Why is venting necessary?

[Pilvr83]

I insulated my garage and have two small windows in a loft area. For a while was cracking these windows but have noticed I have a lot of humidity (live in Florida) so I closed them.

I do have an opening near the garage door (garage door not completely sealed to floor).

I have Hardy board (cement board) as siding. Is it really necessary to vent if the garage is not really air tight?

Should I purchase a cheap vent and drill hole at roof peak? The window idea was okay until we got a lot of rain.

My garage is now a lot more pleasant to work in since I closed the windows.

What I am asking is it really necessary to vent and if I don't how will I know I should have?

Thanks again,

Greg

 

[holdover]

improper venting on a structure will usually lead to wood rotting, mold etc..

 

[Leaflessshadetree]

Do you have a ceiling? Insulation? What type of roofing?
Steel roof, no ceiling, or insulation venting will have minimal effect.
If you do vent, lower vents are as important as the ridge (or other style) upper vents.

 

[bigdav160]

Add A/C

 

[BillK]

Greg,
The biggest issue will be the life of the roofing shingles. I found this out the hard way when the shingles on my detached garage started to fail after about 10 years. Heat will rise and it all goes up and heats up the roof to an unbelievable temperature. I am in Maryland, I imagine it will be a lot worse in Florida. When I redid the roof we added a ridge vent and soffit vents so hopefully it will last a lot longer this time.

 

[DenisG]

I insulated my garage and have two small windows in a loft area. For a while was cracking these windows but have noticed I have a lot of humidity (live in Florida) so I closed them.

I do have an opening near the garage door (garage door not completely sealed to floor).

I have Hardy board (cement board) as siding. Is it really necessary to vent if the garage is not really air tight?

Should I purchase a cheap vent and drill hole at roof peak? The window idea was okay until we got a lot of rain.

My garage is now a lot more pleasant to work in since I closed the windows.

What I am asking is it really necessary to vent and if I don't how will I know I should have?

Thanks again,

Greg

You don't say how you're measuring the humidity. If you don't have one, there are inexpensive digital thermometers that display relative humidity as well as temperature. They might help you determine cause and effect.

There are also powered ventilators that are humidity controlled (like this one): http://www.amazon.com/dp/B00336G1ME/?tag=atomicindus08-20

Louvered vents would also help to keep the rain out.

 

[gungatim]

My wife's uncle is a retired building contractor. he always told me "Ventilation is more important than insulation"...

 

[MScott]

Venting should be on the outside of your insulation. Opening or closing the windows in the loft has nothing to do with proper venting, that is just affecting the living space inside the insulation unless you have insulated the floor of the loft and not the ceiling or roof. As mentioned, you need lower vents (probably in the eaves and upper vents near the peak to get a constant flow of air between the insulation and the roof. Air conditioning might make the place more liveable but will do nothing to improve venting.