Plasterboard and Plumbing - Help Please!

[Joze]

Hi all,

I'm currently building a new darkroom in my attic. It has floorboards, plumbing for hot and cold - or will have, & electricity. I want to section off part of a larger space by building plasterboard walls. What is the best and simplest way of ensuring I don't get light leaks through the joins?

Also on the question of plumbing, what sort of taps system is best, would you say? (I've only ever used the bathroom ones before and now have a chance to buy specially for the darkroom sink) - e.g. separate, or mixers? I don't plan to put in a temperature guage system as I've never used one so far (if this is short-sighted please say) but I want to put in water filters. Any advice on which sort/specifications? (I live in London, moderately hard water.)

Your thoughts are much needed and most welcome!!

[Monophoto]

Joze -

The usual practice in using plasterboard (aka sheetrock) is to apply a joint compound at the point where sheets join together. The joint compound is a plaster-like grout that you apply with a trowel. You put an application over the joint, then lay a strip of tape (either a paper tape or a fiberglass web tape) in the joint, and smooth everything out. If you use the paper tape, it helps to wet it first - otherwise, the dry tape will pull water out of the compound causing uneven drying and cracking. After it dries, you put on a second application of the compount. When that dries, you sand it smooth. The resulting seal is light and dust tight, and after it is painted, it is totally invisible.

Make the individual applications of joint compound as smooth as possible. While you will have some sanding to do, you don't want to have to smooth down mountains! And be careful when sanding - if you dry sand with sandpaper, wear a mask! Alternatively, you can use a damp cellulose sponge to wet-sand the dried compound.

By the way, the edges of sheetrock have a slight taper - the idea is that when you join two sheets, the tapers on adjacent edges provide a recess for the joint compound and tape. That way, the finished joint will be smooth and won't cause a bump on the wall.

Sheetrock comes in standard 4 foot widths, with standard lenghts of 8, 10 or 12 feet, so that presents the question of how the sheets are applied to the wall - horizontally or vertically. Commercial sheetrock application contractors actually use larger sheets (I have always bought 8 foot sheets because it's easier for me to handle), and they apply them horizontally. That means that there will be a horizontal seam that bridges across several studs. I prefer to install sheet rock vertically so that the seams line up with and on top of a stud - the fact that there is a stud behind the joint seems (to me) to make it easier to do the joint.

The fixture I chose for my darkroom was intended for use at a bar - it is a mixer valve with a high neck to allow me to get bottles under the faucet. I have worked in darkrooms that have a thermometer built into the faucet - that's a convenience, but not something that I would pay for.

I don't know if you necessarily need to filter all of the water used in a darkroom - in fact, I would imagine that you won't have a lot of particulate in the potable water system in the London area. We have hard water in our area, and chose to install an ion-exhange water softener for the whole house. I used to do Cibachrome printing, but found that I could not recalibrate after the water softener was installed. Fortunately, I could not detect any impact from the softener on my black and white printing.

We also ave a drinking water filtration system in our home that includes both a carbon filter and a reverse osmosis unit - this feeds a separate tap in the kitchen. I use water from that tap for processing film.

[srs5694]

Monophoto's done a good job of describing the basics of plasterboard installation. One possible exception: As you (Joze) are in England, I'm not sure the 4-foot widths Monophoto mentioned would apply -- or maybe they do, if building construction standards haven't shifted in decades. That's a minor detail, though. I do recommend you buy a book on home improvements, or at least look up the information on the Web. The plasterboard supplier might also have some pamphlets on plasterboard installation. Any of these sources should give you the extra details you'll need.

FWIW, I recently finished putting up some plasterboard and doing other improvements in my darkroom. Getting it light-tight was not a problem. The plasterboard itself is light-tight, as are the seals around the joins created by the joint compound. Holes in the walls for plumbling and electrical fixtures are another matter, but they aren't too difficult to seal up in one way or another. Unfortunately, I think I laid on the joint compound a bit too thickly; my joints all bulge a bit and are rather irregular. A couple of joins also aren't perfectly flat because of support problems. If I were to do it over again I'd add some framing to what was already there in a couple of places, use less joint compound, and sand more thoroughly. That said, I'm not unhappy with my work. It does what it's supposed to do, the fact that it's a little lumpy in places doesn't bother me in my darkroom, and I've learned enough that I'll be able to do much better if and when I do it again.

As to water, I can't imagine that separate hot and cold taps would have much of an advantage over mixed taps. Having multiple taps is another matter, though. If I had more money to spend on it and if I were to do it over again, I'd put in a bigger sink than I've got (I had to settle for an ordinary utility sink) and put in at least two taps. That'd let me do the final rinse step on film or prints while simultaneously washing up tanks, trays, or whatever. If you do this, you could filter one of your taps but not the other.

[gordrob]

In order to keep the amount of dust to a minimum after installing the sheetrock (drywall over here) I covered the walls with cheap wall panelling and offset the joints. Very little taping or mudding and no sanding involved then. A little more expensive but a lot cleaner in the long run. Also no priming or painting of the sheetrock.

As for plumbing I use two sinks - one for trays and one for washing and cleaning bottles and trays. The tray sink has water temperature control and uses a lab type faucet with three different outlets. I use quick connect couplers on one of the outlets to change over to print or film washers quickly. All water pipes are on the outside of the wall so if I want to change any plumbing I don't have to open up the walls to get access to the pipes. The second sink has just H&C water with no temperature control.

Gord

[Bob F.]

Make sure you get the plasterboard with the feathered edge as described above: you can get it with straight edges but then you need to skim it - not a job for the inexperienced... I did one wall in my kitchen using feather edge board nailed to 2x2" battens and it's fairly straightforward. A quick google will pull up articles on how to use plasterboard and build timber partition walls.

I just use an instant water heater (3kW) for hot water in my darkroom - don't see the point of using industrial strength mixers unless you are plumbing in a minilab or something...

One thought occurs: your floor. What type of joists are the floorboards laid on? Most attic joists are only designed to take the weight of the ceiling that is nailed to them. Unless they have been reinforced, you may have problems - make sure the ceiling below does not start cracking from the flexing as you walk around and put tables etc in there.

Have fun! Bob.

[Rlibersky]

Bob makes a good point. If the joist are 2x6 you could have an issue with ceiling cracks below.

How hot does your attic get? That could be a big problem, without air conditioning. Then you would have to be careful not to blow a lot of dust in with the heat or cooling system.

I've found many thin coats of joint compound is better then a few heavy coats. Less screaming and sanding.

Good Luck
Randy

[Joze]

Thank you all very much for your help and advice - this should set me in the right direction. Fortunately I have helpers otherwise it would be hard, but I'll be doing the decison-making and organising myself!! I feel a bit more confident now. No doubt I will come back with more questions, as they arise though!....

I'm also following Cheryl's thread.

What type of joists are the floorboards laid on?

I think I'm O.K. here, the joists are the same as the rest of the house - the floorboards are original. It's a great space, max. height 15 ft, headroom everywhere except into the eaves, which I will have to block off in my darkroom bit, along with the roof areas, for light & dust (& insulation). Half the houses in our road have original rickety stairs up to the attic (which also has original window) but when the houses were built (1908) you had to pay an extra £20 for the stairs (which our original owners didn't do, so we have the hatch and ladder, unfortunately). People with the stairs use the room like any other, but unfortunately for us to put in new stairs etc. now we'd have to follow building regs which would involve more reinforcements etc. and the whole floor coming out, at a cost of around £30,000 minimum. My own view is our neighbours seem to be doing fine with their original "top floors" so we should be 0.K. The best thing about it is that when we saw round the house the estate agent didn't show us the attic (which is 20ft x 20ft at least) so it was a fantastic surprise. And until we can afford the full conversion, ALL MINE!!!!!

How hot does your attic get?

It does get a bit hot in the summer (but this IS England). There is a largish window (outside the darkroom space) I can open - I hope it won't be too much problem with dust. I'm planning to get an air filter to filter out fumes.

[Matt5791]

OK - I think I can add some details here - I also renovate and convert historic buildings (most recent was converting a medieval barn into office space - sounds awful, but was very sympathetic and better then converting to a house)

You should build studding from minimum of 2"X4" softwood sawn timber (sized in metric but still known as 2X4 in builders merchants) Plasterboard can be had in 8'x4' or 3'x'6 - you might find 3x6 better to handle up into an attic especially if you are doing it on your own. Also you only really need 3/8" thickness as opposed to 1/2" (12mm) which, again, makes the sheets easier to handle.

When you build the stud, start with a base plate - one piece of 2x4 running across the floor where the wall is to be. Affix this to the floor at reasonable intervals with probably 2"1/2" screws - these slightly counterbored (if you are driving them in with a drill/driver they will sink themselves) will make an ideal penetration into the floor - highly advise piloting first with a 1/8" (3mm) drill bit. Ideally position the screws slightly off centre in a zig zag alternately. From this base plate you can take verticals up to the roofwhere you will have positioned another timber to fix them to. Position the verticals at 400mm centres. You can then position the horizontal studs between them.

As Bob says, get the feather edged boards and you will be able to simply mix some filler for this purpose and trowl it over the crack in one swoop. Also screw the boards to the studding and if you are using a drill/driver set the clutch to a weak setting otherwise you will just pummle the screws right through the board.

As an extra, for what it costs, get some fibreglass wool and line the roof with it between the rafters and cover with plasterboard - lot more work but it keeps the heat out aswell as the heat in - attics get stupidly hot in summer and cold in winter.

I think we are in a similar position as I am just doing exactly the same thing to my attic! although it sounds like you have a better attic to start with than me. I will however definitely be lining the roof with fibreglass.

Matt

[Robert Hall]

Don't forget ventilation. You need to have fresh air in there with chems. Fans for the WC work well.

[Joze]

Thanks, Matt and Robert.

A question for Matt : I'm thinking about insulation, but to do the whole attic is a major task, as it's pretty big. The darkroom bit will just have one wall that is made up of eaves - of the others one is brick (the adjoining wall of the next house), two will be plasterboard (one containing the entrance). The ceiling of my 'darkroom box' will be suspended below the roof vault (supports are already there from when roof was replaced some years ago), covering just over half the room. I could just insulate the one wall that's going to be boarding over the eaves for now, and possibly the rest later if lack of insulation is a problem (it would be hard to get above the 'ceiling' anyway, as the supports run all the way across the ceiling vault, not enough space between them - why on earth did they do that??). Do you think doing that one wall would make any difference at all? (it's going to be 3/4 length of the whole attic length).

Thanks again for all your help.
Am watching other threads too - It's great to think of darkrooms of varying types and sizes being built from here to Alaska!!