Replies

1. Expert Member
   Peter Engle | Dec 09, 2020 04:41pm | #1

   There are too many variables here to really provide an answer, including exactly how you use the door. I have a dog door cut into the storm door outside my primary (energy efficient) back door. The dog can only come and go when the interior door is open, and that's most of the time when the weather is nice. We don't generally leave it open when we're not home, unless the dog is home alone and it's going to be a while.

   If you're installing a permanent through-the-wall sort of door, then it's going to have a permanent impact on energy and one of the multi-flap style doors would probably be appropriate. The only way to tell its impact on blower door testing is to test it. Most likely, the 50 Pa test pressure would be enough to open most of the flaps, so you'll have to cover it for the testing. If the flaps are magnetic or otherwise reasonably self-sealing, you can probably ignore its effect on air leakage. You'll pay an R-value price, but for only a few square feet, that's not much.

   As far as security, I've always believed that if the dog door is big enough for someone to crawl through, then the dog is probably big enough to discourage crawling through the door. Although in our house in CA, we had a BIG lizard come in through the door to steal dog food. The dog didn't have a clue what to do about that, so she just watched.

1. Expert Member
   MALCOLM TAYLOR | Dec 09, 2020 09:24pm | #2

   Peter,

   We have had racoons through our cat door that ransacked the kitchen, but a giant lizard? No thanks!

2. 
   bluesolar | Dec 09, 2020 10:13pm | #3

   Interesting. I read recently that burglars trivially overcome the dog problem by simply giving them treats. That would almost certainly work on our dogs...

   But they're small, so we could go with a medium door. Only very small hominids could get through it, but I expect a marked increase in crime rates over the next few years because of the anti-police activism, and that increase should include minors. It was minors who burglarized us over Christmas a few years ago, totally cleaned us out. Minors are small, so I'm concerned about the door. But I don't want our dogs to have to hold it for the 10 hours we're typically gone on most days...

   Sealing these types of penetrations is an interesting problem. I've been toying with different ideas for handling vents and fresh air circulation, automated closures and so forth. I guess the R-value hit won't be significant, though it looks like the air sealing of a lot of these dog doors doesn't hold up over time. Not a lot of engineering effort going into them, not the kind of robustness I've seen in defense contracting. I'm tempted to organize a crack team of engineers that would focus on nailing the hell out of simple products, one after another. So start with something like the perfect bucket or gate latch (Home Depot actually launched a sort of perfect bucket commissioned by a similar effort, but I don't think they sell it anymore), and just knock everything out of the park by bringing humanity's accrued capabilities at this stage in history to solving all these problems that the market has so far done poorly with.

1. Expert Member
   MALCOLM TAYLOR | Dec 10, 2020 09:21pm | #7

   BlueSolar,

   "I'm tempted to organize a crack team of engineers that would focus on nailing the hell out of simple products, one after another ... and just knock everything out of the park by bringing humanity's accrued capabilities at this stage in history to solving all these problems that the market has so far done poorly with."

   The hubris in this post is just stunning.

2. 
   jberger | Dec 10, 2020 02:55pm | #4

   I'll share my experience, but it is probably not directly relatable to your installation.
   We have a couple of large dogs and 2 cats, so we dedicated a basement room with exterior door as their space.
   They are free to come and go during the day, but we lock them in the room at night.
   The house came with a petsafe flap installed in the exterior door of the room.

   After we moved in, I replaced the flap with the "extreme" version that has a set of magnets that help hold the flap in the closed position. One of our labs likes to eat everything, so he usually consumes one flap a year.

   The flap doesn't seem to change the airflow thought the opening by much, if at all, when it's windy outside. But it does help keep the humidity lower during the summer and a bit warmer in the winter. On cold nights, I stick a 1" piece of foam between the flap and the plastic panel and that makes a much bigger difference.

   The amount of dust and dirt that comes in through the petsafe door is staggering. I ended up air sealing the room itself from the rest of the house to keep the dust and humidity in check.

   We are replacing the entire exterior door as part of a renovation, and I'm leaning toward the freedom pet door. It looks like it is engineered to work much better than the petsafe unit and it's cheap enough to replace the flap when one of the dogs makes it a chew toy.

   https://energyefficientdogdoors.com/product/insulated-dog-doors-for-doors/

3. 
   andy_ | Dec 10, 2020 05:29pm | #5

   When I converted our detached two car garage into a work studio with some expensive equipment inside, I had all the same concerns:
   1. A dog that can't decide if it wants to be inside or outside for more than a few minutes.
   2. A dog that is big enough to need a door that a person could squeeze through.
   3. Air sealing.
   4. Security
   My solution was to use a standard dog door flap on the outside, but to build a 1.5" thick solid door inside with a deadbolt so that it can be easily closed and secured when we're not in the office. Couldn't be more simple really. Two pieces of 3/4" plywood glued together, a couple of hinges, a deadbolt, some weatherstripping, and a little trim. If you've ever hung a replacement door slab then you have all the skills needed to do this.

4. Expert Member
   Deleted | Dec 10, 2020 09:20pm | #6

   Deleted