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!!

 

[Troy Hamon]

Hi Joze,

Where is your existing insulation? Is it between the attic floor and the ceiling below? If it is, you will need insulation. Insulating the entire attic might seem daunting, but it is likely simpler than insulating your isolated walls, and may also be better for heat and cooling control. Insulation is a bit of a hassle to install, but having a room that has wild temperature swings and is difficult to heat in the winter is likely worse... Which leads to the question...what is your plan for heat? Is the area naturally hot due to heat rising from the house below? Sounds like a great project (but then, any darkroom sounds like a great project to me...).

 

[vet173]

If you want to texture the wall you will use your mud thinned and a roller right? Thin it down with paint instead of water and it's all done in one process.

 

[Joze]

Where is your existing insulation?.

I've probably misled you a bit here - we have rather basic insulation immediately under all the roof tiles, but I was wondering about doing more insulation for better temperature control.

I have another question about filters: I have decided to have three faucets, one hot and two cold (probably one mixer a part of these). I'm not sure what to do about filters, and what specs. I need for them.

Is there any reason NOT to put them on all outlets? The main problem here is lots of limescale. Having said this, I've never noticed a problem with prints I've done at home (without filters). I haven't yet done film processing at home, but intend to. If I do get filters, what sort should I be looking for?

Thanks again for any help.

When all is finished I will definitely put a picture up on the 'darkroom portraits' thread.

 

[jeroldharter]

You are more likely to get light leaks through electrical outlets, through the baseboard (where the drywall meets the floor), and around door openings.

For water outlets, I use filtered hot and cold water lines that feed a mixer. The mixer feeds a single line that runs the length of the sink. From that line I have multiple outlets that are the ones we used to use in chemistry lab (mine are from Chicago Faucets) and those attach to flexible plastic hose so I can hook up film washers, print washers, or just direct the stream of water wherever I want.

If you have the choice, put in a floor drain or a drain low in the wall. That way you can run a plastic hose from an archival print washer into the floor.

Don't forget good lighting above the sink.

The sink cannot be long enough and it is good to have a low sink to hold a print washer.

 

[dsisaacs]

A couple of tips for your project. I don't recomend 3/8" drywall as it is too thin for most applications.
1. You can cut 4x8 drywall sheets into 2'x8' or even 16"x8' strips for easier handling and movement thru your house, mark across the cuts to match them up later. No matter how carefully you cut the line will be wavy. A method I use is to cut/score the face and fold the sheet lengthwise without cutting the back paper. Then it can be unfolded and applied to the wall without creating another joint. Rub the cut line with the handle of a screwdriver to make a slight indentation and fill with plaster after installation.
2. 1" styrofoam insulation is easy to apply to the walls and ceiling and drywall can be applied over it with longer screws (2-1/2"). This will keep you from creating a condensation problem on the underside of the roof.

 

[markbb]

Joze,
Maybe the water in London varies, but where I am (SE) the water is quite hard - as an indicator the shower head starts to clog up after a month or so. As you are going to all this trouble converting your loft, I would advice you to put replacable filters/water softeners on your lines.

By the way, aren't Estate Agents (realtors in the Colonies) stupid? We live in a Victorian terrace, each house has a large cellar (it varies in size as we are on a slope). Neighbours who moved in recently were not aware of the cellar - neither was the agent! They now have an extra room fitted out as utility space for washers, dryers etc. When your paying £50,000 per room (this is a cheap part of london), such finds are a real bonus.

 

[Max Power]

Joze,
FWIW, for the plumbing question, I might suggest one of those 'Scald Control' shower/bath fixtures. When I renovated my bathroom last year, and tore out the shower, I saved the fixture and installed it in my darkroom. I have the hot and cold running in, and after the mixer itself, I put a single faucet, that way I can set the water at the temp I want, and don't have to reset it each time I want water.

It works really well, and is a darned sight less expensive than a special darkroom fixture.

Kent

 

[danielclift]

Okay - a bit of a 101 re. plasterboard walls, many of you probably know most of this, but it might help a few people.

The plasterboard with the feathered edge is known in the trade as tapered edge - phone a few places like Jewson or Travis Perkins to find the best price in your area - don't bother buying it at Homebase or B&Q as they charge well over the odds for this kind of stuff. Good makes include Gyproc or Lafarge.

You can get the boards in 12mm (1/2") or 9mm (3/8") thickness - the thicker boards are better for walls, particularly if you are looking to perhaps hang some light shelves using plasterboard rawlplugs - the 9mm is normally used for ceilings as it is lighter and easier to manhandle. You could do the walls in 9mm but they would feel a bit thin, particularly if your studwork is lightweight. Standard board size is 8ft x 4ft (2440 x 1220 mm) although the 9mm also comes in 6ft x3ft. Cut the boards roughly with a Stanley knife by scoring through the front paper, breaking the board at this cut, and then cutting through the paper at the back with a knife. For accurate cutting use a normal handsaw - preferably an old one that you don't worry about blunting.

Your studwork should be of at least 2" x 3" timbers i.e. giving a frame 3" thick if it is to be sturdy - you don't need to use planed timber which is more expensive - rough sawn stuff is fine for studwork, but do try to buy the straightest timbers you can pick out at the timber yard - it makes a big difference to the quality of your finished wall (an obvious tip I know but often overlooked), and try to buy timber that looks as if it has been kept dry - it is less likely to warp as it dries out before you build your wall. Your finished stud wall will typically have a top and bottom horizontal rail fixed to the floor and ceiling with vertical studs attached every 2 feet. If you can measure the spacing of the verticals accurately starting at one end of your wall, it will mean the edges of the 4 ft boards will meet in the centre of every other stud for fixing. Use a spirit level/plumb-bob to make sure everything is vertical.

If you are going to be making a wet area, it might be worth paying a bit more for moisture resistant boards (normally used in bathrooms) just for the bit of wall behind the sink/taps.

When you fix the boards to the studwork make sure you put them finish-side-out - you can tell which is which as the finish paper wraps around the edges to the back of the board - also the writing is typically on the back. Use proper plasterboard screws (35mm should be long enough for a single layer) to fix the boards (you can get these from the same supplier as your boards) - the screw head should should just pull tight into the surface of the board so that it is slightly countersunk without breaking through the paper surface for the strongest fix. Taping and jointing the boards has already been touched upon in an earlier post - if you use the sticky fibre mesh tape you should put this on first before the jointing compound (which you can buy ready mixed in big tubs).

For walls higher than 8 ft the pros will try to make sure that the horizontal joints between boards are staggered i.e. if you used a full board at the bottom of the last row with an infill at the top, then start the next row at the bottom with the infill piece. Fix a timber offcut where you have a horizontal or other join that doesn't meet over a piece of timber for the best finish. You can also reinforce areas of your wall before plasterboarding with extra studwork pieces if you know for example that you will need to fix a heavy enlarger in that location - this way you will have something decent to fix into.

For electrical sockets and switches use proper drywall boxes which can be cut very easily into the plasterboard wall, and if fitted properly don't normally let light through. Run your bare (but not live) wiring before you clad the wall making sure you put it through the centre of the studs far enough from the front surface of the wall so that your plasterboard screws won't get near it.

You can get all sorts of info about using these products from both the Lafarge and British Gypsum websites, particularly if you are looking to do something more complex.

Good luck with your darkroom.

 

[Craig]

Your finished stud wall will typically have a top and bottom horizontal rail fixed to the floor and ceiling with vertical studs attached every 2 feet. If you can measure the spacing of the verticals accurately starting at one end of your wall, it will mean the edges of the 4 ft boards will meet in the centre of every other stud for fixing. Use a spirit level/plumb-bob to make sure everything is vertical.

I've used an easier way to make walls, and that it to lay it all out on the floor, and assemble it there. Then you have easy access, and you can use a framing square to make sure that everything is square, and best of all the wood stays where you put it, as gravity is working for you. Once you have your wall all nailed together ( I use 3" common nails), then have an assistant help you tip the wall up into place, and then you just have to nail it top an bottom through the sill plates to your joists and rafters. If you can rent one, and air/power nailing gun is worth its weight in gold.

Once the stud wall is in place, then you can run all your rough plumbing and electrical, screw your electrical boxes to the studs, and finally attach the gyproc.

 

[Bob Carnie]

Just my 2cents

Floor Drain, Floor Drain, Floor Drain.
Make sure of this , I have flooded the tenents below in my past and believe me , can be a major, major pain in you know where.

All above advice great, but make sure you have a certified plumber hook you up .

 

[stormbytes]

In contrast to posts advising against wetting joint tape, i would advise you to compromise as follows:

Apply a thin layer of joint compound directly on the seem. THEN apply the tape along the now-wet seam and, using a 4' plaster knife, press the tape down firmly on the seam while moving the plaster knife along the entire length. Follow up by applying another thin layer of joint compound along the top surface of the tape and presto! you're done.

As for plumbing:

I would strongly advise you to invest in a good leedahl mixing panel. These can be had relatively inexpensively on eBay nowadays. Doing so would solve/address several issues simultaneously. Most Leedahl mixing panels have an integrated filtration system eliminating literaly 90% of anything you'd have to worry about and, you can easily attach a 1/2" copper pipe to the outlet of the mixing panel which can then be used to set up as many spouts/spigots as you want, each with it's own independent valve. This would give you filtered, tempered water for all your darkroom applications.

Coincidently I just finished a 60+ hour darkroom plumbing marathon a few days ago. Integrating the Leedahl mixing valve into my darkroom plumbing was the best thing since buying a pro print washer. I now have total temperature control over all my water and won't risk shocking emulsion with radical temperature changes.

My 2 Cents

 

[Buster6X6]

All advise is good so fahr. I just would like to add. In north America studding is done 16" centre to centre. You should build the walls first. Get your plumbing sorted out and installed. Your wiring and fixtures sorted out and installed.Insulate whole area with fiberglass insulation and what no one had said yet is to install vapour barrier on all outside walls and the ceiling.Use fiberglass tape to tape joints it is self adhesive and then you trowel on your drywall compound.If you don't install vapour barrier it will sweat and mildew in time.

My two sents Greg

 

[George Collier]

One small addition to all this great advice. When all done, you will see, from the inside with lights off for a half hour, all the little leaks in corners, around pipes, etc. Get an can (pressurized) of eurithane insulation. It comes with a small straw-like tube, which you insert into the nozzle (like WD40 oil). You can fill all those little leaks with this material, which comes out a thick ooze, and expands considerably as it dries. Then it trims off easily with a razor blade, and, I think can be painted (I didn't bother). You would do this before painting, but do all of them at once, I seem to remember that once the can is used, there is a limit on how long it will stay good. It takes the pressure off making perfect joints.