I have been able to reduce the leakage rate of a challenging house built in the 1920s.

Still, the homeowners are adamant about wanting to address a couple of tough spots, and I need some help. The two spots are the mail slot in the front storm door and the attic fan.

The mail slot:

The attic fan:

So, the attic fan is the focus for now. Notice the door hardware on each side of the wood panel walls. The HOs still want to be able to access the closets with whatever solution is pursued. They do not want to remove the fan.

Originally, I was going to fabricate a panel of rigid foam insulation that would extend from the floor to the ceiling. I was going to make sure the rigid foam panel could be easily removed and replaced. 

Any thoughts on how to seal the attic fan and\or mail slot in the storm door?

Thanks in advance!


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Well, it is a metal, single-pane glass storm. As for the thermal bridge concern, the front door is an older solid wood door and the mail slot in it is def a thermal bridge, yet I am not sure what could be done to address this. They lock the storm door, so maybe the best bet is to find a way to seal and insulate the mail slot on the main, wood door. By the way, door replacement is not an option for the HOs.

Ok I am confused - the mail slot only goes through the storm door, not the wood one? If it does go through the wood one also they do make covers with springs & weatherstripping

As for the "attic fan" that appears to be a whole house fan - they do make speciality ones with covers & you maybe able to buy or create your own similiar type of covers (If it is fully inside the attic & not the conditioned space I sense some confusion on just what should be airsealed & what matters)

As for that other duct - it needs to be pulled from it's current place & either run above the "attic fan" if it is for an intake or out through the roof if it is for exhaust based on this picture

As for the mail slot through the storm door, it does not connect fully to the mail slot through the wood door (i.e. it's an inch or two above the mail slot through the wood door).

Yeah, it's more of a whole-house fan than anything else. I have seen and fabricated some of the covers for whole-house fans, but I don't think that will work for this application, but I could be wrong. 

The fan is in the attic, but the attic is basically within the thermal boundary (as the roof and end walls are insulated). The issue is that the walls and roof have not been sealed in any fashion, but the majority of the leakage is still through the fan. I can see a great improvement for the house where the roof and end walls get a few inches of spray foam or at least a flash and batt approach. But, after hearing a lot from y'all about pressure planes, etc. I am feeling less comfortable about creating tight air seals in attics and\or basements when atmospherically-vented appliances are in the house. 

The duct is actually for the clothes dryer. Does it really make sense to vent it through the roof (because in this case they have a slate roof)? I can see moving it to a location above the whole-house fan.

My .02 then...

Spring & weatherstripped for front door then

I agree the area is pretty tight for prefabbed one unless they may consider replacing it with a slightly smaller more efficient one with integrated cover / switch --- If not you may consider making a drop down or swing up cover

Atmospheric venting appliances - either they replace with direct vent or we place them in their own area with fire rated door where they will not get any air from inside - only through exterior intakes

I bet they have a ton of issues with their clothes dryer & might not even realize it - the longest it should be is 25' and every little bend adds 5' to the length. No I wouldn't want to vent that onto a slate roof (I was thinking bath fan & even then I wouldn't want to on a slate roof) but it needs to be run lower & directly outside as quickly as possible.    

Thanks Sean (and others).

All good suggestions. Now I just need to approach the HOs in a way where they see the benefit in making such changes (such as upgrading to a smaller, high-efficiency fan and having the dryer venting re-directed). I will definitely be mentioning to them that some of my colleagues ("real experts") have helped invaluably in proposing said solutions!

One caution I would mention Patrick, is their anticipation of a significant improvement.  My experience has told me it takes a lot of little fixes to add up to something one can feel and/or measure.  Seal a draft that is blowing directly on where they sit might get a response.  But a wood front door and the attic, I would prepare them for little or no change.


I definitely have to agree with Bud

Should these areas be corrected, yes...

Are they liable to notice big improvements, probably not unless every time they sit down for dinner or watching TV a breeze is coming through the slot

Now as for the dryer hose - once that's cleaned out & rerun, they might not notice it in there power bill, but they should hopefully notice that the clothes are drying just a little bit quicker (careful though, that dryer could also be packed full of lint & might need service also)

Shoot I remember switching out all the lights in my house in Phoenix (about 30 or so 100 watt bulbs) to CFL's & my bill was still around $300 bucks the next month - i.e. no real perceived gain. With that said because I did track my usage year over year I could see how my bills were just a bit lower every month. Did I ever see that $8 a year saving per bulb - nope, but that's because we always turned them off when leaving the room, etc...

The SoloTube's I installed in the kitchen - again no perceived gain again on my bill, but it sure was nice not having to flip on the hallway light to get to the kitchen in the middle of the night because of the light coming in. Better yet was not having to turn the lights on in the kitchen during the day

The dryer vent should be replaced with a smooth wall pipe.  How long is the run.  The dryer run should not be more than 25' and each 90degree elbow adds 5 feet.

That fan is what 30x 30 or 36x 36 with metal flaps.   Its seems as if that is a conductor, isnt metal 400x more conductive than wood and wood is not a good insulator. That doesnt even consider air leakage.  That old inefficent fan motor on that would draw a lot of electricity. It should be a no brainer replace it and have an insulated cover made. The only insulated models I am aware of are not made for an exterior wall.


Do they need the mail to drop in the house? Why not let it drop between the doors. Patch the hole in the wood door.

Thanks Robert. I am probably going to bring up the idea of replacing the fan after all the input from you guys.

I only know of insulated fan covers for the ones installed in ceilings as well.

I'll Aldo address the idea of sealing the wood door. 

Forget about the storm door - it is already sinking huge amounts of heat to the outside in winter and does not add much of an air seal in the present desired condition.  I'd concentrate on the wood entry door - block off the outside of the mail slot with a decorative panel (or leave the original flapper panel in-place), foam the hole closed, provide a decorative inside panel; ensure all 4 edges of the door are properly weatherstripped.

For the whole-house fan, you do not say whether or not the attic space is part of the conditioned space or just used for storage.  If conditioned (or the HOs access the storage area often enough that it may as well be) then you should consider the roof/dormer walls/side walls the pressure/thermal boundary and the fan needs to come out in the non-venting seasons (can be replaced by a much smaller window fan that will work just as well and is easier to install/remove).  If not in the conditioned space, then consider the top floor ceiling the pressure/thermal boundary and construct a gasketed/counterweighted hatch panel for the hole over the stairs.  Raise the panel when needing access or turining the fan on; lower the panel during the extreme winter/summer temps. Edit - I now see that the HOs are considering the attic included with the lower conditioned space so you need to provide an alternative window fan other than this whole-house-fan-in-a-window.  With added insulation and reduced air flow the HOs might not need as much fan movement so you might suggest occupied area ceiling fans instead of this attic fan monster.  Also - insulated window coverings on the East, South and West sides will greatly reduce summer heat gain (which exacerbates the need to run the fan in the first place).

And re-run the dryer vent with hard PVC/joints (with clean-out plugs) to the existing exit in the dormer.

Thanks a lot for all your input David.

The consensus is to seal\patch the mail slot in the wood door.

I need to discuss with the HOs about removing the existing insulation in the rafters and end walls (FG batts). 

At this point my goal will be to convince them to replace the fan in the attic with a much smaller and more efficient one. I've been doing some research on such fans, any recommendations?


You don't mention the ages/physical conditions of the HOs, but I'm assuming they would not like an onerous Spring/Fall fan install/removal routine.  I have seen several dual-fan window units that seem to be fairly light and easy to install.  I would recommend 1 of these as a start, and add more (even in lower level windows) as needed after the retrofit work is accomplished.  I really think switching from fiberglass batts to spray foam, greatly reducing air infiltration/exfiltration and adding tight-fitting insulated window coverings will minimize the need for such fans to the point that maybe 1 lightweight unit will suffice.


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