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mgarman
Exterior vs. Interior Doors
mgarman

I am replacing the door from my family room to my 3-season sunroom. Currently, an exterior grade patio slider is in place. I am looking to add french doors instead, so when using the room, I can open it up wider.

My question is around interior vs. exterior grade doors. Exterior french doors are a lot more expensive than interior grade. Do they provide that much more insulation? The doors do not need to protect against wind/water, etc. obviously. However the sunroom is unheated (has a heater, but we keep it off most of the time except when using the room for parties, etc). We are in the Baltimore, Md. area so we do have cold winters.

Would interior single pane doors, with perhaps a cloth doorstopper underneath keep the main part of our house warm enough or do the double pane/weatherstripped doors really provide that much more protection?

ed21
Re: Exterior vs. Interior Doors
ed21

I would go with an exterior grade door with weatherstripping. The insulation glass will provide you with more comfort(less drafts) and will be less likely to have condensation. Forget the cloth draftstopper and use real weatherstripping. Insulating glass will help in the summer too.
Don't forget a French door consumes wall space on either side, while a slider doesn't.

dj1
Re: Exterior vs. Interior Doors
dj1

Definitely use exterior doors in this case.

Sombreuil_mongrel
Re: Exterior vs. Interior Doors
Sombreuil_mongrel

If you want an uninterrupted floor you would have to use an interior set. If the idea of a full threshold and sloping sill between two living spaces is okay, then an exterior set will give you full weatherstripping at the most economical price. There are weatherstripping solutions that can be implemented on ordinary solid wood doors that are almost undetectable and do not have a threshold, but they are not cheap to install. Google "mechanical door sweep".
manufacturer of the best metal weatherstripping, including mechanical door bottoms:
http://metalstrips.accurateweatherstrip.com/viewitems/door-weatherstrips/automatic-door-bottoms-soundproof-lightproof
Casey

Re: Exterior vs. Interior Doors

Most likely utilize outer surface entryways as a part of this case.

drewp
Re: Exterior vs. Interior Doors
drewp

I have the exact same situation as you AND I live in NJ (similar climate). We had an exposed deck before we made the three season room SO I have an exterior grade French door and it works and looks great. Our sun room will get quite warm in the winter with bright sun exposure (70ish degrees) so that we can sometimes leave the door ajar. I couldn't imagine having a interior grade door in place. On cloudy days, or at night, the adjacent interior room would be freezing.

Fencepost
Re: Exterior vs. Interior Doors
Fencepost

Differences between exterior vs. interior doors:

  • Size? Exterior = 1+3/4" thick; interior = 1+3/8" thick
  • Not wood, or wood-skinned? Exterior = insulated; interior = not insulated
  • Solid Wood? Insulation value about the same
  • Glass? Exterior = double-pane; interior = single-pane
  • Weatherstripping? Exterior = yes; interior = no
  • Hardware? Exterior = stronger, more secure; interior = weaker, less secure

As others have noted, the temperature difference between the sunroom and your home can be very great. The superior insulation qualities of exterior doors make them the better choice to be able to efficiently maintain the temperature in your family room.

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