Framing a darkroom against concrete wall

[Drew Wiley]

I put R23 insulation in between in my own darkroom - it's the coziest place I've got - both easiest to warm up and to keep cool in summer, just like a cave, at least the inner parts of it. The more shop-related outer room isn't pleasant in winter at all.

[archphotofisher]

Here's one way to do it, always like these guys they listen to their architects.

https://www.youtube.com/watch?v=oKQdo88Ne74

[cuypers1807]

I kept me concrete walls open. What ever you decide, I recommend you paint the concrete with a latex base masonry waterproofer. It will do an amazing job keeping moisture from seeping in from outside.

[Louie Powell]

When I built a darkroom in the corner of the basement in our former home (built to early 1950 codes), I was faced with this situation, but with the additional complication that there were major plumbing runs along both of the cinderblock walls. I opted to construct lightweight sheetrock walls to completely enclose the darkroom and spaced far enough away from the cinderblock to allow for the plumbing. By lightweight, I mean that I framed the inner wall with 2x3 studs rather than 2x4, on 24" centers rather than the standard 16" centers. I did apply a coat of waterproofing paint on the walls to try to minimize moisture incursion through the concrete. Also, there was a basement window in one wall that I removed and closed up with cinderblock. The main sanitary drain for the house was along one wall, with a cleanout where it penetrated the wall to go out to the septic tank; I built the inner wall with a removable panel in case it was necessary to get to that cleanout. I never actually needed to use it, but I'm sure that if I had omitted that opening, we would have had a plumbing problem that would have required destroying the wall. And the drain from the kitchen passed along the second wall, so I framed the inner wall far enough out that I could just barely squeeze into the space in case it was necessary to work in that area. That was good planning because we did later have to replace that pipe.

The situation in our new home was different because at the time it was built in 2002, local building codes required that basement spaces be insulated. The builder had framed an inner wall, and installed insulation and a vapor barrier, but did not go all the way to put up sheetrock. So all I had to do was hang sheetrock.

In both instances, I was concerned about light (err, dark) control, dust and humidity. In the first instance, I put sheet rock on the ceiling joists. The ceiling height was only 7', and applying sheetrock directly on the joists maximized the interior space. In the newer house, the joist height is 8', so I opted instead to hang a suspended ceiling (I really don't enjoy hanging sheetrock, especially overhead).

[Ron McElroy]

Like others have mentioned I framed my basement darkroom away from the concrete walls and used black plastic for a vapor/light shield.

[Ernest MacMillan]

Without really understanding the dynamics of moisture in your home, I recommend 1-2 inches thick pink foam attached with tapcons and fender washers. This gives you insulation and a vapor barrier at one shot with a fairly simple installation process. You could caulk the edges to the concrete and you can leave a 1-3 inches gap at the top and bottom to monitor leakage of water or progress of termite tunnels. I personally would then put a 2x4 frame insulated with fiberglass and sheathed with drywall in front. But you could just paint the foam and it is easy to remove if you sell your house and someone balks at your work.

[John Layton]

What worked well for me are the Dow/Corning "Insult-Pink" rigid foam boards, the edges of which are cut in to allow for flush (surface) mounted 1/3 wood firring strips (which do not contact the cement) - which are then drilled to accept cement screws long enough to secure to the wall. Creates its own vapor barrier, good r-value, and the firring tips provide enough material for attaching sheetrock. Has held up well...the only caveat being that any wiring needs to be surface-mounted.

[domaz]

Thanks for all the responses. I think my plan for now is to keep the wall open, but frame in a way that I could add rigid foam with furring strips later on. I don't really trust this wall not to leak at this point, although it seems dry so far this year, even though Northwest fall rain is in full force. At some point I will need to develop a strategy for the ceiling too. This is a 1920s house with a very low basement ceiling (76 or so inches), the ceiling joists aren't particularly even on the bottom so hanging sheetrock may be a challenge. Others have told me hanging sheetrock in old houses like this usually requires a lot of shimming, so we will see how that goes..

[Roger Thoms]

Have you considered leaving the ceiling open and simply painting it?

Roger

[domaz]

Have you considered leaving the ceiling open and simply painting it?

Roger

That's a good idea, sounds a lot simpler. The only downside might be that dust seems to come down from the small gaps in the subfloor as people walk overhead. This is an old pine planked subfloor, not continuous plywood. Having said that maybe I could add some plywood from below to shore things up and keep out the dust at the same time.