut a bevel into the top side of the 1" x 4" and ensure that the tapered edge gets tucked behind the siding.

A person must “Think Like Water” to see what course of action will prevent any future problems long term.


Step flashing is never exposed to the weather and could be reused for a hundred years. Depending in bens, holes, cracks, etc. A hole in outer edge is OK. Use the same hole when renailing. Not likely to hit same hole in wood. Rust is a no-no. Termite shield is a no-no.
I’m a 3%er too. After 40 years of roofing, I trust my judgement when evaluating the condition of existing flshing. Any doubt at all, and I replace it all even if I didn’t spec that.
It will boil down to judgement and experience…

I forgot to add. If you’re one of the few that has lead-head pipe collars and they’re in good condition, seal the nail holes, paint and reuse them. THey are good for 70+ years. The plastic ones are good for 7 years.

With a 30 year warranty against leaks you have to make a good judgement call on re-using flashing when replacing is an option.

Does that 30 year warranty include the 7-10 year pipe collars they sell now? Old rusty lead-head would go that far and then some.

i always replace old flashing no matter what.If I see that it’s going to take longer than usual when i am up on the roof for the estimate then i figure out what i think it will take to do and add the cost to the total estimate.

So you are a siding contractor and a painting contractor also?

You ever have to make multiple trips to the paint store? Or paint a whole wall because the paint you used didn’t match up perfectly and aged like the rest of the outside wall.

What about priming time?
Are you using a primer?
Are you putting on two coats of primer like the directions say?
Are you putting on two coats of paint?
How much drying time between coats?

My point being is…Are you really tearing up peoples walls, siding, paint jobs so you can
"replace flashing every time" if the flashing is installed correctly and has no rust on it?