How to add gable roof to meet existing gable

Hey guys… I’m trying to build a new roof for a porch that we have on the front of our house. The current roof isn’t constructed properly and leaks even during a light rain. I want to build a gable style roof that will match the existing gables on the house. It seems easy enough, but the location of the add-on is right next to the bottom of another gable and I’m not sure how to tie them together. It is hard for me to explain so I took a picture of the house and quickly drew up my idea. I hope you can see what I am trying to do. I can take a better picture from the left side if that would help. I’m thinking I may need to use a “cricket” on the left side where the valley will be flat to drain off rain water. Any ideas?

lets see left side.

What you’re asking is fairly easy if you have any carpentry skills. And you are right, if the two valleys intersect, you will want a small cricket joining the two valleys and exiting where the existing gable and the new gable meet.
You will want to Ice & Water shield the entire valley/cricket area.

Ok, here are a couple more pictures. I think you got it just about right, bcdemon. Any more info on where I can get some specs on how to make the cricket? I am pretty handy on carpentry stuff so I’m sure I can do it. Also, since this thing probably won’t be any wider than 15ft, would I be ok building the trusses myself, or should I try to get them prebuilt? I have a pretty good idea on the I&WS from reading other posts. Thanks for the quick replies! It really helps…


All you really need is a flat roof properly installed on that, unless you’re trying to change the look or something.

If I were to go with the flat roof option, how would I tie it into the left side where it would meet the slope of the part of the roof without it leaking? I could just move the whole porch roof over to the right where it wouldn’t touch the left side of the roof, but then it would allow the rain to come through so we couldn’t come out the door and onto the porch without getting wet. Any ideas? I’m obviously not a roofer…

do you plan to re-roof the rest of the house while you are at it?

Absolutely… this porch roof is the only thing holding me up from replacing the whole thing. We have had a few good wind storms this year. This seems like a good time to get the porch roof done right.

[quote=“dccordell”]Ok, here are a couple more pictures. I think you got it just about right, bcdemon. Any more info on where I can get some specs on how to make the cricket? I am pretty handy on carpentry stuff so I’m sure I can do it. Also, since this thing probably won’t be any wider than 15ft, would I be ok building the trusses myself, or should I try to get them prebuilt? I have a pretty good idea on the I&WS from reading other posts. Thanks for the quick replies! It really helps…

The cricket would be easy, just a triangle piece of plywood with some 2x4 / 2x6 bracing underneath. You could start the cricket about 3 feet up the existing valley, 3 feet up the new valley, and meet at the point of exit of your two gables.

I can’t tell you to go ahead and build your own trusses, that may be illegal in your area. I’m sure you could build it strong enough, but politics gets in the way. You can find out if you need engineered trusses or not when you get your building permit.[/quote]

Well theres nothing wrong with what you wanted to do originally but its not necessary. However, It would be fairly easy to tie in a flat roof material to the valley area with the proper flashing. Then again Im a roofer for a living so you might want to have a roofer come look at it. Price wise id leave the structure alone and either install a flat roof system or you could remove the flat portion, run ice and water shield across the whole low slope section and up the adjacent slopes 18" then re-roof with a dimensional material. This is only recommended is the slope is at least 2.75:12 or higher. Usually 3:12 is what you should go by, so if its at least that then long as you use ice and water shield you should be ok. This only applies to a dimensional roofing material, not The three tab material you have in place now. three tab requires 4:12 or higher.

If you do decide to build the gable section. As long as the cricket is sloped enough to drain water off your fine. The diagram that was drawn for you should do just fine. you will need to roof the area with either a low slope material such as roll roofing or sheet metal that runs underneath all surrounding areas 18".

All in all I’d say stick with what you have and just do it right and you shouldn’t have an issue.

good luck!

Marc

[quote=“Gatesroofing”] This is only recommended is the slope is at least 2.75:12 or higher. Usually 3:12 is what you should go by, so if its at least that then long as you use ice and water shield you should be ok. This only applies to a dimensional roofing material, not The three tab material you have in place now. three tab requires 4:12 or higher.
[/quote]

this is a bit of an area of debate here.

MOST roofers agree that 3 tabs do MUCH better on low slope than dimensional shingles.

based on personal experience, many times over… 3 tabs are a better choice for low slope.

Ok those are some great ideas… I wasn’t sure about the cricket, for some reason I was thinking it was more complicated than that, but I understand what it is now. We are located way out in the country so I won’t have to worry about any permits. I guess I just have to decide now whether to remodel the whole thing or just try to keep it flat. I’ll let you guys know how it goes and expect a few more questions to follow! Oh, btw, that drawing helped a lot bcdemon. Thanks to all of you…

GAF, TAMCO, PABCO and Certainteed 3-Tabs are all approved for 2/12 and up pitch. As long as you double layer your felt you’re within warranty.

dccordell, your roof looks to be a 4/12 pitch, which would put your cricket around 2/12 or so. Sure it’s only a small area (the size of your cricket) but ALL the water from both gables and the main roof above the cricket will run onto the cricket. I might even suggest a torch on material on the cricket running up the gables and main roof, then your shingle of choice for the rest of the roof.

I’ve heard of the torch on stuff before… I’ll have to do a little more reading on that. Do you think it would be absolutely necessary or just a good idea in this situation?

Absolutely necessary? No
It’s just the lower slope cricket and all that water combined. You could, and I have just I&W and shingle something like that. But if it were my home, I think I would torch in the cricket, and shingle the rest.

Oh and get a roofer to do the torch on (if you go that way), you don’t want to mess anything up, or worse, burn down your house :smiley:

Yeah, definitely don’t want to burn down the house! I’ll have to check on that a little more but I’ll probably end up using I&WS… I usually go the way that I can do myself.
Now I’m wondering why I waited until the temps are in the 90s almost to do a roof job… :shock: better than 100s I guess

alright you guys win. I like to play it on the safe side and so i do not apply any shingle under 3:12 even with ice and water shield.

I am curious as to why three tab would be better then dimensional on a low slope application? I would have to speculate it all has to do with fastener placement? Any insight would be helpful as no matter how long your in this industry you can never stop learning!

To the OP - You would be solving different problems if you build the gable. The cricket, the building of the gable, the siding of the gable. Just those three are more time and money consuming then putting a flat roof on the porch. The money saved by doing your roof yourself would be much less then to do the additions yourself.

If you are able to frame in a gable to an existing like that then I am sure you can figure out how the flat goes in the valley. (Or hire a roofing contractor).

I would put EPDM roofing on that porch and be done with it. You can probably do this yourself, or maybe see if you have some kind of DIY help roof guy in your area.
Its hard to say from the pics, but that roof looks like less than a 4/12 to me. If it is a 4/12 I would shingle away.

[quote=“Gatesroofing”]alright you guys win. I like to play it on the safe side and so i do not apply any shingle under 3:12 even with ice and water shield.

I am curious as to why three tab would be better then dimensional on a low slope application? I would have to speculate it all has to do with fastener placement? Any insight would be helpful as no matter how long your in this industry you can never stop learning![/quote]

water runs off of 3 tabs a lot better than archs