Roof ventilation

The homes have isynene insulation over all of the living areas.
The roof structures over the open exterior patios are completely enclosed with no ventilation at all.
Both new homes under construction and existing homes that have been inspected by the city.
The builder and the builder’s architect claim “common practice” and “no problem”.
I am looking for proof of the need to ventilate these areas.


Here are some have many more… Roy

Thanks Roy

Roy, Thanks for the information.

I am referring to roof enclosures over exterior patios. There is very little and somewhat conflicting information available about these areas.

Hmmm good post. It’s common here to see them enclosed with no ventilation. With no conditioned floor below I always thought it wasn’t that big of a deal. I am curious now though.

as with any contentious installations
you can advise client of BEST building practices, cite code and provide whatever documentation you deem necessary
the AHJ has the final say and the purchaser gets to live and pay for any adverse end results
we have properties that are being inadequately built that get certificates of occupancy every day, follow the money
this among other factors is the main reason we have job$
gotta love America

Gotta to love Canada also as this keeps us hoping!

What deficiencies and adverse conditions result from these attic spaces not having adequate ventilation.

Plywood delamination and wood rot (humid climates)

If moisture gets into the attic yes .
I expect we will see many sealed attics in the future.

No…cool/temperate & cold climates

Thanks Barry;

Those studies and testing results are on and about attic spaces over interior living areas.

My concern is ventilation requirements in roof cavities over outdoor non-conditioned areas.

I’m surprised there hasn’t been any more comments on this.

Many might be not convinced there just might be a better way.

Well I don’t see how it’s a problem for outside especially when the walls are insulated. I am interested in learning though.

I am trying to find scientific data that either confirms or disproves the need for ventilation in roof cavities over unconditioned spaces.
Specifically in Florida but certainly interested in different climates as well.


That’s still not what he’s looking for

Seeing more and more sealed attics due to the ever increasing energy efficiency requirements.
Like yourself most I see do separate the conditioned areas of the home from unconditioned I.E. garages ,covered patios. The areas that are not sealed construction must still be vented per section 806.2 of the IBCR. The total net free ventilating area shall not be less than 1/150 of the space ventilated except the reduction of the total area to 1/350 is permitted provided that at least 50 percent and not more than 80 percent of the required ventilating is provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet above the eaves or cornice vents with the balance of the required ventilation provided by eave or cornice vents