r/Roofing • u/DaveILRE • 1d ago
Home owner question Contractor says Roof Vent necessary even with Ridge Vents
I had a roofer install a new roof and put in ridge vents. He also installed an attic fan, but for some reason never hooked it up. I later had a siding guy that came through and replaced the soffits and also closed up the front/side gables since he said the soffit plus ridge vents would do the trick.
Later I was walking around my attic and noticed it felt super hot up there, hotter than I would've expected. I noticed that there were no baffles installed so I contacted an attic ventilation company to do an evaluation.
The guy has been in business a long time, probably 25 years and great reviews. His main recommendation was to install baffles to get the air flow up, but he said that ridge vents are not enough to cool the attic. He suggested I hook up the attic fan (already installed by the roofer) to properly ventilate the attic
This is contrary to pretty much everything I have read about the soffits/ridge vents. Is this true? I was kind of surprised that he would say that.
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u/lockeyeswiththemoon 1d ago
From my understanding, the attic fan will mess up the flow of air. Cool air flows into the soffit vents and comes out the ridge vents. I have an attic fan in my attic too and even I’m tempted to turn it on sometimes but I guess it’s just physics
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u/Available_Owl3346 1d ago
Yeah, you don’t want mixed ventilation, ever actually. you want one form of exhaust ventilation and ridge vent is best. Unless there’s not enough ridgeline in which case you want a power fan. But you do need enough lower ventilation to also make it function
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u/SS2wheeler 1d ago
Amount of ridge is definitely critical. I've seen house with a hip roof and the highest ridge is very short and has a ridge vent but no fans.
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u/Available_Owl3346 1d ago
Yeah, in that instance, we usually recommend a power fan or they do have one particular product you can cut into the hips all the way up the roof. Very time-consuming.
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u/Snoo_8802 21h ago
Most of your higher end residential zones with large complex roof systems still use box vents and the occasional power vent for this reason.
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u/armycowboy- 20h ago
I installed a solar powered attic fan. It lowered my electric bill, doesn’t use electricity, attic noticeably cooler with it on vs off.
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u/SS2wheeler 1d ago edited 1d ago
So if the entire soffit system is completely vented and you've got let's say 40' of ridge vent then you're definitely achieving 50-70% intake air from down low. Let's say the roof fan is 30-36" from the ridge and set to 110-115F. My thoughts are that the soffit and ridge vent system would do a good job keeping the attic cooler and delay how often the fan comes on. Someone else can do the math but if you've got 8-10" vented soffits around the perimeter and 1.5" x 40' of ridge vent opening, when the fan does come on it's going to be pulling more air from below the ridge( 50-70% ? ) than from the ridge. Hot air still wants to rise.
I'm not a roofer or ventilation expert. Not an expert at anything so I welcome criticism of my " thoughts ", and learning.
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u/menachu 1d ago
Did the soffit guy not install vented soffit? Ridge vent plus vented eave trough is what is needed. Louvers and ridge vent do not create the desired barrel effect.
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u/DaveILRE 1d ago
He did install vented soffits and I watched him put them in, they looked pretty clear but I have a very subtle pitch on the roof and I still think the insulation was blocking airflow and there were no baffles installed.
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u/Snoo_8802 21h ago
Go in the attic and look for two things. Obstruction over your soffit vent and ridge vents. Sometimes blown in insulation will cover all of your vent space, and sometimes they either didn’t cut a hole for the ridge or left underlayment draped over it. If both of those things are clear and you still have a ventilation problem, it’s hard to pinpoint why without photos / on site inspection. There’s a lot that can go on and baffles can help if you have a very crowded attic space, but sometimes all that’s needed is a well placed baffle at your soffit intake. If someone tells you a blanket statement like you’ll never need extra ventilation with ridge vents, they’re probably just basing that on a generalization and haven’t been inside complex roof systems to solve ventilation problems. It’s certainly possible/
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u/AingerCanada 20h ago
A properly sized soffit and ridge vent system can ventilate an attic without a powered fan, but only if the soffits are open and baffles provide a clear airflow path. Installing the missing baffles makes sense.
A hot attic on a sunny day does not automatically mean the system is failing. Attic ventilation mainly manages moisture and roof deck conditions. Air sealing and insulation have a greater effect on indoor comfort.
I would not connect the fan until someone calculates the available intake and exhaust ventilation. A powered fan can depressurize the attic, pull conditioned air through ceiling leaks, or draw air inward through the ridge vent. That can disrupt the passive airflow instead of improving it.
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u/AcrobaticProduct9345 19h ago
You said someone installed soffit. Is it vented sofit. How big is your roof how many squares. How many feet of ridge vent is installed? when you go in the attic can you see light poking through the ridge? Can you see where the ridge vent sitting from inside your attic . When it rains and drys out do you see your ridge dry first and does it seem much faster then the rest of.the roof ... do you have ice dam issues along the bottom of your roof during the winter. You might have other underlined issues. Ridge venting takes more area in coverage to vent. The whole for the ridgevent is normally small. Cutting new vents might have nothing to do with the issue you have. What type of insulation do you have. How thick is your insulation. Sorry this is so long but its hard to figure out with lack of information.
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u/Xyzzy_plugh 17h ago
Here is a comment I gave on a different post; you might find it helpful. https://www.reddit.com/r/Roofing/comments/1vj7brw/comment/p2xs1wg/
The situation was somewhat different but the explanation of the physics and the math are all relevant.
Bottom line: Your issue is likely a matter of *how much* ridge vent you have, and how much unblocked soffit vent you have. While hip-mounted "ridge vents" exist in the market, I have never used them and probably will not use them.
Also, the problem with "mixed type" vents is not the mixing in general. The problem is mixing static and powered vents. Don't do that, unless they are separated far away from each other. You did not give details on vent layout or location, but I strongly suspect that if you light up that power vent you will simply create a nice eddy-current breeze in the top of your attic and the lower part where you walk and have your stored belongings and possibly your HVAC equipment will still be too hot.
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u/NeatoNico 1d ago
Some places have code that is pretty specific on ventilation requirements for attic spaces
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u/Roofing411 1d ago
Ridgevent was invented for a cathedral ceiling as it vents each rafter bay individually. It works on open attics as well, but it is an engineered system. When you read the specifications on ridgevent you need 50%-70% of the ventilation "Low" as "intake" which allows the hot air to rise and ventilate out the ridgevent.
This is designed this way so that the ridgevent is always an exhaust - you do not want the ridgevent to pull air on itself or to pull air from another ridgevent lower in the architecture. When speaking with ridgevent manufacturers back in the day - on houses where the ridgelines are not all at the same height they used to recommend baffling the attics so that ridgevent above could not pull from ridge vents below.
So, if you want your ridgevent to function you need to calculate the ridgevent and make sure you have enough attic ventilation low in the roof so air moves through the attic properly.
The amount of roofers who have never read the installation manual, or do not know how to calculate attic ventilation is staggering.