Roof shingles/ridge vent/low slope roof
Sinc 2006 my new garage roof has been leaking from being improperly installed. I have learned a lot about roofing since then, but today, I learned something else which is confusing and thought someone could help.
1. The front of my garage is OK with a nice pitch, the back 1/2 16' is either 2/12 or just under 2/12 which GAF tech support said I can use their deminsional singles?
2. It was suggested that I put I/W on the entire roof as well as up the side of the house under the 1st few layers of siding in addition to adding step flashing.
3. Also, GAF as well as the contractor today advised that I install a ridge vent on my unheated soffited wih air flow garage?
4. I was told that someone did an experiment with COBRA and the AIR VENT with smoke in the building. The 1/2 with AIR VENT bellowed lots of smoke out from the ridge vent, but the COBRA hardly had any smoke coming out - this was to show that AIR VENT had more air flow.
I called the contractor, who I signed the contract with, he said he does not carry AIR VENT but gave me 3 telephone numbers to call to find out if they have it in stock. I also tried the big box stores, but they only carry COBRA also.
If AIR VENT II is a better product, which I am not sure that it is and only going by what one contractor said, why wouldn't the supply houses carry it? I would think the purpose of having the ridge vent would be to get the air flowing out as fast as possible?, no?
I also read some blogs here about the ridge venting and the snow blowing in. What is the best type of ridge vent then to prevent rain/snow, etc., from entering the garage or attic and giving the necessary air flow needed to cool off the area?
If the pitch is 2/12 or under 2/12,why would one contractor want to use a 'rolled roofing material' that will not last over the GAF shingle? Preference? If GAF said it can be used, what is the issue?
I was burnt once from roofer and he now has made a bad name for all others.
Thank you L. firstname.lastname@example.org
Lowes carries the Shingle Vent II from Air Vent and so do all of the supply houses I deal with.
Cobra Vent is usually priced cheaper, so from a sales standpoint, they can sell more of that product intstead of the better version.
Cobra also has a version called Snow Country, which is a similar designed product as the Shingle Vent II from Air Vent.
3 tab shingles or a properly installed Flat Roofing System should have been recommended for such a low slope and I only mentioned 3 tabs, since you already had shingles on the roof.
A 2/12 pitch is not designed for shingles and is technically considered a flat roof.
I wouldn't put shingles on a 2/12 and LOL at GAF saying it's ok.
Thank you Ed for your quick input.
Now you know why I am confused. Yes GAF said I can put their Timberline on 2/12 as long as I put them closer together, added extra protection (all i/w underlayment), venting the top, etc.
This house is over 55 yrs old. It has ALWAYS had shingles on the roof and the roof neve leaked until this guy installed the roof.
I had a roofer there yesterday who pulled back some shingles to inspect, he noticed there was no felt (or cut back short that he couldn't see presently), there was "old" step flashing, but mismoshed.
I do need a professional assistance.
Technically a 2/12 pitch is a low slope roof (as far as residential standards go), anything under is flat. I believe that's the same for commercial, not sure tho as it's been a couple decades since I worked commercial/industrial type roofing.
Flat goes down to 1/4" (I believe) slope than becomes dead flat.
I have shingled 2/12's before with out problems, but I always have and do preach against doing it.
The shingles on a 2/12 will not last as long as the shingles on steeper slopes,
so I always recommend a residential low slope system like GAF's Liberty or Certainteeds Flintlastic.
(If the pitch is 2/12 or under 2/12,why would one contractor want to use a 'rolled roofing material' that will not last over the GAF shingle? Preference? If GAF said it can be used, what is the issue)
There's a big difference between a 2/12 and under 2/12.
Also when installing shingles on any low slope from a 4/12 pitch an down the condition of the sheathing plays a much larger part then on steeper slopes.
If there is a lot of sagging or bubbling in the sheathing it will allow water run off weep into the side joints of the shingles in such a high volume that it will/can leak through the fasteners.
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