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Low Slope Roof Ventilation

9K views 8 replies 4 participants last post by  Jim F 
#1 · (Edited)
I just closed escrow on my first home, and the roof need replacing. I am trying to find a good affordable solution for an attic vent. More details below:

The house is in Moreno Valley, CA - so it is quite dry and hot most of the year with little rain. The house is 900 sq ft, and is swamp cooled. Most of the home is open beam, save for 200 square feed that has an attic over it. The roof is a 1:12 roof. It has rolled Ashpalt on it now, and I plan to replace with rolled.

The home inspector said that the attic space, although quite small, needs some sort of vent to be up to code.

I am wondering what sort of vents can be used on a low slope like this? I originally intended to get a turbine style vent, but I cannot find them at my local hardware stores (Weird?) except for one at Lowes that has some pretty poor reviews and is an unsightly black (its a white low slope roof). Besides that, I'd rather not spend $50 on something that will have a negligible effect on my comfort of the house (the attic only covers the bathroom and hallway)

Their really isn't room for soffit vents, and Gable vents are impossible (the ones at the side of the house that make a triangle) because most of the house is an open beam ceiling.

I want to avoid a powered fan because I am not comfortable doing the electrical work, and I don't fancy the extra power consumption.

Any ideas? I have seen some low profile vents, but I am concerned they will not work well with low slope roofing.

Heres what I have found

Turbine that reportedly breaks after two weeks

Low Profile Vent

Vent that looks like water would run into it

Not sure why this is so expensive, also looks like water might run in, but says "for flat tile roofs"
Thanks so much for your help DIYers! Sorry for the long post, I just wanted to be exact and clear.
 
#3 ·
Thanks for the suggestion. Unfortunately, their websites do not contain a lot of information about their products.

Many of the vents at Lowes (Home Depot does not provide as much info) say the vents are for 3:12's and up.

Also, the inspector said that I only need one vent to get up to code. Is that accurate? Or will I need an intake and exhaust vent? (I believe my municipality uses ICC codes or something like that for everything except plumbing and mechanical)
 
#5 ·
Those look really cool! In fact, I would love a solar fan of some sort, BUT, I should have been more clear.

What is the cheapest piece of junk, that will work with a 1:12 slope, that will satisfy a home inspector when I turn the house around 5-10 yrs down the line?
 
#6 ·
Having suffered through many such previous owner quick fixes I would not be inclined to help you with this one. Consider this: you will have to live with it for those 5-10 years. The cheap fixes you are thinking about may not last that long. It's always best to do it right the first time.
 
#7 ·
Oh thanks - that's a lot of help (Sarcastic).

I am just trying to get a basic ventilation system for my tiny attic. Its still an improvement because right now it has no ventilation at all. And I don't want to spend $250 on a solar attic fan. Nor do I want to do shotty electrical work myself, or pay someone a couple hundred bucks to do it for me.

I think I am just going to shell out $50 for the turbine vent at Lowes and hope it doesn't break in two weeks.
 
#8 ·
First off you should not install shingles on a 1:12... just so we are clear on that. You need a low slope material such as a single ply membrane or modified bitumen. Shingles are not warranted below 3:12 or 2:12 depending on manufacturer.

Second, steep slope and low slope roofs are designed different. There is such a thing as a warm deck design and a cold deck design. To summarize, a warm deck is that where the roof is insulated and is very common for low slope roofing. A warm deck would NOT be ventilated. A cold deck design is where the ceiling is insulated and the roof is then ventilated. Before one can say weather or not your roof should be ventilated and how it should be ventilated would depend on the design of the roof. Is it a warm deck or cold deck?

Let's assume your inspector has a clue and let's assume the design is a cold deck, then yes we should ventilate the roof. Going back to the first statement about the roof being a low slope roof, you would not want to install any kind of steep slope ventilation. Instead you would need a product engineered to be properly installed on a low slope roof. If you like fane, you would want a curb mounted fan. truth be told these are elusive beasts, I have to go to an industrial supplier to find these, none of my roofing suppliers sell them. I often see steep slope attic fans installed and then "hacked in". They always leak. If you choose to go with some kind of passive vent, there are one way and two way breather vents that are commonly referred to as "silver bullets". You may want to look into those.


Finally listen to Jim's advice. Do it right the first time or don't even bother messing with it.
 
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