First Time Homeowner Reroof Question


Wanted to start off by saying I have no experience with roofing other than cutting out a roof deck for a ridge vent a few years back. I’m a decent DIY’er that’s mechanically inclined and loves new tools.

I have a 20 year old detached garage with 20 year old 3 tab shingles. It’s a simple gable roof (5/12, I believe) with one penetration for a powered ventilator. The roof still appears to be in serviceable condition with no past or current leaks as far as I can see. There are handful of shingles with material missing from hail presumably, and there are only a few shingles that appear to be cupping at the tabs, which appears to be caused by tree debris that has gotten under them and can be cleared out.

This roof has no underlayment which is making me nervous - the shingles are nailed directly to the 3/4" plywood. The garage is drywalled and the roof deck is supported with 24oc 2x4 trusses.

Given the age of the 3 tab shingles, I would like to get ahead of this vs. waiting to see water spots on the garage ceiling.

In your opinion would this roof be a good candidate for a reroof w/ architectural shingles vs. tear off?

I’m not opposed to doing a tear off if needed, but I will be a lone wolf for this project and don’t want to create extra labor for myself if it isn’t going to help me out in the future. I probably won’t live here for more than 5ish years so I personally am not concerned with what happens the next time this roof needs to be replaced.

Any help/insight greatly appreciated. I’ve always loved the sound of roofers shooting their nailers so regardless of reroof or tear off, I cannot wait to get up there and blast off a million nails.

Edit: Images

While it’s always better to tear off, this is the type of job I would be willing to go over with another layer of shingles and not have any worries about it.

P.s. don’t just rush to nail as fast as possible. I know it sounds cool but proper nailing is one of the things that separate quality installers and mediocre ones. And it’s even more important to place your nails properly if it’s a 2nd layer.

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Personally I prefer a tear off over adding a second layer and would make that recommendation, however that’s my preference, and provided the current conditions are accurate and everything will lay flat, with solid decking that’s not soft or needing replacement, there’s no reason you cannot add a layer over what you have, but I stress that i myself would tear off and start over… although your looking at relocating in the future, I’d seriously take time and do it right. If you don’t have time to do it right the first time, your never going to find time to go back and fix it the 2nd time.
Otherwise be mindful of the manufacturers installation instructions and I’m sure it will work out. Post a few pictures after your finished if you can. Good luck and be safe

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Be careful with an overlay. Architectural shingles can be heavier than the three-tab you have. Extra weight might be a problem with the 2x4x 24"oc roof structure you have.


In Texas, in the 80’s, we would TAB a 20yr shingle. Don’t know if any other areas did it, but it was an old school layover. Half the trash, no deck cleanup, no nesting, pulling nails, reduced weight of the new shingles and we could install new underlayment. Just FYI> I’ve had a few closings get held up from the insurance companies not wanting to cover a home when they find out it has 2 layers.


We worked on an old shed that had shingles directly on the plywood. The shingles were stuck to the plywood and it was extremely time consuming to remove them.

I don’t see anything wrong with that roof, other than staining. I do a lot of repairs, and when I get a roof done by the rapid fire gunners that have torn holes with the majority of nails shot due to improper placement, I get to tell the homeowner they need a tear off. If you nail over shingles with a gun you’re going to put a hole through the shingle every time you hit a void. If you must, get a sheet of plywood and blast the hell out of that. I’m know a lot of contractors do layovers and claim the roof is perfect, but that’s only if you don’t look…

We did some tab cuts when they were curled bad. I think tear off was about the same amount of time.

It looks like it is only about 8 square.
I would strongly recommend you removing this roofing before proceeding.
A few reasons besides the obvious ones…

Looks like a 4/12 pitch to me.
And that is not the same story as a 5/12.
I treat it differently.

The discovery of no underlayment

And the tree.
I am confident its leaking and doing damage under the shingles under the tree.
It just hasnt worked its way through that awesome thickness of wood yet to see from the bottom.
But you will clearly see what it has been doing after you remove it.

If i was your roofer,
I would tell you to remove that entire large limb as soon as possible.
Also, i would expect you not to take my advice Because of the cost of the professional remover
So i would install Ice and water shield underlayment over that entire side of the roof.
Its only 2 rolls.
Do the whole roof with 4 rolls…
I buy mine for 56 dollars a roll retail.
Might cost you a little more.
I’ll sometimes buy them from other roofers for 15-20 dollars a roll.
Ps. Dont buy the Gaf ice and water shield underlayment from homedepot/lowes.
Its over priced And its the worst.

The roof looks fine, I would put a dab of adhesive any tabs that can lift with the wind and call it a day. If you are concerned about no underlayment, tear it off and put on underlayment (then blast it full of holes, haha). Having 2 layers does not count as underlayment and will be more likely to leak or blow off as the shingles will not lay as flat and nails will blow through.

…If you live in an area with ice dams I would tear off and use Install Grace ice shield bottom 2 layers