Increasing ventilation in home w/ only gable vents


#1

All - sorry if this has been discussed before - but need some tips on how to increase attic ventilation in a 1950 colonial with 2 gable vents. I am getting frost on nail tips on the side of house that faces north - nothing extreme but i believe indicates a need for more venting.

House does not have soffit vents (or really any kind of meaningful soffit surface). Attic fan in roof present for hot temps only which works fine in summer.

My guy says add a ridge vent. Others say this is counteractive with gable vents. The soffits are only 1-2 inches wide so questionable (and costly/labor intensive) if that would be the answer. Seems I am dealing with typical 1950-era construction technique. Roof is 5 yrs old and no major construction is in process.

Insulation is throughout and probably equivalent of R19 (under a floor); no bath fan issues, and attic door reasonably insulated.

If a ridge vent is not compatible with gable vents and my soffits (or lack of) dont make that an option, what would someone in the know advise here?

Thanks in advance.


#2

hi there, i’m a residential roofer with 20yes exp. i believe the best answer without seeing it would be to ditch the attic fan and go with gable vents and ridge vent. your attic fan is drawing outside air in through the ridge vent. all the roofing specs will tell you to remove the fan. you want your attic space to be the same temp as the outside air temp. that is if the space is used for storage or remain empty. using gable vents will allow a cross wind to enter attic and exhaust through the ridge vent.


#3

Your best bet would be to increase the soffit venting with either a “smart vent” or “fascia vent”. If economically possible.

Otherwise add the ridge vent. There won’t be a problem.

And/or increase the size of the gable vents.


#4

Put regular roof vents 2-3’ up from bottom of roof every 10’ or so.It works.


#5

First things first… r19 is hardly enough insulation, you should be around an R_49 value. That will help alot with the leakage of hot air into the attic. Second, without any tyoe of soffit vents or smart vent the ridge vent will do nothing at all. Ridge vent must have soffit to work without short circuting the roof, another way to understand it is it will cut the roof inhalf and not ventilate the lower portions and you will be back in the same place you are right now just half of the roof frosting up. Smart vent will work rather well in this situation but it will tear up most of the roof to install it. Also the length of the ridge will determine if you can use it. If the ridge is all cut up then ridge vent will not work since it only flows a max of 18 inches per foot.

To properly do any ventilation you will need smart vent and either static can vents or ridge vent, but you must have the smart vent for either of them to work properly. The gable vents are what is called a gray area in the industry. Some say its ok some say its not. I was taught to close them off when using ridge vent. Either way smart vent must be used. Hope this helps. Have a great day


#6

Thanks all for the replies. Appreciate the perspectives on the ridge vent. I seem to be on the cusp of any issue.

I went up there this morning and no moisture on nails (it is under 20 degress out in NJ today) until I left the pull down stairs open for awhile - and then just very slight in one area near the opening. No more frost since making sure the insulation was complete with no voids (still R19). Previously there were some voids over two bathrooms.

My house has the original gable vents with the wooden slats in them that direct air upward - which have been subsequently covered from the outside with a more updated looking plastic vent/slat trim cover. So looks like I have kind of two sets of slats/covers at each gable vent - the original wood slats which have been covered from the outside with a vinly/plastic slat-type cover and bug screen.

I am considering removing the original wooden slats in the gable vent from inside the attic since the slat type cover and bug screen cover has been added to outside when the house was re-sided. Thinking this may give a little more airflow plus allow me to clean the bug screen from the inside which has a little lint in it at one end of the house.

Any additional thoughts on this appreciated. Since my issue is slight, I am trying to avoid major construction considering the expense and the fact that house has survived for 57 yrs ok with the original roof sheeting/planks. thanks!