Insulated door vs. insulated wall panel

[Ashful]

I am finishing (insulating, heating, installing receptacles) the room above my garage, to be a music studio. The space was roughed in, mostly insulated, and drywalled by the prior owner. However, one end wall, which was installed around an air handler for one of our HVAC systems, was somehow left un-insulated. Insulating this wall will be a real challenge (largely inaccessible and roof-line space), but that's a topic for another thread.

Of interest here is the pair of access doors, used once per year for servicing the air handler. They are currently un-insulated barn doors, filling a rough opening 50"W x 73"H. My first thought was to replace them with insulated double doors, but considering they really only need to be opened to service the air handler (less than once per year), and the considering the cost of custom double doors... I'm thinking of building or buying an insulated wall panel instead. The idea would be that this wall panel could be removed or re-installed with minimal effort, hopefully making use of the existing rough opening, although I could re-frame as necessary while I have things torn up right now.

Any advice? Can one buy such an insulated wall panel, or will I need to build? Another idea may be to leave the existing doors, and then just install some insulated plug behind them, which could be pulled out when access to the HVAC system is required.

 

[Ashful]

 

[Frozen Canuck]

I you want an insulated wall panel with rigidity it's going to be hard to beat a SIP (Structural Insulated Panel). We typically use a 6" here R 44. Don't know what the construction/manufacturing scene is where you live but it's worth checking out. 2 small cut outs from windows or 1 large one from...a double door should do the trick. They're trash unless someone speaks up for them. Most crews/manufacturers would be happy to trade for a bottle of good stuff.

Dont forget to put on 2 good chest handles so you can remove it. Cut right they fit real snug.

Those units have an adequate outside air supply? You don't want to choke them off.

 

[Ashful]

Good idea!

Not sure what you mean by "those units," as it's just the air handler for a traditional AC system. It has plenty of ventilation... an entire attic full, with soffet and ridge vents, to boot!

 

[semipro]

I think I'd consider 2" of EPS foam board with paneling/trim glued to the front of it. You could install some weatherstripping around the back and/or edges and make it an interference fit. Add handles as FC suggests to allow you to remove it.

In general, unconditioned space is a bad place for an air handler and duct work. Any chance you could insulate the entire attic space instead?

 

[Swedishchef]

I agree with FC and semipro. Those are 2 good ways to get the problem fixed. Not to mention the foam will cut down on the sound too.

 

[EatenByLimestone]

The foam would have a reflective barrier on one side that will radiate the summer heat back out of the room.

Matt

 

[woodgeek]

yarg, just glue some rigid foam board to the insides of the doors. For extra credit, you could insulate the handler too.

Before you bother, does it really get cold in there? Why can't you put foam board on the exterior wall (I guess, behind the handler) Remember, an R-1 wall in our climate costs 100 kBTU/year per sq ft. 20 sqft of wall at R-2, maybe 1 MBTU/yr, or $15-20/year in heating.

 

[Ashful]

I'm thinking of going with your plan of just insulating the back of the existing doors, woodgeek. Honestly, I'd love to insulate the entire space around the air handler, but this would be almost impossible at this point. That air handler is blocking my only access to that space, and behind is a large area where many roof lines come together, a mess of trusses and framing.

My concern with insulating behind the doors with rigid foam is draft and dust control. The space housing the air handler is a large attic bay filled with blown-in insulation (very dusty), and vented with miles of soffit and ridge vent. I will need some sort of draft control / weatherstripping that works in conjuction with the rigid foam on the doors.

 

[woodgeek]

I see. I think you will want some weatherstripping then. Infrequently opened, it will be easy and last a long time (unlike weatherstripping a front door).

 

[peakbagger]

The biggest heat loss is infiltration from the cracks between the doors. Replace the doors with a panel and the amount of crack space goes down and thus infiltration. With fixed panel you can have trim board overhang out over the trim and put a gasket between it and the wall plus put some resilient weatherstripping in the sides of the opening. Then screw the panel in place or get fancy and set some threaded inserts in the wall and bolt it shut. I have a similar setup to access my crawl space and when we ran a blower door test, there was almost no leakage.

 

[Ashful]

peakbagger, you and I are thinking along the same lines, with one exception. I think I'm going to leave the doors where they are, and do this panel BEHIND the doors, so that it's hidden. This way, I can focus more on function than pretty, and then hide this well-sealed panel behind the doors.

Bad idea?

 

[peakbagger]

That will work I would add some furring strips to reduce the opening a bit so you can have a lip at the front.

 

[jharkin]

The rigid foam is exactly what the insulation contractors did for our attic door. Its 2in polyiso, with cut outs to fit over the battens (same as you have), screwed in place and foil taped. The door is also weatherstripped airtight with rubber foam strips.



(edit: fixed crooked tablet photos)

 

[Ashful]

Your floors are amazing, Jeremy. What's the width of that plank in front of the door?

In my case, the primary difficulty in weatherstripping will be that these are double doors with no center divider, and the room will be carpeted. These challenges can be overcome with a threshold and removable center divider, or I could just make the foam board into a plug, independent of the doors. Keep the ideas coming, guys!

 

[semipro]

Your floors are amazing, Jeremy. What's the width of that plank in front of the door?

You won't find much pine (looks like pine to me anyway) that size anymore. Beautiful!

 

[jharkin]

Good eye guys. That one is a 19incher. I found 2 20inchers in the subfloor under my living room. Most of the main level finish floor is 12 in.


Its part of the enduring mystery of this place. Those boards could be from the 1700s, but they are installed with c1820 factory made cut nails. I would guess they had been reclaimed from an older building, but there are no extra nail holes you would expect in that case. Still can't make heads or tails of it.

 

[Ashful]

That's half the fun of these old houses! I was convinced my floors must be newer, since they're sawn only 6" - 10" wide, until a local architectural historian visited our house and convinced me they're original. I've since found evidence that he is correct.