Flat roof w a sinking corner

[Jmaggs]

Hi there,

Looking for some advice. My house is a bungalow with a peaked shingled roof in the middle and flat BUR roof on either side, kind of like this --^--

The portion of the flat roof on the back right hand side started to sink last year, and is getting progressively worse and worse (approx 3-4" now). Main reason is due to the initial depression, all the water pooled and started to run under the flashing instead of hitting the roof drain. It is rotting out the wood underneath, including the soffets . Luckily, this portion of the roof is over a car port, and not over the actual house itself, so it hasn't had much of an impact at this point. (Also, I noticed that the soffets aren't ventilated around the section of the roof around the carport. Is this normal? )

The eventual goal is to convert the flat sides into sloped, shingled areas with gutters, but for the time being, I just want to temporarily fix the sinkhole to funnel water towards the drain.

My plan is to cut out up the sunken section, replace the rotted wood (also sister up the joist if it is also rotted), and then put down new plywood ensuring it is angled towards the drain. Where I'm not 100% sure what to do is what type of roof covering to use. I want something I can do myself, so what would work other than the typical felt that is installed using a torch??? I'm not even sure what other options there are if any.

Any suggestions would be appreciated!

Thanks!

[pushkins]

The "sinking" roof is a problem and should be addressed sooner rather than later as you mentioned.
What is the grade of this roof ?....1:12, 2:12, 3:12 ?

Shingles shouldn't be used on any roof under 3:12 (some shingle manufacturers will say down to 2:12, but you need two layers of roofing felt and most building inspectors frown upon 2:12 shingle installation.
This leaves you with the options of rolled roofing or steel roofing. Rolled is basically the same as shingles just in 3' wide sections rolled out the full length of your roof and nailed down just like shingles. Rolled will be your cheapest option.
You could always install steel roofing yourself but depending on how the flat roof attaches to the hipped roof, flashing it correctly might become tricky and much more time consuming.

[Jmaggs]

Thanks for the quick reply. I'm only looking to fix the sinkhole for now, not re-grade the roof yet, so my repair is going to be on the built up flat roof. Would you apply rolled roofing on a flat roof?

[pushkins]

Depends on just how "flat" the roof is, what is the actual pitch of the roof in question ?

[Jmaggs]

Originally Posted by pushkins

Depends on just how "flat" the roof is, what is the actual pitch of the roof in question ?

Well, to my untrained eye, it's completely flat. I'm sure there is a bit of a pitch to ensure water goes towards the drains, but for all intents and purposes it's flat.

[pushkins]

Use a level with a mark on it at 1', put one end of the level on the roof making it level and measure up from the roof to the level at the 1' mark.

If it measures at 1" at the 12" mark then the pitch is 1:12
If it measures at 2" at the 12" mark then the pitch it 2:12