1) You can brace or block the joists per standard construction, but what might be easier is to strap the bottom edges of the joists. Typical strapping is done with a 1x3, but a lot of times I'll simply use a 2x4. Run a 2x4 across the bottoms of the joists, perpendicular to the joists. Add a dab of PL adhesive and use a couple of screws at each fastening point. You have specific needs here, so spacing the 2x4s as you need will work very well. What it does is if a single joist wants to deflect downward, the strapping transfers that load to the adjacent joists as well. So it's good as a floor stiffener. For a washer/dryer set up, it also dampens the entire floor platform in terms of the possibility of the spin cycle causing the floor to reverberate. The strapping serves the same purpose as cross-bracing or solid blocking between the joists. It's code-approved, though code only requires it for 2x12 joists, with the strapping being made of 1x3, and the strapping spaced every 8'. The strapping is more effective long-term than bracing or blocking, due to fitment, installation, and shrinkage issues. 2) Do the whole floor. There are only restrictions on maximum spacing (every 8'). So if you make it every 2', or 3', or 4', no worries. Strapping is also easier because you're not wrestling with any of the utilities that take up space between the joists. 3) Your joists span 8-1/2'. For simplicity, why not do run three pieces of strapping? One at 1/4 span, one at half-span, the other at 3/4 span. Just a little over 2' spacing. 4) 3/4" ply over the diagonal boards is plenty. It does not have to be exterior grade. 5) Your floor sandwich can be made up of: -Tile -Ditra -Floor heat wires encased in SLC (no wires under the washer/dryer area through, see comments later) -Plywood underlayment covered with SLC primer -Diagonal plank subfloor -joists I usually advocate a small platform under the washer/dryer stack. It's more for damping than load spreading. I've done sandwiches of plywood/cement_board/plywood, or plywood/MLV/plywood. MLV is mass-loaded vinyl. Screw through the top layer of ply, through the middle material, and into the bottom layer of plywood to secure it together. Or just use construction adhesive. I drill a hole through the middle of the platform sandwich to accommodate the flood pan's drain line. I usually put a square of rug pad on the floor. The inexpensive, maybe 1/8" thick, rubbery mesh or open weave type of rug pad. It acts as a bit of a damper, but also holds the platform in place. I then set the platform on the rug pad. Then put the flood pan over the platform with the drain plumbed through the hole in the platform. Then set the washer in place and the dryer on top of that. I recommend you tile the entire floor, but again, no heating wires under the location of the washer. You'll be putting the sandwich platform on top of the tile in that area, and the insulative value of that platform can shorten the life span of the heating element. Pricklypear, the Ditra-XL is simply thicker than regular Ditra. It really wasn't designed for a specific tile size. It's sole purpose is to allow the thickness of "Ditra plus tile" to match up with the thickness of a typical hardwood floor.

Sorry for the duplicate! It didn't seem that my initial post had been posted. Sorry!!!

Bummer about the tree but perhaps it's a good thing in the long run. I'm a silver lining kinda gal. =) I'm not a huge fan of seeing so much of the kitchen from the front door. I'd rather see the dining room so I came up with this proposal for you: I moved the patio door closer to the front of the house. Is this where you come in from the car, carrying groceries to the kitchen? If so, I figured you'd want to keep it. But if you can eliminate it, using the front or slider you're proposing to install, let us know. Given your small kitchen, I think you should get front load, stacking washer and dryer and have them face into the kitchen. They would fit with a little room to spare against the closet wall. Machines are 27" wide and need an inch of clearance between machine and wall. I removed the door and bit of wall between kitchen and pantry closet, opting for either open pantry shelving or shallow cabs. One less door in the area is a good thing, IMO. Open shelving can be industrial or attractive like this (left side): If you opt for open shelving but don't want to see what's on the shelves, you can partition the space with drapes like this: You could even add a rod and drapes between machine side and pantry area. You'll want to keep the drapes open when you're doing laundry, especially when you're using the dryer to help dissipate any heat build-up. Adding a vent fan above the W/D would also help with that. I added a window where the door was to bring more light into the kitchen. You'll need to do some siding repair to the exterior. Hopefully that's doable. A good contractor should be able to remove siding, move the door and weave the siding back together so that the change isn't noticeable. Moving the door down gives a nice long stretch of wall for a 36" w, CD (counter depth) fridge, 30" range and plenty of storage. I added a MW drawer in this run but you could also do a MW on a shelf below the counter like this: Store cutting boards, cookies sheets, etc above the fridge like this: I eliminated the short wall where the fridge currently is to allow room for a long peninsula with enough room for sink, DW and drawer storage. I recommend a single bowl sink with an offset drain so that you have room below the sink for pull-out trash. Here's my trash pull-out under my sink (love it!): There is NO peninsula seating. You just don't have enough room for back to back seating (60" aisle recommended). Instead I added shallow storage to the backside, perfect depth for cans and many boxed food items. It also gives you a little deeper peninsula/splash zone behind the sink. To make the best use of the DR area, I created a banquette with additional storage at each end of the bench and under the bench like this: And this: If you need room for the DR light switch, you can add the switch to the cab side like this (left side of photo): Oops, one thing I meant to add but forgot to draw in was a drop zone for keys, mail, etc in the stud space in the LR wall by the patio door, something like this (but shallower): HTH!

Katelyn Newell --- I’ll add my 2 cents worth on considering your choices as being between a portable washer unit and putting an all-in-one washer-dryer front-load combo (or a compact washer alone) in the linen closet. For you and your landlord to figure out if a compact or combo unit is feasible in your space, you all will need to understand the four issues to be faced when retrofitting laundry into a small space in an old building like the one you live in. These four are: space, water supply, drainage, and power. The advantage of a portable washer is that you and your landlord don't have to address any of those issues. However, you mostly have to put up with more tradeoffs and limitations than with combo, although the Magic Chef suggested by Ci-lantro seems to have fewer of them and has goodcustomer reviews. Of course, combos have their own (different) tradeoffs and drawbacks. . If you haven’t yet explored washer dryer combos and portables, you might find it helpful to start research with the Wirecutter article “The Best Washer-Dryer Combo (But We Don’t Recommend It)” and also look at their March 2019 discussion of portables which you can find at the end of their article, "The best compact washers and dryers." Also, Consumer Reports has an article about combos with the basic conclusions being that they do a good to very good job in their rather demanding tests of washing functions but are extremely slow and score only fair to poor in CR's tests of drying functions. ETA: on portable washers and dryers, there is a company called Laundry Alternative which makes and sells portable washers and dryers of various sizes and capacities for tiny houses, small apartments, boats, and RVs. An owner of the company frequently participates in the discussions of all kinds of washers over at automaticwasher.org and had a thread last month on some new models. If that sounds interesting here is a link to that automaticwasher thread. To me, a combo unit, even with its own tradeoffs and drawbacks, would be preferable to a portable unit, especially when dealing with "pretty gross" work clothes as you mentioned. The question with a combo (or a solo compact washer with no dryer like the set-up hcbm has) will be whether you can address all four of the old-building-retrofit issues of space, water, drainage and power. Based on what I’ve seen done over the years by friends and neighbors with spaces similar to yours, I think you may be able to solve the first three issues for a compact combo without large expense other than the cost of a machine. It's the electrical that might be the intractable issue for a compact washer or combo, as I will explain below. 1. The problem of space: IOW, what you can fit in where. The linen closet looks like the more convenient location for reasons that katinparadise, Aphaea and others have already pointed out. The question is what you can put in there -- you specifically asked if you could fit a 23½” wide compact stack (as opposed to an all-in-one). The answer is you can but there are a couple of considerations to address. The first consideration with putting a washer-dryer stack in that linen closet is that the back wall would be the only place in your linen closet where there would be room for power and hose connections for a stack. That's what Scottie Mom and Ci-lantro were talking about when they mentioned access to the connections being a problem. Putting them on the back wall is undesirable because you could not reach the connections without the onerous work of pulling the whole stack completely out of the closet. No such problem with an all-in-one front-load combo unit. Those are the size of a compact washing machine, alone. Easy to mount the connections on the right-hand (bathtub side) wall and they could be placed above the washer where the connections would be easy to reach when you need to do so. FWIW, somebody here in this Forum recently discussed this aspect as a reason she chose a LG all-in-one (model WM3488, IIRC) for her similarly confined laundry space. I remember this being in rococogurl’s long thread about the Bosch 500 compact series washers and dryers, but I haven’t been able to find the thread to provide a link, yet. The other space consideration may be more apparent than real. This is the concern raised by several posters, including wdccruise, about installation instructions that prescribe an inch or two of clearance on each side for closet installations. Obviously, you don't have that space with a closet that you measured at 24½" wide. However, most compact laundry is designed to be able to go under a counter in the same 24” wide spaces as for a dishwasher, i.e., where there would be next to no side clearance. It turns out that the side clearance usually is not for ventilation but, rather, is prescribed to assure sufficient wiggle room when pushing a heavy and awkward washer-dryer stack into a narrow closet. I recently confirmed this when I called Miele tech support while helping a friend with one of the Miele washers recommended above, and Miele confirmed that one could put their 23½" washer in a 24" wide closet as long as one could mange to insert the stack without damaging the walls or the machines while doing so. Also, it may be worth noting that Electrolux’s instructions for its compact washer, EFLS210, specifically say it is designed for zero side and rear clearance. (As an aside, If you can live without a dryer and can solve the other installation requirements, the Electrolux compact might be a good choice for a "washer only" option. If interested, you can find some long and favorable discussions of the Electrolux compacts both here and at the automaticwasher.org site. IIRC the lead poster used the screenname of Practigal if you want to search for those posts. Also, IIRC, hcbm has posted --- or maybe somebody else posted in an hcbm thread? --- about ways to successfully run indoor drying when you have a small apartment and only a washing machine . Would be worth looking for hcbm's posts if you decided to go with a "washer only" set up.) 2. Water Connections: Not a problem in that linen closet. Relatively easy and therefore not very expensive to cut a hole in the closet's right-side wall (plaster?), tap into the existing hot and cold supply lines for the tub, mount a recessed box with hook-up fixtures on the closet side of the wall, and then patch and paint to cover the rest of the hole. It can be a basic handyman job unless your city’s codes require the plumbing connections to be done by a licensed plumber. With a combo unit or a washer-only set-up, it would be easy to put the hookups on that right wall slightly above the top of the combo or washer. They would be readily accessible there whenever you needed to get at them. 3. Drainage: The issue here is that old buildings usually have old plumbing and old plumbing does not drain as quickly as current washing machines require. A standard solution for this problem is to drain the washer into a large laundry sink. Basically, a laundry sink acts as a reservoir to hold wash water while it is draining through the small (and therefore slower) old drain pipes. You don't have room to add a laundry sink, but your bathtub can double as one. Indeed, you can drain a portable washer into one (and people do) so why not a compact washer or combo? BTW, portable washers don't have the same drain problem because they use smaller volumes of water and drain more slowly; the inflow and outflow are low enough that they can be run from and into kitchen sinks and sometimes even bathroom sinks. For a piped-in drain, washers now drain so quickly that “code” requires 2” as the minimum diameter for standpipe drains, as ci-lantro pointed out. Code also require a plumbing vent stack (a/k/a DWV) within 5 horizontal feet of where the drain pipe from the washer connects to the house drain pipes. . Older plumbing won’t likely have the requisite stack and will be smaller diameter pipe, 1¼” or maybe 1½” diameter. Although some compact washers' and combos' instructions do say that they can drain to 1¼" or 1½"pipes, the actual diameter of very old pipes will likely be even less because of the calcification and scale that builds up in old pipes over the decades. Basically, it probably will not be permissible to cut a laundry drain into the drain-pipe below the bathtub. But, doubling up the use of bathtub for also serving laundry duties will solve that problem and also will be much less expensive to do. A side benefit could be that the wash and rinse water flows would clean your bathtub without your having to scrub it. ;>) This is something you will want to check with a local expert as I've read a few posts reporting that there are a few cities whose code enforcers will not permit this. FWIW, I’ve seen the "double-up the use of the bathtub" solution used a couple of times in my town where we have lots of very old, very small houses. The Code enforcement folks signed off on it both times. In their view, they said they saw no direct connection to the sewer lines (there being a gap between the end of the drain hose and the water in the tub so there would be no chance of siphoning wastewater back into the tub or washer). They said no code provision otherwise prohibits doing laundry in bathtubs. (A reprise of the idea that doing this with a regular washing machine is no different than doing it with a portable washer.) Of course, you won’t want to be running a wash load while bathing, but that seems like a minor inconvenience in a one person apartment. One thing you may want is a lint trap on the end of the drain line or in the bathtub drain hole. You don’t want laundry lint snagging on and plugging up in the rough & scalely old drain pipes. You will want to frequently check and clear the lint trap. If you improvise one with pantyhose over the end of the drain hose (as you might do if you run across the many internet recommendations for doing so), you may need to clean it out with every load. May want to bear that in mind when considering portable washers, as well. 4. Power This might be the intractable issue for your getting a compact washer or compact all-in-one combo in your apartment. You need electric outlets to run your laundry machines. Your photos do not show any outlets in the linen closet. Most compact washers and most all-in-one front load combos run on standard 120v power. Practically speaking, you might be able to run an extension cord to a nearby existing outlet. Do note, however, that many appliance manuals warn against using extension cords with their washers and some cities' codes also forbid it. The big obstacle here is that codes generally require major appliance outlets to be on dedicated circuits. A "dedicated circuit" has one outlet and does not serve other lights, outlets, etc. The electrical in old buildings usually offers only a few circuits in each apartment so additional wiring would have to be run for permanently installed appliances like fridges, washing machines, dishwashsers, and etc. Your old building may or may not have the electrical capacity to add additional 120v circuits and, if it does, it may not be easy to run additional wiring to and inside your apartment with some major renovation work. Also, with regard to some of the above suggestions for stacking compact washers and their dryers in the linen closet, be aware that most ventless dryers – other than Miele’s --- need a 240v outlet. (There are numbers of "portable" 110v dryers but the y all seem to require venting, as far as I could tell from the last time I researched this). Formost ventless dryers, the obstacle to getting one is that many old urban buildings do not not have the capacity to provide a 240v circuit and, if they do, running the circuits may require tearing into walls to run a 240v circuit to a second floor apartment. A big problem in an occupied building, eh?. Something to be checked out with your building. Maybe the electrical was upgraded in the last decade or so? (Heck, maybe the plumbing was updated, too, so most of the issues might already have been solved. Something else to check out when your landlord considers looking into what might be installed and where.) As a side note, most compact all-in-one combos run from a single standard 120v outlet. The Miele compact washers and dryers (recommended above) both run on 120v power,. The Mieles, however, have their own complication because the washer and dryer have to be on separate circuits. IIRC, the manuals (and warranties) and the company's published q&a responses are pretty clear that the combined loads for for the washer and dryer will exceed the capacity of single 120v circuits. For your apartment, the difficulty of providing two circuits to the linen closet could put a Miele stack out of consideration even apart from their being so expensive and even apart from the inability to provide accessible hookups for a "stack" in that closet. Of course, the dryer does not have to be stacked, but is there anyplace else to put one in that apartment?