Shed: to sheath or not to sheath, that is the question (among others)

[porridgebear]

Hello everyone,

I'm undertaking my first ever build of anything non-computer-software, and that be a shed in the garden.

It has a range of challenges, it's 4m x just 1.90m and against a boundary fence allowing for 10cm air gap, I have no other option and the neighbour is fine with it, it's at the back.

Been fun? researching lots of videos on You Tube, reading lots online, and generally seeing that everyone more or less does it differently, with some common factors.

Whilst mine will be a storage shed, I am nonetheless doing a bit extra with insulation under the floating joist floor (I went with a MOT1 base + sand blind + landscape fabric + ProBASE plastic grid system filled with gravel everywhere) then 75mmx75mm Class 4 bearers/skids onto which I have a 16" centres 4x2 C24 joist frame with 18mm ply on top.

I got it pretty level but being new to this I worry that in some places the bubble is evvvver so slightly right or left of centre. It never breaches the black guides though. I am hoping this is fine.

On the diagonals of the frame to check square it's out by I think 1cm, again no idea if that's OK - when you tighten everything up things tend to move so I guess that's where that happened.

Questions for the road ahead:

1) Ply goes on next, should I take the opportunity to sort out the 1cm non-squareness should the ply not be perfectly aligned or shall I just trim to the frame and sort that out with perfecting the stud framing?

2) I am reluctant due to width of 1.9m to add 22mm of OSB3 sheathing. Seen loads of videos of people who sheath, and also those who don't. I plan to wrap with Tyvek and put PIR insulation between studs. I understand sheath is for rigidity mainly vs. thermal function? At 1.9m width and 16" centres and 4x2 I think it should be pretty rigid. Was thinking of using some metal supports at corners and metal band to shore up rigidity too.

3) I am going to have fun because the back wall facing the fence I need to construct fully with frame + wrap + battens + cladding and then rotate to lift into position as no human access behind. I worry about the weight of that as lifted into place on one side. Think I should sandbag on the front side to provide balast/balance of downward pressure?

Thanks all, looking forward to being told I've done something wrong but if yous do have anything on especially (2) that would be useful.

Cheers!

 

[DBT85]

The 1cm will be fine, you'll just have to work with it for the boarding. No need for it to be perfect. Ask any of the house builders. consider that at 1cm of difference with the diagonals, you are 10mm out over am expected 4272mm distance. If you feel that worried unscrew it and bang the ends with a mk10 persuader until its fine. I'd leave it.

Have you already put the ply down on the floor?

The walls don't need to be clad with 22mm osb unless you planned for some reason to use them as your actual outside face (which wouldn't last I imagine). Mike who used to post here (and oft the most helpful when building things like this) would suggest putting 11mm OSB on the inside, insulation between the studs and then membrane on the outside, covered with battens and then cladded. The idea being that OSB is so full of glue that it acts as a vapour barrier. I don't honestly know if its true or not, but he does it and has had many many outbuildings made this way, so I did the same .

I'm nt sure why the width being 1.9m would cause an issue with what type of sheathing you use though? On my build the sheet goods are there for the internal wall faces, as well as making it impossible for the structure to rack because it's secured square with that sheathing. I didn;t use anything extra like metal corners or bands on my entire workshop so I'm not sure there's any need at all.

For the wall that you can't get to, i hope its the 1.9m one! I'd build the frame on the floor, get it into position where it would just need to pivot up and then do all your membrane and exterior cladding. It'll be heavy enough with the cladding on that you won't want to be moving it any more than absolutely neccacary, and bvery slowly at that. Though I'd no worry about needing sandbags on the other end. The frame you have built will have a fairly heavy mass by all account and I'm guessing secured down?

 

[porridgebear]

That's very helpful, thank you

No ply is not yet down, but PIR is in between the floor joists so not sure whether I can bang it into shape with it being so rigid now.

Glad to hear the sheathing is not necessary. I just meant it added extra width (just 22mm sure) that takes away from my 1.9m. You're right though, I planned to use 11mm ply on the inside walls and use a vapour barrier sheet. The idea of using OSB to achieve the same without a vapour barrier is interesting. I want to hang things off parts of the wall, I had thought ply would be best suited at 11mm vs OSB.

No unfortunately the back wall is one of the 4m ones, and I will need to build the frame, membrane, battens and cladding all in one go on the floor for it, then as you say pivot it up. I will likely enlist friends help for that, I am not He-Man.

I have not fastened the base to the floor - the skids just lie across the ProBASE - I did think about how on earth I could or should anchor these to the ground. There were some railway sleeper style things I could have used but I thought the weight of this thing is going to be so heavy it's not going anywhere and there isn't enough wind to cause issues. Do you think it's important to get some anchoring down and if so any idea for skids?

Thanks again!

 

[Fitzroy]

Ply and bap barrier on the inside will be much nicer than osb, was only aware of 12mm or 9mm though, either will do although with 12mm you can hang anything anywhere, on 9mm you can’t.
As you’re going to the expense and bother of insulation, make sure of your details. Foam around the osb edges, tape joints, eliminate all gaps. Thinks about door and window details. A few drafts will severely detract from the insulation efficiency.
Fitz.

 

[DBT85]

Ah, well you can try cracking a corner with a mallet. It only needs to move a tiny bit. But really wouldn't worry about it.

If you are going to place very dense things in there with small footprints, maybe consider 24mm flooring?

Ah now i see about your 22mm, certainly no need to put osb on both the inside and outside. Just sounds like pointless extra work and for a way of any moisture that does get behind one to really struggle to get out again.

For the inside walls you can use ply if you prefer. The finish is nicer at least but its a shed after all. But for the action of nailing things up, anything you are worried about can get secured to studs anyway. 11mm of osb and a few screws is fine for a lot of stuff. If you wanted to hang a cabinet or something then you'd always find a stud anyway IMO.

With the back wall being 4m id have to be tempted to do it in 2 bits since you need to lift it fully cladded too. Would be a pain as you'd have a cladding join which while not visible isn't ideal.

No idea on securing the base to the floor. I'd do it if possible, even if only some galvanised strapping wrapped under the skids though I'm guessing thats not now possible.

 

[porridgebear]

You're right, it's 12mm for ply, just getting mixed up between the sheeting options. Cool yeah I will stick with the ply I think for the finish and use a vapour barrier.

Roger on taping etc. I've been using some Gorilla aluminium tape so far on the floor joist joints before I pop the ply on and have seen a bunch of products folk are using for other gaps etc. I think I saw a Lumberjack product that glues/foams joints.

Want to get that done this weekend, the 18mm seems plenty heavy/thick enough - you've worried me with 22mm! I hope that's not necessary?

I was also going to butt up the ply sheet to sheet - I saw some people leave an expansion gap but I think the last video I watched suggested that was unnecessary but can't for the life of me remember why. I am not planning on putting flooring over the ply floor, though I suppose I could stick something thin over. Lino, but not Lino, because I don't like Lino

Back wall in 2 halves is an interesting idea. Nobody is seeing the cladding, so it _could_ be split centrally, though there would be no opportunity to close/seal the joint so it would be a water ingress point. Is your concern just one of weight? If I get a bunch of people I'm thinking it should be possible and then I was going to have the 2 sides already made to install to support it all.

 

[MARK.B.]

Could you make the frame for the back wall and put it on a couple of wheels - roll it into position ish then lift of the wheels

 

[DBT85]

You're right, it's 12mm for ply, just getting mixed up between the sheeting options. Cool yeah I will stick with the ply I think for the finish and use a vapour barrier.

Roger on taping etc. I've been using some Gorilla aluminium tape so far on the floor joist joints before I pop the ply on and have seen a bunch of products folk are using for other gaps etc. I think I saw a Lumberjack product that glues/foams joints.

Want to get that done this weekend, the 18mm seems plenty heavy/thick enough - you've worried me with 22mm! I hope that's not necessary?

I was also going to butt up the ply sheet to sheet - I saw some people leave an expansion gap but I think the last video I watched suggested that was unnecessary but can't for the life of me remember why. I am not planning on putting flooring over the ply floor, though I suppose I could stick something thin over. Lino, but not Lino, because I don't like Lino

Back wall in 2 halves is an interesting idea. Nobody is seeing the cladding, so it _could_ be split centrally, though there would be no opportunity to close/seal the joint so it would be a water ingress point. Is your concern just one of weight? If I get a bunch of people I'm thinking it should be possible and then I was going to have the 2 sides already made to install to support it all.

18mm ply (depending on type) will be fine 90% of the time for the floor, just in case you decided to put a 200kg tool in there like a cast iron table saw which feet might not land on a joist. If it's general storage 18mm will be fine.

The gap between sheets would have been for expansion, maybe less for the sheets and more for the substrate they are secured to? If its just storage then leave it as is. Maybe put something on it if you think it'll get wet with any regularity.

If you've enough people to lift it then fine. Just be careful. Tip it too far and your fence is wiped out because you won't stop it falling without casualty! You can save some weight by only making the wall frames on 24" centres though. No need for 16". Once the classing is on a 4m wall is going to be substantially heavy!

 

[Charlie]

If you are thinking about the 'two halves' route you could put a thin batten along the joining edge that over laps each side by say 50 mm. Attach it to one half before it is erected first, then run some sealant along it before raising the second side. as you fix the second side you'll seal the gap and make it weatherproof.
Just a thought...

 

[Fergie 307]

Having lifted similar walls on a number of occasions my advice would be to attach a rope to the top edge in the centre, or ideally one at each end. You can then have people on the ropes to control it whilst another two or three lift it into place.

 

[Inspector]

When I was a pup out of high school I was a framers helper and two of us would frame and put up much longer walls, so a couple of you should be able to lift it no problem.
*Firstly position the bottom plate on the floor 4" (or whatever the wall thickness is) in from the outside of the floor and nail a few 2"/50mm nails in on an angle about 3/4"/20mm up from the plywood. This will keep the bottom kicking out and off the floor as you lift the wall. When done you can cut the nails off or hammer them in tight to the corner. If you prefer a few short lengths of plumbers strap would work too. The nails may split a little off the bottom plate but it won't affect anything. If you are worried about going too far you could nail a rope to the top of the wall and the floor. You get to figure the length. Know that it will be a tripping hazard in a small area like that.
*Put 1 spike (3"/75mm) into a 2x4 on the outside of each end of the wall long enough to form a 45º from the wall to the floor when up. Have another couple nails in the floor end of the brace ready to nail into the floor when the wall is up. Once up add another nail at the top end. When it is up you actually want the top of the wall to be just past vertical a few centimetres. This will allow you to build and stand the end wall up without hitting. The brace will stop it from going too far.
*When ready to lift the wall have a few 2x blocks and a pair of strong sawhorses ready.
*Start the lift by using a pry bar or hammer claws to lift it so you can shove a block under. Then a second on the first. Now you have room to get your hands under.
* Now with the knees lift the wall to your waste and kick a sawhorse under each end. Take a breath.
* Lift to vertical and then one of you starts the bottom brace nails in each end. Once both ends are on you can go to one end and pull the nail out and then lean the wall out a touch and drive the nail and a couple more in both ends. Repeat for the other.
* Put up the end walls and then remove the brace nails enough to pull the long wall against the short and nail/screw together.
* Put the last long wall up.
* The best part. Step back and sit on the lawn and admire your handiwork. Enjoy a beverage if the day is over.

I am going to build a couple 10' x 10' / 3m x 3m garden sheds this summer myself and I have no fears of lifting the walls alone. Safer than with SWMBO if you know what I mean.

Pete

 

[porridgebear]

When I was a pup out of high school I was a framers helper and two of us would frame and put up much longer walls, so a couple of you should be able to lift it no problem.
*Firstly position the bottom plate on the floor 4" (or whatever the wall thickness is) in from the outside of the floor and nail a few 2"/50mm nails in on an angle about 3/4"/20mm up from the plywood. This will keep the bottom kicking out and off the floor as you lift the wall. When done you can cut the nails off or hammer them in tight to the corner. If you prefer a few short lengths of plumbers strap would work too. The nails may split a little off the bottom plate but it won't affect anything. If you are worried about going too far you could nail a rope to the top of the wall and the floor. You get to figure the length. Know that it will be a tripping hazard in a small area like that.
*Put 1 spike (3"/75mm) into a 2x4 on the outside of each end of the wall long enough to form a 45º from the wall to the floor when up. Have another couple nails in the floor end of the brace ready to nail into the floor when the wall is up. Once up add another nail at the top end. When it is up you actually want the top of the wall to be just past vertical a few centimetres. This will allow you to build and stand the end wall up without hitting. The brace will stop it from going too far.
*When ready to lift the wall have a few 2x blocks and a pair of strong sawhorses ready.
*Start the lift by using a pry bar or hammer claws to lift it so you can shove a block under. Then a second on the first. Now you have room to get your hands under.
* Now with the knees lift the wall to your waste and kick a sawhorse under each end. Take a breath.
* Lift to vertical and then one of you starts the bottom brace nails in each end. Once both ends are on you can go to one end and pull the nail out and then lean the wall out a touch and drive the nail and a couple more in both ends. Repeat for the other.
* Put up the end walls and then remove the brace nails enough to pull the long wall against the short and nail/screw together.
* Put the last long wall up.
* The best part. Step back and sit on the lawn and admire your handiwork. Enjoy a beverage if the day is over.

I am going to build a couple 10' x 10' / 3m x 3m garden sheds this summer myself and I have no fears of lifting the walls alone. Safer than with SWMBO if you know what I mean.

Pete

That's awesome Pete, if a little worrying how little I had thought about this! I'll update the thread on how this goes in the next few weeks - just got the floor down this weekend then had to BBQ as weather too nice not to.

 

[porridgebear]

I think I said I would update the thread once this was done. Held a BBQ and with 4 people it was super easy to lift - 4m x 180cm, 4x2 stud wall clad with 19mm larch. 3 people probably would have done it too. We built the back wall on the shed floor - studs, membrane, battens, mouse mesh, and cladding (right down past the floor) so that we needed to put the pivot point exactly so the lip would go over the edge of the floor - no nails or anything was possible to support the wall kicking out but it's just 20cm from the fence so it would not have gone miles. In the event it went up in one go with enough control (we all did a test lift first to test weight and determine that it would be safe). The photo is now 4 weeks old - all walls and rafters are up now. Thanks for the suggestions.