Planning to build a mudroom bench and lockers and have some questions

[smoky olive]

Hi, i'm planning to build a mudroom style bench + lockers and I have a few pretty basic questions.

I'm taking inspirations from these two videos https://www.youtube.com/watch?v=fD4iv9N-Y6I and https://www.youtube.com/watch?v=mKw1CJLt6Fk

I'm currently planning to use 18mm plywood for most of it, the options that are available to me locally are Bükk (which google tells me is Beech Tree) and Nyir (which google tells me is Birch)

My initial focus will be producing a bench (with an open bottom), the available width i have is around 2900 mm so it would need to be smaller than that. I have baskets that have a width and depth of 400mm that will need to do in each of the sections of the bench at the bottom.

Apologies I don't really know the right vocabulary to express my questions but I will try and use some pictures to help myself

My first question relates to the structure / strength of the design. She has built sections and connected them with 1x3's to create kind of a skeleton. At the front top. back top and back bottom (see picture)

1. If I am recreating something like this. And instead of using 1x3s I wanted to just use plywood the same depth/height of the dividers at the top or bottom, does this increate strength? or does it not make a difference and is mostly just using extra wood for no reason.

Also in order to make it a bit easier for my to build. I have considered instead of building one big section, to instead build individual ones and then secure them to each other. So you'd end up with all of the internal "sections" having 2x pieces of plywood as dividers (that i would cover with a face) instead of 1:

2. Does this increase strength because there are more places for weight to get to the ground? or maybe decrease strength because of all the connections (or make no meaningful difference. Is there anything else about this approach that I should be aware of?

When I want to create the back for the bench (I will need a back because it will not sit flush against the wall for the whole of the length). Is it OK to just use one large piece of plywood and assuming all of the sections that are connected are level, screw/nail/glue it into the back of all of them?

If instead I had the outer frame with a depth of say 500mm and the inner vertical sections with a depth of 482 mm (the depth of the plywood) and instead inserted the piece of wood into the back with the main difference being that this way the "outer frame" of the bench sits on top of the backing. Does this make any difference at all? is one option preferable?

I do have more questions but they relate to the top part and for now i'm just going to build the bench. Any help would be very very appreciated

(also it's possible I am just overthinking this)

[lament idol]

The 1x3 braces are partially for strength and partially as a structure to hold the bench together.

Plywood unfortunately is not very strong when laid flat. On it's edge it is very strong. The front of that bench is going to be weak in between the vertical supports. and regardless of whether the support in the front is solid wood or plywood that bench will not support a large person sitting or standing on it. At least not without some significant sagging.

This can help you calculate sag
https://woodbin.com/calcs/sagulator/

#2 Building in sections can be smart. If you are building this in a tight location it would allow you to build the pieces elsewhere and install them in pieces. As for stronger or weaker it depends... The only way it would be weaker is if by building separate boxes the top pieces are also separate. Then when they sag from someone sitting on it the only have the two verticals supporting them and not the entire run.

Adding a back to cabinets makes them stronger; though, you really should probably scribe your cabinet to be flush to the wall. At least the bench top.

Also consider that your wall probably isn't flat and neither is your floor. You're going to need to scribe the bottoms of those to the floor as well.

You're not over thinking this. 🙂

[smoky olive]

Thanks for your answer! I’ve had a look at the sagulator before, honestly it’s quite intimidating I’m not sure about some of the questions it asks.

If I wanted to increase the strength in terms of somebody sitting on it. Would it likely be sufficient/ make a marked difference to use something like 2 x 4s as braces instead.

I also do hope to scribe the bench top that I put on, as far as scribing the cabinets, because of the requirements thrust upon me by my wife, my current plan is to build the whole thing in front of the inset parts of the wall and make a few… I’m sure there is a word for this, maybe a bracket? but basically connect 4 pieces of wood in a square or rectangle (make a few of these, probably 6 so 3 for each side) and drill one end into the wall and secure the other end to the upper part of the lockers (perhaps also the bench part). The picture might make my bad explanation make sense (excuse the mess, the hope is that the bench and lockers will help with this)

Is this a reasonable idea or a hair brained plan

Something like this

[lament idol]

So please forgive me... I'm much more used to SAE units than metric... I punched your numbers into Sagulator and it isn't that bad for the 400mm span you are talking about. Probably if you added the pine 1x3 underneath you wouldn't have that much sag.

I'm not an engineer so when I have strength questions I either overbuild or I make a mock up and test it. You could always make a single box as per the design, sit on it, bounce on it a little and see if it feels solid. Everything will also feel more solid once you get them wedged between a couple of walls.

[smoky olive]

Thanks, I may just do that. Though tbh it won't be between walls, it will be in front of them 😦 because of the design that has been requested from me