Which joints to use?

[BigShot]

I wonder if some of you fine folks might be able to give me some advice.

Being the most inclined to do such things, it's fallen to me to make some firewood stores (a bit late in the year, I know) and so I've come up with a bit of a design to fit the available space.
I've attached a couple of pictures of the main structure as knocked together in SketchUp. (I've removed the slatted sidings for clarity in the main one.)

Before I go ordering a load of wood though, I thought I'd ask what kind of joinery people think is best to use. I know a lot of wood stores are just screwed together, and I'm sure many use more traditional joinery. I might be able to knock out some mortise and tenon joints, and I'm reasonably happy that I'd be able to manage to birdsmouth the rafters and cut a lap joint if that's the right idea for the top.
Importantly, I've still not managed to persuade everyone involved to start disposing of garage clutter so I'm still workbench-less and still stuck with doing my woodwork at ground level. Not the end of the world, being a reasonably-sprightly reasonably-young thing - but I'll have to keep things simple. (Not that my skills allow much more than simple, mind.)

I'm not wedded to the shape though. I'd be more than happy to move things around a little and am completely open to suggestions for the best kind of joinery for something that will likely be fairly neglected and will certainly be rained on as much as it rains in Manchester... which is plenty.

Any input appreciated.

 

[MickCheese]

I would tend to keep it simple. Just glue and screws and maybe simple half lap joints if it were me.

What I do think you have to address is the possibility of racking so maybe some corner bracing.

Mick

 

[BigShot]

Thanks Mick.

I hadn't even realised I'd neglected to draw the bracing.
You are right of course, I'll be putting diagonal bracing in each of the sections that can be braced (so both sides and back sections).
I may put in a couple at the top corners of the front opening too, but I'm undecided on that one.

I imagine all the planks I'll be screwing on the outside would do a pretty good job of bracing it alone, but I'll brace anyway.

Do you think screw and glue is likely to be enough for the bottom rails? The side ones really just tie the uprights together, but the long ones at the front and back will have to carry the full weight of the firewood so I want to be sure it'll be strong enough.


I should have said in the OP that the dimensions are slightly south of 2300mm wide, about 600mm deep, apex height of about 1500mm and eaves about 1300mm. That's a fair amount of firewood.

Any thoughts?

 

[MickCheese]

I would just cut the front rails into the uprights so they end up flush to the inside face of each 'leg'. Looking at the diagram it looks like 150mm x 25mm rails, so just a 150mm x 25mm housing for it to slot into.

Mick

 

[BigShot]

As drawn it's 50x50 uprights and 50x100 rails. I'm not fixated on those sizes though, that's just what I drew.
I think one of the two ways illustrated below are what you mean though.

So since I've not sued the sizes you've assumed, any thoughts on what sizes I should use?

 

[MickCheese]

Your drawings look right. I would go with the far one with the full width housing. You are looking at holding a fair deal of weight so maybe it needs larger posts, 3" x 3" or even 4" x 4" and rails 4" x 1" or 6" x 1". These as far as I know are standard fence sizes so will be fully treated off the shelf.

As a life long DIYer I tend to make these things up as I go along but someone with proper professional experience may have a better idea.

Good luck.

Mick

 

[Jacob]

If it's going to be rained on I'd just do lap joints and nails. Perhaps a coach bolt/scew here and there. Joints would just hold water and shorten it's life.

 

[BigShot]

Any thoughts on which of these joints would be best?
Uprights = 3"x3".
Rails = 1"x4".

 

[Jacob]

Neither. Both weak with no racking resistance (in one direction at least) and the bottom of the housing has no strength at all
I'd nail the long board in position as for the top drawing, but without the housing, then nail the short boards right across the ends. Simpler, quicker, stronger.

 

[BigShot]

Jacob - there will be diagonal bracing in place on the three enclosed sides and under the slatted floor.
Still feel the same?

 

[BigShot]

Am I right in thinking this is the arrangement you meant?

 

[Jacob]

Yes that's much better.

 

[BigShot]

Cheers.
Considering my post (at 5:39) about diagonal bracing, would you feel the same way about joining the long rails into the uprights as shown in my previous picture?

 

[Jacob]

Just keep it simple IMHO. A few bolts for strength?
Alternative - as per your last drawing but put the short board on the inside but crossing above the long board.Then they are both slightly protected by the roof.

 

[andy king]

Hi Bigshot,

I'd be inclined to house the rails in, but to the outer faces of the legs so all the rails then sit flush with the outside of the leg.
That gives you a far better surface area for the joint shoulders to help the racking situation, but i'd keep it up off the ground more, maybe 75mmish to prevent a shortgrain problem on the bottom of the leg.
Likewise, the top can be jointed in the same way, and by putting one in at the top as well (just below the roof rafter) you then brace the top identical to the bottom.
I disagree with Jacob's thought about a joint holding water and more prone to rotting - in my experience, an area where a ledge is (unless sloped to shed the water) will wick down the back and rot out quicker, and unless a coated or brass/stainless fixing is used, that can rust out as well.
The housing prevents this, lpus the flush face of the rail gives little chance of water ingress if it's sealed up adequately.
HTH.

cheers,
Andy

 

[BigShot]

Thanks Andy.

Can you explain what you mean by a shortgrain problem?

Lifting the bottom rails to 75mm above the ground would make the platform holding the firewood 200mm off the ground. That's 50mm higher than I was aiming for and it's already going to be a relatively small wood store. It'll hold right on 1 cubic metre of logs as I posted it in the OP. Raising the floor by 2" could have the effect of knocking a single layer of logs off that capacity.

It's only a 4% reduction in actual volume but it could be as much as 8% or more of practical capacity if that translates to removing a layer of logs.

 

[andy king]

Hi BigShot,

it was looking at your initial sketch where your housing looks like it's only about 25mm up from the ground.
That gives a short grain situation where it can easily break away.
I'd certainly look for closer to 50mm or above just to be on the safe side if i was keeping a rail up in a housing.
You could put the rails right to the floor, but then you have a lot of timber in contact with the ground and a rot problem unless you pick it up on bricks or similar.
Alternatively you could notch the rail to gain a bit more space from the ground, but in doing so, you reduce the overall stregth of the rail itself - if that makes sense?!

cheers,
Andy

 

[BigShot]

Thanks, that makes it very clear.
37.5mm actually - but with a target of 50mm or more it's still on the short side.

I do want to avoid putting the rails on the ground and also avoid propping on bricks if possible. I usually hand anything other than straightforward calculations to an engineer, but if my numbers are anything to trust, notching the rail by 25mm probably wouldn't be strong enough.

I wonder if it might be better to go up to 4"x4" uprights and rip an inch off a 4"x2" for the rails. Fully loaded with the heaviest wood it's likely to see it should only bend by about 4mm mid span (a lot on a span of 1.1m but as it's not a floor I don't think that's probably not a problem).

That or I just need to forget it and raise the floor.


How big a problem is short grain likely to be? I don't anticipate the store being moved often and being in a quiet corner it shouldn't be knocked or leaned on much. Really all it'll have to put up with it wood, weather and perhaps the occasional window cleaner.

 

[Jacob]

I forgot to add: the first thing to do is a bit of research i.e. find something to copy or modify. No point in re-inventing the wheel, though for a simple logstore you probably wouldn't go far wrong!
This what the net is for.
Start here.

 

[BigShot]

Thanks Jacob. I came across a thread on this forum from that link and in doing so found a link to sketchup for woodworkers which looks handy.

I've had issues with many of the stores I've seen about.
Roof sloping forwards - looks great but means getting extra-wet if getting logs from the store in the rain.
Horizontal members sitting on the ground.
Much smaller than I'm planning to build and so not designed to hold up to (or even over) half a ton of wood.
etc.
I've actually got some of my design cues from stores I've found online, so thankfully I've not re-invented the wheel from scratch - rather I'm trying to make something I can build and forget about without too much concern for rot, stability, weight and so on.
For example, I've noticed a lot of stores have their bottom row of logs low enough down to get the wood wet from rain splashing up from the ground. That's why I've come up with something to get the logs about 6" up. It should keep them drier which means they shouldn't need to come indoors for final drying quite so soon.

I may be completely over-engineering it though. Haha.
Any critical input is most welcome.