Better attic insulation options

Ooops- forgot....

Radiant barriers were mentioned earlier. They are not a terrible idea in FL, and can be retrofitted. Staple to the underside of the rafters, allowing air space above.

Do the ridge vents have trap doors that only allow air out not in? I'm hoping they do. If not it means I have an army of something up there slamming doors all day long.

SVreX wrote: There is a lot of pretty good general info in this thread, but a lot of it doesn't apply to your house. Let me interject a couple of things... The things previously referred to as "troughs", "tunnels", and "chimneys" are correctly called baffles. They are available in both styrofoam and cardboard. One correction... in most cases, these may not help with ventilation. They keep insulation in place. If they are not there, most of the time your insulation has fallen into the soffits, so you have plenty of ventilation (but lousy insulation). You said you have lots of "off-ridge vents". It is unlikely you have enough with a hip roof. You would need something like 30 of them, all in the top 1/3 of the roof. Since there are none on the front, my bet is you don't have enough. But it doesn't matter. Read on... A hip roof is a trap for natural ventilation. There is insufficient ridge area for the volume of the attic, especially in FL. It is NOT POSSIBLE to have adequate natural flow-through "chimney" ventilation. Don't bother trying. Your solution will be those powered mushroom style roof vents. You will probably need 2. Buy ones with thermostats, as previously mentioned. They make them solar powered too, which will mean no power consumption (but reduced efficiency when they get dirty). After you deal with the ventilation, consider insulation. You should have R-30- R-38. That would be 14"- 18" of loose filled fiberglass. Stick a ruler in it, and see how thick it is. I'd be shocked if you have more than 8". Don't try foam. It is almost impossible to retrofit well. Just blow more fiberglass on top of what you've got. I'm not working these days, so if you need an installer, give me a call. Don't mind a road trip.

Email coming your way!

http://www.nachi.org/installing-attic-insulation.htm

Refer to the rafter baffle below:

We have an upstairs in our cabin and we used rafter baffles. They were styrofoam and we used them for something like 10-12'. We had batt insulation over them since there were just joist and not trusses.

Curmudgeon wrote: That's how most houses are built and it can be considered a 'thermosiphon' system. As hot air rises and escapes it draws cooler air in at the soffit. They do need help sometimes and that's where the powered vent comes in. If you get one with a thermostatic switch it will only run when needed.

And thanks for the insight Curmudgeon. Never cease to be amazed at the things I can learn thanks to GRM.

RossD wrote: http://www.nachi.org/installing-attic-insulation.htm Refer to the rafter baffle below: We have an upstairs in our cabin and we used rafter baffles. They were styrofoam and we used them for something like 10-12'. We had batt insulation over them since there were just joist and not trusses.

That's a good diagram.

As noted earlier, even if the insulation was installed tight against the roof deck when new with no baffles for ventilation, it is almost certain on a 14 year old house most of the insulation would have fallen into the soffits, which makes plenty of ventilation but leaves big holes in the insulation.

Ventilation at the bottom of the roof is unlikely to be the problem. There is nowhere for it to exit at the top, because it is a hip roof with insufficient ridge venting.

Hot air rises. Even with good eave/ soffit venting, an attic WILL NOT ventilate without exit vents at the top.

And no, Mr, Joshua, ridge vents do not have "trap doors". But your bathroom vent fan and range hood exhaust fan do.